Recent genome-wide association studies have associated polymorphisms in the gene CACNA1C, which codes for Cav1.2, with a bipolar disorder and depression diagnosis.
The behaviors of wild type and Cacna1c heterozygous mice of both sexes were evaluated in a number of tests. Based upon sex differences in our mouse data, we assessed a gene x sex interaction for diagnosis of mood disorders in human subjects. Data from the NIMH-BP Consortium and the GenRED Consortium were examined utilizing a combined dataset that included 2,021 mood disorder cases (1,223 females) and 1,840 controls (837 females).
In both male and female mice, Cacna1c haploinsufficiency is associated with lower exploratory behavior, decreased response to amphetamine, and antidepressant-like behavior in the forced swim and tail suspension tests. Female, but not male, heterozygous mice displayed decreased risk-taking behavior or increased anxiety in multiple tests, greater attenuation of amphetamine-induced hyperlocomotion, decreased development of learned helplessness, and a decreased acoustic startle response indicating a sex-specific role of Cacna1c. In humans, sex-specific genetic association was seen for two intronic single nucleotide polymorphisms (SNPs), rs2370419 and rs2470411, in CACNA1C, with effects in females (OR=1.64, 1.32), but not in males (OR=0.82, 0.86). The interactions by sex were significant after correction for testing 190 SNPs (P=1.4 x 10−4, 2.1 x 10−4; Pcorrected=0.03, 0.04), and were consistent across two large data sets.
Our preclinical results support a role for CACNA1C in mood disorder pathophysiology, and the combination of human genetic and preclinical data support an interaction between sex and genotype.