CACNA1A and episodic ataxia type 2: Two CaV2.1 channelopathies—familial hemiplegic migraine type 1 (FHM1) and episodic ataxia type 2 (EA2)—result from mutations (gain- and loss-of-function, respectively) in human CACNA1A, which encodes the α1 subunit of presynaptic CaV2.1-type calcium channels (Ophoff et al., 1996; Pietrobon, 2010a).