Testicular feminisation syndrome
An unusual inherited disorder in which a person who is genetically male with internal testes has the external appearance of a female. The syndrome is a type of intersex and is the most widespread type of male pseudohermaphrditism.
The cause is a defective response of the body tissues to the male sex hormone testosterone. The causative genes are carried on the X chromosome and so girls can be carriers and pass on the genes to their sons.
Those afflicted seem to be girls throughout childhood. Many develop ordinary female secondary sexual characteristics at puberty but menstruation does not take place because there is no uterus and the vagina is short and blind-ending. People with the syndrome tend to be tall, and are of normal health.
Testicular feminisation syndrome can be diagnosed before puberty if a girl is found to have an inguinal hernia or a swelling in the labia that turns out to be a testis. Otherwise, the diagnosis is often made during investigations at puberty to find the cause of amenorrhoea (failure to menstruate). This is confirmed by chromosome analysis, which shows the presence of male chromosomes, and blood tests, which show male levels of testosterone.
Treatment of testicular feminisation syndrome involves surgical removal of the testes, to prevent cancerous change in later life, and therapy with oestrogen drugs. An affected person is not fertile but can live an ordinary life as a woman.