PRRT2 mutations account for a large fraction of cases of familial benign infantile epilepsy, paroxysmal kinesigenic dyskinesia (PKD) and PKD with infantile convulsions (PKD/IC) and, conversely, 95% of PRRT2 patients have a diagnosis within the benign familial infantile epilepsy PKD/IC-PKD spectrum. This evidence concerns the gene PRRT2 and episodic kinesigenic dyskinesia 1.