Müllerian agenesis

Müllerian agenesis, also known as Müllerian aplasia, vaginal agenesis, or Mayer–Rokitansky–Küster–Hauser syndrome (MRKH syndrome), is a congenital malformation characterized by a failure of the Müllerian ducts to develop, resulting in a missing uterus and variable degrees of vaginal hypoplasia of its upper portion. Müllerian agenesis (including absence of the uterus, cervix and/or vagina) is the cause in 15% of cases 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 is present even when the Müllerian duct is completely absent. 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.

Müllerian agenesis is hypothesized to be a result of autosomal dominant inheritance with incomplete penetrance and variable expressivity, which contributes to the complexity involved in identifying the underlying causal mechanisms. Because of the variance in inheritance, penetrance and expressivity patterns, Müllerian agenesis 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, wherein the same structures are affected, but other body systems, most often the renal and skeletal systems, have additional malformations. Type 2 includes MURCS (Müllerian renal cervical somite).