Organization of the a-Globin Genes in the Chinese a-Thalassemia Syndromes

Abstract

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