Difference between revisions of "5-alpha-reductase deficiency"

Latest revision as of 16:02, 10 February 2006

5-alpha-reductase deficiency (5-ARD) is a condition caused by a mutation of the 5-alpha reductase type 2 gene. This gene encodes an enzyme (the 5-alpha-reductase enzyme) that converts testosterone to dihydrotestosterone (DHT). DHT is necessary for the development of male genitalia in utero, and the resulting DHT deficiency results in ambiguous external genitalia at birth (also known as male pseudohermaphroditism).

5-ARD is an autosomal recessive sex limited condition (caused by a deleterious change on a non-sex chromosome which affects only chromosomal males). Individuals with 5-ARD lack a uterus and Fallopian tubes due to the normal action of Mullerian inhibiting factor. Testes and Wolffian structures (epididymis, vas deferens, seminal vesicles) do develop and tend to terminate in the perineum or in a blind pseudovaginal pouch. The external genitalia can vary from normal male external genitalia, to ambiguous genitalia, to normal female genitalia (with a tendency towards having an enlarged clitoris). 5-ARD consitutes a variety of Intersexual/intersexualism.

More than twenty different mutations have been documented to cause clinical and biochemical symptoms of 5-ARD. 5-ARD is not known to be life threatening though there are several health problems (such as osteoporosis) that can result from having this disorder. One indication of 5-ARD is an elevated serum ratio of testosterone to DHT levels.

Individuals with 5-ARD have XY chromosomes and testes, and tend to have a vagina and labia, but with a small penis capable of ejaculation instead of a clitoris (this penis, however, appears to be a clitoris at birth). These individuals are normally raised as girls. However, when puberty occurs, their testes descend, voice deepen, and they often develop a male sexual identity. However, only limited facial hair develops.

Gender assignment is one of the main issues facing individuals with 5-ARD or parents of a 5-ARD child. Most 5-ARD children are assigned a female gender at birth. During infancy a surgical feminizing genitoplasty can be performed. A vaginoplasty would be required later in life by individuals that choose to remain a female.

See also[edit]

• Intersexual
• Endocrinology

External links[edit]

• 5-alpha-reductase deficiency
• NCBI
• Journal of Clinical Endocrinology & Metabolism
• Amersham Health