What Is 5-Alpha-Reductase Deficiency?

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5-alpha-reductase deficiency is a congenital condition that affects male sexual development in XY individuals. It is considered a disorder of sexual differentiation, also described as an intersex condition. Children born with this condition may appear to be female at birth but will develop male genitalia during puberty.

Children with 5-alpha-reductase deficiency have testicles (testes) but do not have a penis or scrotum. With this condition, the testes produce normal amounts of testosterone. Normally, the 5-alpha-reductase enzyme converts testosterone to dihydrotestosterone (DHT), which promotes virilization (masculinization) prior to puberty. Because the male genitals can't develop without adequate amounts of DHT, infants with 5-alpha-reductase deficiency are often born with genital structures that appear to be a clitoris and a vagina, and they are often assigned female at the time of birth.

At puberty, the body starts making more testosterone. In adolescents who have 5-alpha-reductase deficiency, the testicles descend, the penis enlarges, and the rest of the body starts to reshape to have a more masculine appearance.

In one community in the Dominican Republic where this condition is found, individuals with 5-alpha-reductase deficiency are reportedly known as Guevedoces—meaning penis at 12.

Group of pre-teens sitting on a fence.

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5-Alpha-Reductase Deficiency Symptoms

In infancy, the symptoms of 5-alpha reductase deficiency are not necessarily recognizable. The appearance of the genitals varies. Some babies will have bodies that appear as if they are XX, and some will have an appearance with traits in between a typical XX and a typical XY body.

Infants with this condition have normal testes, but they are located in the inguinal sac or the abdomen, where they are not seen—instead of a scrotum. These children are born without a penis and scrotum. They are born with what appears to be a clitoris, labia, and vagina.

The structures that typically become the scrotum before an infant's birth are the same as the structures that become the labia—but they fuse during prenatal development to become the scrotum.

At puberty, individuals with 5-alpha reductase deficiency will likely see growth of the clitorophallic complex. The testes may descend into the unfused labia. They may start growing facial hair and experience deepening of the voice.

However, males with 5-alpha-reductase will usually have less facial and body hair than their peers and most are infertile.


5-alpha-reductase deficiency is a hereditary condition caused by an autosomal recessive mutation. This means that individuals only develop the condition if they have two copies of the mutated gene (one from each genetic parent). There are more than 40 identified mutations that can cause 5-alpha-reductase deficiency.

This deficiency is relatively rare in White people. It is still rare, but more common, in populations where there is a lot of intermarriages. The most well-known clusters of cases occurred in the Dominican Republic. However, cases have been identified around the world.


How and when 5-alpha-reductase deficiency is diagnosed is highly dependent on whether an infant is born with visibly ambiguous genitalia.

  • If the child's genitalia appears female, and there was no fetal genetic analysis that identified the apparently female infant as XY, it is possible the condition might not be diagnosed until a child experiences virilization at puberty.
  • If a child is born with ambiguous genitalia, 5-alpha-reductase deficiency is one of the conditions doctors may consider as a cause.

When there is any question about the gender of the child—whether at birth, during puberty, or some time in between—the diagnostic process can involve:

  • Imaging tests of the pelvis, abdomen, or brain
  • Chromosome analysis
  • Gene sequencing
  • Hormone tests
  • A test that measures testosterone/dihydrotestosterone ratio after stimulation with hCG


Treatment for 5-alpha-reductase deficiency varies. Gender assignment at the time of birth is generally based on the size and appearance of the external genitalia. This is because the appearance of genitalia correlates with testosterone and DHT exposure prior to birth, which may also be related to gender identity formation. However, the process is complex.

Historically gender assignment has often been followed by genital surgery. However, in the United States, there is a recent and growing concern about the ethical implications of performing non-medically necessary genital surgeries on infants. Therefore, some of the traditional treatment options—including reducing the size of the clitoris if it was thought to be too small for a male gender assignment—are being banned by certain high-profile children's hospitals.

For individuals with 5-alpha-reductase deficiency who develop male gender identities, early surgery to make the genitals appear feminine could deeply problematic.

Individuals with 5-alpha-reductase deficiency who are raised as girls should be educated about their condition and given the option of orchiectomy (having their testes removed) before they hit puberty.

  • Those who are comfortable with their feminine gender assignment will not experience unwanted virilization if the testes are removed.
  • Girls with 5-alpha-reductase deficiency who continue to assert a female identity may also choose to undergo vaginoplasty in order to create a functional vagina once they reach adolescence or adulthood.
  • Those who feel uncomfortable with the female gender assignment can maintain their testes and experience virilization at puberty.

Individuals who are raised as boys may undergo:


Children with 5-alpha-reductase deficiency don't necessarily have any noticeable symptoms until puberty.

When they are young, the condition can be more of a concern for their parents. They may feel significant anxiety about what the condition means for their child's future, their treatment options, or their choices regarding the gender they have chosen to raise their child with.

It is also helpful for youth and their parents to talk to doctors and therapists who have expertise in the field. Getting multiple opinions can help make better decisions. Different doctors have very different philosophies of care.

As a child approaches puberty and moves through adulthood, they may benefit from participating in their medical and psychological care. Understanding the changes they experience in their body can be confusing. In addition, for those raised as female, it can be difficult to make informed decisions about orchiectomy without additional support.

If you or your child has been diagnosed with 5-alpha-reductase deficiency, it may be useful to reach out to reputable intersex groups for information. The organization InterACT was developed to advocate for Intersex youth and has a library of resources, including links to other groups that provide support.

A Word From Verywell

While the majority of individuals 5-alpha-reductase assigned as female at the time of birth continue to identify as female through adulthood, a far greater percentage develop a male gender identity than in the general population. Many of those transition to living as male.

Researchers have hypothesized that androgen (male hormone) exposure in the brain during fetal development may affect gender identity. It is plausible that this increased likelihood of developing a male identity could be related to differences in testosterone exposure in the brain, but there's no definitive answer. It could also reflect other factors like culture, the desirability of male gender, and the way people were raised.

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  1. Bales ME, Zhu Y-S, Imperato-McGinley J. Chapter 7 - 5α-Reductase deficiency syndrome: The impact of androgens on gender identity and gender role. In M. J. Legato (Ed.), The Plasticity of Sex (pp. 81–87). 2020. Academic Press. doi:10.1016/B978-0-12-815968-2.00007-4

  2. Kumar G, Barboza-Meca JJ. 5 alpha reductase deficiency. StatPearl. Updated 2020.

  3. Byers HM, Mohnach LH, Fechner PY, et al. Unexpected ethical dilemmas in sex assignment in 46,XY DSD due to 5-alpha reductase type 2 deficiency. Am J Med Genet C Semin Med Genet. 2017;175(2):260-267. doi:10.1002/ajmg.c.31560

  4. Cocchetti C, Ristori J, Mazzoli F, Prunas A, Bertelloni S, Magini A, Vignozzi L, Maggi M, Fisher AD. 5α-Reductase-2 deficiency: is gender assignment recommended in infancy? Two case-reports and review of the literature. J Endocrinol Invest. 2020 Aug;43(8):1131-1136. doi:10.1007/s40618-020-01193-w

  5. Islam R, Lane S, Williams SA, Becker CM, Conway GS, Creighton SM. Establishing reproductive potential and advances in fertility preservation techniques for XY individuals with differences in sex development. Clin Endocrinol (Oxf). 2019;91(2):237-244. doi:10.1111/cen.13994

  6. Khorashad BS, Aghili Z, Kreukels BPC, et al. Mental health and disorders of sex development/intersex conditions in Iranian culture: Congenital adrenal hyperplasia, 5-α reductase deficiency-type 2, and complete androgen insensitivity syndrome. Arch Sex Behav. 2018;47(4):931-942. doi:10.1007/s10508-017-1139-6

  7. Hiort O. The differential role of androgens in early human sex development. BMC Medicine. 2013;11(1), 152. doi:10.1186/1741-7015-11-152

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