alpha-Thalassaemia in Sardinian infants.

Abstract

A Hb survey carried out in southern Sardinian newborn infants showed an overall incidence of 12.9% with Hb Bart''s of > 1%. The distribution was trimodal: low (1-2%), intermediate (2-10%) and high (about 25%). A considerable overlap was seen between the first 2 groups. Both the 1-2% and 2-10% groups had thalassemia-like red cell indices at birth. Newborn infants ascertained as having .alpha.-thalassemia at follow-up did not necessarily have unbalanced .alpha./non-.alpha. chain synthesis at birth. At follow-up examination, 2 subjects in the 25% group developed Hb H disease, and the 2-10% group had thalassemia-like red cell indices and unbalanced globin chain synthesis ratios indicative of heterozygous .alpha.-thalassemia. The 1-2% group had normal or slightly reduced .alpha.-chain synthesis ratios, indicative of the silent .alpha.-thalassemia carrier state. Two subjects with 2.0% and 2.5% Hb Bart''s at birth had heterozygous .beta.-thalassemia at follow-up. Therefore, they were double heterozygotes for .alpha.- and .beta.-thalassemia with .alpha./.beta.-globin chain synthesis ratios of 0.81 and 0.86, respectively. Genotype assessment in a few families showed that infants with Hb Bart''s levels of > 2% may have genotype -.alpha./-.alpha. or --/.alpha..alpha.