Beta-thalassaemia of clinical significance in adult Jamaican Negroes.

Over a 9-year period, three adult Negro patients with beta-thalassaemia of clinical significance were recognized out of approximately 185 000 new adult patients attending the University Hospital. These patients, aged 15-58 years, have clinical and haematological characteristics within the spectrum of beta-thalassaemia intermedia; which in this paper refers to phenotypes resulting from defects in beta-chain synthesis clinically intermediate between classical Cooley's anaemia and beta-thalassaemia trait, genetic classification being dependent on family study. Family studies established the presence of two beta-thalassaemia genes conclusively in one case (proposita, family A); presumptively in another (propositus, family C); while in the remaining subject (proposita, family B), who has two similarly affected siblings, homozygosity is suspected, but not proven by family study. In simultaneous 59Fe and 51 Cr studies, estimates of effective erythropoiesis are in reasonable agreement with measurements of red cell destruction.