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Hb adana or α 2 59(E8)Gly→Aspβ 2 , A severely unstable α 1 ‐globin variant, observed in combination with the ‐(α)20.5 KB α‐thal‐1 deletion in two Turkish patients
Author(s) -
Çürük M. A.,
Dimovski A. J.,
Baysal E.,
Gu LH.,
Kutlar F.,
Molchanova T. P.,
Webber B. B.,
Altay Ç.,
Gürgey A.,
Huisman T. H. J.
Publication year - 1993
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.2830440410
Subject(s) - hemoglobin variants , hemoglobin , aspartic acid , residue (chemistry) , thalassemia , globin , amino acid , glycine , chemistry , genetics , hemoglobinopathy , microbiology and biotechnology , mutation , haplotype , gene , biology , hemolytic anemia , biochemistry , genotype , immunology
We have identified a severely unstable hemoglobin variant through sequencing of amplified DNA involving the α 1 ‐globin gene; the mutation is located in codon 59 (C C G C A G) andresults in a Gly—Asp replacement. This amino acid substitution concerns a glycine residue at an internal position in the E helix, which is in close contact with a glycine residue of the B helix; introduction of the larger and charged aspartic acid residue greatly affects the stability of the molecule. This variant was present in association with a common α‐thalassemia‐1 deletion [‐(α)20.5 kb] in two adults and caused a severe type of Hb H disease with anemia, low levels of Hb A 2 , increased → chain, and Hb Bart's. In vitro chain synthesis in reticulocytes showed a high specific activity of the variant α chain. Only a minute quantity of Hb H was present but instead about 10% of Hb Bart's was observed. The increased synthesis of γ chains was likely due to specific characteristics of a chromosome with haplotype #3, which was present in both patients. The same family was studied 18 years ago [1]; the improved methodology presently available has led to a corrected diagnosis for these patients. © 1993 Wiley‐Liss, Inc.