Androgen insensitivity syndrome
Androgen insensitivity syndrome (AIS), also known as the testicular feminisation syndrome, results from end-organ resistance to androgens, particularly testosterone. AIS may be complete or incomplete with variable imaging findings.
The incidence may vary dependent on whether it is complete or incomplete. Rough estimated incidence rates is ~1 in 20,000 to 50,000 live births.
Patients can often present with primary amenorrhoea.
Affected individuals are genotypically male with a 46XY karyotype but with a female phenotype (male pseudohermaphroditism). Individuals often have bilateral cryptorchidism. The undescended testes often produce oestradiol. There may be a blind-ending vagina.
Thought to carry an X linked recessive inheritance 3 where multiple mutations in the androgen receptor (AR) gene has been localized to the long arm of the X chromosome (i.e. Xq11-13).
Although it is a disease spectrum it may be sub typed according to the extend of severity as:
- complete androgen insensitivity syndrome (CAIS): Morris syndrome
- incomplete: partial androgen insensitivity syndrome / Reifenstein syndrome
General imaging features include:
- bilateral cryptorchidism +/- juxta-testicular Mullerian duct cysts
- absent/rudimentary uterus
- shortened vagina
Usually, the first modality to locate the testes, and document absent uterus.
Modality of choice to accurately delineate mullerian duct anomalies, and localize testes. It may also diagnose testicular malignancy, if any, in cryptorchid testes 7.
Mayer-Rokitansky-Kuster-Hauser syndrome have female karyotype with normal female genitalia, and ovaries, however uterus is rudimentary or absent 7.
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