The homozygous state of G to A--117A gamma hereditary persistence of fetal hemoglobin

During a study of Sardinian families with hereditary persistence of fetal hemoglobin (HPFH), two unrelated subjects with unusually elevated Hb F levels were identified. By selective amplification of the A gamma gene promoter and hybridization to synthetic oligonucleotides, we demonstrate that these subjects are homozygous for the -117A gamma G---- A substitution that is responsible for a form of nondeletional HPFH. The hemoglobin synthetic pattern of these patients is discussed.