HB KURDISTAN [ALPHA-47(CE5)ASP-]TYR], A NEW ALPHA-CHAIN VARIANT IN COMBINATION WITH BETA-THALASSEMIA

Abstract

We have characterized the structural abnormality of a new alpha chain mutant found in a Kurdish; family. The clinical and hematological investigation of eight individuals have shown that the a variant is associated with a beta degrees-thalassemia mutation (nonsense codon 39). The tryptic peptide map and sequencing of the abnormal peptide revealed the substitution of an aspartic acid by a tyrosine residue at position 47 of the alpha chain; furthermore, selective amplification and molecular analysis of both alpha genes have assigned the new mutation to the alpha 2 gene. The variant, named Hb Kurdistan, is clinically silent but the percentage of this hemoglobin found in the only double heterozygote for beta degrees-thalassemia and alpha-Kurdistan, presumably indicates a lower affinity of the abnormal chain for the beta polypeptides