Androgen insensitivity syndrome Dr Trisha Macnair Androgen insensitivity syndrome (AIS) is a condition that affects development of the reproductive and genital organs.

In this article

What causes it?

What are the symptoms?

What's the treatment?

A mutation in the androgen receptor gene is responsible for AIS. This abnormal gene is found on the X-chromosome.

People with AIS are genetically male, as they have XY chromosomes. Normally, androgen hormone stimulates the development of male characteristics, but in AIS the body doesn't respond as usual to the hormone because of the abnormal gene.

Some people are totally insensitive to the effects of androgen and develop external genitalia that are female in appearance. This is known as complete androgen insensitivity syndrome (CAIS).

Others have varying degrees of sensitivity to androgen, called partial androgen insensitivity syndrome (PAIS), which results in external genitalia development that ranges from completely male to completely female, or somewhere in between.

People born with complete AIS are not usually identified until puberty, when pubic hair doesn't grow and periods fail to start. The child has external female genitalia but no internal female genitalia (no fallopian tubes, uterus or upper two-thirds of the vagina).

During childhood, a girl may be found to have bilateral inguinal hernias, often containing the testes.

There's no cure, although medical treatments and surgery may help a person to function in the gender they feel most comfortable with.

The most important part of managing AIS is the explanation and counselling given to parents and the child concerned. An expert psychologist should be involved.

The problem can be compounded by not being diagnosed at birth.

This article was last medically reviewed by Dr Rob Hicks in October 2007