Reifenstein syndrome is an inherited disorder that causes underdevelopment of the male reproductive tract and sexual dysfunction in males, which includes an inability to make sperm, undescended testicles (the testicles do not descend into the scrotum), and development of breasts. See also testicular feminization.

Reifenstein syndrome is one of a group of diseases in which the body is unable to respond appropriately to the male sex hormones (androgens), which include testosterone.

In this genetic disease, the affected gene codes for the androgen receptor, which is the key protein that allows cells to respond to androgens. This particular mutation makes the cells less responsive to these hormones -- hence the alternative name, Partial Androgen Insensitivity Syndrome.

By default, human babies develop female genitalia. It is only when androgens are made by the testes of male fetuses that male sexual organs arise. As a result, boys with the most severe cases of Reifenstein syndrome may appear to be girls at birth even though they are genetically male, or they may have very small penises.

The disease is inherited in an x-linked recessive manner, which means that women are not affected but may carry the gene, and males who inherit the gene from their mothers will have the condition.

• Abnormal male genitals, including undescended testes; a small scrotum, with a line down the middle (bifid) or incompletely closed; a small penis; and hypospadias (the urethra exits the body on the side of the penis, not the tip)
• Breast development in males at time of puberty
• Infertility
• 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.

Androgens are most important during early development in the womb. A male with Reifenstein syndrome can have a normal lifespan and be totally healthy, with the exception of infertility and possible psychological problems related to gender identity.

In the most severe cases, feminized external genitalia or an extremely small penis tend to cause psychological and emotional problems for these boys. In these cases, some parents have tried to raise people with Reifenstein syndrome as girls; however, this is rarely effective.

Genital surgery should be postponed until the affected person can make an informed choice. There are numerous accounts of people with ambiguous genitalia who had surgery during infancy to feminize their organs (since it is easier to do this than to create male organs) who later feel maimed.

• Infertility and failure to develop normal male gonads/genitals.
• Breast development in men can be a cosmetic concern.
• Psychological problems like depression may occur.

Prenatal testing is available for known androgen receptor mutations. People with a family history of these conditions should consider genetic counseling. Testosterone treatment that is started early may prevent some infertility.