Partial deletion of the 5' β-globin gene region causes β°-thalassemia in members of an American black family

Restriction endonuclease mapping defined a partial deletion of about 1.35 kb in the β-globin gene of a black American patient with hemoglobin S-β° -thalassemia and in his uncle with a β°-thalassemia trait. The 5' endpoint of the deletion is about 600 bases upstream from the cap site, and the 3' endpoint lies within about 500 bases from the 5' splice junction of the second intervening sequence. The deletion is different from that of a previously reported Indian β°-thalassemia allele, where 0.6 kb is deleted at the 3' end of the β-globin gene.