CACNA1C and bipolar disorder: Several GWASs found that abnormalities in genes encoding ion channel proteins such as SCN5A, CACNA1C and KCNQ2 are not only associated with inherited arrhythmia syndrome (Chen et al., 1998; Juang et al., 2015; Napolitano et al., 2012) but also with bipolar disorder (Ament et al., 2015; Psychiatric GWAS Consortium Bipolar Disorder Working Group, 2011).