USRF Research

The 'Guevedoces'
of the Dominican Republic

During the early 1970s, Dr. Julianne Imperato, a Cornell endocrinologist, conducted an expedition to the Dominican Republic to investigate reports of an isolated village where children appearing to be girls turned into men at puberty. In the village, these children were known as 'guevedoces' (literally, penis at 12 years). Also known locally as machihembras ('first women, then man'), these pseudohermaphrodites were documented serially in the following photographs published originally in the American Journal of Medicne (Am. J. Med. 62: 170-191, 1977):

In an isolated village of the southwestern Dominican Republic, 2% of the live births were in the 1970's, guevedoces (actually male pseudohermaphrodites). These children appeared to be girls at birth, but at puberty these 'girls' sprout muscles, testes, and a penis. For the rest of their lives they are men in nearly all respects (see photograph 6 below). Their underlying pathology was found to be a deficiency of the enzyme, 5-alpha Reductase.

1. At 18 months, the appearance is female though undescended testes are present.
2. Lacking dihydrotestosterone (DHT) in utero, this boy's external genitalia develop as female. However, internally the gonadal tissue is that of normal male and his karyotype is 46 XY (normal male).
3. In utero, DHT is essential for the normal male development of the external genitalia. After complete maturation, DHT seems to have no important biological function.
4. Just before puberty, prior to the testosterone outpouring, the phenotype is still female.
5. With the testosterone surge at puberty, the phenotype changes to male: the voice deepens, the testes descend, the phallus grows, erection and ejaculation begin, and a male psychosexual orientation develops.
6. And for the rest of their lives, the guevedoces resemble the other Dominican men in all respects except:
* Beard growth is scanty.
There is no hairline recession.
None has acne.
The prostate remains small.

The story of the guevedoces was originally presented at a Federation meeting in Atlantic City, NJ in 1973 and published in Science in 1974 (Imperato-McGinley J, Guerrero L, Gautier T, Peterson RE. Steroid 5alpha-reductase deficiency in man: an inherited form of male pseudohermaphroditism. Science 1974 Dec 27; 186 (4170): 1213-5). Specific inhibition of 5-alpha Reductase is the mechanism of action of the prostate drug, finasteride (Proscar), which in adults, shrinks the prostate without affecting the male phenotype.

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