Androgen Insensitivity syndrome (AIS), (formerly known as “testicular feminisation”) causes primary amenorrhoea (where a woman never has a period) and accounts for 10% of all cases of primary amenorrhoea. There’s an underlying genetic reason for this as the women actually have XY sex chromosomes (these are the sex chromosomes for a man), but their body appears to be almost 100% female due to problems with their sensitivity to male hormones (androgens).
There are two possible ways this can happen:
- Due to an absence of androgen receptors
- The androgen receptors are present, but they fail to function
The absence of receptors or a lack of response by the receptor cells to male hormones can either prevent or reduce the normal masculinisation of the genitals of the developing (male) fetus that normally starts in the seventh week of pregnancy. There are three categories of AIS that reflect the degree of masculinisation of the external genitals:
- Complete androgen insensitivity syndrome (CAIS) is when the external genitalia are those of a normal female
- Partial androgen insensitivity syndrome (PAIS) is when the external genitalia are partially (but not fully) masculinised
- Mild androgen insensitivity syndrome (MAIS) is when the external genitalia are those of a normal male
The internal gynaecological structures for all women with AIS are different to the norm in that even though they have a vagina, a uterus won’t have formed, which makes pregnancy impossible.
Explaining the full consequences of AIS is beyond the scope of this article and requires great deal of care and sensitivity.
A karyotype test (a chromosomal analysis) is used to determine a person’s chromosomal make-up to either confirm or exclude AIS.
Information about Androgen Insensitivity syndrome can be found on the website of the Androgen Insensitivity Syndrome Support Group (AISSG): www.aissg.org