What makes a person’s body develop as a boy or a girl?
There are many factors that are important for how the body develops. These include genetics and hormones. In terms of genetics, most boys have one X and one Y chromosome. Most girls have two X chromosomes. However, some boys and girls have different chromosome patterns. For example, some girls have a Y chromosome.
In terms of hormones, two important hormones are testosterone and estrogen. These are made by glands called gonads. There are two types of gonads: testes and ovaries. Testes make testosterone. Ovaries make estrogen and some testosterone. Before birth, testosterone usually makes the body develop as a boy. People whose bodies do not make large amounts of testosterone develop as a girl. Some people’s bodies make testosterone but do not respond to it. Their bodies also develop as a girl. Later, hormones make the body change at puberty.
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 or girl/woman, or 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 testes. Their testes make hormones called androgens. Testosterone is one type of androgen. However, their bodies do not respond much or at all to androgens. Their bodies do not receive the “messages” that the androgens are trying to send. 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. This makes the body develop differently before birth and at puberty.
Because people with AIS have a Y chromosome, 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. In CAIS, it does not respond at all. In PAIS, it responds partially.
What is Complete AIS (CAIS)?
When a person has CAIS, their body does not respond to androgens at all. Their body develops as a girl before birth. During puberty, they grow little or no pubic or armpit hair. (Pubic hair is the hair that grows in the area covered by underwear.) During puberty, they develop breasts. (This is because some of the testosterone is changed into estrogen.) They do not have periods.
What is Partial AIS (PAIS)?
When a person has PAIS, their body responds partially to androgens. Depending on how much their body responds to androgens, their genitals may appear more female or male, or both female and male. (The table shows some of the findings that some people may have if their genitals appear more female or male.)
Clitoris may be larger than expected
Penis may be smaller than expected
Labia may be partly closed
Scrotum may not connect in the middle
Vagina may be smaller
The hole where urine (“pee”) comes out may not be at the penis’ tip. It may be on the underside instead.
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.
When is AIS suspected?
- PAIS may be suspected in babies based on the appearance of their genitals.
- CAIS may be suspected at puberty when girls do not start their periods.
- Both PAIS and CAIS may be suspected at any age during a routine checkup because a doctor feels bumps in the groin.
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.
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 includes endocrinologists, gynecologists, urologists, psychologists and geneticists. Care and treatment plans depend on each patient’s individual needs. Treatment involves regular clinic visits. We check growth and development at each visit. We also address patients’ and families’ needs at different ages and stages of life. Some patients may need to take hormones. Others may decide to have their gonads removed. Our team helps patients and families understand and weigh treatment options, answers questions, addresses issues, and provides support and counseling.
Our team wants all our patients and families to experience the best quality of life possible.