Persistent Müllerian Duct Syndrome

Persistent Müllerian duct syndrome (PMDS) is a rare disorder of sex development (DSD) characterized by the persistence of Müllerian derivatives, the uterus and/or fallopian tubes, in otherwise normally virilized boys.

Epidemiology

The exact prevalence in the general population is unknown.

Clinical description

All affected subjects are, by definition, genotypically (46, XY) and phenotypically (normally virilized external genitalia) male. Index symptoms are cryptorchidism or inguinal hernia. Testes are normally differentiated and, in the absence of long-standing cryptorchidism, usually contain germ cells. However, affected males may be infertile as the testes are frequently not properly connected to male excretory ducts due to aplasia of the epididymis and the upper part of the vas deferens. Testosterone levels are usually normal, unless testicular degeneration has occurred.

Etiology

Genetic analysis of more than 100 families has shown that around 45% of cases are caused by mutations in the anti-Müllerian hormone gene (AMH; 19p13.3). Mutations in the gene encoding the AMH receptor (anti-Müllerian hormone receptor, type II, AMHR2; 12q13) are responsible for a further 40% of cases, with around half of these patients carrying the same mutation (a 27-base pair deletion in exon 10). Ovarian function appears to be normal in female relatives of affected males, however, further studies are required to determine whether female homozygous carriers of AMH or AMHR2 mutations are subject to early menopause.

Diagnostic methods

PMDS is usually discovered incidentally during surgery for undescended testes or inguinal hernia in boys with normal external genitalia. A specific ELISA test can be used to determine AMH levels in the serum and is a useful screening method to guide the molecular diagnosis.

Genetic counseling

PMDS is transmitted in an autosomal recessive manner.

Management and treatment

Treatment is surgical and consists of replacement of the gonads within the scrotum, requiring careful dissection of the Müllerian derivatives. Total hysterectomy is not recommended because of the risk to the vas deferens.

Prognosis

Early diagnosis and treatment may decrease the risks of degeneration and malignancy of the testes associated with longstanding cryptorchidism. Sexual function is normal, but fertility is compromised, even in treated patients. Hemospermia has been observed in older patients, but otherwise the presence of Müllerian derivatives is not harmful.