Evidence for secondary 5α-reductase deficiency in genital and supra-pubic skin of subjects with androgen insensitivity syndrome

Abstract

Abstract. The activity of 5 in genital and supra-pubic skin (homogenate or fibroblasts) from subjects with complete or incomplete androgen insensitivity syndrome was low compared with mean activity in samples from normally differentiated male controls. Also, in two subjects with incomplete androgen insensitivity syndrome the ratio of the concentration of testosterone to that of 5α-dihydrotestosterone in plasma was raised after hCG stimulation but normal under basal conditions. In three subjects with complete androgen insensitivity syndrome there was no evidence of raised ratios of testosterone to 5α-dihydrotestosterone in plasma under basal or hCG-stimulated conditions. The activities of other steroid metabolizing enzymes, e.g. 17β-hypdroxysteroid dehydrogenase, 3α/β-hydroxysteroid dehydrogenase, were not decreased. The low 5α-reductase activity of androgen insensitive subjects reported here, and by others, may imply that this enzyme in genital skin is in some way androgen dependent, or responsive to other factors associated with androgen insensitivity syndrome.