A variety of genome-wide association studies (GWAS) have robustly linked a cluster of single nucleotide polymorphisms (SNPs) in the first intron of the fat mass and obesity-associated gene (commonly abbreviated as FTO) to obesity [1–3], which is a well-established risk factor for certain types of malignancies, including colorectal cancer [4]. This evidence concerns the gene FTO and obesity due to melanocortin 4 receptor deficiency.