partial corpus callosum agenesis-cerebellar vermis hypoplasia with posterior fossa cysts syndrome (Monarch Disease Ontology entry MONDO_0018430) is a rare, hereditary, cerebral malformation with epilepsy syndrome characterized by severe global developmental delay with no ability to walk and no verbal language, intractable epilepsy, partial agenesis of the corpus callosum and cerebellar vermis hypoplasia with posterior fossa cysts.