Mutations in human CACNA1A cause episodic ataxia type 2 (EA2) and familial hemiplegic migraine type 1 (FHM1), which have distinct clinical presentation from SCA6 (Guida et al., 2001; Tottene et al., 2002) and have been linked to altered calcium channel function, consistent with channelopathies. This evidence concerns the gene CACNA1A and episodic ataxia type 2.