The effect of several polymorphic genes involved in FA metabolism, including methylenetetrahydrofolate reductase (MTHFR) on CRC susceptibility and progression has been investigated8 MTHFR catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate; the latter is the methyl donor for the conversion of homocysteine (Hcy) to methionine, whereas the former, and its derivatives, are essential cofactors for both thymidylate and de novo purine synthesis9, 10. Here, MTHFR is linked to colorectal carcinoma.