Androgen insensitivity syndrome is a rare condition that affects the sexual development and function of an individual. The body is insensitive to the action of the male sex hormone androgen, and hence, despite having the genetic makeup of a male, the child grows to up to demonstrate female sexual characteristics.
Male and female sexes are differentiated by their sexual organs. The male reproductive system consists of the testes, present in the scrotal sacs, and penis. The female reproductive system consists of the ovaries, fallopian tubes, uterus, cervix, vagina, clitoris, labia and separate openings for the urinary tract and vagina.
Sexual development can be determined by:
Genetic make of XY (for male) and XX (for females) and presence or absence of specific genes on the Y chromosome
The androgen hormone, produced by the testes, determines development of external organs. The presence of the hormone triggers male sex organs, while its absence in females directs the formation of female sex organs.
Androgen insensitivity is caused by a genetic mutation in the AR gene, which is responsible for making androgen receptors on cells so that they can respond to the androgen hormone. With abnormal receptors, the body does not use the hormone despite its presence in normal levels.
The faulty gene is usually passed on from the mother to son as an X-linked recessive trait. This gene prevents the body of the child from responding to androgen and male sexual development is inhibited.
Androgen insensitivity can lead to infertility and increase the child's risk of developing testicular cancer.
Apart from this, parents of children suffering from androgen insensitivity may find it difficult to accept their child's condition. They will have to make a tough decision in choosing the gender in which they will raise the child. The child and family as a whole will require constant support in dealing with situations that would arise due to the condition. This decision can be further complicated if the child displays both male and female characteristics.
Androgen insensitivity can be divided into two main types:
Complete androgen insensitivity: The sex organs are completely insensitive to androgen; hence, the sex organs of the child have a female appearance, with undescended testes.
Partial androgen insensitivity: The sex organs respond partially to androgen; hence partially developed male and female genitalia may be present, and the testes are partially descended.
In case of complete androgen insensitivity, symptoms are not obvious at birth. The genitalia appears female with the presence of labia and vagina, while the undescended testes are often not detected until later investigation. Symptoms appear after puberty, when menstrual periods do not occur, and there is the presence of scant or no pubic or underarm hair growth. Breast development occurs normally. The vagina is shorter, which may cause difficulty during intercourse, and uterus and ovaries are absent.
In partial androgen insensitivity, affected babies have a micro penis (very small penis) or enlarged clitoris, partially undescended testes, and hypospadias (urogenital opening of the penis on the underside rather than the tip). Small breasts can develop. While the external genitalia may appear female, there is no uterus or ovaries present.
Androgen insensitivity is suspected based on the appearance and development of the child and can be confirmed with blood tests, scans and biopsies. Partial androgen insensitivity can be suspected immediately after birth due to abnormal appearance of the genitalia. Complete androgen insensitivity is usually diagnosed at puberty when the normal sexual changes do not occur or when a hernia occurs at the region of the undescended testicles. A biopsy (sample of tissue is removed) is done to confirm that the hernia is caused by testes and not ovaries.
When androgen insensitivity is suspected, blood tests are ordered to determine the genetic makeup and also detect high levels of testosterone in the blood. An ultrasound can confirm the internal reproductive organs (uterus and ovaries). Tests can be ordered during pregnancy such as chorionic villus sampling of the placenta between weeks 11-14 of pregnancy and amniocentesis, where the amniotic fluid is collected between weeks 15-20.
Possible complications of androgen insensitivity include infertility and psychological issues. Testicular cancer can also occur if an undescended testicle is not surgically removed.
Treatment for androgen insensitivity involves:
Psychological care and support
Hormonal replacement / supplementation
With proper care and support most people with androgen insensitivity are able to lead normal lives.
Extensive research is being undertaken to better understand androgen insensitivity. Some recent studies involve:
MB Oakes, AD Eyvazzadeh, E Quint, Smith YR. Complete androgen insensitivity syndrome--a review.J Pediatr Adolesc Gynecol. 2008 Dec;21(6):305-10.
A Hashmi, F Hanif, SM Hanif, Abdullah FE, Shamim MS. Complete Androgen Insensitivity Syndrome. J Coll Physicians Surg Pak. 2008 Jul;18(7):442-4.