CACNA1C and familial or sporadic hemiplegic migraine: Genome-wide association studies have found evidence for an association between CACNA1C (alpha 1C subunit of the L-type voltage-gated calcium channel) gene variants and BD (Ferreira et al., 2008; Sklar et al., 2011) and mutations in a calcium channel encoding gene CACNA1A (alpha 1A subunit of P/Q type voltage-dependent calcium channel) have been found to cause familial hemiplegic migraine type 1 (Gargus, 2009).