Complete Androgen Insensitivity Syndrome (CAIS)

Complete androgen insensitivity syndrome (CAIS) is a genetic defect in which, though an individual is genetically male (with one X chromosome and one Y chromosome), the external sex organs are female.

With CAIS (as opposed to “incomplete-” or “partial” androgen insensitivity), the penis and other male parts do not develop. Testicles are present, but remain internal and must be removed after puberty to avoid cancer.

CAIS occurs once in 20,000 births and is rarely diagnosed until the lack of a period and the inability to become pregnant due to the absence of a uterus and ovaries.