The current study examined variation in nine key genes involved in circadian rhythm regulation or their transcription (BMAL1, CRY2, CSNK1E, KLF10, NPAS2, PER3, REV1, SENP3, TIMELESS) as predictors of epithelial ovarian cancer risk, histopathologic subtype, and invasiveness. The gene discussed is REV1; the disease is ovarian carcinoma.