Non-synonymous polymorphisms in the circadian gene NPAS2 and breast cancer risk.

Three known non-synonymous polymorphisms (Ala394Thr, Ser471Leu and Pro690Ala) in the largest circadian gene, Neuronal PAS domain protein 2 (NPAS2), were genotyped in a breast cancer case-control study conducted in Connecticut, USA (431 cases and 476 controls). We found that women with the heterozygous Ala394Thr genotype were significantly associated with breast cancer risk compared to those with the common homozygous Ala394Ala (OR = 0.61, 0.46-0.81, P = 0.001). This is the first evidence demonstrating a role of the circadian gene NPAS2 in human breast cancer, suggesting that genetic variations in circadian genes might be a novel panel of biomarkers for breast cancer risk.