5-alpha reductase deficiency
Last updated 6 Mar 2025
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5-alpha reductase deficiency is a condition that affects sexual development before birth and during puberty. People with this condition are genetically male, with one X and one Y chromosome in each cell, and they have male gonads (testes). Their bodies, however, do not produce enough of a hormone called dihydrotestosterone (DHT). DHT has a critical role in male sexual development, and a shortage of this hormone disrupts the formation of the external sex organs before birth.
Description
5-alpha reductase deficiency is a condition that affects sexual development before birth and during puberty. People with this condition are genetically male, with one X and one Y chromosome in each cell, and they have male gonads (testes). Their bodies, however, do not produce enough of a hormone called dihydrotestosterone (DHT). DHT has a critical role in male sexual development, and a shortage of this hormone disrupts the formation of the external sex organs before birth.
Many people with 5-alpha reductase deficiency have external genitalia that appears female. In other cases, affected infants have male-typical external genitalia, often an unusually small penis (micropenis) and the urethra opening on the underside of the penis (hypospadias). Still other affected infants have external genitalia do not look clearly male or clearly female.
During puberty, an increase in the levels of male sex hormones leads to the development of some secondary sex characteristics, such as increased muscle mass, deepening of the voice, development of pubic hair, and a growth spurt. The penis and scrotum (the sac of skin that holds the testes) may grow larger. People with 5-alpha reductase deficiency do not develop much facial or body hair. Most affected individuals are unable to have biological children (infertile) without assisted reproduction.
Inheritance patterns
The source lists the following possible inheritance patterns: Autosomal recessive. More than one pattern can apply in different cases.
Related genes
Other names
PPSH
Pseudovaginal perineoscrotal hypospadias
Steroid 5-alpha-reductase deficiency
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Further reading and references
- 5-alpha reductase deficiency; MedlinePlus, National Library of Medicine.
- Bahceci M, Ersay AR, Tuzcu A, Hiort O, Richter-Unruh A, Gokalp D. A novel missense mutation of 5-alpha reductase type 2 gene (SRD5A2) leads to severe male pseudohermaphroditism in a Turkish family. Urology. 2005 Aug;66(2):407-10. doi: 10.1016/j.urology.2005.02.021.
- Baldinotti F, Majore S, Fogli A, Marrocco G, Ghirri P, Vuerich M, Tumini S, Boscherini B, Vetri M, Scommegna S, Rinaldi R, Simi P, Grammatico P. Molecular characterization of 6 unrelated Italian patients with 5alpha-reductase type 2 deficiency. J Androl. 2008 Jan-Feb;29(1):20-8. doi: 10.2164/jandrol.107.002592. Epub 2007 Jul 3.
- Cohen-Kettenis PT. Gender change in 46,XY persons with 5alpha-reductase-2 deficiency and 17beta-hydroxysteroid dehydrogenase-3 deficiency. Arch Sex Behav. 2005 Aug;34(4):399-410. doi: 10.1007/s10508-005-4339-4.
- Hackel C, Oliveira LE, Ferraz LF, Tonini MM, Silva DN, Toralles MB, Stuchi-Perez EG, Guerra-Junior G. New mutations, hotspots, and founder effects in Brazilian patients with steroid 5alpha-reductase deficiency type 2. J Mol Med (Berl). 2005 Jul;83(7):569-76. doi: 10.1007/s00109-005-0651-7. Epub 2005 Mar 16.
- Lee PA, Houk CP, Ahmed SF, Hughes IA; International Consensus Conference on Intersex organized by the Lawson Wilkins Pediatric Endocrine Society and the European Society for Paediatric Endocrinology. Consensus statement on management of intersex disorders. International Consensus Conference on Intersex. Pediatrics. 2006 Aug;118(2):e488-500. doi: 10.1542/peds.2006-0738. No abstract available.
- Okeigwe I, Kuohung W. 5-Alpha reductase deficiency: a 40-year retrospective review. Curr Opin Endocrinol Diabetes Obes. 2014 Dec;21(6):483-7. doi: 10.1097/MED.0000000000000116.
- Sultan C, Lumbroso S, Paris F, Jeandel C, Terouanne B, Belon C, Audran F, Poujol N, Georget V, Gobinet J, Jalaguier S, Auzou G, Nicolas JC. Disorders of androgen action. Semin Reprod Med. 2002 Aug;20(3):217-28. doi: 10.1055/s-2002-35386.
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