Monarch Disease Ontology term MONDO_0019375 (megalencephaly-polymicrogyria-postaxial polydactyly-hydrocephalus syndrome) is characterized by megalencephaly, polymicrogyria, and hydrocephalus with variable polydactyly. It has been described in six unrelated patients. Intellectual deficit or slow development is also present. The mode of inheritance of this syndrome is unknown since all cases were sporadic. Also known as: MPPH syndrome.