Started with the discovery of genetic variants in the fat mass and obesity-associated gene (FTO) reported in 2007 [26, 27], so far, more than 1000 loci carrying variants including single nucleotide polymorphisms (SNPs) significantly associated with measures of obesity like BMI have been identified in meta-analyses of large-scale GWAS. The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.