Androgen insensitivity syndrome

Humans typically have 46 chromosomes. This includes twenty-two pairs of numbered chromosomes and two sex chromosomes. Usually, females have two X chromosomes (46, XX) and males have one X and one Y chromosome (46, XY).

The gene that causes androgen insensitivity syndrome (AIS) is located on the X chromosome. AIS is inherited when a mother passes on an X chromosome with an AR genetic change (mutation) to one of her sons. The mother is a carrier and will typically not have any symptoms of the disease since she has another X chromosome with a functioning copy of the AR gene with no mutations. However, 10% of the time, carriers may have subtle characteristics of AIS such as sparse growth of pubic hair.

Each son of a carrier has a 50% chance to have AIS and each of her daughters has a 50% chance of being a carrier for androgen insensitivity syndrome. This is called X-linked recessive inheritance.

In 30% of cases of AIS, the mutation in the AR gene has occurred for the first time in that individual by chance, called a de novo mutation, and it has not been inherited, or passed down, in the family.

To learn more about the inheritance of AIS, talk with your doctor or contact a genetic counselor. Genetic counselors can be found on the National Society of Genetic Counselors website.