Mapping the ?-globin genes in HB J Mexico carriers

Abstract

The organization of the α-globin genes was studied by restriction endonuclease mapping, in subjects carrying the α variant Hb J Mexico. A subject homozygous for Hb J synthesized both Hb J (about 55%) and Hb A and had two α loci per chromosome. His restriction site map was found to be identical to that obtained with a normal DNA, except for a mutant Bgl II site which was observed on the Hb J chromosome proximal to the 5′α-locus. We have also mapped the DNA of a compound heterozygote for Hb J and α-thalassemia, who synthesizes 38% Hb J and we have found a single α gene corresponding to a −α^3.7 haplotype on one chromosome and two α genes, respectively α^J and α^A, on the other.