A form of hereditary persistence of fetal haemoglobin characterized by uneven cellular distribution of haemoglobin F and the production of haemoglobins A and A2 in homozygotes.
Thirteen members of a British family were found to have elevated levels of haemoglobin F (Hb F) which segregated into two groups with mean values of 19.8+/-0.52% and 8.9+/-3.1% respectively. Genetic data indicate that the individuals in the former group are probably homozygous, and those in the latter group heterozygous, for the gene causing persistent Hb-F production. There is a significant reduction in the level of Hb A2 in the homozygotes. The Hb F is heterogeneously distributed among the red cells of each of the affected family members. In each case the haematological findings are normal and biosynthetic studies indicate balanced globin-chain synthesis. Chemical studies indicate that the Hb F consists mainly of the Agamma type together with a small (c 10%) but significant amount of the Ggamma type in both homozygotes and heterozygotes. The other red-cell proteins and antigens are of the adult variety in all affected family members. The condition differs from previously described forms of hereditary persistence of fetal haemoglobin by virtue of the heterogeneous distribution of the Hb F and the presence of beta and delta-chain synthesis in homozygotes. Its possible basis as a controller-gene mutation is discussed.