Structural brain abnormalities including hemimegalencephaly (HMEG) and focal cortical dysplasia (FCD) associated with early onset epilepsy.
Mutations are most often post-zygotic (mosaic; i.e. present in a fraction of cells).

Diffuse brain overgrowth with polymicrogyria with changes in the pigmentation of the skin associated with:

  • Epilepsy
  • Oromotor weakness (expressive speech delay, difficulties handling oral secretions, dysphagia and other feeding issues)

Mutations are usually post-zygotic (mosaic) or rarely germline (constitutional).

Diffuse brain overgrowth without cortical dysplasia associated with:

  • Intellectual disability
  • Autism spectrum disorders
  • Behavioural issues

Mutations are most often heterozygous de novo or rarely post-zygotic (mosaic).