FTO and obesity due to melanocortin 4 receptor deficiency: For example, a PheWAS study from 2014 in 2 EHR-based cohorts explored pleiotropy in the fat mass and obesity gene (FTO); this study replicated well-described associations between FTO variants and obesity while also identifying novel phenotype associations and demonstrating that pleiotropic effects of the FTO gene may be mediated by obesity.12