CACNA1A and familial hemiplegic migraine: Genetic studies performed on rare monogenic migraine subtypes, including familial hemiplegic migraine, identified causal mutations in the calcium voltage-gated channel subunit alpha1 A (CACNA1A), ATPase Na+/K+ transporting subunit alpha 2 (ATP1A2) and sodium voltage-gated channel alpha subunit 1 (SCN1A) genes that are involved in transport of ions at synapses and glutamatergic transmission (reviewed in [21]).