MV displays several clinical similarities with familial hemiplegic migraine (FHM) and episodic ataxia type 2 (EA-2), which have been linked to mutations in 3 genes, CACNA1A, encoding a neuronal calcium channel alpha subunit, ATP1A2, encoding a catalytic subunit of a Na(+)/K(+)-ATPase, and most recently the voltage-gated sodium channel SCN1A.