Hematological Phenotype of the Double Heterozygous State for Alpha and Beta Thalassemia

Abstract

In this study, we have correlated the hematological phenotype of 56 Sardinian β° -thalassemia heterozygotes with their α-globin genotype as defined by restriction endonuclease mapping. We found that the coinheritance of the deletion of one α-globin and, more obviously, two α-globin genes tend to normalize the thalassemia-like hematological phenotype commonly associated with the β°-thalassemia carrier state. On the other hand, the association of the deletion of three α-globin genes caused a more severe phenotype. By globin chain synthesis analysis, those β°-thalassemia heterozygotes with the (-α/αα) α-globin genotype had less deficiency of β-chain synthesis than did those with the normal α-globin genotype (αα/αα). In heterozygotes with the (-α/-α) and in those with the (-/-α) α-globin genotype the imbalance was actually reversed with a mild or marked α-chain synthesis excess respectively.