PER3 and cancer: For PER3 4/5-repeat variant, we found a moderate increase in risk of cancer among individuals with the 5-allele compared to individuals with the 4-allele, although this association was not statistically significant (homozygous model: odds ratio [OR] 1.17, 95% confidence interval [CI] 0.81–1.67; recessive model: OR 1.17, 95% CI 0.82–1.67).