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.