Health Library

Androgen Insensitivity Syndrome (AIS)

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

Many things help decide how our bodies grow and develop. Two important ones are genetics and hormones. Genetics are like instruction codes and hormones are chemical messengers that tell the body what to do. When it comes to genetics, there are two special chromosomes called X and Y. These help guide how a person’s reproductive parts grow. Most boys have one X and one Y chromosome. Most girls have two X chromosomes. But not everyone fits this pattern. For example, some girls have one X and one Y chromosome.

When it comes to hormones, two important hormones that help our bodies grow are testosterone and estrogen. These hormones are made by part of the body called gonads. There are two types of gonads: testicles and ovaries. Testicles mostly make testosterone and some estrogen. Ovaries mostly make estrogen and some testosterone. These hormones are important for how the reproductive parts of the body grow before a baby is born. Testosterone usually helps the body grow in a more male way. If the body does not make much testosterone, it usually grows in a more female way. Some people’s bodies make testosterone but do not respond to it, so their bodies may still grow in a female way. Later, during puberty, hormones make the body change again.

What Happens in People With AIS?

People with AIS have one X and one Y chromosome. Because of their Y chromosome, their bodies grow testicles, which make hormones called androgens, like testosterone. These hormones send messages or signals to help the body grow in certain ways. But in people with AIS, the body does not receive those messages very well—or at all. This is because the part that is supposed to receive the messages, called a receptor, does not work properly. This happens because of changes in the genetic instructions to make the receptor.

Because of this, their bodies grow differently than expected. Their private parts, called genitals, might look female. They do not have a uterus, so they will not get periods during puberty or be able to carry a baby.

What Are the Types of AIS?

There are two types of AIS: Complete AIS (CAIS) and Partial AIS (PAIS). The type someone has depends on how much their body responds to androgens.

People with CAIS do not respond at all to androgens. Because of this, their genitals grow in a female way before they are born. During puberty, their bodies make testosterone, but it turns into estrogen. They may grow breasts, but they usually do not get pubic hair, and their voice does not get deeper. They do not have periods.

People with PAIS respond only partially to androgens. Because of this, their genitals may look more female, more male, or somewhere in between. During puberty, they may grow some pubic or armpit hair and their voice gets deeper. They may grow breasts. They do not have periods.

How is AIS Diagnosed?

CAIS and PAIS may be suspected before birth due to prenatal testing or a family history. PAIS may be found in babies if their genitals look different than expected. PAIS or CAIS may be found during a checkup at any age if a doctor feels bumps in the groin. CAIS may be found at puberty if a girl does not start having periods.

The doctors may order tests, such as:

• Karyotype: This is a blood test that looks at a person’s chromosomes, including the X and Y chromosomes.
• Other genetic testing: This is a blood or saliva test to look for changes in the gene that causes AIS, called AR.
• Hormone levels: This is a blood test to check which hormones the gonads are making and how much.
• Pelvic ultrasound: This is an imaging test that looks for the gonads inside the body 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 AIS by working as a team. Our team includes doctors and healthcare workers who specialize in endocrinology, gynecology, urology, psychology, genetics, ethics, social work and child life. We work closely with each person and their family to make a treatment plan that fits their needs.

Our team will talk about treatment choices and help families understand them so they can make decisions. We also help with feelings and give support. Our goal is to help each person and their family have the best quality of life possible. We explain what to expect and share information and resources to help with the road ahead.

Medical Care

Care plans depend on what each person needs at different ages. At each visit, we check how each person is growing and developing. Some people may have questions about hormones or about their gonads. Our team helps explain choices and supports families in making decisions.

Psychosocial Care

AIS is something a person lives with their whole life. That can sometimes feel confusing or stressful—for the person and their family. Our team includes a psychologist and a social worker who help people talk about their feelings and figure out what kind of support they need. We also help families think about how to share information about AIS with others. Our goal is to support everyone and help them feel confident and cared for.