MC4R and obesity due to melanocortin 4 receptor deficiency: The gene network map of interacting pair rs1121980 (chr16:53809247) and rs6567160 (chr18:57829135) is annotated to FTO and MC4R respectively, as shown in Fig. 2A. Interaction between FTO and MC4R has been documented in only a couple of studies for obesity in children and adolescents35, and large artery atherosclerotic risk36, both studies done in less than 500 subjects, and for gene-diet interactions in 7052 individuals with high cardiovascular risk37.