The megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndrome is characterized by:

  • Megalencephaly (MEG) – often congenital
  • Polymicrogyria
  • Hydrocephalus – may require neurosurgical intervention
  • Polydactyly – typically postaxial polydactyly

Mutations are most often heterozygous de novo. Mosaic mutations and autosomal dominant mutations are rarely seen as well.

Bilateral perisylvian polymicrogyria is characterized by:

  • Epilepsy
  • Oromotor-dysfunction including dysphagia, difficulties handling oral secretions and expressive speech delay

Mutations are most often heterozygous de novo or mosaic mutations.