In the reverse study (BC on the risk of CD), no genetic effects of overall BC (OR: 1.082; 95% CI: 0.989-1.183; p=0.085), ER+ BC (OR: 1.039; 95% CI: 0.950-1.136; p=0.405), and ER− BC (OR: 1.033; 95% CI: 0.924-1.156; p=0.567) on the risk of CD were detected (Table 4). Here, ESR1 is linked to breast cancer.