Androgen insensitivity syndrome (AIS) is an inherited genetic intersex problem that affects about one in every 20,000 people. It has also been called testosterone insensitivity syndrome, Reifenstein syndrome, Rosewater syndrome, Lub syndrome and Goldberg-Maxwell syndrome.
Those affected have normal male chromosomes (46XY) but fail to respond to androgens (male hormones such as testosterone) and so do not develop any male characteristics. It is caused by an abnormal gene on the X chromosome. A genetic female (46XX) with an abnormal gene on one X chromosome will be a carrier of AIS but unaffected herself as she will have a normal gene on the other X chromosome.
Androgens are made mainly in the testes, but to some extent in the adrenal glands that are on top of each kidney.
There is a very wide range of variation in the degree of androgen insensitivity so that those affected can appear male but be unable to produce sperm, have a mixed appearance and genitalia between both sexes, or appear female but have no uterus or ovaries. Doctors have a classification syndrome that grades the different degrees of AIS. Most appear as normal, although often tall, women.
Androgens are responsible for the development of male characteristics in the foetus (eg. penis, scrotum) and at puberty (eg. facial hair, deeper voice, penile enlargement). With no androgens, a foetus will develop as a female in appearance but with no uterus and often a small vagina. With limited androgen response a mixed result occurs. None are able to have children as they have no uterus or ovaries.