Locus on human X chromosome for dihydrotestosterone receptor and androgen insensitivity

We have studied androgen binding characteristics of cells for androgen insensitivity from an obligate heterozygote, who is the mother of three male pseudohermaphrodites with dihydrotestosterone (17beta-hydroxy-5alpha-androstan-3-one) receptor deficiency. Specific dihydrotestosterone binding by skin fibroblasts from her wrist and pubis is within the normal range and indicates that androgen insensitivity is X-linked in man and is therefore homologous to the tfm locus in the mouse. A significant population of clones from the heterozygote has deficient receptor activity, and this finding is compatible with inactivation of one X-linked allele at this locus. Our results indicate the presence of a gene on the human X chromosome that is essential for normal male sexual differentiation and provide further evidence for homology between X chromosomes of all mammals.