O- thalassaemia in Sardinian infants

summdARY A haemoglobin survey carried out in southern Sardinian newborn infants showed an overall incidence of 12.9 % with haemoglobin Bart's of more than 1%. The distribution was trimodal: low (1 to 2%), intermediate (2 to 10%), and high (about 25%). A considerable overlap was seen between the first two groups. Both the 1 to 2 % and 2 to 10 % groups had thalassaemia-like red cell indices at birth. Newborn infants ascertained as having ac-thalassaemia at follow-up did not necessarily have unbalanced a/non-a chain synthesis at birth. At follow-up examination two subjects in the 25 % group had developed haemoglobin H disease, and the 2 to 10 % group had thalassaemia-like red cell indices and unbalanced globin chain synthesis ratios indicative of hetero-zygous ac-thalassaemia. The 1 to 2 % group either had normal or slightly reduced a.-chain synthesis ratios, indicative of the silent oc-thalassaemia carrier state. Two subjects with 2.0 % and 2.5% haemoglobin Bart's at birth had heterozygous,-thalassaemia at follow-up. Therefore, they were double heterozygotes for ac- and r-thalassaemia with ac/3-globin chain synthesis ratios of 0.81 and 0.86. Genotype assessment in a few families showed that infants with haemoglobin Bart's levels of more than 2 % may have one of the genotypes a /-ac or- / aoac. The ac-thalassaemias (ac-thal) are a group of geneti