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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.
The exact prevalence in the general population is unknown.
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.
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.
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.
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.
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.
- Clinical practice guidelines
- Deutsch (2016)