Complete Androgen Insensitivity Syndrome

Complete Androgen Insensitivity Syndrome is a condition that affects the body's ability to respond to male hormones called androgens. It involves the reproductive system, where individuals have a typical male XY chromosome pattern but develop female physical traits instead. This happens because the body's cells cannot use androgens properly, leading to the development of female external genitalia despite having testes inside the body. People with this condition usually have normal female external appearance but do not have a uterus or ovaries and do not menstruate. The condition mainly affects sexual development and fertility. It is caused by changes in the gene responsible for the androgen receptor. Diagnosis often occurs during puberty when menstruation does not start.

Complete Androgen Insensitivity Syndrome (CAIS) is a genetic disorder characterized by a 46,XY karyotype with a mutation in the androgen receptor gene leading to complete resistance to androgens. This results in a failure of masculinization of the external genitalia despite normal or elevated levels of circulating androgens. Individuals present with female external genitalia, absent or rudimentary internal female reproductive structures due to Müllerian inhibiting factor secretion by testes, and undescended testes. The condition is caused by mutations in the AR gene on the X chromosome, impairing androgen receptor function. Clinically, patients have normal breast development but absent or sparse pubic and axillary hair. CAIS is significant because it causes primary amenorrhea and infertility in phenotypic females with a male genotype. It requires differentiation from other disorders of sexual development.