5aR2 (also known as SRD5A2) is an enzyme responsible for converting T to DHT in target cells, particularly the prostate and testes. High DHT levels are linked to conditions like excessive hair growth and eventually loss, prostate enlargement, bladder, and urinary problems, and even certain cancers.
Finasteride and Dutasteride, two anti-androgen medications used to reduce hair loss and/or enlarged prostate gland work by reducing 5aR2 enzyme activity.
The important two variants (V89L and A49T) on the 5aR2 gene known to affect 5AR2 enzyme activity.
The GC genotype of this V89L variant is associated with less active 5aR2 and therefore predisposition to lower conversion of testosterone to DHT in the prostate and testicles. This is positive since high DHT levels in the prostate can lead to androgen-linked conditions such as prostate enlargement. This variant is thought to be dominant over the A48T variant below, helping to reduce overall levels of DHT. Smoking, high caffeine intake, and high insulin levels increase 5aR activity regardless and should be avoided. Specific substances that help to naturally reduce 5aR activity include pumpkin seed oil, green tea, saw palmetto, nettle, and zinc.
The TT genotype of this A49T variant is linked to increased conversion of testosterone to DHT. This is negative because DHT has been shown to increase the risk of androgen-dependent conditions such as male pattern balding and benign prostatic hyperplasia (BPH). Risk increases if you have the high-activity variant on AR (see pages 13 & 14 below). Smoking, high caffeine intake, and high insulin levels increase 5aR activity further. Specific substances that help to naturally reduce 5aR activity include pumpkin seed oil, green tea, saw palmetto, nettle, and zinc.