The duplicated human alpha globin genes lie close together in cellular DNA.

The organization of alpha globin genes in normal human DNA was examined by restriction endonuclease mapping, alpha globin-specific fragments in endonuclease digests of total cell DNA were identified after electrophoresis by hybridization with [32P]cDNA following the blotting procedure of Southern [(1975) J. Mol. Biol. 98, 503--517]. The data provide direct evidence for the duplication of alpha genes and further indicate that these loci are closely linked within a single restriction fragment. The HindIII sites (codons 90/91) of these duplicated genes lie approximately 3.7 kilobases apart in the physical map proposed for this region. This organization of alpha genes can be altered in DNA of individuals with alpha-thalassemia.