Persistence of Mullerian remnants in complete androgen insensitivity syndrome

One of the unusual findings in androgen insensitivity syndrome (AIS) is the persistence of Mullerian derivatives. Several hypotheses have been advanced to explain such persistence: the coincidental occurrence of mutations affecting the androgen receptor (AR) and the synthesis and/or action of anti-Mullerian hormone (AMH); the loss of AMH paracrine action due to early testicular descent; the exposure to drugs such as diethylstilbestrol. We describe a patient with complete AIS for whom surgical and laboratory findings rule out all these hypotheses. She has a missense mutation on the AR gene but no mutations were detected on the genes coding for AMH and AMH receptor. The gonads were found very close to the Mullerian structures (enough to exert a paracrine action), gonadal tissue stained positively for AMH, and yet Mullerian derivatives were present and well developed. These findings indicate the possibility of interactions between the androgen receptor and AMH action.