SUMMARY We present the findings of a survey to determine the prevalence of inherited haemoglobin disorders in the Coloured (mixed ethnic origin) population of South Africa. A variety of haemoglobins was found. Of the structural variants, Hb E and Hb S were the most common, the former probably originating from South-East Asia and the latter from East Africa and possibly Madagascar. The oa+ (-cx) for Hb E (Hb AE) and Hb C (Hb AC) were estimated at 0-9% and 0-3% respectively for the Cape Malay Coloured population and as 1% and 0.3% for the non-Malay Coloured group.2 In the white population, the same survey gave the following frequency estimation: Hb AS 0-2%, Hb AE 0-2%, and Hb AC 0-4%, but these figures seem rather high for a purely Caucasian population. Reports of homozygous Hb C disease in a white family have been published,6 7 but a report of sickle cell anaemia in this population group is difficult to substantiate.8 The rarity of the sickle cell gene among South African Blacks is well documented.9 "' Haemoglobin S has been described in a South African Indian population," including reports of the homozygous state,'2 13 but we are
The clinical, haematological and biosynthetic features of subjects with Hb E variants are described. An association with red cell hypochromia and microcytosis was confirmed, although this was not invariable in Hb E trait. Imbalanced globin chain synthesis was found in the majority of Hb E carriers. A patient doubly heterozygous for Hb E and Hb S, a condition we have not previously seen reported, had a benign clinical course with minor haematological changes, despite a relatively large amount of Hb S (67%).
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