Finasteride is a popular drug recommended for males who have male-pattern baldness or enlarged prostate. It works by blocking a certain enzyme known as 5-alpha-reductase. What many people don't know about is how it was developed. The story will then take us to a small remote part of the Dominican Republic.
In this tiny village, many of the children are called Guevedoces, a word that translates to "penis at twelve." This is because around this time, the penises become more prominent or identifiable. Before they reach this age, they are often treated as girls.
Cornell Medical College's Dr Julianne Imperato-McGinley was one of the first researchers who comprehensively studied this unusual phenomenon back in the 1970s. Intrigued by a rumor that this area had "girls growing penises," she traveled the long distance to find out herself.
She then discovered that these children was deficient in an enzyme called 5-alpha-reductase, which is responsible for converting testosterone, a sex hormone, to dihydro-testosterone.
The gender of the baby is determined by the chromosomes. If it is a male, then it has XY chromosomes. The Y chromosome helps create the gonads, which then becomes the testicles, around two months of the pregnancy. The testicles, or testes, meanwhile, then start producing testosterone, which then travels to the tubercle. There, testosterone is converted into dihydro-testosterone, which helps change the tubercle to a penis.
With the Guevedoces, the enzyme deficiency means delayed development of the penis. When they reach adolescence, a time when hormones are on a high, the penis then begins to "grow."
But this is not her only finding. Due to the condition, which is believed to be genetic, men have smaller prostates. This is the basis for the development of finasteride by Merck, led by Roy Vagelos. This drug inhibits the enzyme, lowering dihydro-testosterone.
Guevodeces children usually live the rest of their lives as males, although some undergo operations to remain girls.
