The persistent Müllerian duct syndrome: a molecular approach.

A rare form of male pseudohermaphroditism is characterized by the persistence of Müllerian derivatives in phenotypic males. To determine the etiology of this syndrome, we studied the expression of anti-Müllerian hormone (AMH) in six boys, including three brothers, with the persistent Müllerian duct syndrome. All except one presented with an inguinal hernia containing the Müllerian derivatives, and in two boys the hernial sac contained the contralateral testis. AMH was normally expressed in the testicular tissue of two patients, as shown by bioassay of anti-Müllerian activity and immunocytochemistry. The testicular tissue of the other patients had no detectable bioactive or immunoreactive AMH, yet they expressed AMH mRNA with a normal transcription initiation site and in the amount expected for their age. These results prove the heterogeneity of the persistent Müllerian duct syndrome and suggest that it may sometimes involve peripheral insensitivity to AMH.