Distributions of MTHFR Gene Polymorphism according to the Location of Colon Cancer

ABSTRACT

PURPOSE: Colon carcinogenesis seems to vary according to the original location of tumor, especially theright and the left sides. Two common methylenetetrahydrofolate reductase (MTHFR) polymorphisms, 677C->T and 1298A->C, are now known. Especially, the TT type of the 677C->T mutation shows reduced catalytic activity at a rate 30% that of wild type. The aim of this study is to investigate the distributions of MTHFR polymorphisms of 677C->T and 1298A->C according to the location of the colon cancer. METHODS: Blood samples were collected from 112 patients diagnosed in our hospital, as having colon cancer 34 proximal and 78 distal cases to the splenic flexure and 448 healthy control subjects. In order to characterize MTHFR polymorphisms, we applied the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: The distributions of MTHFR 677C->T polymorphisms as genotypes CC, CT, and TT were 32.4%, 53.1%, and 14.5% in the control group, and 34.8%, 58.0%, and 7.1% in the cancer group (P=0.056). In the 34 proximal cancers, the CC, CT, and TT distributions were 44.1%, 55.9%, and 0% (PC polymorphism by genotypes, AA, AC, CC were 69.6%, 28.6%, and 1.8% in the control group, and 58.9%, 38.4%, and 2.7% in the cancer group. The proximal and the distal groups show genotype distributions of 44.1%, 53.0%, and 2.9% and 65.4%, 32.0%, and 2.6%, respectively, but the differences were not statistically significant. CONCLUSIONS: There are no definite differences between control subjects and colon-cancer patients in the two polymorphisms 677C->T and 1298A->C. However, the TT genotype shows a lower frequency in the cancer group than in the control group with a marginal statistical value (P=0.056), which suggest a reduced risk of cancer incidence for this type, compared with a CC or a CT type.