CRP and breast cancer: This approach may provide a relatively unbiased causal inference between CRP and breast cancer risk, because (i) MR can reduce potential confounding given random assignment of exposure owing to randomly assorted relevant genetic alleles at the time of gamete formation; the alleles are thus generally unrelated to environmental factors, and (ii) MR can address short-term exposures to inflammatory biomarkers by using the associated alleles as a proxy for lifelong exposure (16, 17).