4,5-dihydrotestosterone; 5
α-androstan-17
β-ol-3-one; a potent metabolite of testosterone, formed by either of the steroid 5
α-reductases. It mediates many of the differentiating, growth-promoting, and functional actions of testosterone by binding to the
androgen receptor. Many mutations that inactivate steroid 5
α-reductase 2 cause an autosomal recessive form of
testicular feminization.