Altogether, these findings suggest that these variants in the TIMELESS and RORA genes may confer susceptibility to BD and impact on circadian phenotypes in carriers who thus had lower ability to properly adapt to external cues.
Analysis of clock gene variants revealed that PER3 and RORA genotype predicted period lengthening by Li, whereas GSK3β genotype predicted rhythm effects of Li, specifically among BD cases.
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.