Steroid 5-alpha reductase 2 (SRD5A2)

Steroid 5-alpha reductase 2 (SRD5A2) is a critical membrane-bound enzyme primarily expressed in androgen-sensitive tissues such as the prostate, seminal vesicles, and skin. It catalyzes the irreversible conversion of testosterone into dihydrotestosterone (DHT), a significantly more potent androgen that is essential for the development of male external genitalia and secondary sexual characteristics. Overactivity of this enzyme is a primary driver in the pathogenesis of benign prostatic hyperplasia (BPH) and androgenetic alopecia (male pattern baldness), making it a major therapeutic target. Conversely, loss-of-function mutations in the SRD5A2 gene result in 5-alpha reductase deficiency, a rare condition where genetic males are born with ambiguous or female-appearing external genitalia. Pharmacological inhibitors like finasteride and dutasteride are widely used to manage BPH and hair loss by reducing systemic and local DHT levels. However, these treatments are associated with notable safety concerns, including sexual side effects and potential mood disturbances, often referred to in clinical literature as post-finasteride syndrome.

Other names

3-oxo-5-alpha-steroid 4-dehydrogenase 25-alpha-reductase type 2S5AR 2SR type 2Steroid-5-alpha-reductase alpha polypeptide 2Type II 5-alpha reductase

Irreversible inhibition of the 5-alpha reductase enzyme, preventing the conversion of testosterone into the more potent androgen dihydrotestosterone (DHT).