National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

5-alpha reductase deficiency



Other Names:
Pseudovaginal perineoscrotal hypospadias; PPSH; Male pseudohermaphroditism due to 5-alpha-reductase deficiency; Pseudovaginal perineoscrotal hypospadias; PPSH; Male pseudohermaphroditism due to 5-alpha-reductase deficiency; Familial incomplete male pseudohermaphroditism, type 2 See More
Categories:

5-alpha reductase deficiency is an inherited condition that primarily affects male 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), which is critical for male sexual development. Most are born with external genitalia that appear female. In other cases, affected individuals may have ambiguous genitalia. Others may have genitalia that appear predominantly male, often with an unusually small penis (micropenis) and the urethra opening on the underside of the penis (hypospadias). This condition is caused by mutations in the SRD5A2 gene and is inherited in an autosomal recessive pattern.[1]
Last updated: 12/2/2011

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormality of the endocrine system 0000818
Ambiguous genitalia, male
Ambiguous genitalia in males
0000033
Bifid scrotum
Cleft of scrotum
0000048
Cryptorchidism
Undescended testes
Undescended testis
[ more ]
0000028
Decreased fertility
Abnormal fertility
0000144
Hypoplasia of penis
Underdeveloped penis
0008736
Perineal hypospadias 0000051
Scrotal hypoplasia
Smaller than typical growth of scrotum
0000046
Urogenital sinus anomaly 0100779
Percent of people who have these symptoms is not available through HPO
Abnormal hair morphology
Abnormality of the hair
Hair abnormality
[ more ]
0001595
Abnormality of metabolism/homeostasis
Laboratory abnormality
Metabolism abnormality
[ more ]
0001939
Abnormality of the voice
Voice abnormality
0001608
Autosomal recessive inheritance 0000007
Micropenis
Short penis
Small penis
[ more ]
0000054
Uniparental disomy 0032382
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Last updated: 7/1/2020

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources


Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnosis includes complete androgen insensitivity syndrome, partial androgen insensitivity syndrome, 17-beta-hydroxysteroid dehydrogenase 3 deficiency and Leydig cell hypoplasia (see these terms).
Visit the Orphanet disease page for more information.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease


These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on 5-alpha reductase deficiency. This website is maintained by the National Library of Medicine.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss 5-alpha reductase deficiency. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.


  1. 5-alpha reductase deficiency. Genetics Home Reference. April 2008 ; http://ghr.nlm.nih.gov/condition/5-alpha-reductase-deficiency. Accessed 12/2/2011.