In susceptible individuals of both genders, pattern hair loss is triggered by the conversion of testosterone (T) to dihydrotestosterone (DHT).  This is precipitated by the enzyme 5 alpha-reductase (5AR).  5AR comes in several isoforms, each associated with specific pathological consequences.  Type 2 5AR is primarily associated with benign prostatic hyperplasia (BPH, a non-cancerous enlargement of the male prostate gland.  At puberty and beyond type 1 5AR is expressed primarily in the skin and hair follicles.  Interestingly, it has been found that the blockade of 5AR can therapeutically ameliorate the onset, progression and pathogenesis of both BPH and AGA.  More on this in our next blog post.