Perampanel markedly improved clinical seizures in a patient with a Rett-like phenotype and 960-kb deletion on chromosome 9q34.11 including the STXBP1.

Intractable epilepsy was successfully controlled using perampanel, an α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid-type glutamate receptor antagonist, in a 27-year-old woman who presented with a Rett syndrome-like phenotype and novel 960-kb deletion involving syntaxin-binding protein 1 on chromosome 9q34.11. Perampanel may be an effective antiepileptic drug for intractable epilepsy associated with STXBP1 mutations.