However, previous research on MTHFR and MTRR has focused on limited candidate SNPs for their relevance to CRC prognosis, including our prior analysis in which only two candidate SNPs in MTHFR (i.e., C677T and A1298C) were evaluated; none have used a gene-wide tag SNP panels that cover the majority of all common variations in the MTHFR and MTRR genes to detect risk alleles that are associated with CRC survival. Here, MTRR is linked to colorectal carcinoma.