Focal brain malformations including hemimegalencephaly (HMEG) and focal cortical dysplasia (FCD) characterized by early onset, often intractable, epilepsy.
Mutations are most often post-zygotic (mosaic).
Diffuse megalencephaly (MEG) with polymicrogyria with pigmentary abnormalities of the skin associated with:
- Epilepsy
- Oromotor dysfunction (expressive speech delay, difficulties handling oral secretions, dysphagia and other feeding issues)
Mutations are post-zygotic (mosaic) or rarely germline (constitutional).
Diffuse megalencephaly without cortical dysplasia associated with:
- Intellectual disability
- Autism spectrum disorders
- Behavioural issues
Mutations are most often heterozygous de novo or rarely post-zygotic (mosaic).