Hb Iraq-Halabja beta10 (A7) Ala-->Val (GCC-->GTC): a new beta-chain silent variant in a family with multiple Hb disorders.
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Deutsch S, Darbellay R, Offord R, Frutiger A, Kister J, Wajcman H, Beris P
Hb Iraq-Halabja beta10 (A7) Ala-->Val (GCC-->GTC): a new beta-chain silent variant in a family with multiple Hb disorders.
Am J Hematol. 1999 Jul;61(3):187-93.
- PubMed ID
- 10398311 [ View in PubMed]
- Abstract
A patient originating from Iraq was referred to our laboratory upon suspicion of a hemoglobinopathy. Routine hematological tests revealed a microcytic and slightly anemic phenotype with an elevated HbA2 suggestive of beta-thalassemia. Samples were obtained for several members of the family which upon examination revealed highly heterogeneous phenotypes that prompted us to investigate the case further. Sequencing of the beta-globin gene and alpha cluster mapping in the propositus and his brother showed a previously undescribed beta-globin variant:Hb Iraq-Halabja, beta10(A7) Ala-->Val (GCC-->GTC), associated with beta0-thalassemia IVS-2 nt1 G-->A and either alpha-thal-2-3.7 kb deletion (brother), or alpha-globin gene triplication anti-3.7 kb type (propositus). Detailed functional studies of the variant gave a normal oxygenation curve, a normal heterotopic action of 2,3 DPG, and normal heat stability and isopropanol precipitation tests. The variant shows a clear difference in migration properties compared to normal beta-chain only when run on PAGE urea Triton. As expected, alpha/beta-globin mRNA ratios were influenced by the concomitant presence of an alpha-globin gene pathology and the beta0 thalassemia and not by the presence of the beta-globin variant which apparently is clinically silent.