ATP1A2 and familial or sporadic hemiplegic migraine: Currently, we know of the following monogenic forms of migraine: Familial hemiplegic migraine type 1 (FHM1; mutations in the calcium channel gene CACNA1A), type 2 (FHM2; mutations in the sodium/potassium-transporting ATPase gene ATP1A2) and type 3 (FHM3; mutations in the sodium channel gene SCN1A) (32, 33).