December 9, 2016
In Salinas, a village southwest of the Dominican Republic, an epidemic called the guavedoces is seen in about one percent of males. The guavedoces is a condition where males are born without male genitalia so they are females. Around eight weeks after conception, sex hormones develop to determine the sex of a fetus. If the fetus is male, Y chromosomes instruct gonads to become testicles which produces testosterone that is sent to a tubercle. In the tubercle, the testosterone converts to a hormone called dihydro-testosterone. If the fetus is female, dihydro-testosterone will not be produced and the tubercle becomes a clitoris. The reason behind males being born without male genitalia is due to a deficiency in the 5-alpha-reductase enzyme (News, BBC). The enzyme creates the “…male sex hormone dihydro-testosterone, which prevents the development of male sex organs…” (Dockrill).
Imperato-McGinley made the discovery of the condition. They observed that “…the affected males were born with ambiguous external genitalia and therefore initially reared as girls” (Okeigwe). The males do not begin to develop male phenotypic features until they hit the stage of puberty. They develop muscle mass, enlargement of the phallus, lack of breast development, testicular descent, and deepened voices. Because they possess the deficiency, they are more likely to be subject to having little to no facial hair, a small prostate, and minimal acne. Imperato-McGinley tested their hypothesis by comparing dihydro-testosterone and testosterone levels in people who were either affected by the deficiency or unaffected. In concluding their findings, they discovered that “…a 5-alpha reductase defect resulted in decreased conversion of testosterone to DHT and furthermore that DHT functioned to facilitate differentiation of the male external genitalia and prostate” (Okeigwe).
In cell signaling, the androgen receptor is a type of nuclear receptor that is “…activated by binding either of the androgenic hormones, testosterone, or dihydrotestosterone in the cytoplasm and then translocating into the nucleus” (“Androgen”). Androgen genes are important in maintaining the male sexual phenotype. The testosterone flows to the 5-alpha reductase enzyme before it goes into dihyrotestosterone.
Dihydrotestosterone and testosterone, types of androgen, are distinct hormones for multiple reasons. Structurally, they differ only by a double bond found between the fourth and fifth carbon on the leftmost ring. Dihydrotestosterone is a hormone that stimulates growth and function of male characteristics. It is derived from testosterone and the amount of dihydrotestosterone in the body is dependent upon the amount of testosterone produced. Testosterone is produced every day in adults and is related to the prostate and testes for a male; and in the ovaries for women.
Dihydrotestosterone is related to the skin and other parts of the body due to its function. It contributes to the start of puberty because it enlarges male genitalia, growth of pubic/facial hair, and affects sexual behavior. The hormone is thought to be “…more potent than testosterone and many of the effects that testosterone has in the body can only happen after it has been converted to dihydrotestosterone” (“You”). When those affected hit the age of puberty, because they have increased levels of the enzyme, the testes produce more testosterone causing secondary male sex hormones to form. When the secondary male sex hormones are produced, the formation of a phallus and other male characteristics come in; they are then considered to be a male (Dockrill).
“Androgen Receptor.” Wikipedia. Wikimedia Foundation, n.d. Web. 09 Dec. 2016.
Dockrill, Peter. “In This Remote Village, Some Boys Don’t Grow a Penis Until They’re 12.” ScienceAlert. N.p., 21 Sept. 2015. Web. 08 Dec. 2016.
Mahler, Mike. “Testosterone Is Great but Is Dihydrotestosterone the King of All Male Androgens?” Testosterone Is Great but Is Dihydrotestosterone the King of All Male Androgens? – Mahler’s Aggressive Strength. N.p., n.d. Web. 08 Dec. 2016.
News, BBC. “The Extraordinary Case of the Guevedoces.” BBC News. N.p., 20 Sept. 2015. Web. 08 Dec. 2016.
Okeigwe, Ijeoma, and Wendy Kuohung. “5-Alpha Reductase Deficiency: A Forty Year Retrospective Review.” Thomson, n.d. Web. 08 Dec. 2016.
“You & Your Hormones.” You & Your Hormones | Hormones | Dihydrotestosterone. N.p., 06 Jan. 2015. Web. 08 Dec. 2016.