Androgen Insensitivity Syndrome

Question 1

What is androgen insensitivity syndrome?

Answer 1

Androgen insensitivity syndrome is a condition where cells are unable to respond to androgen hormones due to a lack of androgen receptors. It is an X-linked recessive genetic condition, caused by a mutation in the androgen receptor gene on the X chromosome. Extra androgens are converted into oestrogen, resulting in female secondary sexual characteristics. It was previously known as testicular feminisation syndrome.

Question 2

What patients are affected with androgen insensitivity syndrome?

Answer 2

Patients with androgen insensitivity syndrome are genetically male, with XY sex chromosome. However, the absent response to testosterone and the conversion of additional androgens to oestrogen result in a female phenotype externally. Typical male sexual characteristics do not develop, and patients have normal female external genitalia and breast tissue.

Question 3

Features of androgen insensitivity syndrome?

Answer 3

Patients have testes in the abdomen or inguinal canal, and absence of a uterus, upper vagina, cervix, fallopian tubes and ovaries. The female internal organs do not develop because the testes produce anti-Müllerian hormone, which prevents males from developing an upper vagina, uterus, cervix and fallopian tubes. Normal female external genitalia.

The insensitivity to androgens also results in a lack of pubic hair, facial hair and male type muscle development. Patients tend to be slightly taller than the female average. Patients are infertile, and there is an increased risk of testicular cancer unless the testes are removed.

Question 4

Partial androgen insensitivity syndrome?

Answer 4

This section mainly covers complete androgen insensitivity syndrome. There is also a condition called partial androgen insensitivity syndrome, where there the cells have a partial response to androgens. This presents with more ambiguous signs and symptoms, such as a micropenis or clitoromegaly, bifid scrotum, hypospadias and diminished male characteristics.

Question 5

How do patients present with androgen insensitivity syndrome?
Dx?

Answer 5

Androgen insensitivity syndrome often presents in infancy with inguinal hernias containing testes. Alternatively, it presents at puberty with primary amenorrhoea.

The results of hormone tests are:

Raised LH
Normal or raised FSH
Normal or raised testosterone levels (for a male)
Raised oestrogen levels (for a male)

Question 6

Management of androgen insensitivity syndrome?

Answer 6

Management:

Bilateral orchidectomy (removal of the testes) to avoid testicular tumours
Oestrogen therapy
Vaginal dilators or vaginal surgery can be used to create an adequate vaginal length

Generally, patients are raised as female, but this is sensitive and tailored to the individual. They are offered support and counselling to help them understand the condition and promote their psychological, social and sexual wellbeing.