The story of finasteride begins with scientists who were working with certain Dominican Republic people who had a genetic trait that caused them to give birth to male children with ambiguous genitalia. Female babies were not affected. In many cases it was difficult to determine such an infant’s gender by observation alone. At puberty, when hormone levels in these affected individuals increased, most of these young boys normalized. They eventually had children of their own, and perpetuated the genetic trait.
No hair loss: It was also observed that the adult males in this group being studied never suffered enlarged prostate glands, never developed prostate cancer, nor did they lose their hair. No male pattern hair loss! Genetic research showed that their gene for producing the 5-alpha-reductase enzyme was inactive. With no 5-alpha-reductase enzyme, testosterone was not readily converted to DHT.
5-alpha-reductase regulation: Scientists figured that if they could create or find a medication to regulate the activity of 5-alpha-reductase they could accomplish some of the positive effects of this genetic trait, such as prostate gland normalization and hair loss prevention.