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Androgen Insensitivity Syndrome (AIS)
Monday, 18 August 2003
Tuesday, 23 November 2004
Testicular Feminization

What

Androgen insensitivity syndrome (AIS) is a disorder found in individuals who are genetically male (have one X and one Y chromosomes, XY). Individuals with AIS have a defect in a cell structure called androgen receptors and, thus cannot respond to androgens, or male sex hormones. As a result, these genetically male individuals develop the physical characteristics of a female. Patients with AIS are divided into two categories, depending on whether they have complete or incomplete androgen insensitivity. Those with complete androgen insensitivity cannot respond to androgens at all, and thus look completely female on the outside. In contrast, individuals with incomplete AIS can respond to a small amount of androgen, and therefore can maintain some physical characteristics of a male. The degree of sexual ambiguity varies according to the severity of the androgen receptor defect.

Who

AIS occurs in males, starting during childhood. It is inherited as an X-linked recessive disorder, which means that males develop the condition when they inherit a broken copy of the X chromosome from their mother.

Signs and Symptoms

Complete AIS: These individuals may develop some or all of the following symptoms:

  1. Person looks like a female on the outside (i.e. has a vagina), but does not have female internal structures (i.e. uterus, cervix).
  2. At puberty, normal female breasts start to develop, but menstruation does not occur.
  3. Presence of testes within the abdomen (as detected by a physician).
  4. Infertility.


Incomplete AIS: An individual with incomplete androgen insensitivity may develop both male and female features, including:

  1. Ambiguous genitalia (their gender may be unclear based on their external sexual features alone).
  2. Enlarged clitoris.
  3. Abnormal vagina.
  4. Breast enlargement.
  5. Presence of testes within the abdomen.
  6. Low sperm count.

Possible Causes

A baby’s gender is determined by the type of sex chromosomes it receives from its parents. Humans have two types of sex chromosomes, the X and Y chromosome. Males have one X and one Y chromosome (XY), while females have two copies of the X chromosome (XX). During pregnancy, a male fetus with an XY make-up will develop testes, which are responsible for secreting androgens such as testosterone. These androgens act on specific cells to initiate the development of male external structures, such as the penis, scrotum, and prostate. AIS occurs when there is a defect in the androgen receptors. As a result, cells can no longer recognize and properly respond to androgens (male sex hormones). Without this signal, cells do not get the information to develop into male genitalia. Instead, they will develop into female external genitalia, even though they should be males. Thus, there is a mistake in the signals for sexual differentiation.

Diagnosis

A doctor can diagnose AIS by doing a physical examination, taking blood tests to evaluate hormones, and taking a picture to see the inside structures of the abdomen and family history. A sonogram can also be taken to see if there are testes present, or if there is no uterus present, in the abdomen. Molecular genetic testing for AIS is available and it detects greater than 95% of the mutations in the gene.

Treatment

Treatment for patients with AIS can include reconstructive surgery, hormone therapy, and gender assignment. Usually, AIS patients must undergo surgery to remove the testes in the abdomen because it can pose as a risk for cancer. This surgery typically occurs after the child has gone through puberty.

Prognosis

The prognosis for individuals with AIS is variable, and all patients will be infertile. A complication associated with this disorder is testicular cancer; patients will need to undergo surgery to remove the testes in the abdomen. If properly taken care of, the prognosis should be good for these individuals.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

Androgen Insensitivity Syndrome Support Group Website
A great site with detailed information about the disease, treatment options and support groups. Mayo Clinic: “ambiguous genitalia:

When gender is unclear at birth”
A nice overview of the disease with links to other informational and support group websites.

Google Search for Androgen Insensitivity Syndrome (AIS)

References and Sources

Cotran, R.S., Kumar, V., and T. Collins. Pathologic Basis of Disease. W.B. Saunders Company, 6th edition. p 176. 1999. Harrisons Online: “Concise Review: New Insights into Androgen Insensitivity Syndromes” harrisons.accessmedicine.com/server-java/Arknoid/amed/harrisons/ex_editorials/edl2985_p01.html Mayo Clinic: “Ambiguous genitalia: When gender is unclear at birth” www.mayoclinic.com/invoke.cfm?id=CC00016 MedlinePlus: “Androgen Insensitivity Syndrome” www.nlm.nih.gov/medlineplus/ency/article/001180.htm