Abstract

A family of mixed Indian-Portuguese ancestry is reported in which there is a hereditary persistence of foetal haemoglobin and β-chain thalassaemia.

The propositus, a 17-year-old boy, was found to have a mild haemolytic anaemia characterized by slight splenomegaly, microcytosis, numerous target cells, decreased osmotic fragility, a very high level of foetal haemoglobin (75%), and normal haemoglobin A₂ level.

Examination of 12 other members of the family showed the following: Three individuals (father, sister, and nephew) had high levels of foetal haemoglobin (25%) but without other clinical or haematological abnormalities. Two individuals (mother and sister) had the features of thalassaemia trait with increased haemoglobin A₂ and normal levels of foetal haemoglobin.

The condition in the propositus appears to be the result of heterozygosity for a gene which is responsible for the hereditary persistence of foetal haemoglobin (high F gene) combined with heterozygosity for a β-thalassaemia gene and provides further evidence for allelism of these genes.

The possible genetic basis for the high F state and β-chain thalassaemia is discussed.