AKR1C4
Aldo-keto reductase family 1 member C4, also known as 3α-Hydroxysteroid dehydrogenase type 1 (3α-HSD1), is an enzyme that in humans is encoded by the AKR1C4 gene. It is known to be necessary for the synthesis of the endogenous neurosteroids allopregnanolone, tetrahydrodeoxycorticosterone, and 3α-androstanediol. It is also known to catalyze the reversible conversion of 3α-androstanediol (5α-androstane-3α,17β-diol) to dihydrotestosterone (DHT, 5α-androstan-17β-ol-3-one) and vice versa.