Persistent müllerian duct syndrome (PMDS) refers to the presence of a uterus and sometimes other müllerian duct derivatives in a male. Typical features include undescended testes (cryptorchidism) and the presence of a small, underdeveloped uterus in a male infant or adult. This condition is usually caused by deficiency of fetal anti-müllerian hormone (AMH) effect due to mutations of the gene for AMH or its receptor.
Because both the wolffian ducts and müllerian ducts begin to develop, the tissues are often intertwined, resulting in obstruction or nonpatency of the vas deferens or other parts of the male excretory ducts. This can result in infertility, the most serious potential problem caused by this condition.
Cryptorchidism in AMH deficiency suggests that AMH may play a role in transabdominal testicular descent, perhaps by facilitating contraction of the gubernaculum.
Other müllerian derivatives which may be present in at least a rudimentary form are the cervix, upper part of the vagina, and fallopian tubes.
The condition can come to attention because of a bulge in the inguinal canal of a male infant due to herniation of the uterus. The presence of a uterus may be noticed if an ultrasound or MRI of the pelvis is performed to locate the testes or for other reasons. Occasionally the uterus is discovered during abdominal surgery for some other purpose in later childhood or adult life.
Surgery (orchiopexy) to retrieve the testes and position them in the scrotum is the primary treatment. Occasionally they are unsalvageable if located high in the retroperitoneum. During this surgery, the uterus is usually removed and attempts made to dissect away müllerian tissue from the vas deferens and epididymis for the purpose of improving the chance of fertility. Testosterone replacement will be necessary at puberty if the testes cannot be rescued.
Although persistent müllerian duct syndrome is classified as an intersex condition, it does not involve ambiguity or malformation of the external genitalia.
Molecular genetics and inheritance
PMDS type I results from mutations of the gene (AMH) for AMH on chromosome 19p3.3.
PMDS type II results from mutations of the gene (AMH-RII) for the AMH receptor on 12q13.
Both types of disorders are inherited as autosomal recessive conditions with expression limited to males (as females with AMH deficiency have no identified problems).