Androgen insensitivity syndrome (AIS) is a genetic condition that affects sexual development before birth and during puberty. It occurs when a person who is genetically male (who has one X and one Y chromosome) is resistant to male hormones (called androgens) . As a result, the person has some or all of the physical traits of a female, despite having male chromosomes. There are two main types of AIS:

• Complete androgen insensitivity syndrome (CAIS): In this type, the body is unable to use testosterone, so the genitals are entirely female. People with CAIS appear female and are often not diagnosed until puberty, when periods do not start and pubic and underarm hair does not develop.

• Partial androgen insensitivity syndrome (PAIS): In this type, the body is partially able to use testosterone, so the genitals may appear as female or male. PAIS is usually noticed at birth because the genitals appear different.

AIS can also be classified as mild androgen insensitivity syndrome (MAIS), where a persons genitals appear male, but they are usually infertile. People with AIS may have other disorders, such as failure of one or both testes to descend into the scrotum after birth, hypospadias, or Reifenstein syndrome. AIS is usually diagnosed during childhood because the person may have both male and female physical traits. Tests used to diagnose this condition may include blood tests to check levels of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), genetic testing (karyotype) to determine the persons genetic makeup, and pelvic ultrasound. The outlook for complete AIS is good if the testicle tissue is removed at the right time to prevent cancer. However, complications of AIS include infertility, psychological and social issues, and testicular cancer.