The CACNA1 gene belongs to a family of genes that provide instructions for making calcium channels. CACNA1C encodes a subunit of L-type voltage-gated calcium channel, involved in excitatory signaling in the brain, and has been linked to conditions characterised by mood instability. The CACNA1 AG genotype is mildly associated with altered brainstem volume and increased CACNA1 excitatory signalling. The A allele is associated with a predisposition to depressive and bipolar disorder. Methods to decrease excitatory signalling, such as ensuring adequate omaga 3 fatty acid intake, as well as the use of mood stabilisers, may be used if clinically indicated.