Abstract
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). 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.