Factor V Leiden (rs6025), prothrombin G20210A (rs1799963), PAI-1 4G/5G (rs1799889), MTHFR 677C>T (rs1801133), fibrinogen gamma 10034C>T (rs2066865), and factor XIII Val34Leu (rs5985) were genotyped in 1,801 patients with colorectal cancer and 1,853 healthy controls from a large German population-based study.
Sixteen patients who had MSI-H CRC (8.2%) had a significantly higher frequency of TT MTHFR (37.5%) and lower folate levels (3.56+/-2.41 ng/ml) than patients with MSS tumors (10.1%, 5.14+/-3.72 ng/ml).
Compared with the MTHFR 677CC and MTHFR 1298 AA genotypes, for individuals who carried both MTHFR 677CC and 1298CC genotypes, the OR of colorectal cancer was 0.103 (95%CI = 0.012-0.900); among individuals who carried both MTHFR 677TT and 1298AC genotypes, the OR for risk of colorectal cancer was 0.169 (95%CI = 0.044-0.654).
Never/occasional consumers of alcohol with the MTHFRrs1801133 CT/TT genotype were also at a reduced risk of CRC compared to never/occasional drinkers with the CC genotype (OR = 0.68, 95% CI, 0.47-0.98) (P for interaction = 0.27).
A common C to T transition (C677T) in the MTHFR gene is reported to reduce the risk for colorectal cancer and acute lymphocytic leukemia in homozygotes (TTs).
Certain common polymorphisms within the MTHFR gene (C677T, A1298C) result in reduced enzymatic activity and have been associated with reduced risk for a variety of cancers such as acute lymphocytic leukemia, lung and colorectal cancer.
Collectively, this meta-analysis suggested that MTHFR 677T allele might provide protection against CRC in worldwide populations, while MTRR 66G allele might increase the risk of CRC in Caucasians.
MTHFRrs1801133 T allele serves as a predictive marker for CRC risk and future studies with larger samples and functional evaluation are warranted to validate the current findings.
Females who were heterozygous or homozygous for the C677TMTHFR polymorphism were at increased risk of developing CIMP+ CRC (odds ratio 2.17, 95% confidence interval 1.03-4.57; p=0.037).
We evaluated the relation between the polymorphisms 677C --> T of the methylenetetrahydrofolate reductase (MTHFR) and 2756A --> G of the methionine synthase (MTR) genes and risk of colorectal cancer.
However, in meta-analyses odds ratio for MTHFR c.677C>T homozygotes versus noncarriers were 1.07 (95% CI: 1.01-1.12) for any cancer, 1.77 (1.17-2.68) for esophagus cancer, 1.40 (1.19-1.66) for gastric cancer and 0.85 (0.77-0.94) for colorectal cancer.
Association of Folate and Vitamins Involved in the 1-Carbon Cycle with Polymorphisms in the Methylenetetrahydrofolate Reductase Gene (MTHFR) and Global DNA Methylation in Patients with Colorectal Cancer.
In summary, this meta-analysis suggests that MTHFRC677T polymorphism is associated with increased breast cancer, gastric cancer, and hepatocellular cancer risk in Asians, is associated with increased gastric cancer, multiple myeloma, and NHL risk in Caucasians, is associated with decreased AALL risk in Caucasians, is associated with decreased CALL risk in Asians, is associated with increased breast cancer risk in Asians, is associated with decreased colon cancer risk, and is associated with decreased colorectal cancer risk in male population.
The distribution of MTHFRA1298C genotypes was similar in our CRC and in the HapMap Asian population, but was different from that in the White population.
Whereas our results do not support an association of high enzyme activity and increased risk of colorectal cancer in general, we can not exclude an association of patients with hereditary disease and the MTHFR 1298A --> C variant.
Overall homozygosity for MTHFR variant genotypes is associated with a reduced risk of colorectal cancer, the opposite of what might have been expected a priori.