Since the discovery of the genetic variant fat mass and obesity-associated gene (FTO) reported in 2007 [34], hundreds of loci carrying variants have been identified, including single nucleotide polymorphisms (SNPs) associated with measurable parameters in obesity, such as the ADCY3 gene, which plays an important role in the regulation of body weight in humans [35]. Here, FTO is linked to obesity due to melanocortin 4 receptor deficiency.