PARTIAL DELETION OF BETA-GLOBIN GENE DNA IN CERTAIN PATIENTS WITH BETA-0-THALASSEMIA

We have used restriction endonuclease mapping of cell DNA to investigate the structure of the β-globin gene in β-thalassemias. Among 17 individuals with β+- and β0-thalassemia, we observed three patients of Indian origin with β0-thalassemia whose DNA revealed a consistent mapping abnormality. In one β allele in each disploid cell, 0.6 kilobase of DNA was deleted from β-specific Pst I and Bgl II restriction fragments. This deletion involved 3' β-globin gene sequences and eliminated the EcoRI site normally present at codons 121/122, but it did not extend to the BamHI site at codons 98-100 on the 5' side of the 0.90-kilobase intervening sequence normally present in β-globin genes. Partial β-globin gene deletion appears, therefore, to be a primary molecular defect seen in certain patients with β0-thalassemia.