Alpha-thalassemia in blacks is due to gene deletion.

We used molecular hybridization to test if alpha-thalassemia is due to gene deletion in the black. In 10 families with clinically well-defined alpha-thalassemia-1 (alpha-thal-1), hydribization of alpha-globin cDNA was reduced to the same level as that found in Asians with alpha-thal-1, where two of the four normally present alpha-globin genes are deleted. A black child with hemoglobin H (Hb H) disease also has three globin genes deleted, as do Asian patients with Hb H disease. We conclude that alpha-thalassemia in the black is most commonly due to gene deletion.