5α-Reductase deficiency (5-ARD) is an autosomal recessive intersex condition caused by a mutation of the 5α reductase type II gene.
The condition affects only genetic males (that is, those with a Y-chromosome) because DHT has no known role in female development.
Individuals with 5-ARD are born with male gonads, including testicles and Wolffian structures. They can have normal male external genitalia, ambiguous genitalia, or normal female genitalia, but usually tend towards a female appearance. As a consequence, they are often raised as girls, but usually have a male gender identity. There is a tendency towards a macroclitoris or micropenis, and the urethra may attach to the phallus.
If the condition has not already been diagnosed, it usually becomes apparent at puberty around age twelve with primary amenorrhoea and virilization. This may include descending of the testes, hirsutism (facial/body hair considered normal in males - not to be confused with hypertrichosis), deepening of the voice, and enlargement of the clitoris.
In general, individuals with 5-ARD are capable of producing viable sperm. In individuals with feminized or ambiguous genitalia, the phallus may be capable of ejaculations as well as erections, but may be insufficient for intercourse. Fertility is further compromised by the underdevelopment of seminal vesicles and prostate.
The condition is extremely rare, with reported cases so far in the Dominican Republic, Papua New Guinea, and Turkey.
The cases of the condition reported in the Dominican Republic are of greatest interest due to its prevalence in the small remote village of Las Salinas, where 12 out of 13 families had one or more male family members that carried the genetic mutation, though not all the carriers of the mutation were affected. The overall incidence for the village was 1 in every 90 males were affected carriers.
In the Dominican Republic, the Spanish term for a person with the condition is "güevedoce". This comes from the phrase "huevo/güevo a los doce" with the slang meaning of "ball[s]/penis at twelve [years of age]". Huevo in Spanish means "egg".
The prevalence of this condition in Dominican Republic appears to have been the inspiration for the movie Hermafrodita.
On September, 2015, several articles were published on the topic of the "guevedoces" of Costa Rica, following the filming of a new episode of BBC Two series Countdown to Life, "The Extraordinary Making of You, Against the Odds".
- BBC - The extraordinary case of the guevedoces
- Live Science - 'Guevedoces': Rare Medical Condition Hides Child's Sex Until Age 12