Androgen insensitivity syndromes are examples of disorders of sex development (DSD). An androgen is a hormone that causes a child to develop male characteristics. Testosterone is the most well known androgen and is made by the testes.
There are two general types of androgen insensitivity syndromes:
CAIS is a syndrome where a child’s body is completely immune to the effects of androgens. When these children are born, they generally appear to be normal females and often the diagnosis is not suspected. The complete form of the syndrome is rare and occurs in about 1 in 20,000 live births.
These patients have male chromosomes (46XY), but because androgens have no effect they develop normal female external genitalia. Internally these patients have gonads that look like testes inside the abdomen and the upper part of the vagina, uterus, and fallopian tubes are absent.
These children most commonly present in one of two ways:
These children do go through puberty with breast development because their androgens are converted to a hormone (estrogen) that causes breast development.
Once the diagnosis of CAIS is made families and patients typically have a lot of questions and concerns. It can come as quite a surprise because these patients appear to be completely normal females.
Generally, these patients do not have any other health problems. They typically have a female gender identity because the androgen receptors in the brain also do not sense any androgen which can lead to a male gender identity. Unfortunately, natural fertility is not possible due to the absence of uterus.
While it is somewhat controversial, most specialists recommend removal of the gonads after puberty because of a slightly increased risk of gonad tumors. Once the gonads are removed, estrogen replacement therapy is needed. Occasionally, if the vagina is too short, reconstructive vaginal surgery (Center for Vaginal Reconstruction) is needed to improve function.
(PAIS) is another form of androgen insensitivity. As the name suggests, PAIS patients are only partially sensitive to androgens.
Externally, the patients have ambiguous genitalia ranging from mostly female to almost completely normal male. Internally, the patients do not have a uterus or fallopian tubes. The testes can be in the abdomen, in the groin, or completely descended. These patients typically present soon after birth due to the ambiguous genitalia.
The diagnosis of PAIS is sometimes difficult to make and the management of patients with PAIS can be challenging. Because there is a variable amount of androgen exposure in the brain, it is difficult to predict with certainty male or female gender identity.
If a patient is raised male, they may require challenging reconstructive surgery and may have dissatisfaction with final penile size and function in the future. In addition, due to the conversion of androgens to estrogens males may have breast development that may require surgical management.
If a patient is raised female, there is a risk for gender dysphoria and requesting conversion to a male.
Symptoms may not be noted until puberty and may include:
Complete androgen insensitivity is typically discovered at puberty, when a girl fails to start having periods or doesn’t develop pubic or underarm hair. Occasionally, a child is diagnosed when a growth is felt in the abdomen and determined to be a testicle during surgery.
Diagnosis starts with a thorough medical history and physical exam, including a pelvic exam. Additional testing may include:
Partial androgen insensitivity is usually discovered when the baby is born because the external genitals aren't clearly male or female (ambiguous genitalia)
Testicles that are in the wrong place may not be removed until a child finishes growing and goes through puberty. They typically are removed because they can develop cancer, just like any undescended testicle. The risk of cancer is very low, however, and some individuals may choose to monitor over time with serial imaging, rather than undergo surgery.
After puberty, some patients use vaginal dilators over 3 to 6 months (or undergo surgery) to lengthen the vagina.
Treatment and gender assignment can be a very complex issue, and must be targeted to each individual person. Your doctor can recommend counseling and psychological support for your child and your family.
American Board of Pediatrics/Endocrinology