For ER-negative BC cases, genetically raised MIP1b (OR: 1.04; 95% CIs: 1.02–1.06; P value: 7.69 × 10−4) and IL13 (OR: 1.08; 95% CIs: 1.02–1.15; P value: 7.69 × 10−3) were consistently associated with increased BC risk. The gene discussed is IL13; the disease is breast cancer.