HB A₂-Canada Or A α₂δ₂99(G1) ASP → ASN, a Newly Discovered Delta Chain Variant With Increased Oxygen Affinity Occurring<i>In Cis</i>to β-Thalassemia

Abstract

An Indian family is described in which the father has a delta chain abnormal hemoglobin which is the result of a mutation of the delta gene in cis to a beta-thalassemia heterozygosity. The abnormality concerns a substitution of the Asp residue in position 99 (G1) by an Asn residue. A similar substitution has been found in the beta chain of Hb Kempsey (alpha 2 beta 2 99 Asp replaced by Asn). The observed abnormality results in a greatly increased oxygen affinity of this newly discovered Hb A2 variant.