A 27 base-pair deletion of the anti-müllerian type II receptor gene is the most common cause of the persistent müllerian duct syndrome.

The persistent müllerian duct syndrome, characterized by the lack of regression of müllerian derivatives, uterus and tubes in otherwise normally masculinized males, is a genetically transmitted disorder implicating either anti-müllerian hormone (AMH), a member of the transforming growth factor-beta superfamily, or its type II receptor, a serine/threonine kinase homologous to the receptors of other members of the transforming growth factor-beta superfamily. We have now performed molecular studies in a total of 38 families. The basis of the condition, namely 16 AMH and 16 AMH receptor mutations, was identified in 32 families. The type of genetic defect could be predicted from the level of serum AMH which is very low or undetectable in patients with AMH mutations and at the upper limit of normal in receptor mutations. Whereas AMH mutations are extremely diverse, patients from 10 out of 16 families with receptor mutations had a 27 bp deletion in exon 10 on at least one allele. This deletion is thus implicated in approximately 25% of patients with persistent müllerian duct syndrome. All AMH and AMH receptor mutations were consistent with an autosomal recessive mode of transmission.