Editing Disorders of Sexual Differentiation (section)

==== Impaired production or action of MIS ====

* '''Persistent Müllerian Duct Syndrome'''
** '''Patients with a 46,XY karyotype and normal male external genitalia but internal müllerian duct structures'''
** '''DSD resulting from defective AMH signaling'''
*** '''Aberrant MIS function may be secondary to defects in the gene for MIS or in the gene for the MIS receptor'''
**** Genetically heterogeneous disorder in which some subjects have a defect in the gene for MIS and others have a defect in the gene for its type II receptor. The condition may occur sporadically or may be inherited as an X-linked (or autosomal dominant, sex-limited) trait
** '''Typically, these phenotypic males have unilateral or bilateral undescended testes, bilateral fallopian tubes, a uterus, and an upper vagina draining into a prostatic utricle.'''
*** '''Suggested by the presence of Mullerian structures (uterus, fallopian tube) attached to an undescended testicle (more commonly intra-abdominal)'''
*** '''Usually an intraoperative finding'''
*** Patients should have AMH levels checked and be referred to endocrinology/genetics for investigation
** '''Rarely, can lead to both testicles occupying the same side of the abdomen (transverse testicular ectopia)'''
** '''Management'''
*** '''All patients are phenotypic males who require orchidopexy'''
*** The cases of adult patients with associated testis tumor (most commonly seminoma) probably reflect the increased risk of malignancy in intra-abdominal undescended testes.
*** '''Malignancies have been reported in retained müllerian remnants and at times their attachments can hinder the performance of a tension-free orchidopexy.'''
**** '''When Mullerian remnants are found incidentally during an inguinal orchidopexy, the proximal aspect of the fallopian tube can be transected and removed with the uterus, leaving its distal component attached to the vas deferens, allowing the testis to be brought to a scrotal position''' Such a maneuver avoids separation of the tube from the cord structures, protecting the deferential and testicular blood supply.
***** '''C'''areful surgical excision is required as the vasa deferentia are in close proximity to the uterus and proximal vagina