CRP and coronary artery disorder: We illustrate the approaches using the example of estimating the causal effect of C-reactive protein (CRP) on coronary artery disease (CAD) risk using four genetic variants in the CRP gene region,16 and using 17 genetic variants (eTable A1; http://links.lww.com/EDE/B114) that have been shown to be associated with CRP at a genome-wide level of significance in a large meta-analysis—see eFigure in Ref.