CRC is related to environmental factors (e.g., smoking, diet, obesity, alcohol), immune system dysregulation, or genetics, such as mutations of microsatellite instability (MSI) genes MSH1, MLH1, and MSH6, adenomatous polyposis coli (APC), or nucleotide-binding oligomerization domain 2 (NOD2) (Lawes et al., 2005). The gene discussed is NOD2; the disease is obesity due to melanocortin 4 receptor deficiency.