Other genes at 16p11.2 might modulate the effects of PRRT2 deficiency, as the frequency of paroxysmal kinesigenic dyskinesia in 16p11.2DS (<9% [69]) appears to be much lower than its penetrance in PRRT2 mutation carriers (>60% [67]). The gene discussed is PRRT2; the disease is episodic kinesigenic dyskinesia 1.