HEMATOLOGICAL PHENOTYPE OF THE DOUBLE HETEROZYGOUS STATE FOR ALPHA-THALESSEMIA AND BETA-THALASSEMIA

The hematological phenotype of 56 Sardinian .beta.0-thalassemia heterozygotes was correlated with their .alpha.-globin genotype as defined by restriction endonuclease mapping. The coinheritance of the deletion of 1 .alpha.-globin and, more obviously, 2 .alpha.-globin genes tend to normalize the thalassemia-like hematological phenotype commonly associated with the .beta.0-thalassemia carrier state. The association of the deletion of 3 .alpha.-globin genes caused a more severe phenotype. By globin chain synthesis analysis, those .beta.0-thalassemia heterozygotes with the (-.alpha./.alpha..alpha.) .alpha.-globin genotype had less deficiency of .beta.-chain synthesis than did those with the normal .alpha.-globin genotype (.alpha..alpha./.alpha..alpha.). In heterozygotes with the (-.alpha./-.alpha.) and in those with the (--/-.alpha.) .alpha.-globin genotype the imbalance was actually reversed with a mild or marked .alpha.-chain synthesis excess, respectively.