APC and obesity due to melanocortin 4 receptor deficiency: 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).