The findings that have gained support indicate that genetic variants of RORA (rs2028122) and CRY1 (rs2287161) associate with depressive disorder, those of RORB (rs7022435, rs3750420, rs1157358, rs3903529) and NR1D1 (rs2314339) with bipolar disorder, and those of NPAS2 (rs11541353) and CRY2 (rs10838524) with seasonal affective disorder or winter depression.
Variations in the three circadian clock genes Per2, Arntl, and Npas2 are associated with the disease, supporting the hypothesis that the circadian clock mechanisms contribute to winter depression.