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 pseudo-hermaphrodites with dihydrotestosterone (17β -hydroxy-5α -androstan-3-one) receptor deficiency. Specific dihydro-testosterone 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.