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

  • Brain overgrowth o megalencephaly – often congenital
  • Structural brain abnormalities such as polymicrogyria
  • Hydrocephalus – may require neurosurgical intervention
  • Extra digits (either fingers or toes)

Mutations are most often de novo (i.e. not inherited).Mosaic mutations and autosomal dominant mutations are rarely seen as well.

Bilateral perisylvian polymicrogyria is characterized by:

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

Mutations are most often de novo or mosaic mutations.