Alternative titles; symbols
The alpha and beta loci determine the structure of the 2 types of polypeptide chains in adult hemoglobin, Hb A. Mutant beta globin that sickles causes sickle cell anemia (603903). Absence of beta chain causes beta-zero-thalassemia. Reduced amounts of detectable beta globin causes beta-plus-thalassemia. For clinical purposes, beta-thalassemia is divided into thalassemia major (transfusion dependent), thalassemia intermedia (of intermediate severity), and thalassemia minor (asymptomatic).
Patients with thalassemia major present in the first year of life with severe anemia; they are unable to maintain a hemoglobin level about 5 gm/dl. Clinical details of this disorder have been detailed extensively in numerous monographs and are summarized by Weatherall et al. (1995). Modell et al. (2000) found that about 50% of U.K. patients with beta-thalassemia major die before the age of 35 years, mainly because conventional iron-chelation therapy is too burdensome for full adherence.
Ley et al. (1982) treated homozygous beta-plus-thalassemia in a 42-year-old black American man with 5-azacytidine. An increase in hemoglobin concentration occurred. Hypomethylation of both the gamma-globin and the epsilon-globin gene was shown, as well as an increase in gamma-globin mRNA. Lucarelli et al. (1990) reviewed results from 222 consecutive patients in whom bone marrow transplantation was performed for thalassemia since 1983. The results were analyzed, in particular, in the 116 consecutive patients treated since June 1985. The allogeneic marrow came from HLA-identical donors, and the patients all had beta-thalassemia and were less than 16 years old. They concluded that bone marrow transplantation offered a high probability of complication-free survival, if the recipient did not have hepatomegaly or portal fibrosis.
By autoradiography using heavy-labeled hemoglobin-specific messenger RNA, Price et al. (1972) found labeling of a chromosome 2 and a group B chromosome. They concluded, incorrectly as it turned out, that the beta-gamma-delta linkage group was on a group B chromosome since the zone of labeling was longer on that chromosome than on chromosome 2 (which by this reasoning was presumed to carry the alpha locus or loci). Study of a case of the Wolf-Hirschhorn syndrome (4p-) suggested that the B group chromosome involved is chromosome 4. Barbosa et al. (1975) excluded recombination fraction of less than 0.30 for MN and Hb beta. Use of a combination of somatic cell hybridization and hybridization of DNA probes permitted assignment of the beta hemoglobin locus to chromosome 11 (Deisseroth et al., 1978). Parallel experiments showed that the gamma globin genes are also on chromosome 11, a result to be expected from other data indicating linkage of beta and gamma.
Fine detail of both the mouse (Miller et al., 1978) and the human beta-globin gene was determined in the 1970s (Flavell et al., 1978). The mouse beta-globin gene is interrupted by 2 intervening sequences of DNA that divide it into 3 discontinuous segments. The entire gene, including the coding, intervening and untranslated regions, is transcribed into a colinear 15S mRNA precursor. Because mature globin mRNA is smaller (10S) and does not contain the intervening sequences, the 15S precursor must be processed. Using restriction endonucleases and recombinant DNA techniques, Flavell et al. (1978) prepared a map of the human beta- and delta-globin genes. The beta-globin gene contains a nonglobin DNA insert about 800-1000 basepairs in length, present within the sequence coding for amino acids 101-120. A similar untranscribed sequence may be present in the delta gene. They found that the distance between the beta and delta genes is about 7,000 nucleotide pairs and that the delta gene is to the 5-prime side of the beta gene, as predicted by other evidence. Polymorphism was found at the third nucleotide of the codon for amino acid number 50 (Wilson et al., 1977). Unlike the alpha locus which is double in most persons, the beta locus is unitary (unless the delta locus is considered the equivalent of the beta locus--a fully justified view). McCurdy et al. (1975) thought the beta locus in some persons might be duplicated; they observed a black woman who had hemoglobin A and 2 different variant hemoglobins, each with a beta-globin change. One of these, however, proved to be a posttranslational change (Charache et al., 1977). El-Hazmi et al. (1986) suggested that the presence of 2 beta-globin genes might account for the finding of triple HpaI fragments in a case of sickle cell anemia. They explained its origin by unequal crossing-over.
The order of the genes in the beta-globin cluster was proved by restriction enzyme studies (Fritsch et al., 1979); starting with the 5-prime end, the order is gamma-G--gamma-A--delta--beta--Hpa I. By 'liquid' molecular hybridization, Haigh et al. (1979) studied mouse-man hybrid rearrangements involving chromosome 11 and assigned the nonalpha-globin cluster to the region 11p11-p15. Housman et al. (1979) concluded from study of Chinese-hamster ovary cell lines containing chromosome 11 or selected parts thereof that the beta hemoglobin complex (NAG, nonalpha-globin genes) is in interband p1205-p1208. Housman et al. (1979) used a panel of hybrid hamster-human cells deleted by x-ray and selected by a double antibody technique (the method of Kao, Jones, and Puck) to assign the NAG cluster to 11p12, between LDHA distally and ACP2 proximally. The orientation of the cluster in relation to the centromere was not known. Lebo et al. (1981) studied the linkage between 2 restriction polymorphisms, the HpaI polymorphism on the 3-prime side of the beta-globin gene and the SacI polymorphism on the 5-prime side of the insulin gene. They found 4 recombinants in 34 meioses (12%), giving 90% confidence limits for the interval as 6-22 cM. Given that the beta-globin gene is on 11p12 and the insulin gene on 11p15, that chromosome 11 represents about 4.8% of the genetic length of the genome, and that the total genetic length is 3,000 cM, then one would expect an interval of 29-42 cM.
The beta-thalassemias were among the first human genetic diseases to be examined by means of new techniques of recombinant DNA analysis. In general, the molecular pathology of disorders resulting from mutations in the nonalpha-globin gene region is the best known, this elucidation having started with sickle cell anemia in the late 1940s. Steinberg and Adams (1982) reviewed the molecular defects identified in thalassemias: (1) gene deletion, e.g., of the terminal portion of the beta gene (Orkin et al., 1979); (2) chain termination (nonsense) mutations (Chang and Kan, 1979; Trecartin et al., 1981); (3) point mutation in an intervening sequence (Spritz et al., 1981; Westaway and Williamson, 1981); (4) point mutation at an intervening sequence splice junction (Baird et al., 1981); (5) frameshift deletion (Orkin and Goff, 1981); (6) fusion genes, e.g., the hemoglobins Lepore; and (7) single amino acid mutation leading to very unstable globin, e.g., Hb Vicksburg (beta 75 leu-to-0). Since it had been shown by cDNA-DNA hybridization that some cases of severe alpha-thalassemia result from deletion of all or most of the alpha globin genes, Ottolenghi et al. (1975) applied similar techniques to a study of whether beta genes were present in the forms of beta thalassemia with no synthesis of beta chains. They studied material from persons heterozygous for beta-zero-thalassemia and delta-beta-zero-thalassemia and concluded that at least one of the haploid genomes in this patient had a substantially intact beta globin gene. The beta globin structural gene is intact in beta-zero-thalassemia (Kan et al., 1975) but deleted in both hereditary persistence of fetal hemoglobin (Kan et al., 1975) and delta-zero-beta-zero-thalassemia (Ottolenghi et al., 1975). The possibility that the genetic lesions in beta-plus-thalassemia lie at splicing sites within intervening sequences of the beta globin gene was discussed by Maquat et al. (1980). Beta-zero-thalassemia is heterogeneous. Some cases have absent beta-globin mRNA. Some have a structurally abnormal beta-globin mRNA, usually in reduced amounts. Baird et al. (1981) found a nucleotide change at the splice junction at the 5-prime end of the large intervening sequence (IVS2) as the defect in 3 cases (1 Italian; 2 Iranian). By means of a simplified method for trophoblast biopsy together with restriction endonuclease analysis of fetal DNA, Old et al. (1982) made first-trimester prenatal diagnosis in the case of 3 fetuses at risk for hemoglobinopathy: 2 at risk for homozygous beta-thalassemia and 1 at risk for sickle cell anemia.
Conner et al. (1983) synthesized two 19-base-long oligonucleotides, 1 complementary to the 5-prime end of the normal beta-globin gene and 1 complementary to the sickle cell gene. DNA from normal homozygotes showed hybridization only for the first probe; DNA from persons with sickle cell anemia showed hybridization only with the second; DNA from sickle cell anemia heterozygotes showed hybridization with both. Allele-specific hybridization of oligonucleotides was proposed as a general method for diagnosis of any genetic disease which involves a point mutation in a single-copy gene. Saiki et al. (1985) developed a new method for rapid and sensitive diagnosis of sickle cell anemia that has potential use in connection with other genetic diseases. It combines 2 methods: primer-mediated enzymatic amplification (about 220,000 times) of specific beta-globin target sequences in genomic DNA and restriction endonuclease digestion of an end-labeled oligonucleotide probe hybridized in solution to the amplified beta-globin sequences. In less than a day and with much less than a microgram of DNA, the diagnosis can be made. Saiki et al. (1988) devised a simple and rapid nonradioactive method for detecting genetic variation and applied it to the diagnosis of sickle cell anemia and beta-thalassemia. The procedure involved the selective amplification of a segment of the human beta-globin gene with oligonucleotide primers and a thermostable DNA polymerase, followed by hybridization of the amplified DNA with allele-specific oligonucleotide probes covalently labeled with horseradish peroxidase. The hybridized probes were detected with a simple colorimetric assay.
In Sardinia, Rosatelli et al. (1985) used the synthetic oligonucleotide method for prenatal detection of the beta-zero-39 (nonsense) mutation type of beta-thalassemia. In a mouse model for beta-thalassemia, Holding and Monk (1989) were able to make the diagnosis in single blastomeres removed from embryos of 4 to 8 cells by PCR amplification. Monk and Holding (1990) demonstrated reproducible amplification of a 680-basepair sequence within the human beta-globin gene from individual human oocytes and the first polar bodies isolated from them. They used restriction enzyme digestion of the amplified DNA to confirm the identity of the fragment. The authors proposed that analysis of the DNA from the first polar body will facilitate preimplantation diagnosis of sickle cell anemia. Cai and Kan (1990) demonstrated the usefulness of denaturing gradient gel electrophoresis for detecting beta-thalassemia mutations and suggested that it might be a useful nonradioactive means of detecting mutations in other genetic disorders. Other methods are hybridization with allele-specific oligonucleotide probes, ribonuclease or chemical cleavage, and restriction endonuclease analysis. PCR greatly facilitated implementation of all these detection methods.
In a family of Scottish-Irish descent, Pirastu et al. (1983) studied a new type of gamma-delta-beta thalassemia. The proposita presented with hemolytic disease of the newborn which was characterized by microcytic anemia. Initial restriction enzyme analysis showed no grossly abnormal pattern, but studies of polymorphic restriction sites and gene dosage showed extensive deletion of the entire beta-globin cluster. In situ hybridization with radioactive beta-globin gene probes showed that only one 11p homolog contained the beta-globin gene cluster. Kazazian et al. (1982) observed a similar extensive deletion in a Mexican family.
From in situ hybridization studies, Morton et al. (1984) concluded that the beta-globin gene is situated at 11p15. Their studies included a t(7;11)(q22;p15) in which the beta-globin locus appeared to be at the junction point. Interest relates to the translocation cell line coming from a patient with erythroleukemia and the fact that the ERBB oncogene (131550) is located on chromosome 7 (7pter-q22).
By analysis of family data on 15 restriction site polymorphisms (RSPs), Chakravarti et al. (1984) identified a 'hotspot' for meiotic recombination at the 5-prime end of the beta gene. Recombination leftward (in the 5-prime direction) from a point called chi near the end of the beta-globin gene is 3 to 30 times the expected rate; in the use of RSPs in prenatal diagnosis, it had been assumed that a marker 10 kb from a mutant gene would recombine at a rate of 10(-5) per kb, leading to a diagnostic error of 1 in 10,000. However, their data suggested the error rate using 'loci' on opposite sides of chi may be as high as 1 in 312. By a computer search of the DNA sequences of the beta cluster, they located a chi sequence (5-prime-GCTGGTGG-3-prime) at the 5-prime end of the second intervening sequence of the beta gene. This chi sequence, a promoter of generalized recombination in lambda phage, has been found in high frequency in the mouse genome, especially in immunoglobulin DNA. A recombinational hotspot has been found in the mouse major histocompatibility complex. Matsuno et al. (1992) invoked possible gene conversion at the chi sequence near the 5-prime end of exon 2 (codons 31-34) as the explanation for the finding of a beta-thalassemia mutation common in southeast Asia (frameshift mutation in codons 41 and 42; see 141900.0326), as well as in Japan, on 2 different restriction frameworks (haplotypes). They presumed that the 6 families found in Japan with this particular mutation had inherited it from ancestors who had migrated to Japan from southeast Asia. In a large Amish pedigree, Gerhard et al. (1984) observed an apparent crossover within the beta-globin gene cluster in the region of the recombinational 'hotspot' postulated by Chakravarti et al. (1984) on the basis of linkage disequilibrium in population data. It was also possible to identify the orientation of the beta-globin cluster vis-a-vis the centromere: cen--5-prime--epsilon--beta--3-prime--pter. Camaschella et al. (1988) identified recombination between 2 paternal chromosomes in a region 5-prime to the beta gene, previously indicated to contain a 'hotspot' for recombination. The recombination was identified because in the course of prenatal diagnosis by linkage to RFLPs, a homozygous beta-thalassemia fetus was misdiagnosed as beta-thalassemia trait. In the course of studying an Irish family with beta-thalassemia due to the Q39X mutation, Hall et al. (1993) found a fourth case of recombination in the beta-globin gene cluster. The event had occurred 5-prime of the polymorphic RsaI site at position -550 bp upstream of the beta-globin gene mRNA cap site, within the 9.1-kb region shown to be a hotspot for recombination.
By high-resolution chromosome sorting of human chromosomes carrying segments of chromosome 11 and by spot blotting with various gene-specific probes, Lebo et al. (1985) concluded that the loci for parathyroid hormone, beta-globin, and insulin are all located on 11p15. By in situ hybridization studies of chromosome 11 rearrangements, Magenis et al. (1985) likewise assigned HBB to 11p15. In an addendum, they referred to studies of a t(7;11) rearrangement that further narrowed the HBB assignment to 11p15.4-11pter. Although some workers have put the insulin (176730), beta-globin, and HRAS (190020) genes on 11p15, Chaganti et al. (1985) located these differently by in situ hybridization to meiotic chromosomes: INS, 11p14.1; HRAS, 11p14.1; HBB, 11p11.22; and PTH (not previously assigned), 11p11.21. By high-resolution cytogenetics and in situ hybridization, Lin et al. (1985) placed the beta-globin gene in the 11p15.4-p15.5 segment. Through reanalysis of a Chinese hamster/human cell hybrid that had lost all human chromosomes except 11, Gerhard et al. (1987) reached the conclusion that the beta-globin gene complex is located in 11p15 and that the insulin and HRAS1 genes are located in a segment of DNA approximately 10 megabases long.
Huang et al. (1986) reported the same 'TATA' box mutation leading to the same nondeletion form of beta-thalassemia in Chinese as had been reported in American blacks by Antonarakis et al. (1984); see 141900.0379. There are other illustrations indicating that mutations in the beta-globin gene can recur.
Part of the mutational repertoire of the beta-globin locus is hereditary persistence of fetal hemoglobin (HPFH) due to deletion. Two types (types I and II) occur in blacks and have as their basis deletion of the delta and beta loci. An Italian type and an Indian type are likewise deletion forms of HPFH; see review by Saglio et al. (1986). In 2 Italian brothers with a G-gamma/A-gamma form of hereditary persistence of fetal hemoglobin, Camaschella et al. (1990) demonstrated a deletion starting 3.2 kb upstream from the delta gene and ending within the enhancer region 3-prime to the beta-globin gene. The deletion removed 1 of the 4 binding sites for an erythroid specific transcriptional factor (NF-E1). It appeared that the residual enhancer element, relocated near gamma genes, may increase fetal hemoglobin expression.
Orkin et al. (1982) developed and applied a new strategy for the comprehensive analysis of existing mutations in a class of human disease. They combined analysis of various restriction enzyme polymorphisms in the beta-globin gene cluster with direct examination of beta-globin structural genes in Mediterranean persons with beta-thalassemia. The approach was prompted by the finding that specific mutant genes are strongly linked to patterns of restriction site polymorphism (haplotypes) in this region of the genome. They isolated 8 different mutant genes among the 9 different haplotypes represented in Mediterraneans. Seven of the 8 genes were present in Italians from various locales in Italy, and 6 in Greeks. Several were previously unknown mutations, and 1 of these possibly affects transcription. The strategy is probably applicable to the analysis of heterogeneity in other diseases of single-copy genes. When linkage analysis can be performed in the family, the haplotype analysis will be highly useful in prenatal diagnosis of beta-thalassemia. Indeed, the method of haplotyping proved highly useful both in tracing the origin of mutations and in family studies (see Antonarakis et al., 1982). Losekoot et al. (1992) described a method for rapid detection of beta-globin haplotypes (referred to by them as framework) by denaturing gradient gel electrophoresis.
Rosatelli et al. (1987) analyzed the molecular defect in 494 Sardinian beta-thalassemia heterozygotes. The most prevalent mutation, accounting for 95.4% of cases, was the nonsense mutation at codon 39. The remainder, in decreasing order of frequency, were a frameshift at codon 6 (2.2%), beta-plus IVS1, nucleotide 110 (0.4%), and beta-plus IVS2, nucleotide 745 (0.4%). The DNA sequences along the human beta-globin cluster are highly polymorphic; over 20 polymorphic restriction endonuclease sites have been described in this 60-kb region. As outlined earlier, with examples, RFLP haplotypes have been useful in defining various thalassemia lesions, such as deletions, for prenatal diagnosis of beta-thalassemia, and for tracing the origin and migration of mutant genes. Pirastu et al. (1987) found that the predominant beta-thalassemia in Sardinia, the beta-zero type due to nonsense mutation (CAG-to-TAG) at beta-39, resides on 9 different chromosome haplotypes. One of the haplotypes included a cytosine-to-thymine point mutation 196 nucleotides upstream from the A-gamma-globin gene (142200). This mutation at position -196 is associated with high levels of production of fetal hemoglobin. The beta-39 nonsense mutation may have gotten onto the -196 chromosome through crossing-over. A chromosome carrying such a double mutation could be expected to impart selective advantage because the beta-thalassemia would protect against malaria while the increased gamma-globin production would ameliorate the severity of the beta-thalassemia. A similar mechanism may have been operative in the case of another haplotype which combined the beta-39 nonsense mutation with triple gamma loci produced by the addition of a second G-gamma-globin gene. Pirastu et al. (1987) proposed a schema by which the findings were explained by a single initial mutation with subsequent crossovers between the 5-prime and 3-prime blocks of genes producing 6 other chromosomes and then the creation of 2 others by crossing-over and gene conversion. Additional diversity could have arisen through other beta-39 mutations. The mutation identified in a family of northern European origin by Chehab et al. (1986) was of this type.
Wainscoat et al. (1983) showed that coinheritance of alpha-thalassemia with homozygous beta-thalassemia resulted in amelioration of the beta-thalassemia. Kulozik et al. (1987) showed that heterozygous beta-thalassemia was associated with unusually severe clinical manifestations when coinherited with an extra alpha-globin gene; in each of 5 cases 1 chromosome 16 carried 3 alpha-globin genes. Camaschella et al. (1987) found the same aggravation of the clinical picture with triplicated alpha locus. This is a particularly instructive example of gene interaction. Direct sequencing of specific regions of genomic DNA became feasible with the invention of PCR, which permits amplification of specific regions of DNA (Church and Gilbert, 1984; Saiki et al., 1986). For example, Wong et al. (1986) amplified human mitochondrial DNA and sequenced it directly. Wong et al. (1987) applied a combination of PCR and direct sequence analysis of the amplified product to the study of beta-thalassemia in 5 patients whose mutant alleles had not been characterized. They found 2 previously undescribed mutations along with 3 previously known ones. One new allele was a frameshift at codons 106-107 and the other was an A-to-C transversion at the cap site (+1) of the beta-globin gene. The latter was the first natural mutation observed at the cap site (141900.0387).
In the so-called Corfu form of delta-beta-zero-thalassemia, Kulozik et al. (1988) found that a deletion removed 7,201 basepairs containing part of the delta-globin gene and sequences upstream. The beta-globin gene contained a G-to-A mutation at position 5 in IVS1. The gamma-globin gene promoters were normal. In transfected HeLa cells, a normal message was produced from the mutated beta-globin gene at a level of approximately 20% of the normal, the remaining 80% being spliced at cryptic sites in exon 1 and intron 1. This indicated that the mutation in the beta-globin gene is not the sole cause of the complete absence of hemoglobin A in this form of thalassemia. Kulozik et al. (1988) concluded that the 7.2-kb deletion contains sequences necessary for the normal activation of the beta-globin gene. In the homozygous state there is complete absence of hemoglobin A and hemoglobin A(2) and a high level of hemoglobin F. Traeger-Synodinos et al. (1991) gave further data on the Corfu mutation. In a study of beta-thalassemia in Spain, Amselem et al. (1988) demonstrated the usefulness of the dot-blot hybridization of PCR-amplified genomic DNA in both rapid population surveys and prenatal diagnosis. They found 7 different beta-thalassemia mutations. The nonsense codon 39 accounted for 64%, whereas the IVS1 position 110 mutation (141900.0364), the most common cause of beta-thalassemia in the eastern part of the Mediterranean basin, was underrepresented (8.5%). The IVS1 mutation at position 6 (141900.0360) accounted for 15% of the defects and led to a more severe form of beta(+)-thalassemia than originally described in most patients with this mutation. Diaz-Chico et al. (1988) described 2 families, 1 Yugoslavian and 1 Canadian, with heterozygous thalassemia characterized by mild anemia with severe microcytosis and hypochromia, normal levels of hemoglobin A(2), and slightly raised hemoglobin F levels. In both families the condition resulted from large deletions which included all functional and pseudogenes of the beta-globin gene cluster. The deletion was at least 148 kb in the Yugoslavian family and 185 kb in the Canadian family.
Kazazian and Boehm (1988) gave an update on the variety of beta-thalassemias. Large deletions are a rare cause of beta-thalassemia; as of early 1989, 63 single nucleotide substitutions or small deletions and 7 large deletions had been described as the basis of beta-thalassemia (Kazazian, 1989). Aulehla-Scholz et al. (1989) described a deletion comprising about 300 basepairs in a female heterozygote, resulting in loss of exon 1, part of IVS1, and the 5-prime beta-globin gene promoter region. Laig et al. (1989) identified new beta-thalassemia mutations in northern and northeastern Thailand. Rund et al. (1991) studied beta-thalassemia among the Kurdistan Jews. They identified 13 distinct mutations among 42 sibships, of which 3 were previously undescribed. Four of the mutations (see 141900.0331, 141900.0341, 141900.0373, 141900.0383) were unique to Kurdish Jews and two-thirds of the mutant chromosomes carried the mutations unique to Kurdish Jews. Haplotype and geographic analyses suggested that thalassemia in central Kurdistan has evolved from multiple mutational events. Genetic admixture with the local population appears to be the primary mechanism of the evolution of thalassemia in Turkish Kurdistan, whereas there is evidence for a founder effect in Iranian Kurdistan. Huang et al. (1990) used DNA from dried blood specimens amplified by PCR to study the distribution of beta-thalassemia mutations in southern, western, and eastern China. Huisman (1990) provided a list of over 110 different beta-thalassemia alleles, most of them of the nondeletional type.
As indicated by the work of Villegas et al. (1992), Oron et al. (1994), and Traeger-Synodinos et al. (1996), the thalassemia intermedia is caused by interaction between a triplicated alpha-globin locus (leading to alpha-globin overproduction) and beta-thalassemia heterozygosity. Traeger-Synodinos et al. (1996) reported 3 cases of beta-thalassemia heterozygosity with homozygous alpha-globin gene triplication and 17 beta-thalassemia heterozygotes with a single additional alpha-globin gene. Garewal et al. (1994) likewise reported 2 patients with a clinical presentation of thalassemia intermedia due to homozygosity for alpha-gene triplication and heterozygosity for an HBB gene mutation.
Huisman (1992) edited an up-to-date listing of the deletions, mutations, and frameshifts leading to beta-thalassemia, which had been published 3 times previously, and added a new table on the delta-thalassemias, prepared by Erol Baysal. Kazazian et al. (1992) tabulated a total of 9 beta-globin mutations producing dominant thalassemia-like phenotypes. Widespread ethnic derivation was demonstrated.
Krawczak et al. (1992) reviewed the mutational spectrum of single basepair substitutions in mRNA splice junctions on the basis of 101 different examples of point mutations occurring in the vicinity of splice junctions and held to be responsible for human genetic disease. The data comprised 62 mutations at 5-prime splice sites, 26 at 3-prime splice sites, and 13 that resulted in the creation of novel splice sites such as Hb E. They estimated that up to 15% of all point mutations causing human genetic disease result in an mRNA splicing defect.
Carver and Kutlar (1995) listed 323 beta-chain variants as of January 1995. This number did not include beta-chain variants with deletions and/or insertions or those with extended polypeptide chains. Baysal and Carver (1995) provided an update (eighth edition) of their catalog, or repository, of beta-thalassemia and delta-thalassemia.
Landin et al. (1996) noted that 34 of 316 beta-globin variants due to single amino acid substitutions could be caused by more than 1 type of point mutation at the DNA level. They also noted that 3 beta-globin variants (Hb Edmonton, Hb Bristol, and Hb Beckman) and 1 alpha-globin variant (Hb J-Kurosh) could not be produced by a single nucleotide substitution; 2 substitutions were required.
Huisman et al. (1996) provided a syllabus of human hemoglobin variants listing the characteristics as well as precise molecular change of known beta-globin mutants; these numbered 335 single-base mutations and 17 variants with 2 amino acid replacements as of January 1996. They also included hemoglobin variants resulting from fusion of parts of the beta-chain and delta-chain, variants with elongated beta-chains at both the C-terminal and N-terminal ends, and variants with small deletions and/or insertions in the beta-chain. Not included were deletions and mutations that result in beta-thalassemia, even if such a change, point mutation, or frameshift occurred in one of the coding regions of the HBB gene. Information regarding these abnormalities were provided elsewhere, e.g., Baysal and Carver (1995). Huisman et al. (1996) stated that 138 of the 146 codons of the HBB gene have been mutated; 5 mutations are known for 6 codons (22, 67, 97, 121, 143, and 146), 6 mutations for codon 92, and 7 mutations for codon 99. Most of the mutations have been deduced from the sequence of the amino acid sequence of the variant protein and the known sequence of the HBB gene; slightly more than 10% of the mutations have been determined through DNA sequencing. Occasionally discrepancy was observed, such as at position 50 and 67 of the beta-globin chain.
Huisman et al. (1996) listed (in their Table 6B) 38 HBB variants causing erythrocytosis, plus 20 others causing mild erythrocytosis and 1 causing erythrocytosis in combination with hemolysis.
Sierakowska et al. (1996) found that treatment of mammalian cells stably expressing the IVS2-654 beta HBB gene (141900.0348) with antisense oligonucleotides targeted at the aberrant splice sites restored correct splicing in a dose-dependent fashion, generating correct human beta-globin mRNA and polypeptide. Both products persisted for up to 72 hours after treatment. The oligonucleotides modified splicing by a true antisense mechanism without overt unspecific effects on cells growth and splicing of other pre-mRNAs. This novel approach in which antisense oligonucleotides are used to restore rather than to downregulate the activity of the target gene is applicable to other splicing mutants and is of potential clinical interest.
Several hemoglobin variants were first detected in the course of study of glycated hemoglobin (Hb A1c) in diabetics, e.g., 141900.0429 and 141900.0477. The alternative situation, diagnosis of diabetes during the performance of hemoglobin electrophoresis for study of anemia, was observed by Millar et al., 2002.
Hardison et al. (2002) constructed a Web-accessible relational database of hemoglobin variants and thalassemia mutations called HbVar, in which old and new data are incorporated. Queries can be formulated based on fields in the database. For example, tables of common categories of variants, such as all variants involving the HBA1 gene (141800) or all those that result in high oxygen affinity, can be assembled. More precise queries are possible, such as 'all beta-globin variants associated with instability and found in Scottish populations.'
Cases of gamma-delta-beta thalassemia are known in which the beta gene is intact but deletion 'in cis' occurs upstream, even at a distance, in a region designated LCRB. In a remarkable case reported by Curtin et al. (1985), a deletion extended from the third exon of the G-gamma gene upstream for about 100 kb. The A-gamma, pseudo-beta, delta, and beta genes in cis were intact. This malfunction of the beta-globin gene on a chromosome in which the deletion is located 25 kb away suggests that chromatin structure and conformation are important for globin gene expression. In experiments in which the human beta-globin locus was introduced into the mouse genome, Talbot et al. (1989) found a 6.5-kb control region which allowed achievement of endogenous levels of beta-globin expression. The control region included an erythroid cell-specific DNase I hypersensitive site (HS). Using pulsed field gel electrophoresis and PCR, Driscoll et al. (1989) found, in a case of gamma-delta-beta-thalassemia, a de novo deletion on a maternally inherited chromosome 11 involving about 30 kb of sequences 5-prime to the epsilon gene. The deletion extended from -9.5 kb to -39 kb 5-prime of epsilon and included 3 of the 4 DNase I hypersensitive sites (at -10.9 kb, -14.7 kb, and -18 kb 5-prime of epsilon). The remaining sequences of the beta-globin complex, including the DNase I hypersensitive sites at -6.1 kb and all structural genes in cis to the deletion, were physically intact. Again, a significance of the hypersensitive sites in regulating globin-gene expression was demonstrated.
The significance of the hypersensitive sites to globin gene expression had also been demonstrated by Grosveld et al. (1987) who achieved high levels of position-independent beta-gene expression in transgenic mice with a specially constructed beta-globin minilocus in which 5-prime and 3-prime hypersensitive sequences flanked a beta-globin gene. The hypersensitive sequences, termed locus-activating regions (LARs), are erythroid-tissue-specific and developmentally stable. Curtin et al. (1989) performed experiments similar to those of Grosveld et al. (1987) with like results. (A similar positive control region for the cluster of alpha-globin genes was deduced by Hatton et al. (1990) on the basis of deletion in a case of alpha-thalassemia; see 141800.) See 187550 for evidence of an unlinked remote regulator of HBB gene expression. Townes and Behringer (1990) reviewed the topic of the locus activating region. They presented a model for developmental control of human globin gene expression (see their Figure 2). With respect to the cap site of the human epsilon-globin gene, LAR site I is located at position -6.1 kb; site II, at -10.9 kb; site III, at -14.7 kb; and site IV, at -18 kb. Moon and Ley (1990) cloned murine DNA sequences homologous to the human LAR site II. These sequences are linked to the mouse beta-globin gene cluster in the same basic arrangement as the human beta-globin gene cluster. Furthermore, the 2 LARs share 70% identical sequence and several enhancer-type functions. LAR sequences are almost certainly not confined to the human beta-globin locus. The investigators stated that these sequences may be critical components of any gene family that comprises multiple members that are regulated differently during development.
Perichon et al. (1993) demonstrated interethnic polymorphism of 1 segment of the LCRB region in sickle cell anemia patients. Distinct polymorphic patterns of a simple sequence repeat were observed in strong linkage disequilibrium with each of the 5 major beta-S haplotypes.
Studies by Grosveld et al. (1987) and by Blom van Assendelft et al. (1989) established that 6 DNase I hypersensitive sites flank the globin genes. One HS site is located 20 kb downstream of the beta-globin cluster and 5 HS sites are located 6-22 kb upstream within the locus control region (LCR). Peterson et al. (1996) examined the effects of deletion of the LCR 5-prime HS3 element and the 5-prime HS2 element on globin gene expression by recombining a 2.3-kb deletion of 5-prime HS3 or a 1.9-kb deletion of 5-prime HS2 into a beta-globin locus YAC, which was then used to produce transgenic mice. When the LCR 5-prime HS3 element is deleted there is decreased expression of epsilon-globin in the yolk sac. Deletion of 5-prime HS2 resulted in a minor but statistically significant decrease in epsilon-, gamma-, and beta-globin expression. From these results Peterson et al. (1996) concluded that there is functional redundancy among the HS sites. The effects of the 5-prime HS3 deletion on epsilon-globin gene expression led them to conclude that specific interactions between the HSs and the globin genes underlie activation of globin genes during specific stages of development.
Epner et al. (1998) deleted the murine beta-globin LCR from its native chromosomal location. The approximately 25-kb deletion eliminated all sequences and structures homologous to those defined as the human LCR. In differentiated embryonic stem cells and erythroleukemia cells containing the LCR-deleted chromosome, DNase I sensitivity of the beta-globin domain was established and maintained, developmental regulation of the locus was intact, and beta-like globin RNA levels were reduced 5 to 25% of normal. Thus, in the native murine beta-globin locus, the LCR was necessary for normal levels of transcription, but other elements were sufficient to establish the open chromatin structure, transcription, and developmental specificity of the locus. These findings suggest a contributory rather than dominant function for the LCR in its native location.
Bauchwitz and Costantini (2000) quantified the effects of beta-globin sequence modifications on epsilon-, gamma-, and delta-globin levels in transgenic mice. Embryonic day 11.5 primitive erythroid cells showed a large increase in epsilon-globin in the absence of the beta-globin gene, which is weakly expressed at that stage of development. Embryonic day 17.5 fetal liver and adult erythroid cells, in which beta-globin expression approaches its maximum, showed only a small stimulation of gamma- and delta-globin levels in the absence of beta-globin sequence. Analysis of erythroid colonies produced by in vitro differentiation of embryonic stem cells indicated that the absence of the human beta-globin gene had no effect on gamma-globin expression. The authors concluded that competitive influences need not be linked directly to transcriptional level or distance from the LCR, and that the large increases in gamma-globin levels seen in some human deletional beta-thalassemias and hereditary persistence of fetal hemoglobin conditions are most likely due to effects other than loss of beta-globin competition. In transgenic mice with beta-globin sequences inserted between epsilon and the LCR in a beta-locus, the expression of epsilon-, gamma-, and delta-globins suggested that stage-specific sensitivity to loss of LCR activity may be a more important parameter than position relative to the LCR.
Alami et al. (2000) created a yeast artificial chromosome containing an unmodified human beta-globin locus, and introduced it into transgenic mice at various locations in the genome. The locus was not subject to detectable stable position effects but did undergo mild-to-severe variegating position effects at 3 of the 4 noncentromeric integration sites tested. The distance and the orientation of the LCR relative to the regulated gene contributed to the likelihood of variegating position effects, and affected the magnitude of its transcriptional enhancement. DNaseI hypersensitive site (HSS) formation varied with the proportion of expressing cells (variegation), rather than the level of gene expression, suggesting that silencing of the transgene may be associated with a lack of HSS formation in the LCR region. The authors concluded that transcriptional enhancement and variegating position effects are caused by fundamentally different but interdependent mechanisms.
Navas et al. (2002) generated transgenic mouse lines carrying a beta-globin locus YAC lacking the LCR to determine if the LCR is required for globin gene activation. Beta-globin gene expression was analyzed by RNase protection, but no detectable levels of epsilon-, gamma-, and beta-globin gene transcripts were produced at any stage of development. Lack of gamma-globin gene expression was also seen in a beta-YAC transgenic mouse carrying a gamma-globin promoter mutant that causes hereditary persistence of fetal hemoglobin (see 142200.0026) and an HS3 core deletion that specifically abolishes gamma-globin gene expression during definitive erythropoiesis. The authors concluded that the presence of the LCR is a minimum requirement for globin gene expression.
The eta locus is 1 of 5 ancient beta-related globin genes linked in a cluster, 5-prime--epsilon--gamma--eta--delta--beta--3-prime, that arose from tandem duplications (Koop et al., 1986). The eta locus was embryonically expressed in early eutherians and persisted as a functional gene in artiodactyls (e.g., goat), but became a pseudogene in proto-primates and was lost from rodents and lagomorphs. Sequence studies show that the goat eta gene is orthologous to the pseudogene located between the gamma and delta loci of primates and called psi-beta-1. (The Hb beta-1 pseudogene (psi-beta-1) can be symbolized HBBP or HBBP1.)
(In the allelic variants that follow, as well as in the allelic variants listed under the other globin genes, the codon count begins with the first amino acid of the mature protein because a large portion of the variants were characterized on the basis of a protein rather than the gene itself. It is more customary for the count to begin with the methionine initiator codon as number one. Thus, the Hb S mutation (141900.0243) is designated glu6-to-val; in the gene based system of counting now used, it would be designated glu7-to-val. Some inconsistency is represented by the fact that some initiator mutations in the globin genes are indicated by a system counting from the initiator methionine; e.g., beta-thalassemia due to met1-to-ile (141900.0430).)
Ciavatta et al. (1995) created a mouse model of beta-zero-thalassemia by targeted deletion of both adult beta-like globin genes, beta(maj) and beta(min), in mouse embryonic stem cells. Heterozygous animals derived from the targeted cells were severely anemic with dramatically reduced hemoglobin levels, abnormal red cell morphology, splenomegaly, and markedly increased reticulocyte counts. Homozygous animals died in utero; however, heterozygous mice were fertile and transmitted the deleted allele to progeny. The anemic phenotype was completely rescued in progeny derived from mating beta-zero-thalassemic animals with transgenic mice expressing high levels of human hemoglobin A. The authors suggested that beta-zero-thalassemic mice could be used to test genetic therapy for beta-zero-thalassemia and could be bred with transgenic mice expressing high levels of hemoglobin S to produce an improved mouse model of sickle cell disease.
Hemoglobin disorders were among the first to be considered for gene therapy. Transcriptional silencing of genes transferred into hematopoietic stem cells, however, posed one of the most significant challenges to its success. If the transferred gene is not completely silenced, a progressive decline in gene expression as mice age often is encountered. These phenomena were observed to various degrees in mouse transplant experiments using retroviral vectors containing a human beta-globin gene, even when cis-linked to locus control region derivatives. Kalberer et al. (2000) investigated whether ex vivo preselection of retrovirally transduced stem cells on the basis of expression of the green fluorescent protein driven by the CpG island phosphoglycerate kinase (311800) promoter could ensure subsequent long-term expression of a cis-linked beta-globin gene in the erythroid lineage of transplanted mice. They observed that 100% of 7 mice engrafted with preselected cells concurrently expressed human beta-globin and green fluorescent protein in 20 to 95% of their red blood cells for up to 9.5 months posttransplantation, the longest time point assessed. This expression pattern was successfully transferred to secondary transplant recipients. In the presence of the beta-locus control region hypersensitivity site 2 alone, human beta-globin mRNA expression levels ranged from 0.15 to 20% with human beta-globin chains detected by HPLC. Neither the proportion of positive blood cells nor the average expression levels declined with time in translated recipients.
Persons and Nienhuis (2000) discussed the background of the work by Kalberer et al. (2000), including position effect variegation (PEV). Both PEV and silencing mechanisms may act on a transferred globin gene residing in chromatin outside of the normal globin locus during the important terminal phases of erythroblast development when globin transcripts normally accumulate rapidly despite heterochromatization and shutdown of the rest of the genome.
See Williamson et al. (1990).
See Tentori et al. (1972), Chiancone et al. (1974), and Zhao et al. (1990).
See Miyaji et al. (1966). As indicated by Corso et al. (1990), carriers of the mutation had been found in only 3 families, an American black, a Sicilian, and a Hungarian family, suggesting independent origins of the mutation. Corso et al. (1990) described another Sicilian family in which 5 members carried Hb Agenogi; in 1, it was associated with beta-zero-thalassemia. The proposita, a 40-year-old woman with 2 children, came to attention because of mild chronic anemia and biliary colic due to gallstones.
Noguera et al. (2002) described Hb Agenogi in an Argentinean patient with Syrian and Hungarian ancestry. The mutation had previously been described in only 5 families, one of which was from Hungary.
See Brimhall et al. (1975).
See Lam et al. (1977) and Arends et al. (1987).
See Mant et al. (1977), Stinson (1977), and Wong et al. (1978).
See Marti et al. (1976).
See Zak et al. (1974). Hebbel et al. (1978) used this hemoglobin to make ingenious observations on adaptation of humans to high altitudes.
See Arcasoy et al. (1974) and Harano et al. (1981).
May have arisen either through a second mutation in a person with Hb C or Hb N(Baltimore), or through crossing-over in a person who was heterozygous for both mutant hemoglobins. See Adams and Heller (1977).
See Brown et al. (1976) and Moo-Penn et al. (1977).
Unstable hemoglobin. See Hubbard et al. (1975) and Brennan et al. (1983).
Brennan et al. (1986) described a 25-year-old man with congenital hemolytic anemia who was found to have the mutation of Hb Atlanta (beta75 leu-to-pro) and that of Hb Coventry (beta141 leu deleted) in the same beta-globin chain along with a normal beta-globin chain and a beta-globin chain with only the Hb Atlanta mutation. They stated that this is the sixth known example of 2 changes in 1 beta chain. They postulated that the doubly abnormal beta-globin was a beta-delta globin originating by a Lepore-type-mechanism. Brennan et al. (1992) found on restudy that leu141 was in fact not deleted but replaced by a novel amino acid which they suggested was hydroxyleucine; they proposed that the change resulted from posttranslational oxidation of leu141 as a consequence of perturbation of the haem environment caused by the leu75-to-pro mutation. The finding was consistent with the report of George et al. (1992) who found no evidence of deletion of leu141 in genomic DNA. The heterozygous patients have 3 hemoglobins: Hb A, Hb Atlanta, and Hb Atlanta-Coventry. The last 2 are the products of a single gene. A similar situation obtains with Hb Vicksburg (141900.0293), in which deletion of leu75 is not coded for in genomic DNA. Coleman et al. (1988) posited somatic mutation in that instance; however, a mechanism similar to that with Hb Atlanta-Coventry is possible.
See Moo-Penn et al. (1977).
See Rahbar et al. (1979).
See Wajcman et al. (1982). This is a high oxygen affinity hemoglobin variant.
See Schneider et al. (1977).
See Strahler et al. (1983) and Blibech et al. (1986).
See Kennedy et al. (1974).
See Efremov et al. (1973), Wilkinson et al. (1975), and Ruvidic et al. (1975).
Akar et al. (1995) described a dual restriction enzyme digestion protocol for discriminating between Hb Beograd and Hb D (Los Angeles) (glu121 to gln) when they occur in the same population. Both of these variants migrate like Hb S on cellulose acetate electrophoresis. Hb O (Arab) (glu121 to lys; 141900.0202) represents no problem because that variant migrates differently on cellulose acetate electrophoresis. Also, the glu121-to-ter mutation (141900.0314) represents no problem because it is associated with a thalassemia phenotype. Other codon 121 mutations are Hb D (Neath) (glu121 to-ala; 141900.0445) and Hb St. Francis (glu121 to gly; 141900.0412).
Like Hb Kansas, this variant was associated with clinically evident cyanosis due to very low oxygen affinity (Nagel et al., 1976). (The hemoglobins M are not the only anomalous hemoglobins associated with cyanosis.)
See Hayashi et al. (1971), Adamson et al. (1972), Bunn et al. (1972), and Schmidt et al. (1976). See Hb Rainier.
See Wajcman et al. (1976) and Miller et al. (1986).
See Marinucci et al. (1981).
See Hollender et al. (1969) and Bird et al. (1987).
See Chen-Marotel et al. (1979).
See Baudin-Chich et al. (1988).
This variant is a cause of erythrocytosis. See Lokich et al. (1973).
See Brennan et al. (1981), Rahbar et al. (1981), and Williamson et al. (1983).
See Steadman et al. (1970) and Ohba et al. (1985).
Rees et al. (1996) reinvestigated the patient who was the subject of the first description of idiopathic Heinz body anemia (140700) (Cathie, 1952) and who was subsequently shown to have hemoglobin Bristol. Using both DNA and protein analysis, they showed that the original characterization of hemoglobin Bristol as val67 to asp was incorrect, in that a silent posttranslational modification of met to asp was mistaken for the primary mutation, which is, in fact, val67 to met. They also restudied 2 subsequent patients reported as having hemoglobin Bristol following protein sequencing in whom the same confusion occurred. They were able to describe a novel posttranslational modification in which the variant methionine amino acid residue is converted to an aspartate, probably catalyzed by the neighboring heme group and oxygen. The study emphasized the importance of analyzing both protein and DNA to characterize fully hemoglobin variants. Identification of the lesion as val67 to asp was made by Steadman et al. (1970).
Although DNA codes for 20 primary amino acids, more than 140 different residues have been identified in proteins due to varied posttranslational modifications. Most are relatively simple reactions involving enzymatic modification of the site change of amino acids to enhance or determine the properties of the particular protein; these processes include acetylation, phosphorylation, hydroxylation, and glycation. There are also a number of posttranslational modifications of hemoglobin A, such as glycation and carbamoylation, but these are due mostly to nonspecific metabolic affects that alter the chemical environment of the hemoglobin, rather than direct results of the properties of the hemoglobin itself. Unstable hemoglobin variants are characterized by the reduced solubility of the hemoglobin tetramer in the red cell in peripheral blood. Most result from mutations of amino acids in key positions, for example, heme- or alpha-beta contact points. Mutations can also alter the structure of the molecule such that posttranslational changes can occur, either of the variant amino acid itself or of other residues exposed by changes in the conformation of the molecule. More rarely, so-called silent modifications occur, in which 1 primary amino acid is converted to another primary amino acid. This is what happened in the case of hemoglobin Bristol. The modification of beta-143 leu, such that it appears to be deleted on protein sequencing, in hemoglobin Atlanta-Coventry (141900.0013) is the result of posttranslational modification, possibly from leucine to hydroxyleucine, as a result of the primary mutation that effects the heme surface. The same apparent deletion of leu-149 is observed with Hb Christchurch (141900.0049) and with Hb Manukau (141900.0438), which is also a mutation of val67 (val67 to gly). There are 6 reported hemoglobin variants in which deamidation of an asparaginyl residue to an aspartate occurs as a silent posttranslational modification: these include hemoglobin Osler (141900.0211). The posttranslational change from methionine to aspartate was the first example to be described (Rees et al., 1996); the exact mechanism of the change is not clear.
See Jones et al. (1977) and Stinson (1984).
See Moo-Penn et al. (1980, 1988) and Ulukutlu et al. (1989). Negri Arjona et al. (1992) found a GCT (ala)-to-CCT (pro) mutation in codon 138 in a 6-year-old Spanish girl with chronic hemolytic anemia requiring transfusion. The patient showed Heinz bodies. Her parents and a brother were normal, indicating that her disorder represented a new mutation.
Blouquit et al. (1989) demonstrated that hemoglobin Bruxelles, a beta-globin variant associated with severe congenital Heinz body anemia, has a deletion of 1 of the 2 adjacent phenylalanines, either phe41 or phe42. Other deletions affecting the phe41 or phe42 have been described. The nucleotide sequence of normal beta-globin mRNA is highly repetitive in the region of codons 41 to 46. Blouquit et al. (1989) suggested that the mutation originated through a frameshift mechanism.
See Bradley et al. (1972), Lehmann (1973), and Weinstein et al. (1973).
See Como et al. (1983). This is a high oxygen affinity hemoglobin variant.
See Turner et al. (1976) and Kobayashi et al. (1986).
See Rieder et al. (1974), Ohba et al. (1985), and Efremov et al. (1987).
See Itano and Neel (1950), Neel et al. (1953), Ranney et al. (1953), Hunt and Ingram (1959), Smith and Krevans (1959), Baglioni and Ingram (1961), River et al. (1961), and Fabry et al. (1981).
By restriction haplotyping, Boehm et al. (1985) concluded that the beta-C-globin gene in blacks had a single origin followed by spread of the mutation to other haplotypes through meiotic recombination 5-prime to the beta-globin gene. On 22 of 25 chromosomes studied, they found the same haplotype (defined by 8 polymorphic restriction sites), a haplotype seen only rarely among beta-A-bearing chromosomes. The 3 exceptions showed identity to the typical beta-C allele in the 3-prime end of the beta-globin gene cluster. Trabuchet et al. (1991) presented haplotyping information suggesting a unicentric origin of the Hb C mutation in sub-Saharan Africa.
Rapid detection of the sickle cell mutation is possible by amplifying the region of codon 6 by PCR and digesting the amplification product by a restriction endonuclease whose recognition site is abolished by the A-to-T mutation, the resulting abnormal fragment being detected with ethidium bromide staining after electrophoresis. Detection of the Hb C mutation is more difficult since no known restriction-endonuclease site is abolished or created by the mutation. Fischel-Ghodsian et al. (1990) described a rapid allele-specific PCR amplification technique that allowed detection of the Hb C mutation in an even shorter time span than the one required for detecting the Hb S mutation (141900.0243).
To test the hypothesis that hemoglobin C protects against severe malaria, Agarwal et al. (2000) conducted a study in the predominantly Dogon population of Bandiagara, Mali, in West Africa, where the frequency of Hb C is high (0.087) and that of Hb S is low (0.016). They found evidence for an association between HbC and protection against severe malaria in the Dogon population. Indeed, the data suggested less selection for the HbAS state in this group than for HbAC.
In many children with sickle cell anemia (603903), functional asplenia develops during the first year of life and septicemia is the leading cause of death in childhood. The risk of septicemia in sickle cell anemia is greatest during the first 3 years of life and is reduced markedly by prophylactic penicillin therapy. Less is known about splenic dysfunction and the risk of overwhelming sepsis in children with SC disease, although functional asplenia has been documented by radionuclide liver-spleen scans in some adult patients (Ballas et al., 1982) and an elevated erythrocyte pit count, a finding that indicates functional asplenia in children with sickle cell anemia, also has been found in some children with SC disease (Pearson et al., 1985). Lane et al. (1994) reported 7 fatal cases of pneumococcal septicemia in children with SC disease. The earliest death occurred in a 1-year-old child who had cyanotic congenital heart; the other children were aged 3.5 to 15 years. Only 1 child had received pneumococcal vaccine or prophylactic penicillin therapy. All 7 children had an acute febrile illness and rapid deterioration despite parenterally administered antibiotic therapy and intensive medical support. Erythrocyte pit counts in 2 patients were 40.3 and 41.7%, respectively (normal, less than 3.6%). Autopsy findings in 5 cases included splenic congestion without infarction in 5, splenomegaly in 4, and bilateral adrenal hemorrhage in 3. Lane et al. (1994) concluded that pneumococcal vaccine should be administered in all children with SC disease. The routine use of prophylactic penicillin therapy in infants and children with SC disease remained controversial. The mutation in codon 6 of HBB in Hb S is GAG (glu) to GTG (val); the mutation in Hb C is GAG (glu) to AAG (lys). See also 141900.0039 and 141900.0040.
Modiano et al. (2001) performed a large case control study in Burkina Faso on 4,348 Mossi subjects, and demonstrated that hemoglobin C is associated with a 29% reduction in risk of clinical malaria in Hb AC heterozygotes (P = 0.0008) and of 93% in Hb CC homozygotes (P = 0.0011). These findings, together with the limited pathology of Hb AC and Hb CC compared to the severely disadvantaged Hb SS and Hb SC genotypes and the low Hb S gene frequency in the geographic epicenter of Hb C, support the hypothesis that, in the long-term and in the absence of malarial control, Hb C would replace Hb S in central West Africa.
Red cells containing this hemoglobin, with 2 mutations in the HBB gene, sickle. The sickling is the result, of course, of the glu-to-val mutation, which is not counteracted by the asp73-to-asn mutation. It is called Hb C (not S) because of its electrophoretic properties. See Pierce et al. (1963), Bookchin et al. (1966, 1968, 1970), and Lang et al. (1972).
As in the other cases of doubly substituted beta chains, either double mutation or intracistronic recombination in a genetic compound would explain the observation. This hemoglobin sickles because of its glu6-to-val substitution, but is called Hb C (not S) because of its electrophoretic properties, which are those of classic Hb C. See Goossens et al. (1975) and Hassan et al. (1977).
See Cohen et al. (1973), Cotten et al. (1973), and Honig et al. (1980). See Rucknagel (1986); hemoglobin Motown was formerly thought to be a change at beta 127 (Gibb, 1981). See Ohba et al. (1975); hemoglobin Tokuchi was formerly thought to be a substitution of tyrosine for histidine at beta 2 (Shibata et al., 1963).
See Wilkinson et al. (1975) and Zhao et al. (1990).
See Ahern et al. (1976) and Ali et al. (1988).
See Garel et al. (1975).
See Dash et al. (1989).
See Rochette et al. (1984).
See Yeager et al. (1983). (Hb Hammersmith is beta-42 phe to ser. Despite the functional and structural similarities, the clinical manifestations of Hb Cheverly are much milder than those of Hb Hammersmith.)
See Shih et al. (1987). Hb Chico has diminished oxygen affinity (Bonaventura et al., 1991). Its oxygen-binding constant is about half that of normal. Bonaventura et al. (1991) presented data on the molecular basis of this altered property.
See Carrell (1970).
See Rahbar et al. (1984) and Kutlar et al. (1989). De Angioletti et al. (1992) detected Hb City of Hope by reversed phase high performance liquid chromatography in an asymptomatic carrier in Naples. The gly69-to-ser substitution, identified by fast atom bombardment mass spectrometry, was shown to be due to a TGG-to-TGA substitution by DNA sequencing. The mutation was associated with RFLP haplotype 9, instead of haplotype 1, as previously reported.
See Wajcman et al. (1975).
De Angioletti et al. (2002) described the comparable mutation in the delta chain of hemoglobin A, designated HBA2-Monreale (142000.0038).
See Boissel et al. (1981), Fabritius et al. (1985), and Ohba et al. (1990).
See Williamson et al. (1983).
See Moo-Penn (1981).
The proband was a child who appeared to have 3 different beta chains in addition to the delta chain of Hb A2 and the gamma chain of Hb F (189,188:Casey et al., 1976, 1978). The child had Hb Sydney (beta 67 val-to-ala) and deletion of beta 141 leu. These were in different beta genes. The presence of 3 beta genes suggested to Lehmann (1978) that the beta Coventry chain is in fact a beta-delta fusion chain. Fay et al. (1993) offered the explanation of post-translational modification of leu-141, probably a conversion to hydroxyleucine, which was not detected by standard amino acid analysis and sequencing methods. Of interest was the finding that not only Hb Sydney but also another substitution at the same codon, val67-to-gly in Hb Manukau, showed this feature. Hemoglobin Coventry was also found in association with Hb Atlanta (leu75-to-pro) (141900.0012).
This variant was named for Fort Worth, Texas. Polycythemia is produced. One member of the family was treated with P32 for presumed polycythemia rubra vera (Schneider, 1978; Schneider et al., 1979). This and about 40 other hemoglobin variants are associated with erythrocytes. See Perutz et al. (1984).
This hemoglobin was found in an asymptomatic woman with a compensated hemolytic state due to an unstable hemoglobin variant (Bunn et al., 1975). The hemoglobin had an abnormally long beta chain that, starting at amino acid 144, had the following sequence: lys-ser-ile-thr-lys-leu-ala-phe-leu-leu-ser-asn-phe-tyr-COOH. This is the first Hb A variant known to contain isoleucine. Bunn et al. (1975) concluded that Hb Cranston probably arose by nonhomologous crossing-over between 2 normal beta chain genes, resulting in the insertion of 2 nucleotides (AG) at position 144, to produce a frame shift. Hb Wayne is thought to be a frame shift mutation involving the alpha chain. Hb Tak is another hemoglobin with abnormally long beta chain. Hb Constant Spring, Hb Koya Dora, and Hb Icaria are hemoglobins with abnormally long alpha chains. See Shaeffer et al. (1980).
See Maniatis et al. (1979).
Erythrocytosis results. See Thillet et al. (1976) and Poyart et al. (1978).
See Wade et al. (1967).
See de Pablos et al. (1987).
See Watson-Williams et al. (1965).
See Rohe et al. (1972), Rahbar (1973), and Serjeant et al. (1982).
See Elion et al. (1973) and Ren et al. (1988).
Among 598 children from the Berber population of the Mzab, Merghoub et al. (1997) found Hb C and Hb D-(Ouled Rabah) in the same gene frequency (0.015). Hb D-(Ouled Rabah) is considered a private marker of the Kel Kummer Tuaregs. Haplotype analysis suggested a single origin of the Hb D mutation. Genetic markers calculated from blood group data clustered Mozabites and Tuaregs with the other Berber-speaking groups, Arabic-speaking populations being more distant. However, they found no specific relationship between the Mozabites and Kel Kummers. Tuaregs in general exhibit features that tend to differentiate them from other Berber-speaking groups. Merghoub et al. (1997) concluded that Hb D-(Ouled Rabah) may be specific for Berber-speaking populations. Merghoub et al. (1997) noted that the origin of the Berber people is not clearly established. North Africa was peopled around the sixteenth millennium B.C.; transition to agriculture occurred around 9500 to 7000 B.C., spreading from the Near East to Egypt. The Arab invasion in the seventh and eighth centuries brought Islamization and dispersal of the Berber culture. Present-day populations of North Africa are mostly Arabic-speaking, whatever their remote origin. Berbers, however, with their languages and customs, still live in small niches of northern Morocco and Algeria, and in some northern oases of the Sahara, including those of the Mzab (Algeria). The Tuaregs also speak Berber languages. They inhabit the south of the Sahara and have been involved for centuries in trans-Saharan trade. Tuaregs have their own culture that probably diverged from the Berber world through isolation.
See Benzer et al. (1958), Bowman and Ingram (1961), Stout et al. (1964), Schneider et al. (1968), Lehmann and Carrell (1969), Ozsoylu (1970), Imamura and Riggs (1972), Bunn et al. (1978), Trent et al. (1982), Worthington and Lehmann (1985), Husquinet et al. (1986), and Harano et al. (1987). Hemoglobin D (Punjab) is common worldwide. It is the most frequent abnormal hemoglobin in Xinjiang Uygur Autonomous Region of China (Li et al., 1986). Zeng et al. (1989) used the PCR method for population studies of this variant. Using PCR and direct sequencing, Schnee et al. (1990) demonstrated the predicted G-to-C substitution in codon 121.
See Labossiere et al. (1972), Powars et al. (1977), and Shulman and Bunn (1988).
See Moo-Penn et al. (1978).
See Gacon et al. (1977).
Kamel et al. (1985) investigated a Qatari family with an electrophoretically fast-moving hemoglobin that they found contained an abnormal beta chain with the sequence met-glu-his-leu at the NH2-end. Substitution of glutamic acid for valine at beta 1 apparently prevented removal of the initiator methionine. The methionine was blocked by a molecule not completely identified. No clinical consequences were observed in heterozygotes.
See Beutler et al. (1974).
See Hunt and Ingram (1961), Shibata et al. (1962), Blackwell et al. (1970), Fairbanks et al. (1980), Benz et al. (1981), and Kazazian et al. (1984). Orkin et al. (1982) reported the complete nucleotide sequence of a beta-E-globin gene. They found a GAG-to-AAG change in codon 26 as the only abnormality. Expression of the beta-E gene was tested by introducing it into HeLa cells. Two abnormalities of RNA processing were shown: slow excision of intervening sequence-1 and alternative splicing into exon 1 at a cryptic donor sequence within which the codon 26 nucleotide substitution resides. Antonarakis et al. (1982) used the Kazazian haplotype approach of analyzing DNA polymorphisms in the beta-globin cluster to present evidence that the beta-E mutation occurred at least twice in Southeast Asia, the mutation being G-to-A at the first nucleotide of codon 26. Thein et al. (1987) demonstrated that the GAG-to-AAG change could be recognized by the restriction enzyme MnlI which cleaves DNA at the sequence 3-prime-GGAG-5-prime. Rey et al. (1991) described SE disease in 3 black American children of Haitian origin. They pointed out that the disorder is probably more benign than SC disease, SO(Arab) disease, and SC(Harlem) disease, all of which have increased risk of the complications of sickling including pneumococcal sepsis.
Rees et al. (1996) reported a girl homozygous for Hb E with severe anemia and anisopoikilocytosis, who was also homozygous for pyrimidine 5-prime nucleotidase deficiency (P5N; 266120). In erythrocytes deficient for P5N the stability of the Hb E was decreased.
Hemoglobin E is very common in parts of Southeast Asia. Chotivanich et al. (2002) examined the possible protective role of Hb E and other prevalent inherited hemoglobin abnormalities against malaria in Thailand. They assessed the effect of Hb E by means of a mixed erythrocyte invasion assay. In vitro, starting at 1% parasitemia, Plasmodium falciparum preferentially invaded normal (Hb AA) compared to abnormal hemoglobin red blood cells, including those heterozygous and homozygous for Hb E. The heterozygote Hb AE cells differed markedly from all the other cells tested, with invasion restricted to approximately 25% of the red blood cells. Despite their microcytosis, AE heterozygous cells were functionally relatively normal in contrast to the red blood cells from the other hemoglobinopathies studied. Chotivanich et al. (2002) interpreted these findings as suggesting that Hb AE erythrocytes have an unidentified membrane abnormality that renders most of the red blood cell population relatively resistant to invasion by P. falciparum. This would not protect from uncomplicated malaria infections but would prevent the development of heavy parasite burdens and was considered consistent with the 'Haldane hypothesis' of heterozygote protection against severe malaria for Hb E.
See Vella et al. (1967) and Gonzalez-Redondo et al. (1987). Gurgey et al. (1990) found compound heterozygosity for this mutation and beta-thalassemia of type IVS1-6 (141900.0360). Igarashi et al. (1995) identified Hb E-Saskatoon in a Japanese male. Igarashi et al. (1995) reported what they stated was the first case of Hb-E (Saskatoon) in a Japanese male.
Birben et al. (2001) described Hb E-Saskatoon in homozygous state in a 30-year-old Turkish woman. The consanguineous parents were heterozygotes for the abnormal hemoglobin. The heterozygous son of the proband had mild anemia; physical examination of the child and family members revealed no abnormalities. The parameters of routine hematologic studies were within normal limits.
See Labossiere et al. (1971). Landin et al. (1996) pointed out that 2 nucleotide substitutions in codon 50, either ACT to AAA, or ACT to AAG, would be required to produce this amino acid substitution. The same is true for the amino acid substitutions in Hb Bristol (141900.0030) and Hb Beckman (141900.0442) among the beta-globin variants and Hb J-Kurosh (141800.0066), an alpha-globin variant.
In a Spanish female with mild hemolytic anemia, Villegas et al. (1989) demonstrated this mildly unstable hemoglobin.
See Moo-Penn et al. (1976). In 5 apparently, unrelated Spanish adults, Qin et al. (1994) found a fast-moving hemoglobin variant and observed a GGC-to-GAC mutation at codon 119 which had previously been identified as the abnormality in Hb Fannin-Lubbock. In addition, however, they found a GTC-to-CTC change at codon 111 which led to a val-to-leu substitution. Protein analysis in one of the individuals confirmed that the 2 mutations were located on the same chromosome. Qin et al. (1994) suggested that some other known variants may carry an additional mutation that results in an electrophoretically silent amino acid substitution which may, however, have an effect on the physicochemical properties of the protein. In the case of Hb Fannin-Lubbock, it appeared likely that the val111-to-leu substitution, rather than the gly119-to-asp replacement, was the cause of the instability of the variant. The Hb Fannin-Lubbock variant in these Spanish families had a normal oxygen affinity.
Deletion of val23 from otherwise normal beta chain probably occurred through triplet deletion resulting from unequal crossing-over between 2 normal beta loci in 1 parent of the proband. Two of 3 living children of the proband also had the abnormal hemoglobin, which was accompanied by slight cyanosis in all 3 and by a hemolytic process in the proband. See Jones et al. (1966) and Horst et al. (1988).
See Harano et al. (1990).
See Hidaka et al. (1988).
There is no clinical or hematologic abnormality in the homozygote. See Edington et al. (1955), Gammack et al. (1961), Lehmann et al. (1964), and Milner (1967).
See Sick et al. (1967), Schiliro et al. (1981), and Chen et al. (1985).
See Schneider et al. (1964), Bowman et al. (1967), Vella et al. (1967), Blackwell et al. (1967), Blackwell et al. (1968), Blackwell et al. (1969), Ohba et al. (1978), Niazi et al. (1981), and Dincol et al. (1989).
See Giardina et al. (1978).
See Bowman et al. (1962, 1964).
See Blackwell et al. (1972).
See Blackwell et al. (1970).
This hemoglobin oxy was first described in a family of Calabrian origin by Schwartz et al. (1957). The molecular defect was demonstrated by Hill et al. (1960). Brancati et al. (1989) reported a case of homozygosity in a healthy male with normal hematologic findings. See Hill and Schwartz (1959), Ricco et al. (1974), Wilson et al. (1980), and Schiliro et al. (1981).
See Blackwell et al. (1969), Imai et al. (1970), Kaufman et al. (1975), Welch (1975) and Romero et al. (1985). Schiliro et al. (1991) found this abnormal hemoglobin in 4 members from 2 generations of a Sicilian family.
See Blackwell et al. (1969), Zeng et al. (1981), and Landman et al. (1987).
See Blackwell and Liu (1968).
See Chen et al. (1985).
See Marinucci et al. (1977).
See Como et al. (1984).
Unstable hemoglobin. See Sansone et al. (1967), Labie et al. (1972), Kendall et al. (1979), Shibata et al. (1980), and Hopmeier et al. (1990).
See Baklouti et al. (1987).
Deletion of amino acid residues 93-97 inclusive of beta chain probably through unequal crossing over. This unstable hemoglobin also has absence of half of the normal complement of heme. Other unstable hemoglobins include Hb Zurich, Hb Koln, Hb Geneva, Hb Sydney, Hb Hammersmith and Hb Sinai. (It is possible that the deletion is 91-95 or 92-96 rather than 93-97.) See Bradley et al. (1967) and Rieder and Bradley (1968). See Hb Koriyama (141900.0152).
See Altay et al. (1976) and Huisman et al. (1986).
By isoelectric focusing (IEF) of red cell hemolysates, this hemoglobin variant simulates glycated hemoglobin (Hb A1c). This is the first mutation discovered at beta 116. It was first found in a 6-year-old boy with diabetes mellitus; 5 nondiabetic members of the family had the same hemoglobin variant (Blanke et al., 1988). (Hafnia is Latin for Copenhagen.)
During neonatal screening in Belgium, Cotton et al. (2000) found a newborn of Brazilian origin with Hb Hafnia. Both he and his mother were heterozygous for a CAT-to-CAA transversion at codon 116. Both were clinically and hematologically normal.
See Rahbar et al. (1975).
See Manca et al. (1987) and Wong et al. (1984). Manca et al. (1992) described an easy PCR-based method for demonstration of the mutation. They demonstrated the predicted G-to-A transition at codon 11 which abolishes a MaeIII restriction site. This mutation, which is rather common among Sardinians, involves one of the 5 CpG dinucleotides of the beta-globin gene.
The normal phenylalanine at this site apparently 'stabilizes' the heme with which it is in contact. The substitution of serine leads to severe Heinz body hemolytic anemia. See Dacie et al. (1967), Ohba et al. (1975), and Rahbar et al. (1981). Dianzani et al. (1991) demonstrated a de novo phe42-to-ser mutation using the chemical cleavage of mismatch method (CCM) of Cotton et al. (1988). The responsible substitution was a TTT-to-TCT change. The report of rare cases of this hemoglobinopathy in different ethnic groups also supports the occurrence of independent mutations.
See Blouquit et al. (1985).
Hb Heathrow is a cause of erythrocytosis because of increase in oxygen affinity. The mutation occurs in the same codon as that in Hb Saint Nazaire (141900.0436).
See White et al. (1973).
This is a cause of familial erythrocytosis. See Ikkala et al. (1976).
See Blouquit et al. (1976) and Bardakdjian et al. (1987).
See Miyaji et al. (1968).
Heterozygotes have about 60% hemoglobin Hikari. See Shibata and Iuchi (1962) and Shibata et al. (1964).
This hemoglobin was found in a diabetic because its N-terminal glycation was about 3 times that of the normal (Ohba et al., 1986).
See Moo-Penn et al. (1989).
See Yanase et al. (1968) and Ohba et al. (1983).
Associated with increased oxygen affinity, decreased Bohr effect, and erythremia. (The substitution was formerly thought to be at residue 143.) See Hamilton et al. (1969) and Perutz et al. (1971).
See Miyaji et al. (1968), Brittenham et al. (1978), Ohba et al. (1981), and Arends et al. (1985).
See Minnich et al. (1965), Steinberg et al. (1974, 1976), Charache et al. (1979), Harano et al. (1983), Martinez and Colombo (1984), and Enoki et al. (1989). In a Thai Mien family, Pillers et al. (1992) observed Hb Hope in compound heterozygous state with Hb E. Previous reports of Hb Hope had involved predominantly black Americans, blacks who lived in Cuba, or natives of Mali who lived in France.
See Iuchi et al. (1978) and Shibata et al. (1980). Plaseska et al. (1991) observed this mutation, due to a GAG-to-CAG change at codon 43, in a Yugoslavian family.
See Blouquit et al. (1981).
See Boulton et al. (1970), Lacombe et al. (1987), and Wilkinson et al. (1987).
Hamaguchi et al. (2000) reported the first case of hemoglobin I (High Wycombe) in Japan. It was suspected because of a discrepancy between blood glucose status and glycated hemoglobin measurements in a 55-year-old diabetic female.
See Rosa et al. (1969) and Labie et al. (1971).
Adams et al. (1978, 1979) studied father and daughter with a clinical picture of beta-thalassemia which was due to labile beta-chains resulting in Heinz body formation in normoblasts. The changes in the beta-chains were posttranslational. Baiget et al. (1986) and De Biasi et al. (1988) described 2 new families with the cys112-to-arg mutation. In these families the carriers were not anemic, had normal chromic and normocytic red cells, and displayed only mild reticulocytosis. This prompted Coleman et al. (1991) to restudy the original family with the finding that the mutation in fact was leu106-to-arg. In order to avoid confusion, they renamed the original mutation Hb Terre Haute (see 141900.0398).
One patient had an apparent new mutation; the father was 41 years old and the mother 36 at the patient's birth (Aksoy et al. (1972)). See Beuzard et al. (1972) and Aksoy and Erdem (1979).
De Weinstein et al. (2000) described this hemoglobin variant in a 36-year-old Argentinian female of Spanish-Portuguese origin. She presented with chronic hemolytic anemia, jaundice, splenomegaly, and gallstones from childhood. She required blood transfusion during her only pregnancy at the age of 23. She underwent splenectomy and cholecystectomy when she was 33 years old. Her 13-year-old son also presented with chronic hemolytic anemia, jaundice, and splenomegaly. It was the third observation of this hemoglobin variant. In the first 2 cases, origination was by de novo mutation. This was the first case in which the precise DNA change was identified: codon 92 was changed from CAC (his) to CAG (gln).
See Adams et al. (1975, 1978).
See Elion et al. (1979) and Harano et al. (1990).
See Huisman et al. (1986).
See Williamson et al. (1987).
Fast hemoglobin. See Went and MacIver (1959), Gammack et al. (1961), Sydenstricker et al. (1961), Huisman and Sydenstricker (1962), Weatherall (1964), Chernoff and Perillie (1964), Wilkinson et al. (1967), Wong et al. (1971), and Musumeci et al. (1979).
See Clegg et al. (1966), Blackwell and Liu (1966), Pootrakul et al. (1967), Blackwell et al. (1970), and Iuchi et al. (1981).
See Garel et al. (1976).
See Tentori (1974) and Marinucci et al. (1979).
See Romain et al. (1975). This hemoglobin was discovered in a 2-year-old black child from Chicago, who was hospitalized for iron deficiency anemia. The second case was reported in a Spanish family by Arrizabalaga et al. (1998).
See Bardakdjian et al. (1988).
See Boissel et al. (1982).
The first reported cases were in a Cuban family of African ancestry (Martinez et al., 1977). Wajcman et al. (1988) described a case from Benin in Nigeria. Also see Zhu et al. (1988) and Sciarratta et al. (1990). Yamagishi et al. (1993) identified this mutation in a Japanese family during assay of glycated hemoglobins by ion exchange high performance liquid chromatography. No anemia or hemolysis was observed in the affected members of the family, although one member had a decreased haptoglobin value.
See Gammack et al. (1961), Rahbar et al. (1967), and Delanoe-Garin et al. (1986). Bircan et al. (1990) observed compound heterozygosity of this variant with Hb N (Baltimore) (141900.0188).
See Blackwell et al. (1971) and Blackwell et al. (1972). Chang et al. (1992) described a new RFLP created by this substitution.
See Djoumessi et al. (1981).
See Wajcman et al. (1977) and Prior et al. (1989).
See Lin et al. (1992).
See Salomon et al. (1965) and Sick et al. (1967).
Plaseska-Karanfilska et al. (2000) described Hb Rambam in a family in Argentina. It was combined in compound heterozygous state with a form of beta-zero-thalassemia due to deletion of 2 nucleotides (CT) from codon 5. The latter mutation had been found among Bulgarian, Turkish, Greek, Macedonian, North African, and Middle Eastern populations, and in some populations of the Indian subcontinent.
See Ricco et al. (1974).
See Blackwell et al. (1969).
See Lu et al. (1983).
See Jones et al. (1990).
See Allan et al. (1965).
See Allan et al. (1965). Castagnola et al. (1990) found this variant in an Italian family.
See Allan et al. (1965) and Ringelhann et al. (1971).
Codon 30 (for arginine) is interrupted between the second and third nucleotide by the first intervening sequences of 130 nucleotides. Modifications of the consensus sequence of the donor-splice site of IVS1 will affect the process of splicing. In hemoglobin Monroe, the G-to-C mutation occurred at a nucleotide position adjacent to the GT dinucleotide required for splicing; this substitution would be expected to cause greatly decreased splicing and severe beta-plus-thalassemia, as was observed in the family reported by Gonzalez-Redondo et al. (1989). In a Mediterranean type of beta-plus-thalassemia, Vidaud et al. (1989) found a G-to-C transversion in codon 30 that altered both beta-globin pre-mRNA splicing and the structure of the hemoglobin product. Presumably, this G-to-C transversion at position -1 of intron 1 reduced severely the utilization of the normal 5-prime splice site, since the level of the arg-to-thr mutant hemoglobin (designated hemoglobin Kairouan) was very low in heterozygotes (2% of total hemoglobin). Since no natural mutations of the guanine located at position -1 of the CAG/GTAAGT consensus sequence had been isolated previously, Vidaud et al. (1989) studied the role of this nucleotide in cell-free extracts. They found that correct splicing was 98% inhibited. Thus, the last residue of exon 1 plays a role at least equivalent to that of the intron residue at position 5.
This hemoglobin variant has a low oxygen affinity, resulting in cyanosis. See Reissmann et al. (1961) and Bonaventura and Riggs (1968).
See Reed et al. (1968).
See Delanoe-Garin et al. (1985).
See Clegg et al. (1969).
See Arous et al. (1982), Rouabhi et al. (1983), Galacteros et al. (1984), Elwan et al. (1987), and Kutlar et al. (1989). Hemoglobin Knossos is a cause of beta-thalassemia, as is hemoglobin E. Orkin et al. (1984) isolated the beta(Knossos) gene and examined its expression in HeLa cells. Using a cryptic splice sequence that is enhanced by the Knossos substitution, they found that some beta(Knossos) transcripts were abnormally processed. In addition to Hb E, a silent substitution at beta 24 causes thalassemia by abnormal RNA processing.
See Harano et al. (1986).
See Shibata et al. (1961), Pribilla (1962), Hutchison et al. (1964), Pribilla et al. (1965), Carrell et al. (1966), Jackson et al. (1967), Jones et al. (1967), Woodson et al. (1970), Miller et al. (1971), Lie-Injo et al. (1972), and Ohba et al. (1973). Bradley et al. (1980) described a convincing instance of gonadal mosaicism accounting for an unusual pedigree pattern in a family with Hb Koln. Normal parents had 2 affected children and each of these 2 children had an affected child. This is the most common form of unstable hemoglobin. Horst et al. (1986) prepared DNA of 19 nucleotides, corresponding in length to the normal and mutant gene sequences, and demonstrated its use for the direct assay of the beta-Koln gene. The use of synthetic oligonucleotides established that the Hb Koln mutation is due to a G-to-A transition.
Landin et al. (1994) found Hb Koln as a new mutation in 3 independent cases of chronic hemolytic anemia in Sweden. The 2 children and 1 adult had partially compensated hemolysis and presented with aggravated hemolysis during acute infections in childhood. In 1 patient, acute B19 parvovirus infection induced an aplastic crisis. Diagnosis was based on hemoglobin instability testing and isoelectric focusing of hemoglobin dimers. Landin et al. (1994) demonstrated that PCR-RFLP can be used in diagnosis.
Chang et al. (1998) reported the first case of Hb Koln in the Chinese population.
See Kawata et al. (1988). Whereas 5 amino acid residues are deleted in Hb Gun Hill (141900.0095), 5 amino acid residues are inserted at the corresponding site in Hb Koriyama.
Since this same substitution is present with the sickle hemoglobin change as one of the two defects in hemoglobin C(Harlem), Konotey-Ahulu et al. (1968) suggested that the latter hemoglobin may have arisen by intracistronic crossing-over in an individual with the Korle-Bu gene on one chromosome and the sickle gene on the other. See Konotey-Ahulu et al. (1968) and Honig et al. (1983). Nagel et al. (1993) showed that compound heterozygosity for hemoglobin Korle-Bu (Hb KB) and Hb C (141900.0038) is associated with moderate chronic hemolytic anemia with microcytosis. They found that in vitro hemoglobin crystals formed within 2 minutes compared with 30 minutes for a mixture of 40% Hb C and 60% Hb S and within 180 minutes for 40% Hb C with 60% Hb A. The crystals were cubic in contrast with the tetragonal crystals observed in CC and SC disease. They concluded that the hemolysis observed in the Hb KB/C compound heterozygote is likely to be secondary to the acceleration of Hb crystallization.
See Merault et al. (1986).
See Malcorra-Azpiazu et al. (1988).
See De Jong et al. (1968), Juricic et al. (1983), and Schroeder et al. (1982).
See Honig et al. (1978). A beta-delta (anti-Lepore) variant found in a Mexican family, its amino acid structure of the non-alpha polypeptide indicated a crossover between amino acids 22 and 50. Honig et al. (1978) postulated a series of intergenic crossovers. The residue corresponding to the 137th in the delta chain is deleted. See Hb P(Nilotic).
See Jeppsson et al. (1984) and Ali et al. (1988). This variant was detected by oxygen equilibrium measurements and confirmed by IEF in Finns with erythrocytosis (Berlin et al., 1987) and in Americans of Finnish extraction (Jones et al., 1986). Wada et al. (1987) stated that 'in Finland, there are many patients with benign familial erythrocytosis, some of whom have Hb Helsinki' (q.v.).
See Bromberg et al. (1973) and Francina et al. (1987). Heterozygotes have marked erythrocytosis as in the case of Hb Chesapeake, J (Capetown), Malmo, Rainier, Bethesda, Yakima, Kempsey, and Hiroshima.
This hemoglobin shows decreased stability on warming to 65 degrees C and an increased tendency to dissociate in the presence of sulfhydryl group-blocking agents. Clinically, it results in mild hemolytic anemia. See Keeling et al. (1971), Bratu et al. (1971), and Villegas et al. (1989).
See Schmidt et al. (1977) and Shimizu et al. (1988). Hb Lufkin is unstable, causing a mild but well-compensated hemolytic anemia. It was initially described in a black American boy from Texas. Gu et al. (1995) found this variant in combination with Hb S in a black child who had a mild form of sickle cell disease, comparable to SC or SE disease.
Deletion of beta 17-18 (lys-val). See Solal et al. (1974).
See Gerald and Efron (1961), Hayashi et al. (1969), Perutz et al. (1972), and Horst et al. (1983). This is now usually called simply Hb M (Milwaukee) since Hb M (Milwaukee-2) has been shown to be the same as Hb M (Hyde Park). The family reported by Pisciotta et al. (1959) was of Italian extraction. Hb M (Milwaukee) was also described in a German family by Kohne et al. (1977). Oehme et al. (1983) followed the mutant beta-globin gene through 3 generations of this family by direct SstI analysis at the gene level. The molecular defect is a transversion T to A and because of the known recognition sequence of SstI, the nucleotide sequence corresponding to amino acids 67 and 68 can be established to be GAGCTC instead of GTGCTC.
See Pisciotta et al. (1959), Heller et al. (1966), Shibata et al. (1968), and Stamatoyannopoulos et al. (1976). Rotoli et al. (1992) described the case of a cyanotic 7-year-old girl who was found to have 16% methemoglobin. By molecular genetic studies, they demonstrated that this was a case of Hb M (Hyde Park). Hutt et al. (1998) showed by DNA sequence analysis that the mutation in M (Milwaukee-2), M (Hyde Park), and M (Akita) are all due to a change of codon 92 from CAC (his) to TAC (tyr).
This was the abnormal hemoglobin in the family with autosomal dominant cyanosis reported by Baltzan and Sugarman (1950). See Horlein and Weber (1948), Heck and Wolf (1958), Gerald and George (1959), Gerald and Efron (1961), Shibata et al. (1961, 1965), Heller (1962), Josephson et al. (1962), Hanada et al. (1964), Murawski et al. (1965), Hobolth (1965), Betke et al. (1966), Efremov et al. (1974), Kohne et al. (1975), and Baine et al. (1980). Suryantoro et al. (1995) described the his63-to-tyr mutation in an Indonesian boy with methemoglobinemia and mild hemolysis. The mutation was inherited from the mother. The report further demonstrated the worldwide distribution of Hb M-Saskatoon.
See Harano et al. (1982).
The hemoglobin Madrid variant was first discovered by Outeirino et al. (1974) in a Spanish patient whose parents did not carry the abnormality. A second case was observed in an American black teenager by Molchanova et al. (1993); although there was a family history of chronic hemolytic anemia, none of the family members was available for evaluation. Kim et al. (2000) described Hb Madrid in a Korean family with chronic hemolytic anemia. The amino acid substitution was due to a change at codon 115 from GCC (ala) to CCC (pro).
Yang et al. (1989) found an A-to-G change in codon 19 resulting in beta-plus-thalassemia in a Malaysian.
See Lorkin and Lehmann (1970), Fairbanks et al. (1971), Boyer et al. (1972), Berglund (1972), and Berglund and Linell (1972).
Landin et al. (1996) found this hemoglobin variant with increased oxygen affinity causing erythrocytosis in 2 apparently unrelated Swedish families. In 1 family, the his97-to-gln substitution was caused by a change from CAC-to-CAA; in the other family a CAC-to-CAG change was found.
See Marinucci et al. (1983).
In this abnormal hemoglobin, found by isoelectric focusing in a hematologically normal though diabetic Maltese woman living in Marseille, Blouquit et al. (1984, 1985) demonstrated a double abnormality: a methionyl residue extending the NH2 terminus. This is an example of the increasing number of hemoglobin variants detected in the course of Hb A1c evaluation in diabetics. Without DNA data, the authors concluded that proline in position 2 constitutes a steric impairment to the methionyl peptidase that normally eliminates the initiating methionine. The same hypothesis has been invoked to explain the apparent persistence of the initiator methionyl residue in naturally occurring proteins with a met-X sequence at the NH2-terminus, X being either a charged amino acid or a proline. Initial sequence, with abnormal residues in parentheses, equals H2N-(met)-val-(pro)-leu-thr-glu-glu-. Prchal et al. (1986) showed that the only lesion in DNA is an adenine-to-cytosine transversion in the second codon. Also see Barwick et al. (1985). Boi et al. (1989) detected this variant in Australia in the course of monitoring glycated hemoglobin (Hb A1c) in diabetics. It causes a discrepancy between the Hb A1c measurement and the clinical state of the diabetic patient.
See Ohba et al. (1989).
Sciarratta and Ivaldi (1990) discovered this electrophoretically slow-moving variant in an Italian family. Numerous red cells contained inclusion bodies, and heat and isopropanol tests demonstrated decreased stability of the hemoglobin.
See Buckett et al. (1974).
The beta chain is only 144 amino acids long. The codon for beta 145 tyr has been changed to a terminator. Polycythemia is the clinical manifestation. See Winslow et al. (1975) and Rahbar et al. (1983).
See Hedlund et al. (1984).
See Adams et al. (1985). Hemoglobin Mississippi has anomalous properties that include disulfide linkages with normal beta-, delta-, gamma-, and alpha-chains, and the formation of high molecular weight multimers. Heterozygotes for Hb MS are clinically and hematologically normal and heterozygotes for the beta-plus-thalassemia gene have mild microcytic anemia; however, the proband in the family initially discovered by Steinberg et al. (1987) had all the hematologic features of thalassemia intermedia in the compound heterozygous state. Steinberg et al. (1987) suggested that the unexpectedly severe clinical expression in the mixed heterozygote, as they called the state, may result from the proteolytic digestion of Hb MS as well as the excessive alpha-chains characteristic of beta-plus-thalassemia.
See Harano et al. (1985).
Lepore. For explanation, see hemoglobin P (Congo) (141900.0214). From a DNA sequence analysis of the Hb Miyada gene, Kimura et al. (1984) concluded that the shift from the 5-prime beta-globin gene to the 3-prime delta-globin gene occurred somewhere in a homologous sequence region between the third nucleotide of the 17th codon and the second nucleotide of the 22nd codon of these two genes.
See Nakatsuji et al. (1981) and Ohba et al. (1984).
See Ohba et al. (1977). Keeling et al. (1991) observed this variant in a Caucasian boy from Kentucky.
As noted by Harthoorn-Lasthuizen et al. (1995), Hb Mizuho is one of the more markedly unstable hemoglobin variants and is difficult to detect both by protein analysis and by sequencing of the amplified beta chain. The instability is due to the introduction of a proline residue in helix E, of which 5 residues form part of the heme contact. Harthoorn-Lasthuizen et al. (1995) identified a fourth case in a Dutch boy.
See Shibata et al. (1980).
See Schneider et al. (1975) and Converse et al. (1985).
See Idelson et al. (1974).
See Spivak et al. (1982).
Fast hemoglobin. See Ager and Lehmann (1958), Chernoff and Weichselbaum (1958), and Gammack et al. (1961).
See Clegg et al. (1965), Dobbs et al. (1966), Gottlieb et al. (1967), Ballas and Park (1985), and Anderson Fernandes (1989). In heterozygotes the concentration of Hb N (Baltimore) is the same as that of Hb A. Hemoglobin Kenwood was previously reported incorrectly as having either aspartic acid or glutamic acid at beta 143. See personal communication from Heller in Hamilton et al. (1969).
See Schroeder and Jones (1965).
See Jones et al. (1968).
See Lena-Russo et al. (1989).
See Maekawa et al. (1970). Nakamura et al. (1997) identified a second case in a Japanese family. The proband was a 47-year-old diabetic male. The anomaly was identified during the HPLC assay for HBA1c. The abnormal beta chain comprised about 44% of the total beta chain as opposed to 30% in the previous report.
Hb Nagoya is an unstable hemoglobin found in father and son in Japan (Ohba et al., 1985).
During an investigation for erythrocytosis, Keclard et al. (1990) found this electrophoretically silent beta chain variant in a French-Caucasian male. The sister, mother, and grandmother carried the same abnormal hemoglobin in heterozygous state. The mother showed mild erythrocytosis.
See Moo-Penn et al. (1985).
This variant was found in a Chinese-American family. See Ranney et al. (1967), Kendall and Pang (1980), Saenz et al. (1980), and Todd et al. (1980).
See Finney et al. (1975).
Deletion of phenylalanine, glutamic acid and serine at either beta 42-44 or beta 43-45. See Praxedes et al. (1972).
Increased oxygen affinity. Discovered in a 52-year-old man treated since age 20 years for polycythemia vera with various measures including several courses of 32(P) (Rahbar et al., 1985).
See Arends et al. (1977), Brennan et al. (1977), Adams et al. (1982), and Gurney et al. (1987).
See Gordon-Smith et al. (1973) and Orringer et al. (1978). The patient of Orringer et al. (1978) was a 7-year-old boy with severe hemolytic anemia in whom great improvement in clinical status, including rate of growth, was noted 1 year after he underwent a splenectomy and cholecystectomy. Cepreganova et al. (1992) described severe hemolytic anemia in a 7-year-old Canadian boy with Hb Nottingham. Brabec et al. (1994) reported a fourth case in an 8-year-old girl in the Czech Republic with severe hemolytic anemia.
This hemoglobin has been found in American blacks, Bulgarians, and Arabs (Kamel et al., 1967). Little et al. (1980) illustrated the fact that point mutation can be recognized by the change in susceptibility to cleavage by specific restriction endonucleases. The examples were: Hb O(Arab) with EcoRI, Hb J(Broussais) with HindIII, and Hb F(Hull) with EcoRI. The sickle cell mutation eliminates a site for MnlI. See Ramot et al. (1960), Kamel et al. (1966), Vella et al. (1966), Milner et al. (1970), and Charache et al. (1977).
See Beresford et al. (1972).
High oxygen affinity leads to erythrocytosis. See Moo-Penn et al. (1980).
See Charache et al. (1973).
See Harano et al. (1983).
See Harano et al. (1984).
See Fairbanks et al. (1969) and Lorkin and Lehmann (1970). Thuret et al. (1996) described a second case of this unstable hemoglobin. The clinical course of a 12-year-old boy was characterized by severe hemolytic anemia leading to splenectomy and cholecystectomy at the age of 3.5 years. Priapism occurred 8 years after splenectomy, during a hemolytic febrile episode, and required aspiration of the corpora cavernosa. Splenectomy in cases of chronic hemolytic anemia due to an unstable hemoglobin lowers the frequency and severity of acute hemolytic attacks but vascular complications often occur. The original patient with Hb Olmsted, described by Fairbanks et al. (1969) died of chronic pulmonary disease with pulmonary hypertension at age 36 years. The patient reported by Thuret et al. (1996) had a French mother and Spanish father.
This beta-chain variant, associated with erythrocytosis, was first discovered in a member of a Czechoslovakian family (Indrak et al., 1987). Tagawa et al. (1992) found the same mutation in a Japanese family.
Since GUG to AUG is the only single base change that can result in this substitution, the codon for beta 20 can be uniquely identified as GUG. See Stamatoyannopoulos et al. (1973) and Weaver et al. (1984). Berlin and Wranne (1989) described hemoglobin Olympia in a Swedish family.
Compensatory erythrocytosis results from its high oxygen affinity. See Charache et al. (1975), Gacon et al. (1975), Kleckner et al. (1975), and Butler et al. (1982).
Kattamis et al. (1997) found hemoglobin Osler in 2 members of an African-American family with erythrocytosis. Sequence analysis of DNA from the proband showed heterozygosity for a T-to-A transversion at the first position of codon 145 in the HBB gene, which resulted in the substitution of an asparagine for normal tyrosine. The second cycle of C-terminal amino acid sequence analysis of a mixture of alpha- and beta-globin chains showed tyrosine, aspartic acid, and small amounts of asparagine. Collectively, these results were interpreted as indicating the existence of a mutation at codon 145 of the HBB gene, which codes for asparagine instead of tyrosine, and that asparagine then undergoes initial posttranslational deamidation to aspartic acid. Thus the mutation is tyr145asn, not tyr145asp, as initially thought. Posttranslational modifications had been described in 4 other beta-globin chains and 2 alpha-globin chain variants: Hb Providence (141900.0227), Hb Redondo, or Isehara (141900.0404), Hb La Roche-sur-Yon (141900.0482), Hb J (Singapore) (141800.0075), Hb Wayne (141850.0004), and the only variant in which the posttranslational modification does not involve an asn-to-asp substitution, Hb Bristol (val167met-asp; 141900.0030).
Konotey-Ahulu et al. (1971) first observed this nonpathologic mutant in a Ghanaian patient with Hb S (141900.0243). By molecular analysis of the HBB gene, Giordano et al. (1999) identified the same mutant in 2 unrelated families of African origin living in the Netherlands, one from Ghana and the other from the Dominican Republic. In all carriers of both families, the mutation was associated with haplotype 11, an infrequent haplotype in the West African population, suggesting a single common mutation event. Giordano et al. (1999) stated that because Hb Osu-Christiansborg migrates at a similar rate to that of Hb S in alkaline hemoglobin electrophoresis, it can easily be mistaken for Hb S.
See Silvestroni et al. (1963), Schneider et al. (1969), and Di Iorio et al. (1975).
Lepore. Unlike the delta-beta fusion product of Lepore hemoglobin, the non-alpha chain resembles beta at the NH2-end. Furthermore, Hb A2 is present in normal concentrations and both Hb A and Hb S (or other beta variant) can be present in the patient heterozygous for hemoglobin P (Congo). The explanation for the origin of hemoglobin Lepore and hemoglobin P (Congo) (nonhomologous pairing and unequal crossing-over) is diagrammed in Fig. 2.20 (p. 41) of McKusick (1969). The fusion occurs between beta 22 and delta 116 (Lehmann and Charlesworth, 1970). See Dherte et al. (1959), Lehmann et al. (1964), Lambotte-Legrand et al. (1960), and Gammack et al. (1961).
Hb Miyada. The fusion site is beta 22 to delta 50. Thus, Hb P(Nilotic) is identical to Hb Lincoln Park (141900.0157) except for deletion of delta residue 137 in Hb Lincoln Park. Thus, it is the complement of Hb Lepore (Hollandia). See Badr et al. (1973). Among 8 chromosomes carrying the Hb P (Nilotic) hybrid gene, Lanclos et al. (1987) found only 1 haplotype.
See Brennan et al. (1982).
See Johnson et al. (1980) and Rahbar et al. (1988).
This is an unstable hemoglobin resulting in hemolytic anemia. See Jackson et al. (1973), Honig et al. (1973), Rousseaux et al. (1980), and Shibata et al. (1980).
See King et al. (1972).
Nakanishi et al. (1998) provided the second report of Hb Peterborough and the first of its occurrence in Japan.
An unstable hemoglobin leading to hemolytic anemia. No electrophoretic abnormality. See Rieder et al. (1969) and Asakura et al. (1981).
See Baklouti et al. (1988).
Associated with erythrocytosis. See Blouquit et al. (1980).
See Lacombe et al. (1985).
This hemoglobin has an extra reactive thiol group because of the substitution of cysteine for serine. Octamers and dodecamers form in hemolysates of heterozygotes and homozygotes, respectively, on standing, through linkage between tetramers by disulfide bridges. See Tondo et al. (1963), Bonaventura and Riggs (1967), Seid-Akhavan et al. (1973), and Tondo (1977).
Salzano (2000) tabulated the Hbb variants observed in Latin America and provided further information on Hb Porto Alegre, which had been discovered by his group in a family of Portuguese descent living in the Brazilian city of that name. Substitution of cysteine for serine at the ninth residue of the chain created a sulfhydryl group on the surface of the molecule, allowing formation of intermolecular disulfide bonds. However, polymerization occurs in vitro but not in vivo, and the variant hemoglobin leads to no clinical problems. Lack of polymerization in vivo may be because of a compensatory synthesis of glutathione reductase.
See Charache et al. (1978) and Lacombe et al. (1987).
See Moo-Penn et al. (1978), Horst et al. (1983), and Villegas et al. (1986). Using PCR and direct sequencing, Schnee et al. (1990) demonstrated that the molecular defect is a C-to-G substitution in codon 108; this eliminates an MaeII restriction site.
The beta variant lys108 enhances the stability of hemoglobin in the deoxy-state, conferring low affinity for oxygen binding in vitro. Suzuki et al. (2002) generated mutant mice carrying the Presbyterian mutation at the beta-globin locus by a targeted knockin strategy. Heterozygous mice showed the expression of Hb Presbyterian in 27.7% of total peripheral blood without any hematologic abnormalities, which well mimicked human cases. On the other hand, homozygous mice exclusively expressed Hb Presbyterian in 100% of peripheral blood associated with hemolytic anemia, Heinz body formation, and splenomegaly. Hb Presbyterian showed instability in an in vitro precipitation assay. Erythrocytes from homozygous mice showed a shortened life span when transfused into wildtype mice, confirming that the knocked-in mutation of lys108 caused hemolysis in homozygous mice. Suzuki et al. (2002) stated that this was the first report on the hemolytic anemia of unstable hemoglobin in an animal model. The results confirmed the notion that the higher ratio of an unstable variant beta-globin chain in erythrocytes triggers the pathologic precipitation and induces hemolysis in abnormal hemoglobinopathies.
See Moo-Penn et al. (1976), Charache et al. (1977), and Bardakdjian et al. (1985).
See Tatsis et al. (1972) and Yamada et al. (1977). Schiliro et al. (1991) found this hemoglobin variant in a mother and son in Sicily who were both clinically and hematologically normal.
See Pong et al. (1983).
Cause of polycythemia. See Weatherall et al. (1977).
See Lorkin et al. (1975) and Sugihara et al. (1985). Beta 82 is at the binding site of 2,3-diphosphoglycerate. Hb Rahere is accompanied by erythrocytosis.
See Stamatoyannopoulos et al. (1968), Adamson et al. (1969), Stamatoyannopoulos and Yoshida (1969), Greer and Perutz (1971), Hayashi et al. (1971), and Salhany (1972). Hb Rainier causes erythrocytosis and is the only adult hemoglobin that is alkali-resistant. See Hb Bethesda (141900.0022), with which Rainier was confused earlier. Peters et al. (1985) studied a hemoglobin mutation induced by ethylnitrosourea in the mouse. Substitution of cysteine for tyrosine at codon 145 of the HBB gene was demonstrated by amino acid analysis. They proposed that an A-to-G transition in the tyrosine codon (TAC-to-TGC) had occurred. The mouse was polycythemic.
Carbone et al. (1999) identified a high oxygen affinity hemoglobin variant in a 53-year-old male from Naples, Italy, who suffered from pulmonary thromboembolism and polycythemia. Characterization of this variant at the protein level detected the presence of Hb Rainier. The mutation resulted from an A-to-G transition at the second position of codon 145 of the HBB gene, resulting in a tyr145-to-cys substitution.
Substitution of acetylalanine for valine at beta 1. See Moo-Penn et al. (1977).
See Gilbert et al. (1988).
See Devaraj et al. (1985). Bisse et al. (1991) reported the second affected family. The hemoglobin variant was associated with high oxygen affinity and erythrocytosis.
See Efremov et al. (1969) and Winslow and Charache (1975).
See Moo-Penn et al. (1983).
See Ranney et al. (1968).
See Budge et al. (1977), El-Hazmi and Lehmann (1977), Miyaji et al. (1977), and Pinkerton et al. (1979).
See Merault et al. (1985).
See Gacon et al. (1977) and Danish et al. (1982). Kavanaugh et al. (1992) reported x-ray crystallographic studies.
See Adams et al. (1974).
The change from glutamic acid to valine in sickle hemoglobin was reported by Ingram (1959). Ingram (1956) had reported that the difference between hemoglobin A and hemoglobin S lies in a single tryptic peptide. His analysis of this peptide, peptide 4, was possible by the methods developed by Sanger for determining the structure of insulin and Edman's stepwise degradation of peptides.
Kan and Dozy (1978) used the HpaI restriction endonuclease polymorphism (actually the linkage principle) to make the prenatal diagnosis of sickle cell anemia (603903). As described in 143020, when 'normal' DNA is digested with HpaI, the beta-globin gene is contained in a fragment 7.6 kilobases long. In persons of African extraction 2 variants were detected, 7.0 kb and 13.0 kb long. These variants resulted from alteration in the normal HpaI recognition site 5000 nucleotides to the 3-prime side of the beta-globin gene. The 7.6 and 7.0 kb fragments were present in persons with Hb A, while 87% of persons with Hb S had the 13.0 kb variant. The method is sufficiently sensitive that the cells in 15 ml of uncultured amniotic fluid sufficed. Restriction enzyme studies indicate that whereas Hb S and Hb C originated against the same genetic background (as independent mutations) and the Hb S in the Mediterranean littoral probably is the same mutation as the West African Hb S, Hb S in Asia is apparently a separate mutation. It does not show association with the noncoding polymorphism (Kan and Dozy, 1979).
Mears et al. (1981) used the linkage of the sickle gene with restriction polymorphisms to trace the origin of the sickle gene in Africa. They found evidence that 2 different chromosomes bearing sickle genes were subjected to selection and expansion in 2 physically close but ethnically separate regions of West Africa, with subsequent diffusion to other areas of Africa. The restriction enzyme MnlI recognizes the sequence G-A-G-G, which also is eliminated by the sickle mutation. The MstII enzyme recognizes the sequence C-C-T-N-A-G-G. Predictably, the resulting fragments are larger than those produced by some other enzymes, and MstII is, therefore, particularly useful in prenatal diagnosis (Wilson et al., 1982). The sickle cell mutation can be identified directly in DNA by use of either of 2 restriction endonucleases--DdeI or MstII (Geever et al., 1981; Kazazian, 1982). The nucleotide substitution alters a specific cleavage site recognized by each of these 2 enzymes. The fifth, sixth, and seventh codons of Hb A are CCT-GAG-GAG; in Hb S, they are CCT-GTG-GAG. The recognition site for DdeI is C-T-N-A-G, in which N = any nucleoside. Chang and Kan (1982) and Orkin et al. (1982) found that the assay using the restriction enzyme MstII is sufficiently sensitive that it can be applied to uncultured amniotic fluid cells. The enzyme DdeI requires that the amniotic cells be cultured to obtain enough DNA for the assay.
Antonarakis et al. (1984) applied the Kazazian haplotype method to the study of the origin of the sickle mutation in Africans. Among 170 beta-S bearing chromosomes, 16 different haplotypes of polymorphic sites were found. The 3 most common beta-S haplotypes, accounting for 151 of the 170, were only rarely seen in chromosomes bearing the beta-A gene in these populations (6 out of 47). They suggested the occurrence of up to 4 independent mutations and/or interallelic gene conversions. By haplotype analysis of the beta-globin gene cluster in cases of Hb S in different parts of Africa, Pagnier et al. (1984) concluded that the sickle mutation arose at least 3 times on separate preexisting chromosomal haplotypes. The Hb S gene is closely linked to 3 different haplotypes of polymorphic endonuclease restriction sites in the beta-like gene cluster: one prevalent in Atlantic West Africa, another in central West Africa, and the last in Bantu-speaking Africa (equatorial, East, and southern Africa). Nagel et al. (1985) found hematologic differences between the first 2 types explicable probably by differences in fetal hemoglobin production. Ramsay and Jenkins (1987) found that 20 of 23 sickle-associated haplotypes in southern-African Bantu-speaking black subjects were the same as those found commonly in the Central African Republic, a finding providing the first convincing biologic evidence for the common ancestry of geographically widely separated speakers of languages belonging to the Bantu family. The 3 haplotypes seen with the beta-S gene in Africa are referred to as Senegal, Benin, and Bantu. The 'Bantu line' extends across the waist of Africa; south of the line, Bantu languages are spoken. Based on their study, Ramsay and Jenkins (1987) suggested that the sickle cell mutation arose only once in the Bantu speakers, presumably in their nuclear area of origin, before the Bantu expansion occurred about 2,000 years ago. In Yaounde, the capital city of Cameroon, Lapoumeroulie et al. (1992) observed a novel RFLP pattern in the study of beta-S chromosomes. This chromosome contained an A-gamma-T gene and the RFLP haplotype was different from all the other beta(S) chromosomes in both the 5-prime and 3-prime regions. All the carriers of this specific chromosome belonged to the Eton ethnic group and originated from the Sanaga river valley.
Kulozik et al. (1986) found that the sickle gene in Saudi Arabia and on the west and east coasts of India exists in a haplotype not found in Africa. They concluded that the data are most consistent with an independent Asian origin of the sickle cell mutation. The distribution of the Asian beta-S-haplotype corresponded to the reported geographic distribution of a mild clinical phenotype of homozygous SS disease. Ragusa et al. (1988) found that the beta-S gene in Sicily is in linkage disequilibrium with the Benin haplotype, the same haplotype observed among sickle cell anemia patients from Central West Africa. In addition, this haplotype is either nonexistent or very rare among nonsickling Sicilian persons. They concluded that the beta-S gene was introduced into Sicily from North Africa and that the gene flow originated in Central West Africa, traveling north through historically well-defined trans-Saharan commercial routes.
Zeng et al. (1994) indicated that 5 different haplotypes associated with Hb S had been described, 4 in Africa (Bantu, Benin, Senegal, and Cameroon) and 1 found in both India and Saudi Arabia (Chebloune et al., 1988). There is a correlation between disease severity and haplotype for at least the 2 extremes of severity: patients with the Indian/Arabian haplotype have the mildest course of disease, while those with the Bantu haplotype exhibit the most severe course. Nucleotide -530 is a binding site for a protein called BP1, which may be a repressor of the HBB gene. BP1 binds with the highest affinity to the Indian haplotype sequence and with the weakest affinity to the Bantu sequence, which might explain the differences in clinical course in these different population groups. Zeng et al. (1994) demonstrated the same sequence at -530 bp in patients with the Arabian haplotype as in Indian sickle cell anemia patients. This supports the idea of a common origin of the sickle cell mutation in individuals in India and Saudi Arabia.
Sammarco et al. (1988) presented further strong evidence that the Hb S gene in Sicily was brought by North African populations, probably during the Muslim invasions.
Currat et al. (2002) studied the genetic diversity of the beta-globin gene cluster in an ethnically well-defined population, the Mandenka from eastern Senegal. The absence of recent admixture and amalgamation in this population permitted application of population genetics methods to investigate the origin of the sickle cell mutation (Flint et al., 1993) and to estimate its age. The frequency of the sickle cell mutation in the Mandenka was estimated as 11.7%. The mutation was found strictly associated with the single Senegal haplotype. Approximately 600 bp of the upstream region of the beta-globin gene were sequenced for 94 chromosomes, showing the presence of 4 transversions, 5 transitions, and a composite microsatellite polymorphism. The sequence of 22 chromosomes carrying the sickle mutation was also identical to the previously defined Senegal haplotype, suggesting that the mutation is very recent. Maximum likelihood estimates of the age of the mutation using Monte Carlo simulations were 45 to 70 generations (1,350-2,100 years) for different demographic scenarios.
Embury et al. (1987) described a new method for rapid prenatal diagnosis of sickle cell anemia by DNA analysis. The first step involved a 200,000-fold enzymatic amplification of the specific beta-globin DNA sequences suspected of carrying the sickle mutation. Next, a short radiolabelled synthetic DNA sequence homologous to normal beta-A-globin gene sequences is hybridized to the amplified target sequence. The hybrid duplexes are then digested sequentially with 2 restriction endonucleases. The presence of the beta-A or beta-S gene sequence in the amplified target DNA from the patient determines whether the beta-A hybridization probe anneals perfectly or with a single nucleotide mismatch. This difference affects the restriction enzyme digestion of the DNA and the size of the resulting radiolabelled digestion products which can be distinguished by electrophoresis followed by autoradiography. The method was sufficiently sensitive and rapid that same-day prenatal diagnosis using fetal DNA was possible. The same test could be applied to the diagnosis of hemoglobin C disease. Hemoglobin C (Georgetown) also sickles. See Herrick (1910), Sherman (1940), Neel (1949), Pauling et al. (1949), Allison (1954), Ingram (1956, 1957, 1959), Chang and Kan (1981), and Shalev et al. (1988).
Barany (1991) described a new assay designed to detect single base substitutions using a thermostable enzyme similar to the DNA polymerase used in PCR. This enzyme, DNA ligase, specifically links adjacent oligonucleotides only when the nucleotides are perfectly base-paired at the junction. In the presence of a second set of adjacent oligonucleotides, complementary to the first set and the target, the oligonucleotide products may be exponentially amplified by thermal cycling of the ligation reaction. Because a single base mismatch precludes ligation and amplification, it will be easily distinguished. Barany (1991) demonstrated the utility of the method in discriminating between normal and sickle globin genotypes from 10 microliter blood samples.
Prezant and Fischel-Ghodsian (1992) described a trapped-oligonucleotide nucleotide incorporation (TONI) assay for the screening of a mitochondrial polymorphism and also showed that it could distinguish the genotypes of hemoglobins A/C, A/A, A/S, and S/S. The method was considered particularly useful for diagnosing mutations that do not produce alterations detectable by restriction enzyme analysis. It also requires only a single oligonucleotide and no electrophoretic separation of the allele-specific products. It represents an improved and simplified modification of the allele-specific primer extension methods. (TONI, the acronym for the method, is also the given name of the first author.)
Grosveld et al. (1987) identified dominant control region (DCR) sequences that flank the human beta-globin locus and direct high-level, copy-number-dependent expression of the human beta-globin gene in erythroid cells in transgenic mice. By inserting a construct that included 2 human alpha genes and the defective human beta-sickle gene, all driven by the DCR sequences, Greaves et al. (1990) produced 2 mice with relatively high levels of human Hb S in their red cells. Use of this as an animal model for the study of this disease was suggested.
Turhan et al. (2002) presented evidence suggesting that a pathogenetic mechanism in sickle cell vasoocclusion may reside in adherent leukocytes. Using intravital microscopy in mice expressing human sickle hemoglobin, they demonstrated that SS red blood cells bind to adherent leukocytes in inflamed venules, producing vasoocclusion of cremasteric venules. SS mice deficient in P- and E-selectins, which display defective leukocyte recruitment to the vessel wall, were protected from vasoocclusion. Thus, drugs targeting SS RBC-leukocyte or leukocyte-endothelial interactions might prevent or treat the vascular complications of this disease.
Nitric oxide (NO), essential for maintaining vascular tone, is produced from arginine by NO synthase. Plasma arginine levels are low in sickle cell anemia, and Romero et al. (2002) reported that the sickle transgenic mouse model has low plasma arginine. They supplemented these mice with a 4-fold increase in arginine over a period of several months. Mean corpuscular hemoglobin concentration decreased and the percent high-density red cells was reduced. Romero et al. (2002) concluded that the major mechanism by which arginine supplementation reduces red cell density in these mice is by inhibiting the Ca(++)-activated K(+) channel.
This variant has electrophoretic mobility in standard conditions identical to that of Hb S but shows a slightly higher pI than Hb S on isoelectric focusing. Heterozygous carriers of this variant hemoglobin exhibit sickling disorders. This observation may provide a clue to the unexplained clinical sickling disorders in some A/S carriers, in whom careful biochemical analyses may reveal other examples of double mutations in the beta chain. See Monplaisir et al. (1986). Pagnier et al. (1990) introduced the val23-to-ile mutation into beta-globin cDNA by site-directed mutagenesis. The beta-globin chain was synthesized using an expression vector and hemoglobin tetramers were reconstituted. When mixed with equal amounts of hemoglobin S, facilitation of polymerization was observed. Pagnier et al. (1990) listed 5 other hemoglobin variants which contain both the sickle mutation and a second amino acid substitution in the same beta chain.
Popp et al. (1997) bred 2 homozygous viable Hb S Antilles transgene insertions into a strain of mice that produce hemoglobins with a higher affinity for oxygen than normal mouse Hb. The rationale was that the high oxygen affinity hemoglobin, the lower oxygen affinity of Hb S Antilles, and the lower solubility of deoxygenated Hb Antilles than Hb S would favor deoxygenation and polymerization of human Hb S Antilles in the red cells of the high oxygen affinity mice. The investigators found that the mice produced a high and balanced expression of human alpha and human beta (S Antilles) globins, that 25 to 35% of their RBCs were misshapen in vivo, and that in vitro deoxygenation of their blood induced 30 to 50% of the RBCs to form classic elongated sickle cells with pointed ends. The mice exhibited reticulocytosis, an elevated white blood cell count, and lung and kidney pathology commonly found in sickle cell patients, which should make these mice useful for experimental studies on possible therapeutic intervention of sickle cell disease.
Langdown et al. (1989) described a doubly substituted sickling hemoglobin with the change of glu-to-val at beta 6 (141900.0243) and glu-to-lys at beta 121 (141900.0202). The double substitution resulted in a variant with reduced solubility and apparent increase in red cell sickling tendency. Hemoglobin S (Oman) combines the classic Hb S mutation (glu6 to val), with the Hb O (Arab) mutation (glu121 to lys). Nagel et al. (1998) studied a pedigree of heterozygous carriers of Hb S (Oman) that segregated into 2 types of patients: those expressing about 20% Hb S (Oman) and concomitant -alpha/alpha-alpha thalassemia and those with about 14% of Hb S (Oman) and concomitant -alpha/-alpha thalassemia. The higher expressors of Hb S (Oman) had a sickle cell anemia clinical syndrome of moderate intensity, whereas the lower expressors had no clinical syndrome and were comparable to the solitary case first described in Oman. In addition, the higher expressors exhibited a unique form of irreversibly sickled cell reminiscent of a 'yarn and knitting needle' shape, in addition to folded and target cells. Purified Hb S (Oman) has a C(SAT) (solubility of the deoxy polymer) of 11 g/dL, much lower than Hb S alone (17.8 g/dL). Another double mutant, Hb S (Antilles) (141900.0244), has a similarly low C(SAT) and much higher expression (40 to 50%) in the trait form, but has a phenotype that is similar in intensity to the trait form of Hb S (Oman). Nagel et al. (1998) concluded that the pathology of heterozygous S (Oman) is the product of recipient properties of the classic mutation which are enhanced by the second mutation at beta-121. In addition, the syndrome is further enhanced by a hemolytic anemia induced by the beta-121 mutation. They speculated that the hemolytic anemia results from the abnormal association of the highly positively charged Hb S (Oman) (3 charges different from normal hemoglobin) with the RBC membrane.
To characterize better the clinical and laboratory aspects of Hb S (Oman), also called Hb S/O (Arab), Zimmerman et al. (1999) reviewed the Duke University Medical Center experience. They identified 13 African-American children and adults with Hb S/O (Arab), ranging in age from 2.7 to 62.5 years. All patients had hemolytic anemia with a median hemoglobin of 8.7 gm/dL and a median reticulocyte count of 5.8%. The peripheral blood smear typically showed sickled erythrocytes, target cells, polychromasia, and nucleated red blood cells. All 13 patients had had significant clinical sickling events, including acute chest syndrome (11), recurrent vasoocclusive painful events (10), dactylitis (7), gallstones (5), nephropathy (4), aplastic crises (2), avascular necrosis (2), leg ulcers (2), cerebrovascular accident (1), osteomyelitis (1), and retinopathy (1). Death had occurred in 4 patients, including 2 from pneumococcal sepsis/meningitis at ages 5 and 10 years, 1 of acute chest syndrome at age 14 years, and 1 of multiorgan failure at age 35 years. Zimmerman et al. (1999) concluded that Hb S/O (Arab) disease is a severe sickling hemoglobinopathy with laboratory and clinical manifestations similar to those of homozygous sickle cell anemia.
Gale et al. (1988) described a hemoglobin carrying 2 substitutions, the standard substitution of Hb S (beta6 glu-to-val) and the substitution of Hb Providence (beta82 lys-to-asx). (There is partial postsynthetic deamination of asparagine to aspartic acid.) The double mutation is electrophoretically silent; if hemoglobin electrophoresis alone were done, the abnormality would be missed.
The hemoglobin is unstable, causing hemolytic anemia in the heterozygote. See Schneider et al. (1969) and Bogoevski et al. (1983). Hull et al. (1998) reported 2 cases of Hb Sabine, in a mother in whom the mutation had apparently arisen de novo and her son. They stated that more than 100 unstable hemoglobins causing hemolytic anemia had been described. Less than 20% of the unstable hemoglobins that have been characterized affect the alpha-globin chain.
Produces erythrocytosis by alteration of the site of fixation of 2,3-diphosphoglycerate (Rochette et al., 1984).
See Ohba et al. (1983).
See Beuzard et al. (1975) and Milner et al. (1976).
This hemoglobin is characterized by high oxygen affinity, and erythrocytosis is associated. See Anderson (1974), Nute et al. (1974), and Harkness et al. (1981). Williamson et al. (1995) observed a 30-year-old man of West Indian origin who showed compound heterozygosity for Hb San Diego and Hb S (141900.0243). He had suffered for about 6 months from severe colicky abdominal pain in episodes of several hours duration. He showed erythrocytosis with a hemoglobin value of 18.8 g/dl. The Hb San Diego mutation represented a GTG-to-ATG change. The Hb S mutation was inherited from the mother; Williamson et al. (1995) suggested that the Hb San Diego mutation occurred de novo on the chromosome 11 derived from the father. DNA testing was consistent with the assumed paternity. The Hb San Diego mutation occurred at a CpG dinucleotide. It was concluded that the abdominal pain was due to increased blood viscosity and the symptoms were relieved by venesection.
See Opfell et al. (1968) and Tanaka et al. (1985).
See Huisman et al. (1971).
Probable frameshift mutation resulting from deletion of the second base of the triplet coding for beta his 143; CAC becomes CCA (PRO). The last part of the beta gene code, 143rd residue on, becomes CAC-AGT-ATC-ACT-AAG-CTC-GCT-TTC-TTG-CTG-TCC-AAT-TTC-TAT-TAA, which reads pro-ser-ile-thr-lys-leu-ala-phe-leu-leu-ser-asn-phe-tyr-stop (COOH). Thus, the beta chain is 156 amino acids long rather than 146. See Delanoe et al. (1984).
Hemoglobin Seattle was discovered by Stamatoyannopoulos et al. (1969), who showed that it is associated with a considerable decrease in oxygen affinity with almost normal heme-heme interaction and normal Bohr effect. It was their conclusion and that of Huehns et al. (1970) that the change was ala76-to-glu. However, studies reported by Kurachi et al. (1973) led to the conclusion that Hb Seattle has a substitution of alanine by aspartic acid at position 70 of the beta polypeptide. Chow et al. (1994) reported a second example of Hb Seattle in a Ukranian family.
Ogata et al. (1986) and Honig et al. (1990) studied this unstable variant, which has low oxygen affinity and an increased susceptibility to methemoglobin formation.
The proband had chronic hemolytic anemia aggravated by oxidated drugs and common colds. Her 10-year-old son was also affected. Biosynthesis studies indicated a normal rate of synthesis, but relatively fast degradation of the mutant beta chain (Zeng et al., 1987).
See Felice et al. (1978), Carcassi et al. (1980), and Moo-Penn et al. (1984). Deletion of glutamine at beta 131 in Hb Leslie was reported by Lutcher et al. (1976) and the same deletion was reported in Hb Deaconess by Moo-Penn et al. (1975). Later, Moo-Penn et al. (1984) showed that Hb Deaconess and Hb Leslie are identical to Hb Shelby. All three have substitution of lysine for glutamine at beta 131. Adachi et al. (1993) described a compound heterozygote for Hb S and Hb Shelby. Hb Shelby, like Hb A, can form hybrids with Hb S which participate in polymer formation in vitro. However, Hb S/Hb Shelby hybrids copolymerize with Hb S less than Hb A/S hybrids. The mild clinical presentation of the patient was attributed to this fact.
See White et al. (1970) and Sansone et al. (1977).
See Ryrie et al. (1977).
Williamson et al. (1994) described a 22-year-old Pakistani male with polycythemia associated with homozygosity for this high-affinity hemoglobin mutant. Whereas 2 previously reported persons with the mutant hemoglobin were heterozygotes and were hematologically normal, the homozygous state was associated with compensatory erythrocytosis resulting from decreased delivery of oxygen to the tissues. Both parents and both sibs were heterozygous for the hemoglobin mutant and were hematologically normal. This may have been the first example of a beta-globin mutation producing polycythemia in homozygotes, but not in heterozygotes.
In a Japanese family, Kobayashi et al. (1987) and Naritomi et al. (1988) described a novel HBB mutation that produced the beta-thalassemia phenotype through a posttranslational mechanism. Substitution of proline for leucine at position 110 greatly reduced the molecular stability of the beta-globin subunit, leading to total destruction of the variant globin chains by proteolysis. The mutation could be identified after digestion with the restriction enzyme MspI. They named the variant Hb Showa-Yakushiji, after the 2 districts where the probands resided. Other variant hemoglobins that are very unstable and lead to thalassemia include Hb Indianapolis (141900.0117) and Hb Quong Sze (141900.0005).
This HBB gene variant was discovered in a Thai family by Tuchinda et al. (1965) and was subsequently identified in several Chinese by Blackwell et al. (1972). Chang et al. (1999) observed the same variant in a Taiwanese family. DNA analysis detected a G-to-A transition at the first base of codon 7 (GAG to AAG). This mutation creates an MboII site that is highly specific for Hb Siriraj.
Hb Sogn was first described in Norway by Monn et al. (1968). Fairbanks et al. (1990) described the first known instances of Hb Sogn outside of Norway, in 2 families, both of Norwegian descent. Hb Sogn has been described in Norwegian families and in American families from the upper midwest where settlement of Scandinavian families was common. Miller et al. (1996) described the hemoglobin variant in a family residing in Illinois; the proband's maternal grandfather was Norwegian. Codon 14 showed a CTG (leu)-to-CGG (arg) change. The proband married a person who was homozygous for alpha-thalassemia-2. The couple had 2 daughters who offered the opportunity of comparing data between Hb Sogn heterozygotes with 4 alpha-globin genes and 3 alpha-globin genes. Mild microcytosis and hypochromia in the father was due to the presence of alpha-thal-2 homozygosity and that in the mother to the presence of the mildly unstable Hb Sogn. Striking microcytosis and hypochromia in 1 daughter could be attributed to the combination of a the alpha-thal-2 trait and Hb Sogn heterozygosity.
See Hyde et al. (1972), Jones et al. (1973), and Koler et al. (1973).
The initiator methionine residue (METi) is preserved. This variant was first discovered in a patient who appeared to have markedly elevated Hb A(1c) as estimated by ion exchange chromatography. Glycosylated hemoglobin measured by a colorimetric method with thiobarbituric acid was normal, however. If it were not for the fact that methionine is 1 of the 4 N-terminal amino acids (alanine, glycine, serine, methionine) that participate in acetylation, this abnormal amino acid substitution would have gone unrecognized. Acetylation of the N-terminal methionine residue occurs less easily than in other amino acids; thus, hemoglobin South Florida could not be recognized by hemoglobin electrophoresis. In contrast, acetylation of alanine in hemoglobin Raleigh is 100% and that variant can be recognized by hemoglobin electrophoresis. See Boissel et al. (1985) and Shah et al. (1986). Malone et al. (1987) reported a family study. The fundamental change is not in the codon for the initiator mutation but in the codon for the first residue for the mature beta-globin chain, valine, which is converted to methionine. Because the initiator methionine is retained, this methionine is substituted for valine as residue 2 in the mature chain of Hb South Florida.
Two amino acids, glycine and leucine, are deleted from beta 74 and 75. See Wajcman et al. (1973).
This is a form of Hb M, differing from other Hb M variants by the fact that the substitution is not for the histidine at E7 or F8. Hb M (Milwaukee) is another. Severe Heinz body anemia, in addition to methemoglobinemia, is associated with Hb St. Louis. The beta heme group is permanently in a ferric state. See Cohen-Solal et al. (1974), Anderson (1976), Thillet et al. (1976), and Wiedermann et al. (1986).
This hemoglobin variant has a low oxygen affinity, resulting in cyanosis. See Arous et al. (1981). Poyart et al. (1990) found that the functional properties of St. Mande are intermediary between those of normal Hb A and Hb Kansas (0.0145).
Hb Strasbourg was first observed in a female from northern Portugal and in 1 of her 2 children. Garel et al. (1976) incorrectly thought that the valine at position 20 was substituted. See Forget (1977). Bisse et al. (1998) provided information on a German family with the same abnormality. This was the second observation of this hemoglobin variant. The 23-year-old propositus had a hemoglobin level of 19.8 g/dl. The variant was shown to have a high oxygen affinity. Codon 23 of the HBB gene was changed from GTT (val) to GAT (asp).
No hematologic abnormality. See Wilkinson et al. (1980) and Cin et al. (1983).
See Ali et al. (1988).
Like hemoglobins Koln and Genova, this hemoglobin has no electrophoretic abnormality but is unstable, forming intracellular precipitates. See Carrell et al. (1967) and Casey et al. (1978).
See Jensen et al. (1975).
See Barwick et al. (1985). Combines substitutions of Hb E and Hb O (Arab): substitution of lysine for glutamic acid at beta 26 and of glutamine for glutamic acid at beta 121.
See Blackwell et al. (1971).
See Baur and Motulsky (1965), Brimhall et al. (1969), Idelson et al. (1974), Deacon-Smith and Lee-Potter (1978), and Harano et al. (1985).
The usual terminal dipeptide 145-146 of the beta chain is lacking and is replaced by 10 residues attached to the C-terminal end. Hemoglobin Constant Spring is a termination defect of the alpha chain. See Flatz et al. (1971). Characterized on the basis of amino acid analysis, this variant was assumed to be due to an insertion of the dinucleotide CA into codon 146, CAC-to-CA(CA)C, which abolished the normal stop codon at position 147 and caused a frameshift with elongation of the beta chain by 11 amino acids. The variant had previously been described in a few Thai families. Hoyer et al. (1998) reported the DNA sequence of Hb Tak in an individual of Cambodian descent who was a Hb E/Tak compound heterozygote. In contrast with extended variants of the alpha-globin gene that are expressed as alpha-thalassemias, the hematologic effect of Hb Tak/Hb E was a mild polycythemia. The combination of Hb Tak/Hb E was not expressed as a thalassemia.
See Iuchi et al. (1980) and Kawata et al. (1989).
See Johnson et al. (1980).
In a healthy 34-year-old Chinese male of Han nationality, Li et al. (1990) identified a hemoglobin variant and showed that it had a replacement of glutamine by arginine at residue 39.
This hemoglobin and 3 others with a single amino acid substitution at the same site have reduction in affinity for oxygen. See Bernini and Giordano (1988).
Deletion of residues 56-59 of the beta chain. See Shibata et al. (1970).
See Wajcman et al. (1973).
See Hirano et al. (1981) and Imai et al. (1981).
See Kohne et al. (1976). Philippe et al. (1993) described this hemoglobin variant, a cause of methemoglobinemia, in a 53-year-old Belgian woman. Her father had been cyanotic throughout his life. This was the second report of this hemoglobin variant.
See Mrad et al. (1988).
See Bursaux et al. (1978).
See Kendall et al. (1977).
See Jones et al. (1976).
See Puett et al. (1977) and Paniker et al. (1978).
See Adams et al. (1981). When they failed to find evidence of deletion of leu75 in genomic DNA, Coleman et al. (1988) proposed somatic mutation. A more plausible explanation, perhaps, is one parallel to that obtaining in the case of Hb Atlanta-Coventry (141900.0013).
This mutation was discovered as a silent and asymptomatic variant in an 87-year-old French woman who coincidentally had polycythemia vera (Wajcman et al., 1989).. Carbone et al. (2001) reported the second observation of this hemoglobin variant in 3 related subjects from Montesarchio in southern Italy. The DNA change was ACC to ATC.
See Kuis-Reerink et al. (1976), Ockelford et al. (1980), Sciarratta et al. (1985), and Falcioni et al. (1988). Blanke et al. (1989) reported a possible de novo mutation in a Dane.
See Wilson et al. (1984).
See Perutz and Lehmann (1968) and Lorkin et al. (1974).
See Jones et al. (1976-77), Quarum et al. (1983), and Martinez and Canizares (1984).
Gilbert et al. (1989) found this variant in a 9-month-old child who presented with hemolytic anemia in association with intercurrent viral infection. Instability of the hemoglobin molecule as well as increase in oxygen affinity was demonstrated.
See Taketa et al. (1975).
Polycythemia occurs with this hemoglobinopathy as with hemoglobin Chesapeake. See Jones et al. (1967), Novy et al. (1967), and Osgood et al. (1967).
Hemoglobin Yamagata as reported by Harano et al. (1990) was caused by a change of codon 132 in the HBB gene from AAA (lys) to AAC (asn). Han et al. (1996) found the same amino acid substitution in a 37-year-old Korean woman to be caused by a change of codon 132 from AAA to AAT. No distinctive clinical abnormalities were detected.
See Kagimoto et al. (1978).
See Nakatsuji et al. (1981). Plaseska et al. (1991) described a de novo mutation in a Yugoslavian boy with severe transfusion-dependent hemolytic anemia. The patients of Nakatsuji et al. (1981) were a 33-year-old Japanese woman with chronic hemolytic anemia and her son with milder symptoms.
See Bare et al. (1976) and Kosugi et al. (1983).
Reduced oxygen affinity like hemoglobin Kansas. See Imamura et al. (1969).
Substitution in beta chain results in increased oxygen affinity leading to erythremia and abnormal polymerization manifested in heterozygotes by hybrid hemoglobin molecules containing both the Ypsi beta chain and the normal beta chain. See Glynn et al. (1968) and Rucknagel (1971).
See Yanase et al. (1968) and Marengo-Rowe et al. (1968).
See Harano et al. (1981) and Ohba et al. (1990).
Drug-induced hemolysis results from this variant hemoglobin. The affinity of Hb Zurich for carbon monoxide is about 65 times that observed in normal hemoglobin A. Carboxyhemoglobin content in persons with Hb Zurich varied from 3.9 to 6.7% for nonsmokers and 9.8 to 19.7% for smokers. Hemolysis was less in smokers, presumably because of stabilization of Hb Zurich by CO. See Huisman et al. (1960), Muller and Kingma (1961), Frick et al. (1962), Rieder et al. (1965), Dickerman et al. (1973), Zinkham et al. (1979, 1980, 1983), Dlott et al. (1983), and Virshup et al. (1983).
Miranda et al. (1994) identified Hb Zurich in a 38-year-old woman who had a hemolytic crisis after administration of an antibiotic for urinary tract infection. This hemoglobin variant was first identified by protein analysis and then by DNA sequencing.
Aguinaga et al. (1998) studied 4 members of a Kentucky family whom they had identified as Hb Zurich carriers. During pregnancy, the proband developed hemolytic anemia with Heinz bodies when treated for a urinary tract infection with sulfonamide. Because of severe anemia, the patient was transfused several times and ultimately splenectomized. The Kentucky family studied in this report was part of a larger kindred that was known to contain 19 members who were Hb Zurich carriers.
Zinkham et al. (1979) demonstrated in vitro thermal denaturation of Hb Zurich as a cause of anemia during fever.
This variant was found in Chinese. Chang et al. (1979) and Chang and Kan (1979) presented evidence that beta-zero-thalassemia is a nonsense mutation, the first identified in man. By molecular hybridization they showed that the beta gene is present. In different patients variable amounts of beta-like globin mRNA is present. They sequenced mRNA and found that noncoding regions at both ends were normal but at the position corresponding to amino acid no. 17, the normal lysine codon AAG was converted to UAG, a terminator. Such a nonsense mutation should be overcome by means of suppressor tRNA which allows the ribosome to read through a terminator codon by inserting an amino acid. In vitro addition of a serine suppressor tRNA from yeast resulted in human beta-globin synthesis. Cell-free assays with suppressor tRNAs may be useful for detecting nonsense mutations in other human genetic disorders. Steger et al. (1993) showed that this AAG-to-TAG nonsense mutation and the hemoglobin E mutation, common causes of beta(+)-thalassemia and beta-zero-thalassemia in Southeast Asia, can be detected using allele-specific PCR, known also as the amplification refractory mutation system (ARMS).
Krawczak et al. (2000) pointed out that this was the first single basepair substitution in a human gene underlying a genetic disorder to be reported. Knowledge of the amino acid substitution responsible for sickle hemoglobin permitted imperfect inference of the nucleotide change because of redundancy of the code.
Chehab et al. (1986) found evidence for new mutation in the codon at beta-39 from CAG (glutamine) to the stop codon TAG. The beta-39 nonsense mutation is the second most common beta-thalassemia lesion in Italy, accounting for a third of cases, and the most common in Sardinia, accounting for 90% of cases there. In Sardinia, the beta-39 mutation has been identified with 9 different haplotypes. All this suggested to Chehab et al. (1986) that beta-39 is a mutational hotspot. Trecartin et al. (1981) found that the form of beta-zero-thalassemia that is predominant in Sardinia is caused by a single nucleotide mutation at the position corresponding to amino acid number 39 and converting a glutamine codon (CAG) to an amber termination codon (UAG). (Epstein et al. (1963) described 'amber' mutants of phage T4 in a frequently cited paper in a Cold Spring Harbor Symposium on Quantitative Biology. The origin of the unusual name 'amber' is, as Witkowski (1990) called it, 'an interesting footnote in the history of molecular biology.' Edgar (1966) recounted that R. H. Epstein and C. M. Steinberg, then at the California Institute of Technology, had promised Harris Bernstein, then at Yale University, that the mutants, if any were found, would be named after his mother. They were found and were named 'amber,' the English equivalent of 'Bernstein.' The other 2 'stop' codons, UGA and UAA, are sometimes referred to as 'opal' and 'ochre,' respectively.) Rosatelli et al. (1992) used denaturing gradient gel electrophoresis (DGGE) followed by direct sequence analysis of amplified DNA to study 3,000 beta-thalassemia chromosomes in the Sardinian population. They confirmed that the predominant mutation, present in 95.7% of beta-thalassemia chromosomes, was gln39-to-ter.
See Kazazian et al. (1984). The mutation that Kazazian et al. (1984) demonstrated in Asian beta-thalassemia patients was the result of a TGG-to-TAG mutation. Ribeiro et al. (1992) demonstrated the frequent occurrence in central Portugal of beta-zero-thalassemia due to a change of codon 15 for tryptophan to a stop codon; the basis, however, was a TGG-to-TGA mutation.
See Kazazian et al. (1986), Fei et al. (1989) and Adams et al. (1990).
See Boehm et al. (1986).
Atweh et al. (1988) described a novel nonsense mutation in a Chinese patient: a G-to-T substitution at the first position of codon 43, which changed the glutamic acid coding triplet (GAG) to a terminator codon (TAG). They incorrectly referred to a patient carrying both the beta-17 and the beta-43 nonsense mutation as being a double heterozygote rather than a compound heterozygote.
See Gonzalez-Redondo et al. (1988).
See Fucharoen et al. (1989).
In a person of British extraction, Kazazian et al. (1989) found a gln127-to-pro mutation as the basis of a 'dominant' form of beta-plus-thalassemia. This form of thalassemia is due to instability of the beta-globin chains containing the particular mutation. Kazazian et al. (1992) again reported on the CAG-CGG missense mutation at codon 127 which caused thalassemia intermedia with hemolysis in 3 generations of a British-American family. They commented that the paucity of high-frequency exon 3 mutations and the worldwide distribution of the few that are observed are probably attributable to their phenotypic severity and lack of increased genetic fitness in relation to malaria.
In a Japanese patient with beta-plus-thalassemia, Hattori et al. (1989) found deletion of nucleotides AGG from codons 127 and 128 (CAG to GCT) resulting in replacement of gln127 and ala128 by proline (CCT).
In an Italian with beta-plus-thalassemia, Podda et al. (1989, 1991) found a val60-to-glu substitution.
Frameshift, -AA in codon 8, AAG to G, was found in a Turkish patient by Orkin and Goff (1981). This mutation was also found in homozygous state in DNA from the archeologic remains of a child with severe bone pathology consistent with thalassemia (Filon et al., 1995). The remains came from a grave thought to date to the Ottoman period, sometime between the 16th and 19th centuries. From the tooth development, it was estimated that the child died at the age of about 8 years, whereas patients with this mutation would be expected to be transfusion-dependent from early infancy. Filon et al. (1995) also found a rare DNA polymorphism: a C-to-T transition in the second codon of the HBB gene that did not alter the corresponding amino acid. This polymorphism is found in 13% of present-day Mediterranean beta-thalassemia chromosomes and is part of a haplotype (haplotype IV) that is associated with relatively high levels of fetal hemoglobin. The disease may have run a milder course because of linkage to haplotype IV.
Frameshift, -C, codon 16, GGC to GG, was found in Asian Indians by Kazazian et al. (1984).
Frameshift, -C, codon 44, TCC to TC, was found in a Kurdish patient by Kinniburgh et al. (1982).
Frameshift, +G, codons 8/9, AAGTCT to AAGGTCT was found in an Asian Indian by Kazazian et al. (1984).
Frameshift, -4, codons 41/42, TTCTTT to TT, was found in an Asian Indian by Kazazian et al. (1984) and in Chinese by Kimura et al. (1983).
Lau et al. (1997) found that the deletion of CTTT at codons 41/42 accounted for 40% of all beta-thalassemia alleles in Hong Kong. Chiu et al. (2002) designed allele-specific primers and a fluorescent probe for detection of this mutation in the HBB gene from maternal plasma by real-time PCR. Using this method, they showed that beta-thalassemia major could be excluded from fetal inheritance by demonstrating absence of inheritance of the paternally transmitted mutation. By studying circulating fetal DNA in the maternal plasma for this mutation, Chiu et al. (2002) added beta-thalassemia to the list of disorders that could be prenatally diagnosed using this noninvasive method, which had previously demonstrated usefulness in diagnosing sex-linked diseases (Costa et al., 2002) and fetal rhesus D status (Lo et al., 1998).
Frameshift, -A, codon 6, GAG to GG, was found in Mediterranean patients by Kazazian et al. (1983). Bouhass et al. (1990) found the same mutation in an Algerian patient who was a genetic compound. Rosatelli et al. (1992) found that this mutation accounted for 2.1% of mutations carried by 3,000 beta-thalassemia chromosomes from the Sardinian population. Romey et al. (1993) described an improved procedure that allows the detection of single basepair deletions on nondenaturing polyacrylamide gels and demonstrated its applicability for identifying this mutation.
Frameshift, +A, codons 71/72, TTAGT to TTTAAGT, was found in Chinese by Cheng et al. (1984).
Frameshift, +G, codons 106/107, CTGGGC to CTGGGGG, was found in American blacks by Wong et al. (1987).
Frameshift, -C, codon 76, GCT to GT, was found in an Italian by DiMarzo et al. (1988). Rosatelli et al. (1992) found that this mutation was responsible for 0.7% of the mutations carried by 3,000 beta-thalassemia chromosomes in the Sardinian population.
Frameshift, -G, codon 37, TGG to G, was found in a Kurdish patient by Rund et al. (1989, 1991).
Frameshift, -CT, codon 5, CCT to CC, was found in a Mediterranean patient by Kollia et al. (1989).
Frameshift, -T, codon 11, GTT to GT, was found in a Mexican patient by Economou et al. (1990).
Frameshift, -C, codon 35, TAC to TA, was found in Indonesia by Yang et al. (1989).
Frameshift, -CT, codon 114, CTG to G, was found in a French patient by Beris et al. (1988). Hb Geneva is an unstable hemoglobin producing a hemolytic anemia with inclusion bodies in the peripheral blood after splenectomy. Heterozygotes show manifestations of a thalassemia-like disorder.
Frameshift, +G, codon 14/15, CTGTGG to CTGGTGG, was found in Chinese by Chan et al. (1988).
Frameshift, -7 nucleotides from codons 37-39, TGGACCCAG, was found in a Turkish patient by Schnee et al. (1989).
Frameshift, +TG, codon 94 (GAC), was found in a Mediterranean patient by Pirastu et al. (1990).
Frameshift, -G, codon 64, GGC to GC, was found in a Swiss woman heterozygous for beta-thalassemia by Chehab et al. (1989). This was a spontaneous mutation as originally described by Tonz et al. (1973). The father was 45 years old when the proband was born. By haplotyping, Chehab et al. (1989) showed, furthermore, that the mutation had arisen on the father's chromosome 11.
Frameshift, -G, codon 109, GTG to TG, found in a Lithuanian by Kazazian et al. (1989).
Frameshift, -T, codon 36/37, CCTTGG to CCTGG, was found in Iranian Kurds by Rund et al. (1989, 1991).
Frameshift, +C, codons 27/28, GCCCTG to GCCCCTG, was found in Chinese by Cai et al. (1989).
Frameshift, +T, codon 71, TTT to TTTT, was found in Chinese by Kazazian (1990).
This initiator codon mutant, ATG to AGG, was found in Chinese individuals by Kazazian (1990).
This initiator codon mutant, ATG to ACG, was found in Yugoslavians by Jankovic et al. (1989). The same mutation was found by Beris et al. (1993) in a father and daughter of a family originating from Bern, Switzerland. Unlike the first reported family, of Yugoslavian origin, the Swiss patients had high Hb F levels. The mutation converted the initiator methionine to threonine and abolished an NcoI recognition site.
(In the case of many other genes in which the mutations have been characterized on the basis of the gene itself, the codon count begins with the initiator methionine. In such a system, this mutation would be designated met1-to-thr and the hemoglobin S mutation would be designated glu7-to-val.)
Molchanova et al. (1998) characterized the beta-thalassemia present in 3 generations of a branch of the family of the Russian poet Mihail Yurievich Lermontov. The hematologic data for affected members of 3 generations were compatible with a beta-thal heterozygosity. Sequence analysis showed an ATG-to-ACG change in the initiation codon. The family in which it was first observed by Jankovic et al. (1989, 1990) was said to have been of Croatian origin. In that family, the mutation was accompanied by a CAC-to-CAT change in codon 2 of the same chromosome; this common polymorphism was not seen in the Russian family.
Splice junction mutant, G to A, position 1 of IVS1, was found by Orkin et al. (1982) in a Mediterranean patient.
Splice junction mutant, G to T, at position 1 of IVS1 was found in an Asian Indian and in Chinese by Kazazian et al. (1984).
A splice junction mutant, G to A, at position 1 of IVS2 was found in a Mediterranean by Treisman et al. (1982), in a Tunisian by Chibani et al. (1988), and in an American black by Thein et al. (1988). The same mutation was found by Hattori et al. (1992), who referred to the mutation as IVS2-1 (G-A).
This is one of the earliest mutations at a 5-prime splice site to be described. In an analysis of 101 different examples of point mutations that lie in the vicinity of mRNA splice junctions and that have been held to be responsible for human genetic disease by altering the accuracy or efficiency of mRNA splicing, Krawczak et al. (1992) found that 62 were located at 5-prime splice sites, 26 at 3-prime splice sites, and 13 resulted in the creation of novel splice sites. They estimated that up to 15% of all point mutations causing human genetic disease result in an mRNA splicing defect. Of the 5-prime splice site mutations, 60% involve the invariant GT dinucleotides.
Sierakowska et al. (1996) found that treatment of mammalian cells stably expressing the IVS2-654 beta HBB gene with antisense oligonucleotides targeted at the aberrant splice sites restored correct splicing in a dose-dependent fashion, generating correct human beta-globin mRNA and polypeptide. Both products persisted for up to 72 hours after treatment. The oligonucleotides modified splicing by a true antisense mechanism without overt unspecific effects on cell growth and splicing of other pre-mRNAs. Sierakowska et al. (1996) stated that this novel approach in which antisense oligonucleotides are used to restore rather than to downregulate the activity of the target gene is applicable to other splicing mutants and is of potential clinical interest.
This mutation is frequent among patients in southern China and Thailand, accounting for 20% of beta-thalassemia in some regions. It causes aberrant RNA splicing. Lewis et al. (1998) modeled this mutation in mice, replacing the 2 (cis) murine adult beta-globin genes with a single copy of the human mutant HBB gene. No homozygous mice survived postnatally. Heterozygous mice carrying this mutant gene produced reduced amounts of mouse beta-globin chains and no human beta globin, and had a moderately severe form of beta-thalassemia. Heterozygotes showed the same aberrant splicing as their human counterparts and provided an animal model for testing therapies that correct splicing defects at either the RNA or DNA level.
Splice junction mutant, T to G, at position 2 of IVS1 was found in a Tunisian by Chibani et al. (1988).
Splice junction mutant, T to C, at position 2 of IVS1 was found in an American black by Gonzalez-Redondo et al. (1989). Of 33 thalassemic chromosomes in Algerian patients studied by Bouhass et al. (1990), 7 carried the T-to-C transition at position 2 in IVS1. Thus, the mutation may be common in the Algerian population. They observed 2 patients who were homozygous for the substitution and had no detectable Hb A by standard electrophoresis procedures. Interestingly, the other 2 possible changes at this position have also been observed; see 141900.0349 and 141900.0392.
Deletion of 17 nucleotides that removed the acceptor splice site from IVS1 was found in a Kuwaiti by Kazazian and Boehm (1988).
Deletion of 25 nucleotides that removed the acceptor splice site of IVS1 was found in an Asian Indian by Orkin et al. (1983).
Change from CCACAGC to CCACGGC (A to G at position -2) in the acceptor splice site of IVS2 was found in American blacks by Antonarakis et al. (1984) and Atweh et al. (1985).
This is one of the earliest-described examples of mutation in the 3-prime splice site affecting mRNA splicing. In an analysis of 101 different examples of point mutations occurring in the vicinity of mRNA splice junctions and resulting in human genetic disease, Krawczak et al. (1992) found that 26 involved 3-prime splice sites.
Change from CCACAGC to CCACCGC (A to C at position -2) at acceptor splice site of IVS2 was found in American blacks by Padanilam and Huisman (1986).
Deletion of 44 nucleotides that removed the IVS1 donor splice site was found in a Mediterranean patient by Kazazian and Boehm (1988).
In an Egyptian child with thalassemia major, Deidda et al. (1990) found heterozygosity for a G-to-A substitution at position -1 of IVS1, which altered the conserved dinucleotide AG present in the consensus acceptor sequence. The other chromosome carried the T-to-C mutation at position 6 of the first intervening sequence (IVS1) (141900.0360). The latter mutation was associated with haplotype 6, frequently observed in Mediterranean areas; the new mutation was associated with haplotype 1. This gene can be added to the list of mutations that can be identified by Southern analysis using AflII.
G-to-C change at position 5 of the donor site consensus sequence of IVS1 (CAG-GTTGGT to CAG-GTTGCT) was found in an Asian Indian by Kazazian et al. (1984) and in a Chinese by Cheng et al. (1984).
G-to-T change at position 5 of the donor site consensus sequence of IVS1 (CAG-gttggt-to-CAG-gttgtt) was found in a Mediterranean patient and an Anglo-Saxon patient by Atweh et al. (1987) and in an American black by Gonzalez-Redondo et al. (1988). The 2 cases of Atweh et al. (1987) were in different RFLP backgrounds, suggesting that they represented independent mutations. Atweh et al. (1987) showed that after transfer of the cloned genes into HeLa cells, followed by transient expression, partial inactivation of the normal donor splice site of IVS1 and activation of 2 major and 1 minor cryptic splice sites occur. The effects of this mutation on mRNA splicing were similar to those of another beta-thalassemia gene with a G-to-C transition at the same position (141900.0357). In a rare case of beta-thalassemia in a German family, Eigel et al. (1989) found a G-to-T transversion at the intron 1 donor site of the beta-globin gene. This may be the same mutation. The patient was homozygous for this mutation and had died at age 27 of heart failure resulting from iron overload.
G-to-A change at position 5 of the donor site consensus sequence of IVS1 (CAG-GTTGGT to CAGGTTGAT) was found in an Algerian by Lapoumeroulie et al. (1986).
T-to-C change at position 6 of the donor site consensus sequence of IVS1 (CAG-GTTGGT to CAG-GTTGGC) was found in a Mediterranean patient by Orkin et al. (1982).
A C-to-A change at position -3 in the acceptor splice site of IVS2 (CAG to AAG) was found in an Iranian, an Egyptian, and an American black by Gonzalez-Redondo et al. (1988) and Wong et al. (1989).
A T-to-G change at position -3 in the acceptor splice site of IVS1 (TAG to GAG) was found in a Saudi Arabian by Wong et al. (1989). Indeed, Wong et al. (1989) identified 2 different nucleotide substitutions in consensus acceptor splice sequences of the beta-globin gene leading to beta-thalassemia. One was at the IVS1/exon 2 junction and the other at the IVS2/exon 3 junction (141900.0361). Both mutations were single nucleotide substitutions, T-to-G and C-to-A, at position -3 immediately adjacent to the invariant AG dinucleotide. For the IVS2/exon 3 mutation, abnormal splicing into the cryptic splice site at IVS2 nucleotide 579 was demonstrated.
A C-to-A change at position -8 in the acceptor splice site of IVS2 was found in an Algerian by Beldjord et al. (1988).
A G-to-A change at position 110 of IVS1 was found in a Mediterranean patient by Spritz et al. (1981) and Westaway and Williamson (1981). The mutation created a new splice acceptor site. Kaplan et al. (1990) studied the molecular basis of beta-thalassemia minor, which has a frequency of about 1% among French Canadians residing in Portneuf County of Quebec Province. They showed that there were 2 different beta-thalassemia mutations segregating in the population: an RNA processing mutation involving nucleotide 110 of IVS1 on haplotype 1 and a point mutation leading to chain termination through a nonsense codon at position 39 (141900.0312), occurring on haplotype 2.
A T-to-G change at position 16 of IVS1 was found in a Mediterranean patient by Metherall et al. (1986). The mutation created a new acceptor splice site.
A T-to-G change at position 705 of IVS2 was found in a Mediterranean patient by Dobkin et al. (1983). The mutation created a new acceptor splice site.
A C-to-G change at position 745 of IVS2 was found in a Mediterranean patient by Orkin et al. (1982). The mutation created a new acceptor splice site.
A C-to-T change at position 654 of IVS2 was found in a Chinese by Cheng et al. (1984).
In an American black, Goldsmith et al. (1983) found a change in codon 24 from GGT to GGA. Although silent in terms of changing the amino acid sequence, the mutation affected processing of mRNA.
Gonzalez-Redondo et al. (1989) found a C-to-T change in nucleotide -101 in an asymptomatic Turkish carrier of beta-thalassemia. This is one of the transcriptional mutants causing beta-thalassemia. Ristaldi et al. (1990) showed that this mutation is a relatively frequent cause of beta-thalassemia in the Italian population, where it is always associated with haplotype 1. Compound heterozygosity for this promoter mutation and a mutation for severe beta-thalassemia results in a mild form of thalassemia intermedia (Murru et al., 1991). In studies of infants of Italian couples, 1 member of which was heterozygous for this promoter mutation, Murru et al. (1993) demonstrated that mutation leads to a more severe defect in beta-globin chain production in infancy than in adulthood. The moment of transition from the fetal-infant to the adult pattern of expression seems to be at about 2 years of age. This age-related pattern of expression had not been detected for other beta-thalassemia mutations. Assuming the existence of different distal CACCC box binding proteins with an activating function on the beta-globin gene promoter in fetal and adult ages, Murru et al. (1993) speculated that the fetal type interacts less efficiently with the mutated CACCC promoter as compared with the adult one. They suggested that the findings permit one to predict a mild phenotype even when HbA is absent in the newborn.
Maragoudaki et al. (1999) reported the clinical, hematologic, biosynthetic, and molecular data on 25 double heterozygote beta-thalassemia intermedia patients and 45 beta-thalassemia heterozygotes with the C-to-T substitution at nucleotide position -101 from the cap site, in the distal CACCC box of the HBB promoter. This mutation is considered the most common among the silent beta-thalassemia mutations in Mediterranean populations. Of the 25 compound heterozygotes for the promoter mutation and common severe beta-thalassemia mutations, all but 1 had mild thalassemia intermedia preserving hemoglobin levels around 9.5 g/dl and hemoglobin F levels less than 25%. Strict assessment of hematologic and biosynthetic findings in the heterozygotes for the promoter mutation demonstrated that less than half of them had completely normal (silent) hematology.
Kazazian (1990) found a C-to-T change at position -92 in a Mediterranean patient.
Orkin et al. (1984) found a C-to-T change at position -88 in an American black and an Asiatic Indian.
In a Kurdish Jew, Rund et al. (1989, 1991) found a C-to-A change at position -88.
In a Mediterranean patient, Orkin et al. (1982) found a C-to-G change at position -87.
In a Lebanese, Kazazian (1990) found a C-to-G change at position -86.
In a Japanese, Takihara et al. (1986) found an A-to-G change at position -31. Also see Yamashiro et al. (1989).
In a Turkish patient, Fei et al. (1988) found a T-to-A change at position -30 (a TATA box mutation). Fedorov et al. (1992) found the T-30A mutation in a Karachai patient with beta-thalassemia intermedia.
In a Chinese, Cai et al. (1989) demonstrated a new beta-thalassemia mutation: a T-to-C mutation at position -30 converting a normal TATA box sequence from ATAAA to ACAAA.
An A-to-G change at position -29 (a TATA box mutation) was found in an American black by Antonarakis et al. (1984) and in a Chinese by Huang et al. (1986).
In a Kurdish Jew, Poncz et al. (1983) found an A-to-C change at position -28 (a TATA box mutation).
In Chinese, Orkin et al. (1983) found an A-to-G change at position -28 (a TATA box mutation).
In an American black patient, Orkin et al. (1985) found a change from AATAAA to AACAAA in the 3-prime untranslated portion of the gene. This and several others are RNA cleavage and polyadenylation mutants.
In a Kurdish patient, Rund et al. (1989, 1991, 1992) found a change from AATAAA-to-AATAAG in the 3-prime untranslated portion of the gene. Rund et al. (1992) used this and another polyadenylation mutation (141900.0417) to investigate the function of the poly(A) signal in vivo and to evaluate the mechanism whereby these mutations lead to a thalassemic phenotype. Analysis of RNA derived from peripheral blood demonstrated the presence of elongated RNA species in patients carrying either mutation. Other aspects of RNA processing (initiation, splicing) were unimpaired.
In an Arab patient, Kazazian (1990) found deletion of an A in the 3-prime RNA cleavage-polyadenylation signal, i.e., a change from AATAAA to AATAA.
In a Mediterranean patient, Jankovic et al. (1989) found a change from AATAA to AATGAA in the RNA cleavage-polyadenylation signal.
In a Malaysian patient, Jankovic et al. (1989) found a change from AATAAA to AATAGA in the RNA cleavage-polyadenylation signal.
In an Asian Indian patient, Wong et al. (1986) found a cap site mutation, specifically, an A-to-C change at position 1. The first nucleotide of the transcript is designated the cap site; it is usually 60-100 nucleotides 5-prime of the initiator methionine codon in the untranslated part of the transcript. The cap site is the nucleotide to which a 7-methyl-G cap is added to the mRNA transcript. The mutation reported by Wong et al. (1987) is the only cap site mutation reported to date (Kazazian, 1992).
Wilson et al. (1990) found loss of leu-ala-his-lys at positions 141, 142, 143, and 144 and their replacement by a gln residue. The changes were the result of a deletion of 9 nucleotides, namely, 2 bp of codon 141, all of codons 142 and 143, and 1 bp of codon 144; the remaining CAG triplet (C from codon 141 and AG from codon 144) codes for the inserted glutamine.
In a Spanish patient, Wilson et al. (1990) found that his and val at positions 97 and 98 of the beta-chain had been replaced by a leu residue. The change resulted from the deletion of ACG in codons 97 and 98 and the creation of a remaining triplet CTG (C from codon 97 and TG from codon 98) which codes for the inserted leucine residue. Wilson et al. (1990) considered 2 mechanisms, namely, slipped mispairing in the presence of short repeats, and misreading by DNA polymerase due to a local distortion of the DNA helix, as the basis for the small deletions in hemoglobin Birmingham and hemoglobin Galicia.
In 4 generations of a family of English ancestry, Honig et al. (1990) found 15 persons with erythrocytosis. Elevated hemoglobin levels were accompanied by leftward-shifted whole blood oxygen equilibrium curves. Phlebotomies for relief of symptoms attributable to erythrocytosis had been necessary in 5 of the affected family members. In the affected individuals, 43% of the beta chains contained a leucine-to-phenylalanine substitution at position 105. Oxygen equilibrium curves demonstrated normal Bohr effect but decreased cooperativity.
Bouhass et al. (1990) described an Algerian patient who was a genetic compound for the mutation listed as 141900.0327 and a new mutation consisting of a T-to-A transversion at position 2 of IVS1.
While investigating the mechanism of a beta-thalassemia intermedia phenotype in a 34-year-old Thai male, Bardakdjian-Michau et al. (1990) discovered a new beta-hemoglobin variant, val126-to-gly, which they called Hb Dhonburi. The variant was unstable but exhibited normal oxygen-binding properties. Pagano et al. (1991) found the same amino acid substitution in 3 unrelated families from southern Italy and dubbed it Neapolis. A GTG-to-GGG mutation was responsible for the change. The 8 heterozygous patients showed hematologic and biosynthetic alterations of mild beta-thalassemia. The characteristics were very similar to those of Hb E (141900.0071), Hb Knossos (141900.0149), and Hb Malay (141900.0168), all of which have a single base substitution causing amino acid replacement and alternative splicing of the precursor beta-mRNA by activating cryptic donor sites in exon 1.
Plaseska et al. (1990) found a gly-to-ala mutation at position beta119 in a black infant and her mother. The baby was also heterozygous for Hb S. The change in hemoglobin Iowa did not affect stability or oxygen-carrying properties; hematologic data were normal in the mother and child.
In a Surinam carrier of beta-thalassemia, Losekoot et al. (1990) detected a frameshift insertion in the HBB gene: a single nucleotide (+A) at codon 47 which caused the formation of a termination codon at position 52.
In a 43-year-old woman suffering from chronic anemia since the age of 20, Wajcman et al. (1991) found this new hemoglobin variant which displays decreased oxygen affinity.
This variant was detected in a cord blood sample from a Chinese newborn tested by IEF and reversed phase high performance liquid chromatography (Plaseska et al., 1990). This mutation occurs with another mutation in Hb Masuda (141900.0172).
Adams et al. (1978, 1979) described a hemoglobin variant responsible for severe beta-thalassemia with dominant inheritance. They concluded that the mutation, which they referred to as Hb Indianapolis (see 141900.0117), carried a cys112-to-arg mutation. Subsequent description of 2 families, which indeed carried this mutation but were minimally affected, prompted restudy of the original family. Both of the original carriers of the variants had succumbed to their severe anemia. However, by the use of PCR, enough DNA was recovered from a 10-year-old bone marrow microscope slide to sequence the third exon of the beta-globin gene. These studies showed substitution of arginine for leucine at position 106 of the beta-globin chain. In order to avoid confusion with the cys112-to-arg mutation, to which the name Hb Indianapolis was firmly attached, Coleman et al. (1991) renamed the original variant hemoglobin Hb Terre Haute. The dominantly inherited beta-thalassemias that are due to highly unstable variant beta chains, such as HB Indianapolis, result from the rapid catabolism of the beta chains and consequent erythroblast destruction within the bone marrow. These differ from the classic unstable hemoglobin variants in which most damage occurs to erythrocytes in the circulation, resulting in hemolytic anemia rather than impaired erythropoiesis.
In a Dutch patient with a mild, nontransfusion dependent beta-thalassemia phenotype, Losekoot et al. (1991) found a mutation in the cleavage-polyadenylation sequence. The mutation, AATAAA-to-AATGAA, was detected using denaturing gradient gel electrophoresis (DGGE) and direct sequencing of genomic DNA amplified by PCR.
Kutlar et al. (1991) described a new hemoglobin variant called Hb Valletta, which is characterized by a threonine-to-proline substitution at position 87 of the beta chain. This mutation was found to be linked to that of the gamma-chain variant Hb F-Malta-I (142250.0014) which has a his-to-arg mutation at position 117 of the G-gamma chain. The 2 genes are 27 to 28 kb apart. No chromosomes with one or the other mutation alone were identified.
In a 12-year-old black male with splenomegaly and anemia, Gaudry et al. (1990) found a hemoglobin variant manifest by electrophoretic abnormality. This unstable hemoglobin was found to have a substitution of aspartic acid for valine at position 54 of the beta chain.
Thein et al. (1991) reported a patient with severe heterozygous beta-thalassemia characterized by large inclusion bodies and resulting in a single base substitution, CTG to CGG, in codon 28 in exon 1. The mutant hemoglobin, called Hb Chesterfield, had an unstable beta chain. The patient was a 34-year-old English woman who had presented at the age of 7 years with abdominal pain, anemia, jaundice, and hepatosplenomegaly. She had been transfusion-dependent since the age of 10. Because of increasing transfusion requirements, a splenectomy was performed at the age of 13. Cholecystectomy was required at the age of 28.
Witkowska et al. (1991) found that sickle cell disease in a 3-year-old girl was due to compound heterozygosity for the Hb S gene and a new mutation called Hb Quebec-Chori. ('Chori' is an acronym for the Children's Hospital Oakland Research Institute.) Although the purified variant had gelling properties similar to those of Hb A, a mixture of it with Hb S resulted in a delay time of polymerization very similar to that of a homogeneous solution of Hb S. The sickle gene was inherited from the father, who was black and originally from Guyana. The new mutant was inherited from the mother, who was white and of English-Irish-French Canadian extraction. By peptide analysis, the new hemoglobin was found to have substitution of isoleucine for threonine-87.
In a Portuguese patient suffering from a chronic hemolytic anemia, Wajcman et al. (1991) found an unstable hemoglobin which contained a his92-to-asn substitution. The variant readily loses its heme group and a rapid deamidation occurs in vitro, yielding an asp92 semihemoglobin. The oxygen affinity of the patient's red blood cells was increased, leading to stimulation of erythropoiesis and a macrocytic hemolytic disease. Harano et al. (1991) found the same unstable hemoglobin variant in a Japanese female with hemolytic anemia and called it Hb Isehara.
In addition to Hb Redondo, 6 other rare Hb variants had been reported in which deamidation of an asn residue to an asp occurred as a spontaneous posttranslational modification: Hb J (Sardegna) (141850.0036), Hb J (Singapore) (141800.0075), Hb La Roche-sur-Yon (141900.0482), Hb Osler (141900.0211), Hb Providence (141900.0227), and Hb Wayne (141850.0004).
In a Portuguese family living in Coimbra, Portugal, Tamagnini et al. (1991) identified a high oxygen affinity hemoglobin variant. Aspartic acid at residue 99 was replaced by glutamic acid in the beta chain. Two affected members had erythrocytosis with hemoglobin levels of 18 to 20 g/dl. A GAT-to-GAA mutation at codon 99 represented the seventh type of substitution at this specific location. From a survey of mutations, Tamagnini et al. (1991) suggested that codons GAC(asp), GAT(asp), GAG(glu), and GAA(glu) are particularly susceptible to mutational events.
Lin et al. (1992) described a mutation in the TATA box that has the sequence CATAAA and is located about 30 nucleotides upstream of the cap site. The mutation changed CATAAA to AATAAA.
See Wilson et al. (1991). This hemoglobin variant combines the mutations present in Hb D (glu121-to-gln; 141900.0065) and in Hb Okazaki (cys93-to-arg; 141900.0207).
See Lacombe et al. (1990). The asp52-to-asn mutation is also found in Hb Osu Christiansborg (141900.0212).
This abnormal hemoglobin was discovered in a 75-year-old Japanese male with an unusually low level of Hb A(1c) (397,396:Harano et al., 1990, 1992). The patient was being treated for chronic renal failure. A CAC-to-CAA change in codon 146 was responsible for substitution of glutamine for histidine. Hb Kodaira was the fifth hemoglobin variant involving the terminal codon of the beta chain. The others are Hb Hiroshima (141900.0110), Hb York (141900.0305), Hb Cowtown (141900.0056), and Hb Cochin-Port Royal (141900.0051).
Plaseska et al. (1991) described a new variant with a beta chain 1 residue longer than the normal as a result of the deletion of asp, gly, and leu at positions 73, 74, and 75 and the insertion of ala, arg, cys, and gln in their place. Hb Montreal is unstable.
See Spivak (1989).
See Abourzik et al. (1991). This mutation is at the same nucleotide as that in Hb D (Los Angeles) (141900.0065).
See Harano et al. (1991).
A variant hemoglobin resulting from substitution of aspartic acid for histidine at residue 143 of the beta chain was detected in a 17-year-old male who had mild anemia (Moo-Penn et al., 1992).
In a Japanese family, Hattori et al. (1992) found a GAG-to-TAG change in codon 90, substituting a stop codon for glutamic acid. The mutation had previously been found only in Japanese, the first case having been reported by Harano et al. (1989).
Hattori et al. (1992) identified this mutation in a Japanese patient. The abnormality was a substitution of guanine for cytosine at nucleotide 848 of IVS2. This nucleotide is at position -3 in the acceptor splice sequence. A C-to-A mutation at the same site in an Iranian patient had been reported by Wong et al. (1989); see 141900.0362.
Rund et al. (1992) used a polyadenylation mutation involving the deletion of 5-bp (AATAAA-to-A-----) and another mutation (141900.0383) to study the function of the poly(A) signal in vivo and to evaluate the mechanism whereby polyadenylation mutations lead to a thalassemic phenotype.
In a Sicilian subject, Renda et al. (1992) identified a G-C substitution in the invariant AG dinucleotide at the acceptor splice site of the first intron. In the same nucleotide, a G-A substitution is a frequent cause of beta-zero-thalassemia in Egyptians (see 141900.0356). Although mutations in the invariant GT or AG dinucleotide splice junctions are known to give rise to beta-zero-thalassemia, studies were not performed in the specific patient reported by Renda et al. (1992) to determine that this was in fact a beta-zero-thalassemia mutation.
In 3 out of 3,000 beta-thalassemia chromosomes in the Sardinian population, Rosatelli et al. (1992) found deletion of a single nucleotide G at codon 1 (GTG-to-TG), which resulted in both a frameshift and the formation of an in phase termination codon at codon 3. In addition, sequencing showed at codon 2 of the globin gene a single nucleotide substitution, C to T, which is a common silent substitution in the Mediterranean population (Orkin et al., 1982).
In 2 members of an Arabian family from Oman, Ramachandran et al. (1992) discovered a leu-to-val replacement at position beta-32 by reversed phase high performance liquid chromatography. In 1 person, it occurred with Hb S and in the other with Hb A. Although Hb Muscat was slightly unstable, its presence had no apparent adverse effect on the health of its carriers.
In a young Arabian boy living in Tunisia, Molchanova et al. (1992) detected a leu48-to-pro substitution in the beta chain. Since the parents did not have the variant, it presumably occurred by spontaneous mutation. It was thought not to be the cause of hemolytic anemia.
As alleles of the HBB gene producing beta-thalassemia were discovered, it became evident that there is a relative paucity of beta-thalassemia mutations in exon 3 of HBB even though this exon accounts for about 30% of the coding region. It appears to be a general rule that 1-bp frameshift mutations and nonsense mutations early in exon 3 produce a chronic hemolytic anemia in the heterozygous state. On the other hand, mutations of this type in exons 1 and 2 in the heterozygous state produce beta-thalassemia trait with mild phenotypic deviations from the normal. Kazazian et al. (1992) reported another example of this rule: in a 78-year-old Lithuanian Ashkenazi Jew with chronic hemolytic anemia, they demonstrated a -1 frameshift (-G) in codon 109. The globin was termed beta-Manhattan for the site of residence of the patient.
In 4 members of a Yugoslavian family who exhibited severe microcytosis and hypochromic anemia, Jankovic et al. (1992) found heterozygosity for a G-C mutation in the last nucleotide of IVS2. This change of the invariant AG dinucleotide of the acceptor splice site of intron 2 abolished normal splicing. Two other mutations of the IVS2 acceptor splice site have been identified as causes of beta-zero thalassemia; see 141900.0353 and 141900.0354.
In a family of northern Italian descent (Brescia-Lombardia), Murru et al. (1992) found that a 14-year-old girl with the clinical phenotype of severe thalassemia intermedia had a heterozygous CTG-to-CCG change at codon 114 resulting in substitution of proline for leucine in the beta-globin chain. The resulting hemoglobin tetramer was highly unstable and precipitated to form inclusion bodies in peripheral red blood cells. The unusually severe phenotype present in this heterozygote was thought to be explained by the coinheritance of a triple alpha-globin locus.
In a 29-year-old female of Irish descent with thalassemia-like anemia during her first pregnancy, deCastro et al. (1992) found no gross structural alteration on Southern blot analysis of the globin genes but found an alpha:beta globin chain synthesis ratio of 0.91 (control = 0.94). Because they suspected an unstable hemoglobinopathy and because many of these disorders are due to point mutations in exon 3 of the beta-globin chain, they performed PCR-SSCP analysis, which showed an abnormality. Sequencing demonstrated a T-to-C transition at codon 114 resulting in a leucine-to-proline substitution. They called the hemoglobin variant Durham-N.C. to distinguish it from hemoglobin Durham, named for the city in England. The mutation created a novel MspI restriction site in exon 3 of the HBB gene. DeCastro et al. (1994) demonstrated that this hemoglobinopathy, like several others within exon 3 of the beta-globin gene, e.g., Hb Showa-Yakushiji (leu110-to-pro; 141900.0262), result in a thalassemic and/or hemolytic phenotype with moderately severe microcytic anemia inherited as an autosomal dominant.
Kim et al. (2001) described the molecular and hematologic characteristics of a Korean family with a dominantly inherited beta-thalassemia. Carriers were characterized by moderate anemia, hypochromia, microcytosis, elevated Hb A2 and Hb F levels, and splenomegaly. A CTG (leu) to CCG (pro) change at codon 114 of the HBB was demonstrated. They referred to the abnormal hemoglobin as Hb Durham-N.C./Brescia.
In an asymptomatic Portuguese female, Faustino et al. (1992) found heterozygosity for a C-to-T transition at position -90 in the proximal CACCC box.
In a Portuguese family with 'dominant' thalassemia intermedia, Faustino et al. (1992) found deletion of nucleotides 4 and 5 (AG) in IVS2 of the HBB gene, converting GTGAGT to GTGTCT.
In a 5-generation Portuguese family, Faustino et al. (1998) described an autosomal dominant form of beta-thalassemia intermedia. Carriers showed moderate anemia, hypochromia, microcytosis, elevated Hb A2 and Hb F, splenomegaly, hepatomegaly, and inclusion bodies in peripheral red blood cells after splenectomy. The molecular basis was found to be deletion of 2 nucleotides, AG, within the 5-prime splice site consensus sequence of intron 2 of the HBB gene. The fourth and fifth nucleotides in the sequence GTGAG were deleted. Reticulocyte RNA studies performed by RT-PCR and primary extension analysis showed 3 abnormally processed transcripts, which, upon sequencing, were shown to correspond to (1) skipping of exon 2, and (2) activation of 2 cryptic splice sites (between codons 59 and 60), and at nucleotide 47 in the second intron. In vitro translation studies showed that at least 1 of these aberrant mRNA species is translated into an abnormally elongated peptide whose cytotoxic properties could, in part, be causing the atypical dominant mode of inheritance observed in this family. Faustino et al. (1998) suggested that this elongated beta chain is unable to combine with an alpha-globin chain to form a functional hemoglobin molecule. Its degradation would, then, exhaust the proteolytic defense mechanism of the erythroid precursors, leading to inefficient proteolysis of the free alpha chains in excess.
Wajcman et al. (1992) demonstrated that Hb Duino, an unstable hemoglobin, carries 2 point mutations, the his92-to-pro mutation of Hb Newcastle (141900.0197) and the arg104-to-ser mutation of Hb Camperdown (141900.0042). Family studies demonstrated that the Hb Newcastle abnormality was a de novo mutation of a gene already carrying the Hb Camperdown substitution. One member of the Italian family studied by Wajcman et al. (1992) had hemolytic anemia.
Divoky et al. (1992) analyzed the hemoglobin of a child of German descent living in the former German Democratic Republic and exhibiting typical clinical features of beta-thalassemia intermedia. One of his chromosomes 11 and 1 of his mother's carried a GTG-to-ATG mutation at codon 18, resulting in the replacement of a valine residue by a methionine residue. Called Hb Baden, the newly discovered beta-chain variant represented only 2 to 3% of the hemoglobin in both the patient and his mother because of the presence of an IVS1 +5 G-to-C thalassemic mutation (141900.0357) on the same chromosome. On the other chromosome, inherited from the father, the boy carried the val126-to-gly mutation of Hb Dhonburi (141900.0393), which itself is slightly unstable and associated with mild thalassemic features.
Liu et al. (1992) accidentally detected 2 abnormal hemoglobins by cation exchange high performance liquid chromatography performed with an automated system designed to quantitate Hb A1c in blood samples from patients with diabetes mellitus. The variants eluted together with the fast-moving Hb A1c. One of the variants, found in 4 healthy, apparently unrelated adults, involved a change from a histidine to a leucine residue at position 2 of the beta chain. The second variant was identical to Hb Sherwood Forest (141900.0261).
In a typical beta-thalassemia carrier of Italian descent, Saba et al. (1992) demonstrated a G-to-A transition in the initiation codon of the HBB gene, producing a substitution of isoleucine for methionine. The absence of the initiation methionine led to defective beta-globin mRNA translation and probably determined the complete absence of beta-chain production. Indeed, initiation of translation may have occurred at the first downstream ATG sequence, which is located at codon 21-22; the resulting out-of-frame reading probably terminates at the new UGA termination codon at codon 60-61. Initiation codon mutations previously described in both the alpha (141850.0022) and beta (141900.0344) globin genes all result in complete inactivation of the affected globin gene.
In 7 members of 3 generations of a family living in northern Sweden, Landin et al. (1995) found an initiation codon mutation ATG-to-ATA of the HBB gene. The mutation changed the initiation codon from methionine to isoleucine and resulted in a beta-zero-thalassemic phenotype. The affected family members all presented hematologic findings typical for the beta-thalassemic trait, with slight anemia, marked microcytosis, and increased levels of Hb A2. See 141900.0345 for an initiation codon mutation ATG-to-ACG, which changes methionine to threonine.
In the course of quantification of Hb A(1c) in a 48-year-old Swedish woman, Landin (1993) discovered a variant hemoglobin that comprised approximately 39% of the total hemoglobin. A study demonstrated a GAT-to-CAT mutation in codon 21, corresponding to an asp21-to-his substitution. As predicted from the location of the substitution in the molecule, it was not associated with any overt hematologic abnormalities.
During a routine hematologic evaluation of a 1-year-old boy and his father, Broxson et al. (1993) found a variant hemoglobin that produced a band on electrophoresis in the same position as that for sickle hemoglobin. Screening of other family members showed that the paternal grandmother and an uncle also had the variant. Amino acid analysis demonstrated that glycine at position 83 of the beta-globin chain had been substituted by arginine. This gly83 is an external residue with no significant inter- or intra-molecular contacts, and mutation at this residue would not be expected to cause any changes in the functional properties of the variant.
In a healthy 36-year-old male of Ethiopian descent with normal hematologic findings, Molchanova et al. (1993) found a hemoglobin variant with electrophoretic mobility on cellulose acetate like that of Hb S. DNA studies demonstrated a GAC-to-CAC transversion leading to an asp79-to-his amino acid substitution.
Pistidda et al. (2001) identified the same mutation in a Caucasian in the Sassari district of Sardinia.
Duwig et al. (1987) found a new unstable hemoglobin in a boy of 9 years hospitalized for hematuria and diffuse pains. Clinical examination demonstrated isolated splenomegaly without hepatomegaly or adenopathy. He was anemic and the variant hemoglobin constituted 30% of total hemoglobin. Molecular studies revealed a substitution of arginine for glutamine-131.
In 4 apparently unrelated French families, Wajcman et al. (1993) found 5 patients carrying a hemoglobin variant associated with moderate erythrocytosis. The structural abnormality was a replacement of phenylalanine-103 by isoleucine. The residue involved was the same as that in Hb Heathrow (141900.0102), which is a phe103-to-leu substitution. The increase in oxygen affinity is much lower in Hb Saint Nazaire than in Hb Heathrow. The replacement of phenylalanine G5, which is located within the heme pocket, by leucine abolishes several contacts between heme and globin and leads to an environment of the heme with similarities to that observed in myoglobin. In contrast, the replacement of G5 by an isoleucine is likely to introduce less structural modifications.
In a Czech family, Divoky et al. (1993) found a GCC-to-GAC mutation in codon 115 of the beta-globin gene as the cause of dominant beta-thalassemia trait. The variant hemoglobin was markedly unstable. A mother and daughter, who were heterozygotes, showed moderate anemia, reticulocytosis, nucleated red cells, target cells, Heinz body formation, and splenomegaly. Both had marked increase in fetal hemoglobin synthesis.
Fay et al. (1993) described hemoglobin Manukau in 2 brothers presenting with nonspherocytic hemolytic anemia who became transfusion-dependent by 6 months of age. The severity of clinical expression seemed to be modulated by coexisting alpha-thalassemia. The brothers had a Niuean mother and a New Zealand Maori father. A second unusual feature was a modification of beta-141 leu, which appeared to be deleted because post-translational modification had changed leu-141 to a residue (probably hydroxyleucine) that was not detected by standard amino acid analysis and sequencing methods. The same feature occurs in Hb Coventry (141900.0055).
In a 41-year-old man in Spain with severe erythrocytosis, Wajcman et al. (1993) found an electrophoretically silent hemoglobin variant with very high oxygen affinity and markedly reduced cooperativity. The structural abnormality was determined by mixing normal and abnormal beta chains, isolating the abnormal tryptic peptide by reversed-phase HPLC, and sequencing the peptide by mass spectrometry. Serine-89 was replaced by threonine.
During routine hematologic investigation of a 44-year-old man, Owen et al. (1993) found a novel hemoglobin with high oxygen affinity and a substitution of glycine for tryptophan-37. This change would be expected to result in a destabilization of the deoxyhemoglobin form because of the reduced number of hydrogen bonds, salt bridges, and van der Waal contacts between the alpha-1 and beta-2 chains. Hemoglobin was 16.3 g/dL. The variant constituted 29% of the hemoglobin, indicating either reduced stability of the nascent Hb Howick chain or an impaired expression level.
Stabler et al. (1994) reported a 16-year-old white boy from Denver, Colorado, in whom cyanosis of the skin, lips, mucous membranes, conjunctivas, and nail beds was noted at the time of a dental extraction. The mother also had lifelong cyanosis and, although asymptomatic, had had severe anemia during pregnancy. The maternal grandmother and maternal aunt had chronic cyanosis and mild anemia. No abnormal hemoglobin band separate from that of hemoglobin A was found on electrophoresis, HPLC, and isoelectric focusing. However, a heat test showed hemoglobin instability, and O2 studies disclosed an appreciably right-shifted dissociation curve. On chromatography, the new variant--hemoglobin Denver--was found to carry a substitution of serine for phenylalanine at position 41 in the beta chain. In addition to reduction in O2 affinity, hemoglobin Denver was accompanied by moderate reticulocytosis and mild anemia. The corresponding substitution in the hemoglobin gamma gene is found in hemoglobin F (Cincinnati) (HBG2; 142250.0041) and is associated with cyanosis.
Rahbar et al. (1991) discovered Hb Beckman, an alanine-to-glutamic acid mutation at position 135 of the HBB gene, in a 32-year-old African American woman with chronic anemia and microcytosis and a palpable spleen. While substitution of proline at position 135 (Hb Altdorf; 141900.0007) results in an unstable hemoglobin variant with increased affinity for oxygen, substitution of glutamic acid has a reverse effect, i.e., Hb Beckman has reduced oxygen affinity.
A de novo mutation was reported by Park et al. (1991) in an 8-year-old boy who presented with symptoms of mild anemia and was found to be icteric with moderate splenomegaly. PCR followed by DNA sequencing of the HBB gene demonstrated that the mutation results in a deletion of valine (GGT) at amino acid position 33 or 34 without altering the reading frame in the remainder of the subunit. The deletion appears to disrupt the globin structure badly, producing a clinical phenotype of beta-thalassaemia resembling that of an ineffective erythropoiesis.
Coleman et al. (1993) discovered Hb Medicine Lake in a 17-month-old Caucasian female with hepatosplenomegaly and severe, transfusion-requiring hemolytic anemia. Although an abnormal hemoglobin could not be detected by electrophoresis, isoelectric focusing, or HPLC, DNA sequencing of the beta globin genes from the proband revealed both a codon 98 GTG-to-ATG transition that codes for the val-to-met mutation of Hb Koln (141900.0151) and a codon 32 CTG-to-CAG transversion coding for a leu-to-gln replacement. The hydrophilic glycine residue of Hb Medicine Lake contains an uncharged polar side chain, which distorts the 3-dimensional configuration of the globin; this would be predicted to cause instability but no shift in electrophoretic mobility.
During the course of a genetic survey of the first-year students at a London Medical School, Hb D (Neath) was discovered in an 18-year-old Caucasian female by Welch and Bateman (1993). In the variant HBB chain, the glutamic acid residue at position 121 is replaced with alanine.
Krishnan et al. (1993, 1994) reported a val-to-phe mutation at position 11 of the HBB chain in 6 members in 3 generations of a family of Hungarian-American descent. The proband had primary pulmonary hypertension, and other members of the family were mildly anemic. At least one other Hb variant, Hb Warsaw (141900.0257), has been reported to be associated with pulmonary hypertension. Hb Washtenaw is slightly unstable and has a low oxygen affinity.
Molchanova et al. (1993) discovered Hb Alesha in a 15-year-old Russian patient with severe hemolytic disease, anemia, splenomegaly, Heinz body formation, and continued requirement for blood transfusions despite a splenectomy at age 3. PCR amplification and sequence analysis of the hemoglobin beta gene indicated a GTG-to-ATG point mutation at codon 67, causing a valine-to-methionine transition. Molchanova et al. (1993) postulated that the replacement of valine by the larger methionyl residue significantly reduces the stability of the hemoglobin molecule by disrupting the apolar bonds between the valine and the heme group.
Girodon et al. (1992) reported Hb Dieppe in a 31-year-old French female with chronic anemia. DNA sequencing revealed a missense mutation (GAG-to-CGG) at position 127 of the beta-globin gene, causing a glutamine-to-arginine transition. The hemoglobin variant is highly unstable; the introduction of a positively charged hydrophilic residue at position 127 disrupts the tight contacts between the alpha and beta subunits.
Hb Higashitochigi was discovered by Fujisawa et al. (1993) in a 2-year-old Japanese boy with chronic cyanosis. The variant is missing a glycine residue, due to a deletion of 3 nucleotides in the genomic DNA (codons 24-25: GGTGGT-to-GGT). It is likely that the absence of glycine indirectly distorts the heme pocket, causing decreased oxygen binding of the beta chain and impaired oxygen release of the normal alpha chain in the tetrameric molecule.
Landin et al. (1994) added another example to the more than 40 hemoglobin variants with increased oxygen affinity associated with erythrocytosis. In 3 generations of the family of a 23-year-old male from Trollhaettan in Sweden, Landin et al. (1994) observed heterozygosity for a GTG-to-GAG transition at codon 20 that predicted a val-to-glu substitution, which was confirmed at the protein level. The mutation occurred in the same codon as hemoglobin Olympia (141900.0210), which shows a val20-to-met amino acid substitution.
In a variant hemoglobin designated Hb Tyne, Langdown et al. (1994) observed a CCT-to-TCT change in codon 5 predicting substitution of serine for proline. The variant was first found in a 66-year-old diabetic male after an inappropriately low level of glycosylated hemoglobin was detected by enzyme immunoassay, and confirmatory ion exchange high performance liquid chromatography revealed the presence of an abnormal hemoglobin. Consequently, Langdown et al. (1994) identified the same mutation in an apparently unrelated diabetic male. Neither occurrence of the variant was associated with any abnormal hematologic findings.
Coleman et al. (1995) investigated the molecular basis of transfusion-dependent hemolytic anemia in a Caucasian female infant who rapidly developed the phenotype of beta-thalassemia major. Both the father and mother were normal hematologically. The DNA sequence of one HBB gene demonstrated 2 mutations, one for the moderately unstable Hb Koln (141900.0151) and another for a novel leu32-to-gln change resulting from a CTG to CAG transversion. The new hemoglobin was called Hb Medicine Lake. The hydrophilic gln32 has an uncharged polar side chain that may distort the B helix and provoke further molecular instability. Biosynthesis studies of this mutation showed a deficit of beta-globin synthesis with early loss of beta-globin chains. Coleman et al. (1995) pointed to 14 previously described hemoglobin variants with 2 mutations in the same polypeptide chain. Most of these rare disorders had probably arisen via homologous crossing over. Such a mechanism, however, could not account for the Hb Medicine Lake, since neither parent had a detectable abnormal hemoglobin gene. Therefore, it was presumed that this was a true double de novo mutation.
Harano et al. (1995) used the designation Hb Yaizu, after the city where the carrier lived, for a new beta-chain variant found in a Japanese female who was apparently healthy. Isoelectric focusing showed an abnormal hemoglobin band between the normal A2 and A bands. An asp79-to-asn amino acid substitution was demonstrated.
Curuk et al. (1995) described an American family of English-Scottish descent in which 6 members were found to be heterozygous for beta-thalassemia. Sequencing of the HBB gene showed a G-to-A transition at the splice acceptor site of the second intron, changing the canonical AG to AA. Nucleotide 850 was involved; Curuk et al. (1995) commented that a G-to-C change in the same nucleotide had been found in a Yugoslavian family, whereas a frameshift due to deletion of nucleotide 850 was found in an Italian family. All 3 nucleotide changes lead to beta-zero thalassemia and are rare in the populations in which they were discovered.
Gurgey et al. (1995) observed a highly unstable hemoglobin variant in a 5-year-old Turkish girl with severe hemolytic anemia without Heinz body formation. A modest increase in liver and spleen size was present and level of Hb F was 33%. The variant could not be observed in red cells and was only detected through sequencing of the amplified beta-globin gene and also by hybridization with specific oligonucleotide probes. The variant was presumably a de novo mutation, since the parents were normal. Smears from bone marrow aspirates showed numerous inclusion bodies in erythroblasts and, as a result, erythroid hyperplasia. It was suggested that this hemoglobin variant was unstable and readily lost its heme group because one of the heme-binding sites had been lost and that, as a result, it precipitates in erythroblasts, thus interfering with the maturation process and causing severe anemia.
In 2 sibs with polycytemia in a French family, Wajcman et al. (1995) found a de novo ala140-to-val mutation. The hemoglobin displayed increased oxygen affinity, thus explaining the polycytemia. Both parents were phenotypically normal and study of polymorphic markers from several chromosomes were consistent with paternity. Since 2 brothers were affected, it was considered likely that the mutation had occurred in the germline of the father.
In a 22-year-old Caucasian female, known to be anemic from early childhood and showing scleral subicterus and slightly enlarged spleen on physical examination, Vassilopoulos et al. (1995) described a new unstable hemoglobin variant with reduced oxygen affinity. A phe45-to-cys amino acid substitution was found in beta-globin. The other chromosome 11 carried the gln39-to-ter (141900.0312) mutation that causes beta-zero-thalassemia. The new variant was named for the Greek city where the patient was born.
In a 73-year-old female of Dutch descent, Lafferty et al. (1995) found that a high oxygen affinity hemoglobin variant resulted from an AAT-to-TAT transversion of codon 139, resulting in an asn139-to-tyr amino acid substitution. See 141900.0092 for the asn139-to-asp mutation and 141900.0108 for the asn139-to-lys mutation involving the same codon.
During the assay of glycated hemoglobin by HPLC, Harano et al. (1995) identified a new hemoglobin named Hb Nakano for the district of Tokyo where healthy, 46-year-old Japanese woman lived and showed that it was due to a change of codon 8 from lysine to methionine. See 141900.0135 for the lys8-to-gln mutation, 141900.0191 for the lys8-to-glu mutation, and 141900.0237 for the lys8-to-thr mutation.
Frischknecht et al. (1996) found a new hemoglobin variant in the course of investigation of mild erythrocytosis. Mutation mapping of the beta-globin gene by PCR and denaturing gradient gel electrophoresis (DGGE) followed by sequence analysis revealed a C-to-A transversion at codon 38, predicting a thr38-to-asn substitution. In contrast to the other known mutation at codon 38, thr38-to-pro (known as Hb Hazebrouck; 141900.0101), Hb Hinwil was found to be stable and showed elevated oxygen affinity.
Lacan et al. (1996) described an unstable variant hemoglobin with high oxygen affinity responsible, in the steady state, for an apparently well-compensated chronic hemolytic anemia. The defect was shown to be a leu96-to-pro substitution in the HBB gene. The hemoglobin was named for the hospital in Lyon, France where the patient was observed. This electrophoretically neutral hemoglobin was found as a de novo case in a 6-year-old girl suffering from severe anemia with hemolysis and transient aplastic crisis following infection by parvovirus B19.
In 3 members of an indigenous Belgian family with beta thalassemia, Heusterspreute et al. (1996) found a deletion of 2 nucleotides, CC, from codons 38 and 39. The mutation eliminates an AvaII restriction site and so can be routinely investigated by AvaII digestion of amplified DNA.
In a 46-year-old Japanese male with plethora and erythrocytosis, Ohba et al. (1996) found a lys82gln amino acid substitution in the beta-globin chain. A son also had erythremia due to this hemoglobin variant.
In a 27-year-old man of Italian origin living in Belgium investigated because of mild polycythemia with microcytosis, Kiger et al. (1996) found that the hemoglobin had a negatively charged residue near the distal histidine and a ala62-to-asp substitution. The variant was called Hb J-Europa, presumably because it was found in the proband during a systematic physical examination performed before employment at the headquarters of the European Economic Community (EEC) in Luxembourg.
Lacan et al. (1996) found this mildly unstable variant in a French family without hematologic or clinical features. Although the substitution involves the same residue as in Hb E (141900.0071), the new sequence in this case did not create an additional out-of-frame splice site. The mutated chain was, therefore, normally synthesized.
Miranda et al. (1996) described Hb Camperdown in a 24-year-old Brazilian woman of Italian origin. Although carriers do not show significant clinical alterations, Hb Camperdown is considered an unstable Hb.
Negri Arjona et al. (1996) described a Spanish family with a dominant type of beta-thalassemia. Carriers were characterized by mild anemia, hyperchromia, microcytosis, elevated Hb A2 and Hb F levels, reticulocytosis, and splenomegaly. They found that the molecular basis was the introduction of a CGG triplet between codons 30 and 31 of the HBB gene; this was determined by sequencing of amplified DNA and confirmed by dot-blot analysis. The abnormal mRNA was stable and present in quantities similar to that of normal mRNA. The abnormal mRNA translated into a beta-chain that was 147 amino acid residues long and carried an extra arginine residue between residues 30 and 31. The abnormal beta chain may be unstable and does not bind to the alpha-chain. It probably is continuously digested by proteolytic enzymes in red cell precursors in the bone marrow. The abnormal chain probably binds haem that is excreted after proteolysis causing a darkening of urine, which was a clinical characteristic of the disorder. The insertion occurred at the 3-prime end of IVS1 and the 5-prime end of exon 2. The insertion may have an addition of CGG between codons 30 and 31 or an insertion of GGC between IVS1 129/130.
Rodriguez Romero et al. (1996) discovered an abnormal beta-chain hemoglobin Hb Costa Rica, or beta-his77arg, in a healthy young Costa Rican female. This stable hemoglobin, termed Hb Costa Rica, was present in only 6 to 8% of hemoglobin and was not observed in any relative (the father was not available for study). The expected CAC-to-CGC mutation could not be detected in genomic DNA. Smetanina et al. (1996) presented convincing evidence that the CAG-to-CGC mutation at codon 77 of the HBB gene had occurred as a somatic mutation during embryonic development and resulted in mosaicism with only 6 to 8% of the abnormal Hb Costa Rica in circulating red cells. Bradley et al. (1980) had described an instance of gonadal mosaicism accounting for an unusual pedigree pattern in a family with Hb Koln (141900.0151). Smetanina et al. (1996) incorrectly stated that theirs was the first example of mosaicism in a hematopoietic system.
Beta-thalassemia alleles are uncommon among Ashkenazi Jews as compared with Sephardic Jews and other populations. Oppenheim et al. (1993) described a rare allele, a single-base insertion resulting in a frameshift at codon 20/21, in an Ashkenazi Jewish proband living in Israel. Martino et al. (1997) independently discovered this allele (called fs20/21 by them) in a Montreal Ashkenazi pedigree and investigated the possibility of genealogic connections between the 2 families. They showed by analysis of the mutation and the associated marker haplotype that the Israeli and Montreal probands appeared to be identical by descent and certainly had identity by state at the HBB locus. Genealogic reconstruction suggested that the 2 families had a shared origin in time and space.
Ohba et al. (1997) reported the fifth variant with retention of the initiator methionine and partial acetylation. The proband, a 37-year-old Japanese male, was subjected to detailed studies because of an unexpectedly high HbA1c value on cation exchange high performance liquid chromatography. The findings of their subsequent studies, as well as previous reports, suggested that retention of the initiator methionine and acetylation have no physiologic or pathologic significance, at least on human hemoglobin. The authors found that the variant hemoglobins were not unstable in in vitro tests. Ohba et al. (1997) stated that they must be almost as stable as normal HbA in vivo because they comprise over 40% of total Hb in the peripheral blood. The 4 previously reported Hb variants with retention of initiator methionine were Hb Thionville (141800.0168), Hb Marseille (141900.0171), Hb Doha (141900.0069), and Hb South Florida (141900.0266).
Waye et al. (1997) described a beta-thalassemia trait in a Caucasian woman of British descent living in Ontario, Canada. The 48-year-old woman presented with typical high Hb A2 beta-thalassemia trait. All known family members were of British ancestry. Her father had normal hematologic indices and her mother was deceased. There was no family history of anemia. Direct nucleotide sequencing demonstrated a complex frameshift mutation due to deletion of 5 nucleotides (AGTGA) and insertion of 1 nucleotide (T) at codons 72/73 of the HBB gene. This introduced a premature stop codon (TGA) at codon 88, resulting in beta-zero-thalassemia.
In a Lombardy family (from Gambara, near Brescia in Northern Italy), Ivaldi et al. (1997) described a 45-year-old man and his 2 daughters who carried an abnormal hemoglobin resulting in modest erythrocytosis and mild, compensated hemolysis with slight splenomegaly. The abnormal hemoglobin represented about 52% of the total hemoglobin, and was shown to be stable by the isopropanol test. Sequencing demonstrated a change in the HBB gene of codon 82 from AAG (lys) to GAG (glu) in heterozygous state.
Waye et al. (1998) studied the hemoglobin of a 37-year-old woman who presented during pregnancy with the beta-thalassemia trait. The father and mother were Sephardic Jews whose families had lived for many generations in Tangiers and Gibraltar, respectively. The HBB gene was found to have a single basepair substitution at codon 30: AGG (arg) to GGG (gly). The mutation changed the sequence immediately upstream of the 5-prime splice junction of the first intron: A-to-G at position -2 of IVS1. The authors stated that although mutations had been found at positions -1 and -3 of IVS1, no mutation had been described at the -2 position. The authors thought it unlikely that an arg30-to-gly substitution was responsible for the abnormality and favored the possibility that the mutation impaired the normal splicing of the beta-globin pre-mRNA.
Hattori et al. (1998) identified a new beta-thalassemia allele in a 31-year-old Japanese man who was found to have microcytosis and erythrocytosis during a health check-up. His red blood cell count was 6.53 x 10(12) per liter. The HBB gene in 1 allele was found to have an insertion of T at codon 26: GAG-to-GTAG. The frameshift mutation was expected to result in beta-zero-thalassemia because the translation of the abnormal mRNA produced a peptide with an abnormal amino acid sequence from codon 26 to 42 where it terminates. Such a truncated peptide of 42 residues would be immediately eliminated by proteolysis. Codon 26 is involved in the consensus sequence for cryptic splicing at codon 25. The insertion of T at codon 26 breaks the consensus sequence and is unlikely to affect the alternative splicing. Results of SSCP analysis indicated that the patient was heterozygous for the frameshift.
Hoyer et al. (1998) described a new hemoglobin variant called Hb Silver Springs which resulted from a CAG (gln)-to-CAC (his) change at codon 131 of the beta chain. It was detected only by cationic exchange high performance liquid chromatography. This was the fifth reported substitution at codon 131. The variant did not appear to have any clinical or hematologic manifestations. It was found in 6 African Americans from 4 presumably unrelated families.
In investigating the nature of the unique hemoglobin variant that caused a spurious increase in glycated hemoglobin, Hb A(1c), Elder et al. (1998) found a CAC-to-TAC mutation in the HBB gene that resulted in a his143-to-tyr substitution in the beta-globin peptide. This amino acid substitution affected an important 2,3-diphosphoglycerate binding site and slightly increased the oxygen affinity of the hemoglobin variant. Despite the slight increase in oxygen affinity, the mutation was without hematologic effect, and its only clinical significance was that it coeluted with Hb A(1c) on ion-exchange chromatography and compromised the use of this analyte to monitor the treatment of diabetes mellitus. The variant was encountered in 4 unrelated persons of Irish or Scottish-Irish ancestry.
Gilbert et al. (2000) reported 2 unrelated cases of Hb Old Dominion/Burton-upon-Trent.
Plaseska-Karanfilska et al. (2000) found the same mutant hemoglobin in a 72-year-old Korean woman with type II diabetes (125853).
By globin chain electrophoresis, Grignoli et al. (1999) detected a novel silent hemoglobin variant in a 4-year-old Caucasian Brazilian boy of Italian descent, and in his mother. Sequencing of the HBB gene revealed a G-to-A transition at the first position of codon 34, resulting in a val-to-met substitution. In the boy, this variant was found to be associated with Hb Hasharon (141850.0012) and alpha-thalassemia-2 (rightward deletion).
Van den Berg et al. (1999) identified a novel Hb B variant, termed Hb Nijkerk, in a Caucasian Dutch girl who was slightly icteric at birth and developed hemolytic anemia and hepatosplenomegaly at about 5 months of age. Red cell transfusions were necessary every 3 to 4 weeks. Erythromorphology was markedly abnormal, with large numbers of red cells with inclusion bodies. Splenectomy was performed at the age of 18 months, after which the need for transfusions decreased and they were finally discontinued. Although still anemic, the child's growth was otherwise normal. Repeated hemoglobin electrophoresis on cellulose acetate revealed no abnormalities. At the age of 17 years, a minor abnormal band, migrating slightly faster than Hb A2, was detected on starch gel electrophoresis. Sequencing of the HBB gene revealed heterozygosity for a 4-bp deletion (GCTA) in combination with a 1-bp insertion (T) at codons 138/139. This event eliminated 2 amino acids (ala and asn) and introduced a new residue (tyr) into the protein. The parents did not carry the mutation and paternity analysis showed no discrepancies, indicating that Hb Nijkerk should be considered as a de novo event.
Hojas-Bernal et al. (1999) identified a novel Hb B gene variant, termed Hb Chile, in a 57-year-old Native American living in Chile who was known to be chronically cyanotic. He was hospitalized for elective surgery of left pyeloureteral stenosis. Prior to surgery, he was given sulfonamides. Surgery was terminated when the dark color of his blood was noted. Arterial oxygen saturation was 80%. His blood contained 18% methemoglobin. Repeated intravenous methylene blue was given for the methemoglobinemia but to no avail. Sulfhemoglobin was not increased. Subsequently, an acute episode of hemolytic anemia occurred. Red cell glucose-6-phosphate dehydrogenase and methemoglobin reductase were normal. The patient's father and 1 of his 2 children also showed cyanosis. Tryptic digestion of the beta-globin chain and subsequent chromatography revealed an abnormal beta-T-3 peptide; sequencing revealed a leu-to-met substitution at position 28, predicted to be caused by a CTG-to-ATG transversion in the HBB gene. Hojas-Bernal et al. (1999) concluded that Hb Chile is an unstable hemoglobin that forms methemoglobin in vivo spontaneously at an accelerated rate and predisposes to drug-induced hemolytic anemia.
By chromatographic measurement of glycated Hb in a 90-year-old woman of French origin, Wajcman et al. (1998) identified a novel hemoglobin variant, termed Hb Tende, that showed a moderate increase in oxygen affinity. Sequencing of the HBB gene revealed a CCA-to-CTA transition, resulting in a pro124-to-leu substitution. Three hemoglobin variants at amino acid 124 had been previously described: Hb Tunis (pro124 to ser; 141900.0288) is asymptomatic; Hb Khartoum (pro124 to arg; 141900.0148) is mildly unstable; and Hb Ty Gard (pro124 to gln; 141900.0289) is responsible for increased oxygen affinity leading to erythrocytosis. Wajcman et al. (1998) suggested that the absence of erythrocytosis in the Hb Tende carrier whom they studied was likely due to the relatively low proportion of abnormal Hb (34%), possibly explained by the mild instability revealed by the isopropanol test, and to the normal cooperativity of the variant.
Wajcman et al. (1992) identified Hb La Roche-sur-Yon, an unstable hemoglobin variant resulting from a leu81-to-his substitution in the HBB gene. The variant displayed a moderately increased oxygen affinity. in addition to the substitution at beta-81, about half the abnormal hemoglobin carried a deamidation of the neighboring asparagine residue at beta-80. The authors concluded that the deamidation depends not only on the flexibility of the polypeptide region but also on the presence of a neighboring histidine residue to catalyze the reaction. See also Hb Redondo (141900.0404).
In a family originating from Iraq, Deutsch et al. (1999) identified a novel beta-chain silent variant, a change of codon 10 from GCC to GTC (ala10 to val), in association with thalassemia. The variant, which they designated Hb Iraq-Halabja, gave a normal oxygenation curve, a normal heterotopic action of 2,3-DPG, and normal heat stability and isopropanol precipitation tests. The variant showed a clear difference in migration properties compared to normal beta chain only when run on PAGE urea Triton. The codon involved in Hb Iraq-Halabja is the same as that mutant in Hb Ankara (141900.0009), in which the substitution is ala10 to asp.
Agarwal et al. (1999) found an A-to-G transition in exon 1 of the HBB gene at codon 8 which resulted in a lys8-to-arg amino acid substitution. This change was associated with a splice mutation and was speculated to produce a thalassemia intermedia phenotype in the subject.
Miyazaki et al. (1999) described compound heterozygosity for a beta(+)-thalassemia mutation and a new beta variant with low oxygen affinity, Hb Sagami (asn139 to thr).
Henthorn et al. (1999) reported a new beta-globin variant, phe118 to cys, found in a newborn male of Indian Gujerati origin, living in the Harrow area of London, England. This variant was observed during a systematic program of neonatal screening. The mother also carried the abnormal hemoglobin.
Wajcman et al. (1999) described a beta-globin variant in a 36-year-old French Caucasian male who presented with polycythemia. The variant was named Hb Brie Comte Robert for the place where the carrier resided. It was shown to have high oxygen affinity.
In several members of a French family, Kister et al. (1999) identified a lys144-to-met mutation in the HBB gene. The mutation is a clinically silent variant in which the structural modification disturbs the oxygen-linked chloride binding.
In 3 members of a family from Bologna, Italy, Ivaldi et al. (1999) demonstrated that erythrocytosis was the result of a variant beta-globin chain, a CAC-to-TAC mutation in codon 146 leading to a his146-to-tyr amino acid substitution. Ivaldi et al. (1999) pointed out that this was the sixth substitution that had been identified in the C-terminal residue of the beta-globin chain, the others being his146-to-asp (141900.0110), his146-to-pro (141900.0305), his146-to-leu (141900.0056), his146-to-arg (141900.0051), and his146-to-gln (141900.0409).
Gilbert et al. (2000) described a second case of Hb Bologna-St. Orsola in a family of Anglo-Celtic origin.
In a 15-year-old Portuguese girl with erythrocytosis, Bento et al. (2000) found a new high oxygen affinity variant called Hb Vila Real and characterized by a pro36-to-his (P36H) missense mutation of the HBB gene. The patient's mother had undergone regular phlebotomies over the previous 20 years for polycythemia, with an obstetric history of 2 miscarriages, a stillborn baby, and 2 normal children by elective Cesarean section. A transversion converted codon 36 from CCT to CAT. The variant was named after the city in Portugal where the carrier was born.
Salzano et al. (2002) reported the same rare high oxygen affinity hemoglobin variant in a 22-year-old male patient from Naples, Italy, affected by erythrocytosis. The DNA mutation was identified as a change in codon 36 of the HBB gene from CCT to CAT. The father carried the same hemoglobin variant in heterozygous state.
In a 3-year-old anemic German girl, Bisse et al. (2000) detected an abnormal hemoglobin by cation-exchange high performance liquid chromatography. Further studies characterized the variant as a thr84-to-ala replacement in the HBB gene, which the authors named Hb Saale for the river crossing the city in which the proband lived. Hb Saale could be not be separated by electrophoresis or isoelectric focusing. It was found to be slightly unstable, exhibiting a moderate tendency to autooxidize. Functional properties and the heterotropic interactions were similar to those of hemoglobin A.
Wajcman et al. (2000) found a hemoglobin variant, designated Hb Bushey, in a Chinese baby and his father. The variant was found to be caused by a point mutation leading to a phe122-to-leu substitution in the HBB gene. The same amino acid substitution was found in Hb Casablanca (141900.0493), in combination with another abnormality in the HBB gene, i.e., a lys65-to-met amino acid substitution (Hb J (Antakya); 141900.0121).
Wajcman et al. (2000) found a hemoglobin variant in a family in Morocco and designated it Hb Casablanca. It was found to be another example of a hemoglobin variant with 2 abnormalities in the same chain: the first was identical to that of Hb Bushey (phe122 to leu; 141900.0492) and the second to that of Hb J (Antakya) (lys65 to met; 141900.0121). The stability and oxygen-binding properties of Hb Bushey and Hb Casablanca were identical to those of Hb A.
Oribe et al. (2000) found a new hemoglobin variant in a Japanese male: a change at codon 117 of the HBB gene from CAC (his) to TAC (tyr). The authors designated this variant Hb Tsukumi after the patient's place of residence. Two other hemoglobin variants have a change in his117: a change to arg in the case of Hb P (Galveston) (141900.0213), and a change to pro in the case of Hb Saitama (141900.0250).
North et al. (2001) found Hb Tsukumi in a Moroccan woman.
Analysis of globin chains by reversed phase high performance liquid chromatography, used as an additional tool for characterizing hemoglobin variants, led to the discovery of a new class of variants that display only differences in hydrophobicity. Groff et al. (2000) described 2 such variants: Hb Ernz and Hb Renert (141900.0496). Hb Ernz, a thr123-to-asn substitution, was found in a man of Italian origin who was polycythemic and in 2 of his 3 daughters who were hematologically normal. See 141900.0294 for a thr123-to-ile substitution.
Groff et al. (2000) identified Hb Renert, a val133-to-ala substitution in the HBB gene, in a man from Cape Verde who also carried Hb S (141900.0243) and presented with chronic hemolysis.
Wilson et al. (2001) described a second case of Hb Renert. They commented that this was only the second hemoglobin variant involving beta-133, the other being Hb Extremadura (V1133L; 141900.0074).
Four hemoglobin variants had previously been described that involve the first codon of the HBB gene: Hb Doha (141900.0069), Hb South Florida (141900.0266), Hb Niigata (141900.0471), and Hb Raleigh (141900.0233). Although none of these variants cause any significant clinical problems, mutations of the first codon are of interest because of their potential interference with cotranslational modification at this site during beta-globin synthesis. In eukaryotes, the translation of all peptide mRNAs starts at an AUG codon, producing methionine at the beginning of the nascent peptide chain. In most proteins, including alpha-, beta-, and gamma-globin, this methionine is cotranslationally cleaved when the chain is 20 to 30 amino acids long. This results in the first amino acid being valine in alpha-, beta-, and delta-globin, and glycine in gamma-globin. When the peptide chain is 40 to 50 amino acids long, further modification occurs with acetylation at the NH2-terminal residue. The extent of the acetylation depends on the identity of the N-terminal amino acid; valine is strongly inhibitory to this process, leading to little acetylation of alpha- and beta-globin. However, the N-terminal glycine of gamma-globin is less inhibitory, resulting in about 15% acetylation. Fisher et al. (2000) identified a new Hb variant, Hb Watford, in which a GTG-to-GGG substitution caused a change of the first amino acid of the beta-globin chain from methionine to glycine, mimicking the gamma-globin chain. The proband was a 48-year-old female of Jewish extraction who was evaluated for chronic mild anemia. Another mutation was found in cis with the val1-to-gly mutation: Cap+36G-A.
Yapo et al. (2001) described a val134-to-ala missense mutation of the HBB gene in a 45-year-old man originating from Cameroon, a migrant worker in France. He was a compound heterozygote for this mutation, designated Hb Yauounde, and for Hb Kenitra (141900.0147). Hb Kenitra had previously been described only in persons of Moroccan origin. Hb Yaounde appeared to be neutral; Hb Kenitra is associated with expression at a level slightly higher than that of Hb A.
Papassotiriou et al. (2001) identified hemoglobin Sitia, an ala128-to-val missense mutation in the HBB gene, in a Greek female with slightly reduced red blood cell indices.
In a 33-year-old French Caucasian woman displaying a well-tolerated chronic anemia, Wajcman et al. (2001) found Hb Mont Saint-Aignan, a mildly unstable variant associated with hemolytic anemia, marked microcytosis, and increased alpha/beta biosynthetic ratio. The molecular defect was an ala128-to-pro missense mutation of the HBB gene.
In a Dutch patient of Chinese origin, Harteveld et al. (2001) identified a new hemoglobin variant, Hb 't Lange Land, caused by a GGT-to-CGT transversion at codon 136 in exon 3 of the HBB gene, predicted to result in a gly136-to-arg (G136R) substitution. The authors stated that 3 mutations inducing a single amino acid substitution at codon 136 were known: Hb Hope (gly136 to asp; 141900.0112), and 2 others based on personal communication from H. Wajcman, Hb Petit Bourg (gly136 to ala) and Hb Perpignan (gly136 to ser).
In an asymptomatic Indian male belonging to the Agri caste group and originating from Mumbai in Maharashtra State, India, Colah et al. (2001) found a new hemoglobin variant, Hb D (Agri), with 2 amino acid substitutions in the same beta chain: glu121 to gln (141900.0065) and ser9 to tyr.
Keser et al. (2001) identified a 9-bp (TCTGACTCT) deletion/insertion at codons 3-5 of the HBB gene in a 26-year-old woman with beta-thalassemia trait. The change was found to be the result of a deletion of cytosine (-C) at codon 5 (1 of the nucleotides in the 13th or 14th position of exon 1), and an insertion of thymine (+T) in front of codon 3 at the 10th nucleotide in exon 1 of the HBB gene. As a result of these mutations, the amino acids at codons 3-5 were changed from leu-thr-pro to ser-asp-ser. This partial frameshift mutation led to a very unstable beta-globin chain.
Kyrri et al. (2001) found a nonpathologic Hb variant in a Greek Cypriot male originating from Limassol, a town on the south coast of Cyprus. A G-to-C substitution in codon 8 (AAG to AAC) led to a lys8-to-asn (K8N) amino acid substitution. The 4 previously described amino acid substitutions at residue 8 of the beta-globin chain (lys8 to thr, 141900.0237; lys8 to gln, 141900.0135; lys8 to glu, 141900.0191; and lys8 to met, 141900.0460), and the 2 hemoglobin variants with amino acid substitutions at the equivalent residue of the alpha-globin chain (lys7 to asn, 141800.0187 and lys7 to glu, 141800.0192) are nonpathologic as well.
Badens et al. (2002) described a 'new' mechanism leading to thalassemia intermedia, a moderate form of thalassemia: a somatic deletion of the HBB gene in the hemopoietic lineage of a heterozygous beta-thalassemic patient. The deletion occurred on the chromosome 11 inherited from the mother, who had no abnormality of the HBB gene. The father had a beta-thalassemic trait due to the Mediterranean HBB nonsense mutation (141900.0312). The deletion gave rise to a mosaic of cells with either 1 or no functional beta-globin gene and it extended to a region of frequent loss of heterozygosity called LOH11A, which is located close to the HBB locus. Thus, loss of heterozygosity can be a cause of nonmalignant genetic disease.
Brennan et al. (2002) found hemoglobin Canterbury by chance when a supposedly normal lysate was used as a control for an isopropanol stability test. The sample came from a 55-year-old man with Cowden disease due to a novel mutation in the PTEN gene (601728.0022), reported by Raizis et al. (2000). The isopropanol stability test showed a precipitate, suggesting a slightly unstable hemoglobin.
Prehu et al. (2002) described a heterozygous hemoglobin variant that combined the change of Hb O-Arab (141900.0202) and Hb Hamilton (141900.0099) on the same HBB allele. The other allele carried the Hb S mutation (141900.0243). The patient was a child of Chad-Sudanese descent, suffering from a sickle cell syndrome. Compared to the classic description of the Hb S/Hb O-Arab association, the additional Hb Hamilton mutation did not seem to modify the clinical presentation.
Qualtieri et al. (2002) identified a new neutral hemoglobin variant in a pregnant Italian woman that resulted from a GTG-to-CTG replacement at codon 126 of the HBB gene, corresponding to a val-to-leu amino acid change. Thermal and isopropanol stability tests were normal and there were no abnormal clinical features.
Waye et al. (2002) described a case of dominant beta-thalassemia in a 38-year-old Canadian male of northern European extraction. He was anemic at birth and required periodic blood transfusions until about 2 years of age. Subsequently, he was under close medical supervision for his anemia and thrombocytosis, but did not require further transfusions. He had been asymptomatic throughout childhood. At age 20 years, he was found to have splenomegaly, and splenectomy was performed at age 23 because of mild symptoms and to prevent splenic rupture during karate competitions. After surgery he received Pneumovax, a prophylaxis against pneumococcal infections. He remained on folic acid supplementation, which had been started in childhood. The family history was negative for hematologic disorders. He was shown to have the normal complement of 4 alpha-globin genes. He was heterozygous for a single-nucleotide deletion in the HBB gene converting codon 113 from GTG to TG. This frameshift mutation was predicted to give rise to an extended beta chain of 156 amino acid residues. It was considered to be a de novo mutation. The mutation in this case most closely resembled that of Hb Geneva (141900.0335), an unstable beta-chain variant due to a complex rearrangement at codon 114. Both mutations give rise to extended beta chain variants of 156 amino acids differing only at residues 113 and 114 (cys-val for the codon 113 mutation and val-gly for the codon 114 mutation). In both instances, it was not possible to detect even a trace of the predicted Hb variant in carriers of the mutation.
Waye et al. (2002) stated that more than 30 dominant beta-thalassemia alleles had been reported.
So et al. (2002) described a 35-year-old woman in whom a beta-chain variant was found on assay for Hb A(1c) performed because of impaired glucose tolerance during pregnancy. The raised hemoglobin level was suggestive of a hemoglobin variant with high oxygen affinity. The patient was heterozygous for a CAC-to-CAG transversion at codon 146, corresponding to a substitution of histidine by glutamine in the beta-globin chain. The same amino acid substitution at codon 146 occurs in the high oxygen affinity variant Hb Kodaira (141900.0409); however, Hb Kodaira resulted from a point mutation of CAC-to-CAA at codon 146. Not unexpectedly, the phenotypic manifestation of the 2 mutations was identical. This second form of his146 to gln (H146Q) was referred to as hemoglobin Kodaira II.
Ngiwsara et al. (2003) described a case of Hb Kodaira II in Thailand.
Prehu et al. (2002) described a novel unstable hemoglobin variant with low oxygen affinity and called it Hb Ilmenau for the city where the patient lived. The variant hemoglobin had a phe41-to-cys (F41C) substitution due to a TTC-to-TGC transversion in codon 41. The patient was a 29-year-old man who had suffered from anemia since childhood. When he was 4 years old, a nonspherocytic anemia was diagnosed with hepatosplenomegaly and cyanosis for which no cardiac origin could be found. He was splenectomized at the age of 8 years, without any significant clinical or biologic improvement.
In a 32-year-old woman from Provence, southeast France, Lacan et al. (2002) found a novel unstable beta-chain variant with a GGC-GCC transversion resulting in a gly64-to-ala (G64A) substitution. The presence of Heinz bodies and reduced percentage (23 to 35%) of the abnormal hemoglobin fraction suggested a moderate instability in the hemoglobin, which the authors designated Hb Aubagne.
Cobian et al. (2002) found Hb Colima, a ser49-to-cys change (S49C) of the beta-globin chain, in a 52-year-old Mestizo female who was born in Colima, Mexico. This was the second mutation at beta-49, the first being Hb Las Palmas (ser49 to phe), a slightly unstable variant (141900.0155).
During a screening for hemoglobinopathies in blood donors in Brazil, Kimura et al. (2002) identified a beta-globin variant in a 30-year-old Caucasian woman of mixed Native Indian and Italian origin. The base substitution in codon 61 of the HBB gene from AAG to CAG caused a lys-to-gln (K61Q) change. This was the fourth description of a missense mutation at lys61 of the HBB gene: see Hb N-Seattle (K61E; 141900.0190), found in a black American blood donor; Hb Hikari (K61N; 141900.0106), found in a Japanese family; and Hb Bologna (K61M; 141900.0024), found in a northern Italian family. The missense mutations found at this position (external contacts of the Hb molecule) did not cause clinical manifestations; all the carriers described had been asymptomatic.
In a 31-year-old woman from Trento in northeastern Italy, Ivaldi et al. (2003) found anomalous hemoglobin: an elongated C-terminal variant due to deletion of an A in codon 144. The deletion led to the replacement of lysine by serine at residue 144, the disappearance of the stop codon at position 147, and the presence of 12 additional residues, identical to those observed in hemoglobins Saverne (141900.0255), Tak (141900.0279), and Cranston (141900.0057), which result from a similar mechanism. Hb Trento, amounting to 29% of the total hemoglobin, was unstable and, like the other variants of this group, had an increased oxygen affinity. It led to a mild compensated hemolytic anemia with red cell inclusion bodies.
In a 22-year-old Spanish male presenting with jaundice and suffering from hemolytic crises during infections, Villegas et al. (2003) identified an unstable Hb variant in which the valine residue at position 34 of the beta-globin chain was replaced by aspartic acid (val34 to asp; V34D).
HEMOGLOBIN CASERTA. Beta chain anomaly. See Ventruto et al. (1965) and Quattrin et al. (1970).
HEMOGLOBIN D (FRANKFURT). Beta chain anomaly. See Martin et al. (1960) and Gammack et al. (1961).
HEMOGLOBIN DURHAM-I (HEMOGLOBIN R). Beta chain anomaly. See Chernoff and Weichselbaum (1958) and Chernoff and Pettit (1964).
HEMOGLOBIN J (JAMAICA). Beta chain anomaly. See Gammack et al. (1961).
HEMOGLOBIN K. Beta chain anomaly. See O'Gorman et al. (1963).
HEMOGLOBIN KINGS COUNTY. Probably beta chain defect. Observed in an American black family. Affected persons had nonspherocytic hemolytic Heinz body anemia. See Sathiapalan and Robinson (1968).
HEMOGLOBIN L. Beta chain anomaly. See Ager and Lehmann (1957) and Gammack et al. (1961).
Antonarakis et al. (1984); Antonarakis et al. (1982); Arous et al. (1982); Bank et al. (1980); Barwick et al. (1985); Bernards et al. (1979); Blackwell et al. (1971); Blackwell et al. (1972); Blackwell et al. (1970); Blackwell et al. (1972); Blackwell et al. (1969); Blackwell et al. (1970); Blackwell et al. (1969); Blackwell et al. (1969); Blouquit et al. (1984); Boyer et al. (1963); Brennan et al. (1977); Cai et al. (1989); Cai Yin Lin et al. (1982); Cao et al. (1981); Chang et al. (1983); Chang and Kan (1982); Chang and Kan (1979); Charache et al. (1977); Chen et al. (1985); Chifu et al. (1992); Cole-Strauss et al. (1996); Driscoll et al. (1981); Efstratiadis et al. (1980); Enver et al. (1990); Forget (1979); Fritsch et al. (1980); Gacon et al. (1977); Garel et al. (1976); Gilbert et al. (2000); Gonzalez-Redondo et al. (1989); Gusella et al. (1979); Harano et al. (1985); Harano et al. (1990); Harano et al. (1991); Harano et al. (1990); Harano et al. (1990); Harano et al. (1983); Harano et al. (1981); Hebbel et al. (1977); Heller et al. (1966); Honig et al. (1990); Horst et al. (1983); Housman (1979); Idelson et al. (1974); Jeffreys and Flavell (1977); Johnson et al. (1980); Jones et al. (1967); Kan et al. (1977); Kan et al. (1975); Kan et al. (1975); Kan et al. (1980); Kaufman et al. (1980); Kohen et al. (1982); Lacombe et al. (1987); Lawn et al. (1980); Lebo et al. (1979); Li et al. (1990); Lucarelli et al. (1990); Maniatis et al. (1980); Miyaji et al. (1968); Molchanova et al. (1993); Moo-Penn et al. (1977); Moo-Penn et al. (1976); Moo-Penn et al. (1977); Moo-Penn et al. (1980); Moo-Penn et al. (1978); Nakatsuji et al. (1981); Necheles et al. (1969); Novy et al. (1967); Ohba et al. (1983); Ohba et al. (1989); Ohba et al. (1985); Ohba et al. (1975); Ohta et al. (1971); Orkin et al. (1978); Orkin et al. (1982); Orkin et al. (1980); Orkin et al. (1982); Orkin et al. (1983); Ottolenghi et al. (1976); Ottolenghi and Giglioni (1982); Ottolenghi et al. (1974); Pirastu et al. (1984); Pirastu et al. (1983); Plaseska et al. (1991); Plaseska et al. (1991); Plaseska et al. (1990); Prehu et al. (2002); Proudfoot et al. (1980); Rahbar et al. (1981); Ricco et al. (1974); Rochette et al. (1984); Sanders-Haigh et al. (1980); Schiliro et al. (1981); Schneider et al. (1969); Scott et al. (1979); Shibata et al. (1961); Shibata et al. (1961); Smith and Conley (1959); Spritz (1981); Studencki et al. (1985); Tamagnini et al. (1983); Taylor et al. (1974); Thein et al. (1990); Tilghman et al. (1978); Tuan et al. (1985); Vella et al. (1967); Verma and Edwards (1978); Villegas et al. (1989); Wajcman et al. (1993); Weatherall and Clegg (1981); Williamson et al. (1983); Williamson et al. (1981); Yoon et al. (1996); Zeng and Huang (1982); Zhao et al. (1990); Zinkham et al. (1979)
Victor A. McKusick - updated : 4/17/2003Victor A. McKusick - updated : 3/4/2003Victor A. McKusick - updated : 3/3/2003Victor A. McKusick - updated : 11/19/2002Victor A. McKusick - updated : 10/2/2002Victor A. McKusick - updated : 9/27/2002Victor A. McKusick - updated : 9/16/2002Victor A. McKusick - updated : 8/15/2002Victor A. McKusick - updated : 6/3/2002Victor A. McKusick - updated : 5/31/2002Victor A. McKusick - updated : 5/23/2002Victor A. McKusick - updated : 4/18/2002Victor A. McKusick - updated : 4/16/2002Victor A. McKusick - updated : 4/4/2002Victor A. McKusick - updated : 2/27/2002Victor A. McKusick - updated : 1/22/2002Ada Hamosh - updated : 11/15/2001Victor A. McKusick - updated : 11/2/2001Victor A. McKusick - updated : 11/1/2001Victor A. McKusick - updated : 10/10/2001Victor A. McKusick - updated : 2/28/2001Victor A. McKusick - updated : 2/14/2001Victor A. McKusick - updated : 11/3/2000Ada Hamosh - updated : 10/19/2000Victor A. McKusick - updated : 8/31/2000Victor A. McKusick - updated : 8/16/2000Victor A. McKusick - updated : 7/21/2000George E. Tiller - updated : 5/2/2000Victor A. McKusick - updated : 4/26/2000Victor A. McKusick - updated : 4/26/2000Victor A. McKusick - updated : 4/11/2000Victor A. McKusick - updated : 1/21/2000Victor A. McKusick - updated : 1/18/2000Carol A. Bocchini - updated : 12/14/1999Victor A. McKusick - updated : 12/8/1999Victor A. McKusick - updated : 9/15/1999Matthew B. Gross - updated : 8/26/1999Victor A. McKusick - updated : 8/25/1999Victor A. McKusick - updated : 8/13/1999Wilson H. Y. Lo - updated : 8/12/1999Victor A. McKusick - updated : 7/20/1999Ada Hamosh - updated : 6/27/1999Victor A. McKusick - updated : 5/24/1999Victor A. McKusick - updated : 12/21/1998Stylianos E. Antonarakis - updated : 12/13/1998Victor A. McKusick - updated : 11/19/1998Victor A. McKusick - updated : 8/26/1998Victor A. McKusick - edited : 8/19/1998Victor A. McKusick - updated : 4/30/1998Victor A. McKusick - updated : 3/31/1998Victor A. McKusick - updated : 2/17/1998Victor A. McKusick - updated : 11/5/1997Victor A. McKusick - updated : 9/29/1997Victor A. McKusick - updated : 9/11/1997Victor A. McKusick - updated : 8/13/1997Victor A. McKusick - updated : 5/28/1997Victor A. McKusick - updated : 2/28/1997Victor A. McKusick - edited : 2/21/1997Iosif W. Lurie - updated : 1/17/1997Moyra Smith - updated : 9/5/1996Moyra Smith - updated : 8/15/1996Orest Hurko - updated : 6/13/1995
Victor A. McKusick : 6/24/1986
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