Mild clinical course in two South African cases of sickle-cell anaemia.

Clinical, haematological and gene mapping data are presented on two South African cases of sickle-cell anaemia. Both individuals, who are siblings, have experienced a very mild clinical course. Restriction endonuclease analysis showed that 1 sibling was homozygous for alpha+-thalassaemia (genotype alpha-/alpha-), whereas the other had a full complement of alpha-globin genes. Both showed markedly elevated levels of Hb F. The maintenance of high levels of Hb F is the most probable explanation for the moderate clinical expression of the disorder in these patients.