Müllerian agenesis

Müllerian agenesis, also known as vaginal agenesis and Mayer–Rokitansky–Küster–Hauser syndrome (MRKH syndrome), is a birth defect characterized by a failure of the Müllerian ducts to develop, resulting in a missing uterus and variable degrees of underdevelopment of the upper vagina. It is the cause of 15% of primary amenorrhoea. Because most of the vagina does not develop from the Müllerian duct, instead developing from the urogenital sinus, along with the bladder and urethra, it remains present. Because ovaries do not develop from the Müllerian ducts, affected people might have normal secondary sexual characteristics but are infertile due to the lack of a functional uterus. However, biological motherhood is possible through uterus transplantation or use of gestational surrogates.

It is believed to be of autosomal dominant inheritance with incomplete penetrance and variable expressivity, which has made it difficult to determine the underlying mechanisms. It is subdivided into two types: type 1, in which only the structures developing from the Müllerian duct are affected (the upper vagina, cervix, and uterus), and type 2, where the same structures are affected, but other body systems, most often the kidneys and bones, have additional malformations. Type 2 includes MURCS (Müllerian renal cervical somite).

The majority of cases are sporadic, but familial cases have provided evidence that, at least for some, it is an inherited disorder. The underlying causes are being investigated, with several genes possibly associated.