Organization of the α-globin genes in the Chinese α-thalassemia syndromes

Abstract

The α-thalassemia syndromes are a group of inherited anemias, the clinical severity of which has been shown to increase with the number of α-globin structural genes deleted. Employing restriction endonuclease gene mapping, we defined the organization of the α-globin genes in cellular DNA from Chinese subjects with various α-thalassemia syndromes. The four α-globin genes of normals are at two loci located on a 23.0-kilobase pair (kb) Eco RI fragment. In deletion type hemoglobin-H disease the 5' α-globin locus is deleted and the single 3' α-globin locus is found on a 19.0-kb Eco RI fragment. In α-thalassemia-2 there are two α-globin genes on a 23.0-kb Eco RI fragment and one on a 19.0-kb fragment. In α-thalassemia-1 and the nondeletion type of hemoglobin-H disease the two α-globin genes are at two loci on one chromosome and none reside on the other chromosome.