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Androgen Insensitivity Syndrome (AIS)

What is Androgen Insensitivity Syndrome (AIS)?

Androgen Insensitivity Syndrome (AIS) is a condition that affects how the body grows and develops before birth and at puberty. People who have AIS make hormones called “androgens”. Testosterone is one type of androgen. People with AIS’ bodies do not respond to androgens. Their bodies develop on a less typical path.

What Makes a Person’s Body Develop on a Male or Female Path?

There are many factors that are important for how the body develops. These include genetics and hormones. Genetics are instruction codes and hormones are chemical messengers. In terms of genetics, there are two chromosomes, the X and one Y chromosomes, that guide how the reproductive parts development. Most boys have one X and one Y chromosome. Most girls have two X chromosomes.

In terms of hormones, two important hormones are testosterone and estrogen. They are made by glands called gonads. There are two types of gonads: testicles and ovaries. Testicles make testosterone and some estrogen. Ovaries make estrogen and some testosterone. Before birth, testosterone usually makes bodies develop on a male path. People whose bodies do not make large amounts of testosterone develop on a female path. Some people’s bodies make testosterone but do not respond to it. Their bodies may also develop as girls. Later, at puberty, hormones make the body change again.

How a person’s body grows and develops (their “sex”) is not the same as their “gender”. “Gender” is about a person’s sense of self. It is about their inner feeling of being a boy/man, girl/woman, both, or neither.

Learn more about Gender and Sex: What Makes a Person a Boy or a Girl?

What Happens in People with AIS?

People with AIS have one X and one Y chromosome. Their gonads develop as testicles. Their testicles make hormones called androgens including testosterone. In people with AIS, androgens try to send “messages” to tell their bodies to develop, but their bodies do not receive the “messages.” The part that receives the “messages” is called a receptor. Receptors tell the body to respond to androgens. People with AIS have changes in the genetic code for the receptor. The receptor receives the “messages” weakly or not at all.

Because of the genetics and hormones in people with AIS, their bodies develop on a less typical path before birth and puberty. Their genitals can look female. They do not have a uterus. They will not have periods during puberty, or be able to carry a pregnancy.

There are two types of AIS: Complete and Partial AIS (CAIS and PAIS). The type that a person has depends on how much their body responds to androgens. People with CAIS do not respond at all to androgens. People with PAIS, respond partially to androgens.

What is Complete AIS (CAIS)?

When a person has PAIS, their body responds partially to androgens. Depending on how much their body responds to androgens, their genitals may be more female, more male, or both female and male.

During puberty, people with PAIS may grow some pubic or armpit hair. Their voice may change. They may develop breasts, but do not have periods.

Table. Genital findings in people with AIS

CAIS - No response to androgens PAIS – Small response to androgens PAIS – More response to androgens
Genitals look female Genitals may be more female-looking Genitals may be more male-looking
Clitoris typical for female Clitoris larger than expected Penis smaller than expected
Hole where urine comes out typical for female Hole where urine comes out typical for female Hole where urine comes out may be on the underside of the penis, not be at the tip.
Labia (skin folds) typical for female Labia may be partly closed Scrotum may not connect in the middle

When is AIS Suspected?

  • CAIS and PAIS may be suspected before birth due to prenatal testing or a family history.
  • PAIS may be suspected in babies based on how their genitals look. Both PAIS and CAIS may be suspected at any age during a routine checkup because a doctor feels bumps in the groin.
  • CAIS may be suspected a puberty when girls do not start their periods.

How is AIS Diagnosed?

The doctors may order tests, such as:

  • Karyotype: This is a blood test that looks at all of the body’s chromosomes, including the X and Y chromosomes.
  • Genetic testing: This is a blood test to look for changes in the gene that causes AIS.
  • Hormone testing: This is a blood test that checks what hormones the gonads are making and how much.
  • Pelvic ultrasound: This is an imaging test that looks for the gonads and for a uterus.
  • Laparoscopy: This is a surgery using a small camera. The surgeon looks for the reproductive parts inside the body. The surgeon may also take small pieces of tissue for testing.

How Do We Care for People with AIS?

We care for people with CAIS and PAIS as a team of specialists working together. Our team has specialists in endocrinology, gynecology, urology, psychology, genetics, ethics, social work and child life. Care and treatment plans depend on each patient’s individual needs. Treatment involves regular clinic visits. At each visit, we check growth and development. We also address patients’ and families’ needs at different ages and stages of life. Some patients may need to take hormones.

Our team helps patients and families understand and weigh treatment options. Options may include, decisions about taking hormones and moving or removing gonads.

Our team provides support and counseling to our patients and families. We want all patients and families to experience their best quality of life.

Last Updated 09/2022

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