Occurrence ofGγ Hb F in Greek HPFH: Analysis of Heterozygotes and Compound Heterozygotes with β Thalassaemia

Abstract

Hb F was isolated from red cells of individuals with the Greek form of hereditary persistence of fetal Hb (HPFH), and the glycine/alanine composition of the .gamma.CB3 peptides determined. In contrast to previous reports, the Hb F of the Greek HPFH heterozygotes contained significant amounts of G.gamma. chains and circumstantial evidence indicated that these were the products of the same chromosome that carries the Greek HPFH determinant. Hence this chromosome must be directing the synthesis of G.gamma., A.gamma. and (probably) .beta. and .delta. chains, implying that the Greek form of HPFH did not result from a deletion involving the globin chain structural genes. Analysis of the levels and structure of Hb F from the Greek HPFH heterozygotes and from separated cell populations from the Greek HPFH/.beta. thalassemia compound heterozygotes indicated that the Greek HPFH determinant, while allowing and overall increase in .gamma. chain synthesis, was not the sole factor determining the absolute amount of Hb F production on a cellular basis.