We also found evidence that genetically proxied adult BMI was associated with a lower risk of overall (OR:0.90, 95% CI:0.84–0.96, p = 1.08x10−3), luminal A-like (OR:0.92, 95% CI:0.86–1.00, p = 0.039), and luminal B HER2 negative-like breast cancer risk (OR:0.89, 95% CI:0.80–0.99, p = 0.040). The gene discussed is ERBB2; the disease is breast cancer.