Hb T-Cambodia, a beta-chain variant with the mutations of Hb E and Hb D-Punjab, confirmed by DNA analysis

Hemoglobin variants with two amino acid substitutions affecting one globin chain are relatively rare. Hb T-Cambodia, a doubly substituted beta-globin variant, was characterized. previously by amino acid sequencing as having sequence alterations in beta 26(beta 8)Glu-->Lys and beta 121(GH4)Glu-->Gln (1). It is a variant that migrates cathodic to Hb A(2) on alkaline electrophoresis and with Hb A on acid citrate agar electrophoresis. We report here the mutations of Hb T-Cambodia at the nucleotide level using DNA sequencing, in beta-globin gene codon 121 (GAA-->CAA) and in codon 26 (GAG-->AAG). These are the mutations of Hb D-Punjab and Hb E, respectively.