SCN1A and familial hemiplegic migraine: As such, mutations in the Calcium Voltage-Gated Channel Subunit Alpha1 A (CACNA1A), encoding the α1 subunit of the brain specific P/Q- type calcium channel, in ATPase Na+/K+ Transporting Subunit Alpha 2 (ATP1A2), encoding the sodium–potassium- transporting ATPase, in Sodium Voltage-Gated Channel Alpha Subunit 1 (SCN1A) encoding a voltage- gated sodium channel subunit, can all lead to FHM [26,27].