Men with the persistent Mullerian duct syndrome have a normal male phenotype, testes, bilateral fallopian tubes, a uterus and upper vagina, and variable development of the vas deferens. Such men may have inguinal hernias that contain the uterus, and cryptorchidism is common. Most have uninformative family histories, but the condition can be inherited either as an autosomal recessive or X-linked recessive mutation. Since the external genitalia are well developed and the patients masculinise at puberty, it is assumed that during the critical stage of embryonic development, the foetal testes produce a normal amount of androgen. Mullerian regression, however, does not occur, either because of mutations that impair the formation of normal Mullerian inhibiting substance or its action.
