At the department of Clinical Epidemiology of the LUMC we have a continuous course/journal in which we read epi-literature and books in a nice little group. The group, called Capita Selecta, has a nice website which can be found here. sometime ago we’ve read an article that proposed to include dormant Mendelian Randomisation studies in RCT, to figure out the causal pathways of a treatment for chronic diseases. This could be most helpful when there is a discrepancy between the expected effect and the observed effect. During the discussion of this article we did not agree with the authors for several reasons. We, AGCB/IP/myself, decided to write a LTTE with these points. The journal was nice enough to publish our concerns, together with a response by the authors of the original article. The PDF can be found via the links below which will take you to the website of the American Journal of Epidemiology. The PDF of our LTTE can also be found at my mendeley profile.