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Androgen insensitivity syndrome

Testicular feminization

Androgen insensitivity syndrome (AIS) is when a person who is genetically male (who has one X and one Y chromosome) is resistant to male hormones (called androgens). As a result, the person has some of the physical traits of a woman, but the genetic makeup of a man.

Images

Male reproductive anatomy
Female reproductive anatomy
Female reproductive anatomy
Karyotyping

Causes

AIS is caused by genetic defects on the X chromosome. These defects make the body unable to respond to the hormones that produce a male appearance.

The syndrome is divided into two main categories:

In complete AIS, the penis and other male body parts fail to develop. At birth, the child looks like a girl. The complete form of the syndrome occurs in as many as 1 in 20,000 live births.

In partial AIS, people have different numbers of male traits.

Partial AIS can include other disorders, such as:

Infertile male syndrome is also considered to be part of partial AIS.

Symptoms

A person with complete AIS appears to be female but has no uterus. They have very little armpit and pubic hair. At puberty, female sex characteristics (such as breasts) develop. However, the person does not menstruate and become fertile.

People with partial AIS may have both male and female physical characteristics. Many have partial closing of the outer vagina, an enlarged clitoris, and a short vagina.

There may be:

Exams and Tests

Complete AIS is rarely discovered during childhood. Sometimes, a growth is felt in the abdomen or groin that turns out to be a testicle when it is explored with surgery. Most people with this condition are not diagnosed until they do not get a menstrual period or they have trouble getting pregnant.

Partial AIS is often discovered during childhood because the person may have both male and female physical traits.

Tests used to diagnose this condition may include:

Other blood tests may be done to help tell the difference between AIS and androgen deficiency.

Treatment

Testicles that are in the wrong place may not be removed until a child finishes growing and goes through puberty. At this time, the testes may be removed because they can develop cancer, just like any undescended testicle.

Estrogen replacement may be prescribed after puberty.

Treatment and gender assignment can be a very complex issue, and must be targeted to each individual person.

Outlook (Prognosis)

The outlook for complete AIS is good if the testicle tissue is removed at the right time to prevent cancer.

Possible Complications

Complications include:

When to Contact a Medical Professional

Call your health care provider if you or your child has signs or symptoms of the syndrome.

References

Chan Y-M, Hannema SE, Achermann JC, Hughes IA. Disorders of sex development. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 24.

Donohoue PA. Disorders of sex development. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 606.

Yu RN, Diamond DA. Disorders of sexual development: etiology, evaluation, and medical management. In: Partin AW, Dmochowski RR, Kavoussi LR, Peters CA, eds. Campbell-Walsh-Wein Urology. 12th ed. Philadelphia, PA: Elsevier; 2021:chap 48.

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Review Date: 7/21/2020  

Reviewed By: Anna C. Edens Hurst, MD, MS, Assistant Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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