ESR1 and breast cancer: The strongest associated variant outside the TOX3 region was variant rs147157845, located ~50 kb upstream of the ESR1 gene within a second known breast cancer risk locus at 6q25 (OR: 0.59 (95% CI: 0.50–0.71), P=1.5 × 10−7; P heterogeneity=0.47; imputation information co-efficient=0.92; Fig. 1).