Hereditary Persistence of Foetal Haemogloblll in a Thai Family: The First Instance in the Mongol Race and in Association with Haemoglobin E

Summary. Hereditary persistence of foetal haemoglobin is described in a Thai family. The AF heterozygotes were healthy and had normal haematological findings except the decrease in haemoglobin A2 level and the presence of a large amount of haemoglobin F. The latter, comprising 21–22 per cent, is higher than in the Greek but lower than in the Negro counterparts. Three persons, who were heterozygous for both haemoglobin E and high F genes, were not anaemic but had numerous target‐erythrocytes; haemoglobin E constituted 40 per cent, the rest being haemoglobin F. Acid‐elution staining revealed haemoglobin F in every red cell in both AF and EF heterozygotes. The absence of haemoglobin A in the latter suggests allelism between this type of hereditary persistence of foetal haemoglobin and haemoglobin E or β‐structural gene.