In the case of BMI and obesity, the first large-scale multicenter meta-analysis of genome-wide association studies from four European populations, consisting of 16,876 individuals, observed the FTO association and discovered a common variant near the already established MC4R gene.122 It subsequently became clear that the FTO locus harbors both common and rare variants that contribute to various forms of obesity. This evidence concerns the gene MC4R and obesity due to melanocortin 4 receptor deficiency.