To further scrutinize the role of one-carbon metabolism in CRC development, we investigated a comprehensive panel of 14 circulating biomarkers and 17 single nucleotide polymorphisms (SNPs) in relation to the risk of molecular subtypes of CRC defined by KRAS and BRAF mutation status in a case-control study nested within two population-based cohorts of the Northern Sweden Health and Disease Study. The gene discussed is KRAS; the disease is colorectal carcinoma.