CACNB2 and bipolar disorder: There is also genome-wide significant association of bipolar disorder with CACNA1D (which encodes the Cav1.3 α1 subunit) and CACNB3 (which encodes the β3 subunit) loci70 and studies of rare variants suggest involvement of several other LTCC subunits, including CACNA1D. 65CACNA1C is also a risk locus for major depression and schizophrenia,70, 71 while the CACNB2 locus confers susceptibility to multiple psychiatric disorders including bipolar disorder.70 As well as these diagnostic associations, CACNA1C and other LTCC subunits are part of the genetic contribution to cognition and sleep.