PRRT2 and familial or sporadic hemiplegic migraine: PRRT2 is the major causative gene of PKD, BFIE, and ICCA [5-8,12-19], and is also responsible for several familial or sporadic cases with paroxysmal non-kinesigenic dyskinesia (PNKD), paroxysmal exercised-induced dyskinesia (PED), sporadic BIE, and hemiplegic migraine (HM) [20-24].