CRP and coronary artery disorder: This approach has received much attention since the seminal paper of Davey Smith and Ebrahim,1 and has led to a number of influential results over the last decade addressing a variety of aetiological questions.2 For example, in coronary heart disease (CHD), Mendelian randomization has been used to strengthen the evidence for a causal role of lipoprotein(a),3 but to weaken the case for C-reactive protein.4