Mayo Clinic Health Manager
Get free personalized health guidance for you and your family.
Get Started
About our e-newsletters
- Free e-newsletters
- Mayo Clinic expertise
- We do not share your e-mail address
Housecall, our weekly general-interest e-newsletter, keeps you up to date on a wide variety of health topics with timely, reliable, practical information, recipes, blogs, questions and answers with Mayo Clinic experts and more. Our biweekly topic-specific e-newsletters also include blogs, questions and answers with Mayo Clinic experts, and other useful information that will help you manage your health.
Housecall Archives
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Causes
By Mayo Clinic staffA baby's genetic sex is established at conception, based on the 23rd pair of chromosomes. The mother's egg contains an X chromosome, and the father's sperm contains either an X or a Y chromosome. A baby who inherits the X chromosome from the father is a genetic female (two X chromosomes). A baby who inherits the Y chromosome from the father is a genetic male (one X and one Y chromosome).
Male and female sex organs develop from the same tissue. For example, the same fetal tissue that forms a penis in a male forms a clitoris in a female. The process by which the fetus becomes either male or female is complex and includes sex chromosomes, hormonal signals and early genital structures. In males, a region on the Y chromosome triggers the development of testicles, which produce male hormones. The presence or absence of male hormones controls the development of the sex organs. Male genitals develop in response to male hormones from the fetal testicles. In a fetus without a Y chromosome — without the effects of male hormones — the genitals develop as female.
A disruption of these steps can result in a mismatch between the external genitals and the internal sex organs or the chromosomal sex (XX or XY). These problems are known as disorders of sex development (DSDs). Some babies with a DSD have ambiguous genitalia. A lack or deficiency of male hormones in a genetic male fetus can cause ambiguous genitalia, while exposure to male hormones during development results in ambiguous genitalia in a genetic female.
Many different genes influence fetal sex development. Mutations (defects) in these genes can lead to disorders of sex development. Chromosomal abnormalities, such as a missing sex chromosome or an extra one, can also cause ambiguous genitalia. In some cases, disorders of sex development seem to happen by chance.
Possible causes in genetic females
Causes of ambiguous genitalia in a genetic female may include:
- Congenital adrenal hyperplasia (CAH). Certain forms of this genetic condition cause the adrenal glands to make excess male hormones (androgens). Congenital adrenal hyperplasia is the most common cause of disorders of sex development.
- Prenatal exposure to substances with male hormone activity. Certain drugs, including progesterone (taken in the early stages of pregnancy to stop bleeding) and anabolic steroids, can cause developing female genitals to become more masculine.
- Tumors. Rarely, a tumor in the fetus or the mother can produce male hormones.
Possible causes in genetic males
Causes of ambiguous genitalia in a genetic male may include:
- Impaired testicle development. This may be due to genetic abnormalities or unknown causes.
- Congenital adrenal hyperplasia (CAH). Certain forms of this genetic condition can impair production of male hormones.
- Androgen insensitivity syndrome. In this condition, developing genital tissues don't respond normally to male hormones.
- Abnormalities with testes or testosterone. Various abnormalities can interfere with the testes' activity. This may include structural problems with the testes, problems with production of the male hormone testosterone or problems with cellular receptors that respond to testosterone.
- 5-alpha-reductase deficiency. This is an enzyme defect that impairs normal male hormone production.
- Prenatal exposure to substances with female hormone activity. If a woman continues taking birth control pills during pregnancy, the developing fetus can be exposed to the female hormone estrogen. Some drugs, including the anti-seizure medication phenytoin (Dilantin), can also have hormonal effects.
- Baskin LS. Abnormalities of sexual determination & differentiation. In: Tanagho EA, et al. Smith's General Urology. 17th ed. New York, N.Y.: McGraw-Hill; 2008. http://www.accessmedicine.com/content/aspx?aID=3131473. Accessed Jan. 4, 2010.
- Houk CP, et al. Evaluation of the infant with ambiguous genitalia. http://www.uptodate.com/home/index.html. Accessed Jan. 4, 2010.
- Houk CP, et al. Management of the infant with ambiguous genitalia. http://www.uptodate.com/home/index.html. Accessed Jan. 4, 2010.
- Cunningham FG, et al. Fetal growth and development. In: Cunningham FG, et al. Williams Obstetrics. 23rd ed. New York, N.Y.: Mc-Graw Hill; 2005. http://www.accessmedicine.com/content.aspx?aID=6037835. Accessed Jan. 4, 2010.
- Kajbafzadeh A-M, et al. Detubularized pedicled vaginal onlay flap urethroplasty: A new method for hypospadias repair of ambiguous genitalia. The Journal of Urology. 2008;180:2159.
- Hackam DJ, et al. Pediatric surgery. In: Brunicardi FC, et al. Schwartz's Principles of Surgery. 9th ed. New York, N.Y.: Mc-Graw Hill; 2010. http://www.accessmedicine.com/content.aspx?aID=5029784. Accessed Jan. 4, 2010.
- Diamond DA. Sexual differentiation: Normal and abnormal. In: Wein AJ, ed. Campbell-Walsh Urology. 9th ed. Philadelphia, Pa.: Saunders Elsevier; 2007. http://www.mdconsult.com/das/book/body/177172771-6/935283878. Accessed Jan. 4, 2010.
- Crouch NS, et al. Sexual function and genital sensitivity following feminizing genitoplasty for congenital adrenal hyperplasia. The Journal of Urology. 2008;179:634.
