The interaction of α thalassaemia with heterozygous β thalassaemia

Abstract

Summary. The α globin genotypes of 55 β thalassaemia heterozygotes have been determined by restriction endonuclease analysis to identify those with interacting α thalassaemia genes. A comparison of the haematological and haemoglobin synthesis findings of individuals with normal α genotypes (αα/αα) with those with one (‐ α/αα) or two (‐α/‐α) α genes deleted shows that the latter two groups have more balanced globin chain synthesis ratios, higher haemoglobin levels, and larger, better haemoglobinized red cells. This suggests that the degree of globin chain imbalance is a significant factor in determining the red cell characteristics in heterozygous β thalassaemia. Screening programmes for thalassaemia, based on the detection of low MCVs, could miss cases of the interaction of α and β thalassaemia.