1. Kim YI. Folate and carcinogenesis: evidence, mechanisms, and implications. J Nutr Biochem 1999; 10(2): 66-88.

      2. Choi SW, Mason JB. Folate status: effects on pathways of colorectal carcinogenesis. J Nutr 2002; 132(Suppl. 8): 2413S-2418S.

      3. Ryan BM, Molloy AM, McManus R, Arfin Q, Kelleher D, Scott JM, Weir DG. The Methylenetetrahydrofolate reductase (MTHFR) gene in colorectal cancer: role in tumor development and significance of allelic loss in tumor progression. Int J Gastrointest Cancer 2001; 30(3): 105-111.

      4. Little J, Sharp L. Colorectal neoplasia and genetic polymorphisms associated with folate metabolism. Eur J Cancer Prev 2002; 11(1): 105-110.

      5. Das PM, Singal R. DNA methylation and cancer. J Clin Oncol 2004; 22(22): 4632-4642.

      6. Jones PA, Baylin SB. The fundamental role of epigenetic events in cancer. Nat Rev Genet 2002; 3(6): 415-428.

      7. Eden A, Gaudet F, Waghmare A, Jaenisch R. Chromosomal instability and tumors promoted by DNA hypomethylation. Science 2003; 300(5618): 455.

      8. Herman JG, Baylin SB. Gene silencing in cancer in association with promoter hypermethylation. N Engl J Med 2003; 349(21): 2042-2054.

      9. Esteller M. Aberrant DNA methylation as a cancer-inducing mechanism. Annu Rev Pharmacol Toxicol 2005; 45: 629-656.

      10. Duthie SJ, Narayanan S, Blum S, Piric L, Brand G. Folate deficiency in vitro induces uracil misincorporation and DNA hypomethylation and inhibits DNA excision repair in immortalized normal colon epithelial cells. Nutr Cancer 2000; 37(2): 245-251.

      11. Eichholzer M, Lüthy F, Moser U, Fowler B. Folate and the risk of colorectal, breast and cervix cancer: the epidemiological evidence. Swiss Med Wkly 2001; 131(37-38): 539-549.

      12. Ueland PM, Hustad S, Schneede J, Refsum H, Vollset SE. Biological and clinical implications of the MTHFR C677T polymorphism. Trends Pharmacol Sci 2001; 22(4): 195-201.

      13. Frosst P, Blom HJ, Milos R, Goyette P Sheppard CA, Matthews RG, Boers GJ, den Heijer M, Kluijtmans LA, van den Heuvel LP. A candidate genetic risk factor for vascular disease: a common mutation in methylenetetrahydrofolate reductase. Nat Genet 1995; 10(1): 111-113.

      14. Ma J, Stampfer MJ, Giovannucci E, Artigas C, Hunter DJ, Fuchs C, Willet WC, Selhub J, Hennekens CH, Rozen R. Methylenetetrahydrofolate reductase polymorphism, dietary interactions, and risk of colorectal cancer. Cancer Res 1997; 57(6): 1098-1102.

      15. Molloy AM, Daly S, Mills JL, Kirke PN, Whitehead AS, Ramsbottom D, Conley MR, Weir DG, Scott JM. Thermolable variant of 5,10-methylene-tetrahydrofolate reductase associated with low red-cell folates: implications for folate intake recommendations. Lancet 1997; 349(9065): 1591-1593.

      16. Stern L, Mason J, Selhub J, Choi SW. Genomic DNA hypomethylation, a characteristic of most cancers, is present in peripheral leukocytes of individuals who are homozygous for the C677T polymorphism in the methylenetetrahydrofolate reductase gene. Cancer Epidemiol Biomarkers Prev 2000; 9(8): 849-853.

      17. Sharp L, Little J. Polymorphisms in genes involved in folate metabolism and colorectal neoplasia: a HuGE Review. Am J Epidemiol 2004; 159:423-443.

      18. Chen J, Giovannucci E, Kelsey K, Rimm EB, Stampfer MJ, Colditz GA, Spiegelman D, Willett WC, Hunter DJ A. Methylenetetrahydrofolate reductase polymorphism and the risk of colorectal cancer. Cancer Res 1996; 56(21): 4862-4864.

      19. Slattery ML, Potter JD, Samowitz W, Schaffer D, Leppert M. Methylenetetrahydrofolate reductase, diet, and risk of colon cancer. Cancer Epidemiol Biomarkers Prev 1999; 8(6): 513-518.

      20. Le Marchand L, Donlon T, Hankin JH, Kolonel LN, Wilkens LR, Seifried A. B-vitamin intake, metabolic genes, and colorectal cancer risk (United States). Cancer Causes Control 2002; 13(3): 239-248.

      21. Shannon B, Gnanasampanthan S, Beilby J, Iacopetta B. A polymorphism in the methylenetetrahydrofolate reductase gene predisposes to colorectal cancers with microsatellite instability. Gut 2002; 50(4): 520-524.

      22. Toffoli G, Gafa R, Russo A, Lanza G, Dolcetti R, Sartor F, Libra M, Viel A, Boiocchi M. Methylenetetrahydrofolate reductase 677 C®T polymorphism and risk of proximal colon cancer in north Italy. Clin Cancer Res 2003; 9(2): 743-748.

      23. Ulvik A, Vollset SE, Hansen S, Gislefoss R, Jellum E, Ueland PM. Colorectal cancer and the methylenetetrahydrofolate reductase 677C®T and methionine synthase 2756A®G polymorphisms: a study of 2,168 case-control pairs from the JANUS cohort. Cancer Epidemiol Biomarkers Prev 2004; 13(12): 2175-2180.

      24. Yin G, Kono S, Toyomura K, Hagiwara T, Nagano J, Mizoue T, Mibu R, Tanaka M, Kakeji Y, Maehara Y, Okamura T, Ikejiri K, Futami K, Yasunami Y, Maekawa T, Takenaka K, Ichimiya H, Imaizumi N. Methylenetetrahydrofolate reductase C677T and A1298C polymorphisms and colorectal cancer: the Fukuoka Colorectal Cancer Study. Cancer Sci 2004; 95(11): 908-913.

      25. Wang J, Gajalakshmi V, Jiang J, Kuriki K, Suzuki S, Nagaya T, Nakamura S, Akasaka S, Ishikawa H, Tokudome S. Associations between 5,10-methylenetetrahydrofolate reductase codon 677 and 1298 genetic polymorphisms and environmental factors with reference to susceptibility to colorectal cancer: a case-control study in an Indian population. Int J Cancer 2006; 118(4): 991-997.

      26. Chang SC, Lin PC, Lin JK, Yang SH, Wang HS, Li AF. Role of MTHFR polymorphisms and folate levels in different phenotypes of sporadic colorectal cancers. Int J Colorectal Dis 2007; 22(5): 483-489.

      27. Lima CS, Nascimento H, Bonadia LC, Teori MT, Coy CS, Góes JR, Costa FF, Bertuzzo CS. Polymorphisms in methylenetetrahydrofolate reductase gene (MTHFR) and the age of onset of sporadic colorectal adenocarcinoma. Int J Colorectal Dis 2007; 22(7): 757-763.

      28. Keku T, Millikan R, Worley K, Winkel S, Eaton A, Biscocho L, Martin C, Sandler R. 5,10-Methylenetetrahydrofolate reductase codon 677 and 1298 polymorphisms and colon cancer in African Americans and whites. Cancer Epidemiol Biomarkers Prev 2002; 11(12): 1611-1621.

      29. Plaschke J, Schwanebeck U, Pistorius S, Saeger HD, Schackert HK. Methylenetetrahydrofolate reductase polymorphisms and risk of sporadic and hereditary colorectal cancer with or without microsatellite instability. Cancer Lett 2003; 191(2): 179-185.

      30. Kono S, Chen K. Genetic polymorphisms of methylenetetrahydrofolate reductase and colorectal cancer and adenoma. Cancer Sci. 2005; 96(9):535-542

      31. Brockton NT. Localized depletion: the key to colorectal cancer risk mediated by MTHFR genotype and folate? Cancer Causes Control. 2006; 17(8): 1005-1016.

      32. Frosst P, Blom HJ, Milos R, Goyette P, Sheppard CA, Matthews RG, Boers GJ, den Heijer M, Kluijtmans LA, van den Heuvel LP. A candidate genetic risk factor for vascular disease: a common mutation in methylenetetrahydrofolate reductase. Nat Genet 1995; 10(1): 111-113.

      33. Yi P, Melnyk S, Pogribna M, Pogribny IP, Hine RJ, James SJ. Increase in plasma homocysteine associated with parallel increases in plasma S-adenosylhomocysteine and lymphocyte DNA hypomethylation. J Biol Chem 2000; 275(38): 29318-29323.

      34. Hubner RA, Houlston RS. MTHFR C677T and colorectal cancer risk: A meta-analysis of 25 populations. Int J Cancer 2007; 120(5): 1027-1035.

      35. Huang Y, Han S, Li Y, Mao Y, Xie Y. Different roles of MTHFR C677T and A1298C polymorphisms in colorectal adenoma and colorectal cancer: a meta-analysis. J Hum Genet. 2007; 52(1): 73-85.

      36. Dianov GL, Timchenko TV, Sinitsina OI, Kuzminov AV, Medvedev OA, Salganik RI. Repair of uracil residues closely spaced on the opposite strands of plasmid DNA results in double-strand break and deletion formation. Mol Gen Genet 1991; 225(3): 448-452.