FRIDAY, DAY 5
SEXUALITY AND REPRODUCTION
In the early 1970s, the endocrinologist Julianne Imperato-McGinley made a long journey to a remote village in the mountains of the Dominican Republic, spurred by stories she’d heard about its children. When she arrived, she discovered that there was a group of children who, by all appearances, seemed to be girls at birth and had been raised as females. But during puberty, they began to transform into men: Their voices dropped, muscles developed, testes descended, and penises grew. In the village, these children were dubbed guevedoces (literally, “penis at 12”) and machihembras (meaning “first woman, then man”).
Back in the United States, Imperato-McGinley and other scientists continued to study this condition, which affected about 2 percent of the village children. After a few years, the researchers pinpointed the cause—a genetic mutation that resulted in low levels of the enzyme 5-alpha reductase (5AR). This enzyme is essential for the production of dihydrotestosterone (DHT), a powerful male sex hormone that causes male characteristics, including male pattern baldness and prostate growth. Production of DHT is stimulated at puberty by pituitary gland hormones, which is why the masculine features appear. After Imperato-McGinley’s research was published, other reports surfaced of people with DHT deficiency around the world.
Imperato-McGinley’s work also caught the eye of pharmaceutical researchers. If a DHT deficiency stymies prostate growth, they theorized, then it might just fend off enlargement of the prostate later in life. As a result, finasteride, a drug that inhibits 5AR, was released on the market in 1992. It’s frequently prescribed for benign prostatic hyperplasia (enlargement of the prostate).