MTHFR and colorectal carcinoma: A C-A haplotype in block 3 (rs1801131 and rs12121543) of MTHFR was related to an increased odds of all-cause death of colon cancer (HR = 1.50, 95%CI: 1.05–2.13) and CRC-specific death (HR = 1.54, 95%CI: 1.01–2.35), while a C-C haplotype (rs1801131 and rs12121543) was associated with a higher risk of CRC-specific mortality (HR = 2.18, 95%CI: 1.06–4.51).