Characterization and locus assignment of two α-globin variants present in the Maltese population : Hb St. Luke's [α95 (G2) Pro→ Arg] and Hb Setif [α94 (G1) Asp→ Tyr]

Abstract

Two types of α-globin variants were found in 0.2% of a large number of newborn from Malta. The two hemoglobins were identified from tryptic maps on a Vydac C18 column and by α-globin gene sequencing as Hb St. Luke's (isoelectric point = 7.18 ± 0.017) and Hb Setif (isoelectric point = 7.26 ± 0.010). Hb St. Luke's [α95(G2)Pro→Arg] was found to result from a C→G mutation at the second position of codon 95 on an α1-globin gene, and Hb Setif [α94(G1)Asp→Tyr] resulted from a G→T mutation at the first position of codon 94 on an α2-globin gene. Quantification of Hb St. Luke's (11.1 ± 1.12%) and Hb Setif (14.7 ± 2.22%) in peripheral blood hemolysates indicated that, in the absence of either an α- or a β-thalassemia allele, the protein products of the α1- and α2-globin genes were nearly equal in quantity.