This disease is one of a spectrum of diseases that are due to loss of normal response to the male sex hormones, called androgens (of which testosterone is the best known). In this genetic disease, the affected gene codes for the androgen "receptor." This is the key protein inside cells that receives the androgen hormone and instructs the cell how to respond to androgen hormones. Mutations in the gene render the receptor (and therefore the cell) less responsive -- hence the alternative name Partial Androgen Insensitivity Syndrome.

The disease is inherited in an x-linked recessive manner.

• Abnormal male genitalia, including undescended testes; scrotum that is small, with a line down the middle (bifid) or incompletely closed; small penis and hypospadias (penis tethered to underlying skin)
• Breast development in males at time of puberty
• Lack of fertility
• Decreased body hair and beard with normal pubic and armpit hair

• Male chromosomes -- X,Y
• High testosterone and luteinizing hormone level in blood
• Low or absent sperm count
• Testicular biopsy shows no mature sperm despite normal precursors
• Decreased or absent vas deferens (the tubes through which sperm exit the testes)
• Partial development of female gonads/sex organs
• Decreased ability to bind androgen in cell culture tests
• Mutations in the androgen receptor gene
• Family history of affected males who share a common, unaffected female relative consistent with X-linked recessive inheritance

Early and continuous testosterone treatment may improve the chance that a boy will grow up to be fertile.

There is no simple prevention for genetic diseases. Prenatal testing is available for known androgen receptor mutations. Testosterone treatment that is started early may prevent some infertility.