Large-scale human genome-wide association studies (GWAS) that test the association of millions of genetic variants with adiposity, body mass index, and waist-to-hip ratio have identified >300 genetic loci for obesity traits, such as the FTO, TMEM18, CADM2, and LYPLAL1 loci, among others (Loos et al., 2008; González-Muniesa et al., 2017; Loos, 2018). The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.