The presence of a mutation in the CACNA1A gene, which encodes the α1A-subunit of voltage-gated P/Q-type calcium channels (Cav2.1), results in an array of neurological disorders including SCA6, episodic ataxia type 2 and familial hemiplegic migraine type 1 (Zhuchenko et al., 1997; Matsuyama et al., 1999; Toru et al., 2000). The gene discussed is CACNA1A; the disease is familial or sporadic hemiplegic migraine.