Compared to the reference group (Table 4), in the highest exposed group with at least four consecutive night shifts, CLOCK rs11133373 (OR 2.75, 95% CI 1.07- 7.09), ROR-b rs3903529 (OR 1.87, 95% CI 1.0- 3.61), two SNPs in the AANAT gene (rs3760138 (OR 1.82, 95% CI 1.13- 2.93) and rs4238989 (OR 1.62, 95% CI 1.0- 2.68)) and MTNR1B-rs10830963 (OR 2.48, 95% CI 1.06- 5.8) were associated with increased risk of breast cancer. The gene discussed is MTNR1B; the disease is breast carcinoma.