Homozygous alpha+ thalassaemia in Zimbabwe: an unrecognized cause of hypochromia and microcytosis.

The prevalence of probable homozygous alpha+ thalassaemia in Zimbabwe was found to be 3.25 percent in a survey of hospital patients (n = 2,000), 7.6 percent in a Batonga village (n = 66), and 5.3 percent in 16 kindreds (n = 94) investigated for iron overload. The diagnosis was based on finding a reduced mean cell volume (MCV), reduced mean cell haemoglobin (MCH), increased red cell count (RBC), and a normal Haemoglobin. These cases usually had a normal red cell distribution width (RDW), and of three discriminant functions tested the MCV2 x MCH was the most useful. Iron deficiency was excluded in the community based surveys. The importance of recognizing these changes is emphasized so that inappropriate iron therapy is not given.