Negro alpha-thalassaemia: genetic studies in homozygous sickle cell disease.

Interaction with the alpha-thalassaemia phenotypes lowers the proportion of Hb S in the sickle cell trait and influences the mean cell volume and proportional Hb A2 in homozygous sickle cell (SS) disease. By assigning somewhat arbitrary values to the alpha-thalassaemia 1 and alpha-thalassaemia 2 phenotypes in these conditions, it has been possible to investigate the patterns of inheritance of alpha-thalassaemia in black populations. The results strongly support the hypothesis that the alpha-thalassaemia 1 phenotype represents homozygosity for alpha-thalassaemia 2.