Deletion of the A gamma-globin gene in G gamma-delta beta-thalassemia.

In an individual homozygous for G gamma-delta beta-thalassemia, a physical alteration in gamma-globin gene organization was detected by restriction enzyme mapping. The data indicated that the absence of A gamma-globin chains resulted from extension of the DNA deletion from the delta beta-globin gene region into the gamma-globin gene region rather than a functional disturbance of gamma-gene expression.