Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.5.7.1 (methylenetetrahydrofolate reductase)
 2,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Accumulating evidence from epidemiologic studies suggests that risk of breast cancer is reduced in relation to increased consumption of folate and related B vitamins. We investigated independent and joint effects of B vitamin intake as well as two polymorphisms of a key one-carbon metabolizing gene [i.e., methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C] on breast cancer risk. The study uses the resources of a population-based case-control study, which includes 1,481 cases and 1,518 controls. Significant inverse associations between B vitamin intake and breast cancer risk were observed among non-supplement users. The greatest reduction in breast cancer risk was observed among non-supplement users in the highest quintile of dietary folate intake [odds ratio (OR), 0.61; 95% confidence interval (95% CI), 0.41-0.93] as compared with non-supplement users in the lowest quintile of dietary folate intake (high-risk individuals). The MTHFR 677T variant allele was associated with increased risk of breast cancer (P, trend = 0.03) with a multivariate-adjusted OR of 1.37 (95% CI, 1.06-1.78) for the 677TT genotype. The 1298C variant allele was inversely associated with breast cancer risk (P, trend = 0.03), and was likely due to the linkage of this allele to the low-risk allele of 677C. The MTHFR-breast cancer associations were more prominent among women who did not use multivitamin supplements. Compared with 677CC individuals with high folate intake, elevation of breast cancer risk was most pronounced among 677TT women who consumed the lowest levels of dietary folate (OR, 1.83; 95% CI, 1.13-2.96) or total folate intake (OR, 1.71; 95% CI, 1.08-2.71). From a public heath perspective, it is important to identify risk factors, such as low B vitamin consumption, that may guide an effective prevention strategy against the disease.
Cancer Res 2005 Feb 15
PMID:One-carbon metabolism, MTHFR polymorphisms, and risk of breast cancer. 1573 51

Pulmonary thromboembolism (PE) is found commonly in forensic pathology practice, as it typically causes sudden death. It is attributed to a wide variety of predominantly acquired etiologies. Although likely etiologically multifactorial, some common proximate causes include: surgery, pregnancy, injury, inactivity of any cause, cancer, obesity, or serum hyperviscosity. On occasion, no apparent predisposing condition is identified. In these instances, occult hereditary thrombophilias may play a causal role. Deaths referred to the Office of Chief Medical Examiner (OCME) of New York City between December, 2000 and September, 2003 and due to PE were retrospectively reviewed. Molecular analysis (FRET) was performed on selected cases for three common hereditary thrombophilias: mutations in factor V Leiden (FVL), prothrombin G20210A (PT), and methylenetetrahydrofolate reductase (MTHFR). During the study period, 124 of 15,280 deaths were primarily attributable to PE. Of those, 34 were selected for molecular analysis. One or more mutations were detected in 35% of those, five of which were clearly causally related to death. Given the potential benefits to surviving family members, our data indicate that postmortem molecular testing for the common hereditary thrombophilias is warranted in at least selected cases.
 ...
PMID:Fatal pulmonary thromboembolism and hereditary thrombophilias. 1581 53

The aim of this study was to investigate the association of environmental factors (dietary folate, methionine and drinking status) and polymorphisms in the methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) gene, as well as the combination of these factors, with the risk of colon cancer and rectal cancer. A case-control study of 53 colon cancer patients, 73 rectal cancer patients and 343 healthy controls was conducted. Genotypes of C677T and A1298C polymorphisms were analyzed by PCR-RFLP. The dietary folate and methionine intakes were assessed using food-frequency questionnaires and food consumption tables. Unconditional logistic regression was applied to estimate the odds ratios (ORs) and their 95% confidence intervals (CIs). The frequency of MTHFR 677T and 1298C alleles in healthy population were 39.4 and 17.2%, respectively. After adjustment for specific variants, the MTHFR 677TT genotype showed a significantly reduced risk of colon cancer compared with the wild type (OR=0.22, 95% CI: 0.50-0.98), and 1298C allele-carrier showed an inverse association with the risk of rectal cancer compared to the wild type (OR=0.52, 95% CI: 0.28-0.98). Adequate intake of folate was a protective factor from colon cancer (OR=0.32, 95% CI: 0.12-0.88) and MTHFR C677T polymorphism showed a statistically significant effect (OR=0.25, 95% CI: 0.06-0.93), reducing the risk of colon cancer in groups that have an intake of folate exceeding 115.64ng per 1000kcal per day. This study suggests that MTHFR C677T and A1298C polymorphisms are associated with the reduced risk of colon and rectal cancers, respectively. Adequate folate intake shows an inverse association with the risk of colon cancer. There is a significant interaction between MTHFR C677T polymorphism and folate intake in reducing the risk of colon cancer.
Cancer Detect Prev 2005
PMID:Diets, polymorphisms of methylenetetrahydrofolate reductase, and the susceptibility of colon cancer and rectal cancer. 1582 74

To test the hypothesis that 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphisms modify the risk of pancreatic cancer, we conducted a hospital-based, case-control study involving 347 patients with newly diagnosed pancreatic adenocarcinoma and 348 healthy controls, frequency matched by age, sex, and race. MTHFR polymorphisms were determined using the PCR-RFLP method. Association of these polymorphisms with the risk of pancreatic cancer was estimated by unconditional logistic regression analysis. We found that the C667T (but not the A1298C) polymorphism had a significant main effect on the risk of pancreatic cancer. The frequencies of the MTHFR 667CC, 667CT, and 667TT genotypes were 49.5%, 38.6%, and 11.9%, respectively, among cases compared with 48.5%, 45.0%, and 6.5%, respectively, among controls. Individuals with the 667TT genotype displayed a 2-fold increased risk for pancreatic cancer compared with those with the CC/CT genotypes [adjusted odds ratio (OR), 2.14; 95% confidence interval (95% CI), 1.14-4.01]. Multivariate analyses found that the effect of the 677TT genotype on the risk of pancreatic cancer was present among ever smokers (OR, 5.53; 95% CI, 2.0-15.3) and ever alcohol drinkers (OR, 3.16; 95% CI, 1.30-7.69) but not in never smokers (OR, 0.82; 95% CI, 0.33-2.06) and never drinkers (OR, 1.42; 95% CI, 0.56-3.62). Furthermore, a positive interaction between the MTHFR TT genotype and heavy smoking or heavy alcohol consumption was detected. The OR (95% CI) of pancreatic cancer was 6.83 (1.91-24.38) for heavy smokers among the TT carriers compared with never smokers with the CC/CT genotypes and 4.23 (0.88-20.3) for heavy drinkers with the TT genotype compared with nondrinkers with the CC/CT genotypes. These observations support a role for folate metabolism in pancreatic cancer, especially among smokers and heavy drinkers.
Cancer Epidemiol Biomarkers Prev 2005 Jun
PMID:5,10-Methylenetetrahydrofolate reductase polymorphisms and the risk of pancreatic cancer. 1594 58

Folate metabolism dysregulation may lead to abnormal cell proliferation and predispose to carcinogenesis by inducing DNA hypomethylation. Folate pathways may be modified by polymorphisms in relevant genes, such as that for methylenetetrahydrofolate reductase (MTHFR), or by alcohol consumption. We investigated the relationship between MTHFR mutations at nucleotides C677T and A1298C, which cause reduced MTHFR enzyme activity, and susceptibility to oropharyngolaryngeal carcinoma in 65 patients and 100 controls. We isolated DNA from peripheral blood leukocytes. In oropharyngolaryngeal carcinoma cases the C677T heterozygous genotype was more frequent (p = 0.018), the allele frequency of MTHFR 677T was greater (p = 0.019) and the genotype 677TT/1298AA was more frequent (p = 0.001). A higher risk of carcinoma was found in the case of moderate drinkers with mutant MTHFR homozygosis or double heterozygosis (OR = 21.2 and OR = 9.1, respectively; p trend = 0.002), and the association was maintained for the different cancer sites (glottic, supraglottic, oropharyngeal). Our findings support the hypothesis that the interaction of alcohol intake and MTHFR polymorphisms might contribute to susceptibility to carcinogenesis of the oropharyngolaryngeal tract.
 ...
PMID:Association between methylenetetrahydrofolate reductase polymorphisms, alcohol intake and oropharyngolaryngeal carcinoma in northern Italy. 1594 1

Changes in the folate and vitamin B12 status in the body influence the extent of uracil misincorporation (UrMis) into DNA, which is one of the biomarkers of genomic stability and, thus, portends a risk of cancer. In our study, the level of UrMis into DNA was evaluated by the comet assay (using the specific DNA repair enzyme, uracil DNA glycosylase) in leukocytes from blood donated by healthy young women with positive folate balance achieved by 4 weeks of folic acid supplementation (400 microg/day). The nutritional status was evaluated on the basis of nine food diaries recorded by the subjects during two winter months. The data were computerized, and the intake of nutrients and micronutrients was estimated using the DIETA 2 program (Food and Nutrition Institute, Warsaw, Poland) linked to recently updated Polish food tables. The plasma folate and vitamin B12 concentration, as well as methylenetetrahydrofolate reductase (MTHFR) polymorphisms, were evaluated to determine their influence on the level of UrMis into DNA. The mean value of B12 intake for all subjects reached 100% of the Polish recommended dietary allowances (RDA), whereas the mean value of folate intake, before folate supplementation, was 50%, suggesting moderate deficiency. Folic acid supplementation brought the folate intake way above the RDA, and plasma folate concentration in each individual was above the deficient range (mean value 14.67 ng/ml). The UrMis did not correlate with the plasma folate concentration, but the level of UrMis was significantly lower in subjects with plasma vitamin B12 concentration above 400 pg/ml (P=.02) only after folic acid supplementation. The concentration of folate in plasma correlated (P<or=.05) with the wild-type MTHFR homozygote 1298 AA but not with the MTHFR 677 genotype. When subjects were grouped according to genotype, the mean concentration of folate in plasma was significantly lower in subjects with the MTHFR 677 (CT+TT) polymorphism, which was accompanied by a lower UrMis, compared to individuals with the CC genotype. The significantly higher concentrations of folate in serum, accompanied by increased UrMis, were seen in subjects with the combined MTHFR 1298 (AC+CC) genotype, as compared to the 1298 AA wild type. Our results suggest that more than 400 pg/ml of vitamin B12 in plasma in subjects with a positive folate balance is critical for genomic stability and indicate that the amount of UrMis into DNA is related to the MTHFR genotype.
 ...
PMID:Uracil misincorporation into DNA of leukocytes of young women with positive folate balance depends on plasma vitamin B12 concentrations and methylenetetrahydrofolate reductase polymorphisms. A pilot study. 1604 29

One-carbon metabolism, in which folate plays an essential role, is involved in DNA methylation and synthesis, and is suspected of impacting on colorectal carcinogenesis. Alcohol is well recognized as a risk factor for colorectal cancer (CRC) and interactions with one-carbon metabolism have also been suggested. Therefore, functional polymorphisms in genes encoding members of this pathway, MTHFR C677T and A1298C (genes for methylenetetrahydrofolate reductase), MTR A2756G (gene for methionine synthase) and TS (gene for thymidylate synthase) tandem repeats polymorphisms, have attracted attention. We conducted a matched case-control study with 257 incident CRC cases and 771 non-cancer controls at the Aichi Cancer Center to clarify associations among folate intake and four polymorphisms with reference to CRC risk. Gene-environment interaction between polymorphisms, drinking and folate consumption was also evaluated. None of the polymorphisms showed any significant impact on CRC risk by genotype alone, but when combined with alcohol consumption the MTHFR 677CC type showed a significantly reduced risk (odds ratio (OR) = 0.45, 95% confidence interval (CI): 0.23-0.86) (P = 0.01). MTR GG showed increased risk only among drinkers (OR = 3.35, 1.40-8.05) (P = 0.047). TS polymorphism did not show statistical significance by genotype alone, while interaction with drinking was significant (P = 0.028). The association was not changed even after stratification by daily folate consumption and drinking habit. In conclusion, we found consistently significant interactions between one-carbon metabolism-related polymorphisms and alcohol drinking.
 ...
PMID:One-carbon metabolism related gene polymorphisms interact with alcohol drinking to influence the risk of colorectal cancer in Japan. 1605 37

The 5,10-methylenetetrahydrofolate reductase (MTHFR) gene plays a critical role in folate metabolism. Studies on the association between MTHFR polymorphisms and length changes in short tandem repeat DNA sequences [microsatellite instability (MSI)] are inconsistent. Using data from colon cancer cases (n=503) enrolled as part of an existing population-based case-control study, we investigated the association between MTHFR 677 and MTHFR 1298 polymorphisms and MSI. We also examined whether the association was modified by folate intake. Participants were case subjects enrolled as part of the North Carolina Colon Cancer Study. Consenting cases provided information about lifestyle and diet during in-home interviews as well as blood specimens and permission to obtain tumor blocks. DNA from normal and tumor tissue sections was used to determine microsatellite status (MSI). Tumors were classified as MSI if two or more microsatellite markers (BAT25, BAT26, D5S346, D2S123, and D17S250) had changes in the number of DNA sequence repeats compared with matched nontumor tissue. Tumors with one positive marker (MSI-low) or no positive markers (microsatellite stable) were grouped together as non-MSI tumors (microsatellite stable). MTHFR 677 and MTHFR 1298 genotypes were determined by real-time PCR using the 5' exonuclease (Taqman) assay. Logistic regression was used to calculate odds ratio (OR) and 95% confidence intervals (95% CI). MSI was more common in proximal tumors (OR, 3.8; 95% CI, 1.7-8.4) and in current smokers (OR, 4.0; 95% CI, 1.6-9.7). Compared with MTHFR 677 CC referent, MTHFR 677 CT/TT genotype was inversely associated with MSI among White cases (OR, 0.36; 95% CI, 0.16-0.81) but not significant among African Americans. Although not statistically significant, a similar inverse association was observed between MTHFR 677 CT/TT genotype and MSI among the entire case subjects (OR, 0.54; 95% CI, 0.26-1.10). Among those with adequate folate intake (>400 microg total folate), we found strong inverse associations between combined MTHFR genotypes and MSI (677 CC+1298 AC/CC, OR, 0.09; 95% CI, 0.01-0.59; 677 CT/TT+1298 AA, OR, 0.13; 95% CI, 0.02-0.85) compared with the combined wild-type genotypes (677 CC+1298 AA). This protective effect was not evident among those with low folate (<400 microg total folate) intake. Our results suggest that MTHFR variant genotypes are associated with reduced risk of MSI tumors under conditions of adequate folate intake, although the data are imprecise due to small numbers. These results indicate that the relationship between MTHFR genotypes and MSI is influenced by folate status.
Cancer Epidemiol Biomarkers Prev 2005 Aug
PMID:5,10-methylenetetrahydrofolate reductase 677 and 1298 polymorphisms, folate intake, and microsatellite instability in colon cancer. 1610 55

The genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) have been associated with increased toxicity of methotrexate (MTX), a folic acid antagonist that is widely used to treat cancer and immunosuppressive disorders such as rheumatoid arthritis. In this study, we analyzed all the exons and exon/intron junctions of the MTHFR gene from 200 Japanese individuals. We detected a novel single nucleotide polymorphism (SNP) 148C>T (Arg46Trp) in exon 1. The allele frequency of this polymorphism in the Japanese population appears to be extremely low (0.25%).
 ...
PMID:A novel single nucleotide polymorphism of the human methylenetetrahydrofolate reductase gene in Japanese individuals. 1627 57

Folate metabolism supports the synthesis of nucleotides as well as the transfer of methyl groups. Polymorphisms in folate-metabolizing enzymes have been shown to affect risk of colorectal neoplasia and other malignancies. Using data from a population-based incident case-control study (1,600 cases and 1,962 controls), we investigated associations between genetic variants in the reduced folate carrier (RFC), thymidylate synthase (TS), methionine synthase (MTR), and 5,10-methylenetetrahydrofolate reductase (MTHFR) and colon cancer risk. The TS enhancer region (TSER) variant was associated with a reduced risk among men [2rpt/2rpt versus 3rpt/3rpt wild-type; odds ratio (OR), 0.7; 95% confidence interval, 0.6-0.98] but not women. When combined genotypes for both TS polymorphisms (TSER and 3'-untranslated region 1494delTTAAAG) were evaluated, ORs for variant genotypes were generally below 1.0, with statistically significantly reduced risks among women. Neither MTR D919G nor RFC 80G>A polymorphisms were associated with altered colon cancer risk. Because folate metabolism is characterized by interrelated reactions, we evaluated gene-gene interactions. Genotypes resulting in reduced MTHFR activity in conjunction with low TS expression were associated with a reduced risk of colon cancer. When dietary intakes were taken into account, individuals with at least one variant TSER allele (3rpt/2rpt or 2rpt/2rpt) were at reduced risk in the presence of a low folate intake. This study supports findings from adenoma studies indicating that purine synthesis may be a relevant biological mechanism linking folate metabolism to colon cancer risk. A pathway-based approach to data analysis is needed to help discern the independent and combined effects of dietary intakes and genetic variability in folate metabolism.
Cancer Epidemiol Biomarkers Prev 2005 Nov
PMID:Polymorphisms in the reduced folate carrier, thymidylate synthase, or methionine synthase and risk of colon cancer. 1628 71


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>