The fat mass and obesity associated (FTO) gene, clearly identified to be an obesity-related gene (35), affects expression of upstream and downstream flanking genes, such as retinoblastoma-like 2 protein (Rbl2) gene, which influenced genomic hypomethylation in subtelomeric regions, regulated telomere length indirectly (36, 37). Here, FTO is linked to obesity due to melanocortin 4 receptor deficiency.