MTHFR and colorectal carcinoma: The identified studies, which included 196 to 9723 cases, focused on candidate genes in the FOCM pathway, such as methylenetetrahydrofolate reductase (MTHFR), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and DNA methyltransferases (DNMTs), or known CRC loci.