Table 1.

Familial hemiplegic migraine types and associated features.

	FHM1	FHM2	FHM3
Genes	CACNA1A	ATP1A2	SCN1A
Chromosome location	19p13	1q23	2q24
Year of identification	1996	2003	2005
Mutation summary	Encodes the α-1A subunit of the P/Q type calcium channel	Encodes the α-2 subunit of the Na+,K+-ATPase	Encodes the α-1 subunit of the voltage-gated Na+ channel NaV1.1
Typical functional modulation	Gain-of-function	Loss-of-function	Gain-of-function