MTHFR and colorectal cancer: DNA methyltransferase 3B (DNMT3B: NM_006892.3) and methylenetetrahydrofolate reductase (MTHFR; NM_005957.4) are two key genes which encode enzymes critical to 1C metabolism, disruption of which has increasingly been implicated in colorectal cancer etiology [1], [2].