Polymorphism of foetal haemoglobin in the Sardinian beta +-thalassaemia

12 thalassaemic patients from Northern Sardinia showing the beta + phenotype were examined by isoelectric focusing and high-performance liquid chromatography techniques for the determination of the variant A gamma T globin chain of the foetal haemoglobin. Two patients (16.7%) were homozygotes for the A gamma T gene variant, 2 (16.7%) were heterozygotes and 8 (66.7%) were homozygotes for the normal A gamma I allele. The A gamma T gene frequency was 0.183, much lower than the observed 0.823 in beta zero homozygosity. These data suggest the presence of at least 2 beta +-thalassaemic chromosomes in Sardinians, one associated with the variant A gamma T allele and one associated with the normal A gamma I. The latter is prevalent among adult patients showing the intermediate form of the thalassaemic disease, which is not transfusion-dependent.