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{{Infobox_Disease |
  Name           = 5-alpha-reductase deficiency |
  Image          = Androstanolone_svg.png  |
  Caption        = [[5-alpha reductase]] produces [[dihydrotestosterone]] |
  DiseasesDB     = 11 |
  ICD10          = {{ICD10|E|29|1|e|20}}, {{ICD10|Q|56|3|q|50}} |
  ICD9           = {{ICD9|257.2}}, {{ICD9|752.7}} |
  ICDO           = |
  OMIM           = 264600 |
  MedlinePlus    = |
  eMedicineSubj  = ped |
  eMedicineTopic = 1980 |
  MeshName       = |
  MeshNumber     = |
}}
{{Search infobox}}
{{CMG}}

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==Overview==
'''5-alpha-reductase deficiency''' ('''5-ARD''') is an [[autosomal recessive]] disorder of sex development (DSD, formerly known as [[intersex]]) caused by a [[genetic mutation|mutation]] of the [[5-alpha reductase]] type 2 [[gene]].<ref name="Gpnotebook">{{GPnotebook|852492298}}</ref>

==Normal function==
'''[[5-alpha-reductase]]''' is an [[enzyme]] that converts [[testosterone]] to [[dihydrotestosterone]] (DHT) in peripheral tissues. 5-alpha-reductase deficiency-2 is biochemically characterized by low to low normal levels of testosterone and decreased levels of 5α-DHT, creating a higher testosterone/DHT ratio.
[[Image:Test biosynth 5ARD2.jpg|thumb|center|680px| Biochemical effects of 5-alpha-reductase deficiency-2 in testosterone biosynthesis. Typically levels of testosterone are elevated, while levels of DHT are significantly decreased, leading to male [[undervirilization]].]]

DHT is a potent [[androgen]], necessary for the development of male external [[genitalia]] in utero.

==Signs==
The condition affects only males (i.e. those with a [[Y chromosome]]) because DHT has no known role in female development.<ref>[http://www.emedicine.com/ped/topic1980.htm eMedicine article on 5-ARD]</ref>

Individuals with 5-ARD can have normal male external genitalia, [[ambiguous genitalia]], or normal female genitalia. They are born with [[male]] [[gonad]]s, including [[testicles]] and [[Wolffian structures]], but usually appear to have [[female]] [[primary sex characteristic]]s. Consequently they are often raised as girls and develop a female [[gender identity]]. Individuals with obvious [[virilisation|undervirilisation]] at birth, eg. hypospadia, micropenis or complete [[ambiguous genitalia]] are currently raised as boys.

In individuals with feminised or ambiguous genitalia, there is a tendency towards an enlarged [[clitoris]], or [[micropenis|microphallus]], and the [[urethra]] may attach to the phallus. This structure may be capable of erections as well as ejaculations. Individuals with 5-ARD are generally capable of producing viable [[sperm]], however [[artificial insemination]] techniques or [[in-vitro fertilisation]] are necessary.

At [[puberty]], individuals often have primary [[amenorrhoea]], and may experience [[virilisation]]. This may include descending of the testes, [[hirsuitism]] and deepening of the voice. In adulthood, individuals do not experience male-pattern baldness.<ref name="Gpnotebook"/> As DHT is a far more potent androgen than testosterone alone, virilisation in those lacking DHT may be absent or reduced compared to males with functional 5-alpha reductase. It is hypothesized that rising testosterone levels at the start of puberty (around age twelve) are able to generate sufficient levels of DHT by either the action of 5-alpha-reductase type 1 (active in the adult liver, non-genital skin and some brain areas) or through the expression of low levels of 5-alpha-reductase type 2 in the testes.

==Complications==
With 5-ARD there is a risk of gender identity disorder as well as infertility, due to underdevelopment of seminal vesicles and prostate.

===Gender identity disorder===
Although most people with 5-ARD identify themselves as females, some, however, may develop a male gender identity coinciding the with the pubertal [[virilisation]], or can present themselves with apparent gender dysphoria and transgender behavior. Most cases of gender (role) changes have been reported in large families in the Dominican Republic and Sao Pablo. It is unclear if these patients had the means or possibilities to be treated against virilisation. In some cultures it seems to be socially more beneficial to be a man, than an infertile woman. It is unclear whether this has played any part in the above mentioned gender changes.

===Infertility===
There is an increased risk of [[cryptorchidism]] in 5-ARD, causing infertility, but also a higher risk of [[testicular cancer]]. Fertility is further compromised by the underdevelopment of seminal vesicles and prostate.

On the other hand, fertility depending on the female characteristics are impossible; Although the external genitalia appear female, the "pseudovagina" consists only of the lower two-thirds of a normal vagina; creating a blind-ending vaginal pouch. Due to the normal action of [[Anti-müllerian hormone|Müllerian inhibiting factor]] produced by the [[testis]] in utero, individuals with 5-ARD lack a [[uterus]] and [[Fallopian tube]]s. Thus, individuals with 5-ARD are not able to become pregnant or produce ova.

==Prevalence==
The number of people with this condition varies geographically, depending on how much of a given population is interrelated. In 1974, Jullianne Imperato-McGinley has estimated an incidence of 1:90 males in the Dominican Republic. This can be seen in that certain regions have evolved terminology for the condition:

===Local names===
The term '''Guevedoche''' or Guevedoces is Spanish slang for the condition. It originated in the Dominican Republic where more than three dozen cases have occurred in the small village of Salinas, all descended from a single individual named Altagracia Carrasco. It stands for the vulgar expression ''huevo a los doce'', which translates literally as "balls at twelve". It is also known locally as 'Machihembras' ('first women, then man').

A similar cluster of cases among the Simbari of the Eastern Highlands of Papua New Guinea has the local name 'Kwolu-aatmwol' ('female thing transforming into male thing').

== Popular culture ==
* Jeffrey Eugenides won a Pulitzer Prize for his 2002 novel ''Middlesex'', which explores this deficiency.

* The Carver, a character on the television show ''Nip/Tuck'', has this condition.

* Documentaries on the condition include "Guevote: The Way I Feel Is How I Am" ("Guevote: So wie ich mich fuehle, bin ich"), 1996, by filmmaker Rolando Sánchez,<ref>[http://www.german-cinema.de/app/filmarchive/film_view.php?film_id=131 Guevote - The Way I Feel Is How I Am (Guevote - So wie ich mich fuehle, bin ich)]</ref> and "The Fight to be Male", 1979, British Broadcasting Company.

==References==
{{reflist}}

==See also==
*[[Third sex]]
*[[Intersexuality]]
:*[[17-beta-hydroxysteroid dehydrogenase deficiency]]
:*[[Androgen insensitivity syndrome]]
:*[[Gonadal dysgenesis]]

==External links==
*[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=264600 OMIM article]
*[http://www.emedicine.com/ped/topic1980.htm 5-Alpha-Reductase Deficiency at eMedicine]
*[http://www.newint.org/issue300/trans.html "Whatever I feel..."] Article in the New Internationalist


{{Endocrine pathology}}

[[Category:Intersexuality]]
[[Category:Endocrinology]]
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