Abstract
BACKGROUND: This study examined a PERIOD3 (PER3) gene variable number tandem repeat polymorphism and chronotype as potential BrCA risk factors among Indian women. METHODS: This case-control study included sporadic, histologically confirmed BrCA cases (n = 255) and controls (n = 249) from India with data collection from 2010-2012. RESULTS: Women with the 4/5 or 5/5 PER3 genotype had a nonstatistically significant 33% increased odds of BrCA. Cases were more likely to have a morning (OR = 2.43, 95% CI = 1.23-4.81) or evening (OR = 2.55, 95% CI = 1.19-5.47) chronotype. CONCLUSIONS: Findings are consistent with the possibility that extremes in chronotype may elicit circadian desynchronization, resulting in increased BrCA susceptibility.