MPPH syndrome: two new cases.

This report describes 2 additional cases of megalencephaly and perisylvian polymicrogyria with postaxial polydactyly and hydrocephalus syndrome, a recently recognized disorder of infants and young children with macrocrania, developmental delay/mental retardation, and often epilepsy. Medulloblastoma, a previously unreported feature in megalencephaly and perisylvian polymicrogyria with postaxial polydactyly and hydrocephalus syndrome, developed in one child at 3 years of age. Although the disorder is presumed to be genetic, the cause of megalencephaly and perisylvian polymicrogyria with postaxial polydactyly and hydrocephalus syndrome has not yet been determined.