Hb Kurdistan [alpha 47(CE5)Asp-->Tyr], a new alpha chain variant in combination with beta (0)-thalassemia.

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 alpha variant is associated with a beta(0)-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 (0)-thalassemia and alpha-Kurdistan, presumably indicates a lower affinity of the abnormal chain for the beta polypeptides.