A non-deletion hereditary persistence of fetal hemoglobin (HPFH) determinant not linked to the beta-globin gene complex.

We describe an Asian Indian family with a non-deletion form of hereditary persistence of fetal hemoglobin (HPFH) and beta zero thalassemia. The propositus who has homozygous beta zero thalassemia has an unusually mild form of the disease which is ascribed to the co-inheritance of HPFH. The interaction of HPFH and beta thalassemia was studied in five generations of this family. Linkage analysis showed that the genetic determinant for the HPFH segregates independently from the gamma delta beta globin gene complex. Analysis of HPFH linkage to a panel of genetic markers in such a large family offers the possibility of defining a transacting locus (or loci) involved in the expression of the gamma globin gene.