Characterization and locus assignment of two alpha-globin variants present in the Maltese population: Hb St. Luke's [alpha95(G2)Pro-->Arg] and Hb Setif [alpha94(G1)Asp-->Tyr].

Two types of alpha-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 alpha-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 [alpha95(G2)Pro-->Arg] was found to result from a C-->G mutation at the second position of codon 95 on an alpha1-globin gene, and Hb Setif [alpha94(G1) Asp-->Tyr] resulted from a G-->T mutation at the first position of codon 94 on an alpha2-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 alpha- or a beta-thalassemia allele, the protein products of the alpha1- and alpha2-globin genes were nearly equal in quantity.