The effect of alpha-thalassemia on the expression of the beta- thalassemia/HPFH heterozygote in a black family

A 2-yr-old black girl presented with a thalassemic clinical picture and was found to have nearly 100% fetal hemoglobin in her red cells. Pedigree analysis indicated that she was a heterozygote for the hereditary persistence of fetal hemoglobin gene and for a beta O- thalassemia gene. A brother, who also had nearly 100% fetal hemoglobin in his red cells, manifested, in contrast to his sister, no anemia and only minimal splenomegaly. Examination of the family's alpha-globin loci using the restriction endonuclease Eco Rl demonstrated that the brother had a single alpha-locus deletion that he had inherited from his mother. The mild clinical manifestations of this boy are consistent with the often expressed view that excess alpha chains may contribute significantly to the hematologic manifestation of beta-thalassemia.