Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.5.7.1 (methylenetetrahydrofolate reductase)
2,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A hospital-based case-control study was conducted to evaluate the significance of methionine and folate related polymorphisms, with 72 colon and 70 rectal cancer cases and 241 non-cancer controls. The polymorphisms examined were in the genes for methionine synthase reductase (MTRR A66G), methionine synthase (MTR A2756G) and methylenetetrahydrofolate reductase (MTHFR C677T and A1298C). An unconditional logistic regression model was applied for estimating the odds ratios (ORs) and 95% confidence intervals (CIs). The age-sex adjusted OR for the MTRR GG genotype as compared with the AA and AG genotypes was 2.77 (95% CI: 1.39-5.53, p = 0.004), whereas adjusted ORs for other polymorphisms were not statistically significant. When the ORs for environment factors (smoking, alcohol consumption, body-mass-index, and physical exercise) were calculated according to each polymorphism, no substantial difference was observed except with the MTRR polymorphism. The ORs for the MTRR GG genotype seemed to be modified by the extent of environmental exposure. In conclusion, the present study showed that the GG genotype of MTRR A66G is a risk factor for colorectal cancer in Japanese, while MTHFR and MTR polymorphisms are not. The conclusions, however, need further evaluation in terms of micronutrient status and additional confirmatory studies are required with datasets for various ethnic groups.
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PMID:Methionine Synthase Reductase Gene A66G Polymorphism is Associated with Risk of Colorectal Cancer. 1271 94

We analyzed the association between the methylenetetrahydrofolate reductase (MTHFR) 677C>T and methionine synthase reductase (MTRR) 66A>G polymorphisms with serum homocysteine and with coronary artery disease (CAD) in 504 patients undergoing clinically-indicated angiography between July 1998 and January 1999. Significant CAD (>/=50% stenosis in >/=one artery, blinded to risk factors) was present in 271 patients (54%). Median homocysteine (micromol/l) was 8.8 (interquartile range: 7.5-10.7). The prevalence of the MTHFR TT, CT, and CC genotypes was 11, 44 and 45%, respectively. Median tHcy (with interquartile ranges) for the entire population was 8.8 (7.5-10.7), and for the TT, CT, and CC genotypes was 9.7 (8.2-11.4), 8.8 (7.5-10.7), and 8.6 (7.3-10.6) micromol/l, respectively (P=0.04). On multiple logistic regression analysis, the MTHFR TT genotype was associated with hyperhomocysteinemia (adjusted OR=3.57; 95% CI, 1.47-8.70), but not with significant CAD. The prevalence of the MTRR AA, AG, GG genotypes was 19, 50 and 31%, respectively. There were no differences in mean homocysteine, prevalence of hyperhomocysteinemia and significant CAD between the three genotypes. On multivariate analysis, the MTRR genotypes were not associated with serum homocysteine or with significant CAD.
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PMID:Methylenetetrahydrofolate reductase (MTHFR) 677C>T and methionine synthase reductase (MTRR) 66A>G polymorphisms: association with serum homocysteine and angiographic coronary artery disease in the era of flour products fortified with folic acid. 1280 15

Gene-environment interactions play an important role in folate metabolism, with a potential impact on human health. Deficiencies in the uptake of key micronutrients and variant genotypes can affect the folic acid cycle, modulating methyl group transfer in key processes and leading to increased cancer risk and Down syndrome incidence. So far, the significance of folate status and metabolic genotypes on baseline levels of DNA damage in normal individuals has not been fully elucidated. In this study, the possible modulation of SCE, micronuclei and tail moment values in peripheral lymphocytes by plasma levels of folic acid, homocysteine and vitamin B12, and by the methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase reductase (MTRR) A66G polymorphisms was investigated in 191 healthy subjects. The results obtained show a highly significant (P = 0.001) positive association between plasma levels of vitamin B12 and frequencies of both SCE and high frequency cells (HFC, above 90 degrees percentile) in smokers. No significant effect was observed in non-smokers. Moreover, after correction for age, gender and GSTM1 genotype, a significant association (P = 0.026) between the MTRR 66GG variant genotype and higher micronucleus rates was observed. Tail moment values were not affected by any of the independent variables considered. Overall, the results obtained suggest that both folate status and relevant metabolic genotype can influence background levels of DNA damage in normal subjects. The significant association observed in smokers between plasma vitamin B12 and SCE frequencies may highlight the effect of methylation status on DNA damage and repair, although the role of other, unidentified dietary factors cannot be ruled out. At the same time, micronucleus data indicate that the MTRR 66GG variant may represent another individual trait of relative genomic instability, thus supporting epidemiological data on increased risk of Down syndrome conception in MTRR 66GG subjects.
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PMID:Folate status, metabolic genotype, and biomarkers of genotoxicity in healthy subjects. 1280 60

Contradictory findings have been recently published on the evaluation of genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR 677 C-->T) and methionine synthase reductase (MTRR 66 A-->G) as risk factors for having a child with Down syndrome (DS); however, the influence of polymorphisms of methionine synthase (MTR 2756 A-->G) and of MTHFR 1298 A-->C has never been evaluated. In this study, the risk of being a DS case or having a DS child (case mother) was studied by multiple logistic regression analysis of the independent and combined genotypes and of plasma homocysteine, folates, and vitamin B12 in 92 DS cases and 140 control subjects as well as in 63 case mothers and 72 age-matched control mothers from Sicily. (The MTHFR 677 T allele frequency was not different in DS cases and case mothers, compared to the respective control groups). After adjustment for age, total homocysteine (t-Hcys) and MTR 2756 AG/GG genotype were significant risk factors for having a DS child, with odds ratio (OR) of 6.7 (95% CI: 1.4-32.0, P = 0.016) and of 3.5 (95% CI: 1.2-10.9, P = 0.028), respectively. By comparison, MTR 2756 AG/GG genotype increased significantly the risk of being a DS case, with an OR of 3.8 (95% CI: 1.4-10.5, P = 0.009). The double heterozygosity MTR 2756 AG/MTRR 66 AG was the single combined genotype that was a significant risk factor for having a DS child, with an OR estimated at 5.0 (95% CI: 1.1-24.1), after adjustment for t-Hcys. In conclusion, our results provide evidences that homocysteine and MTR genetic polymorphism are two potent risk factors for mothers to have a DS child in Sicily.
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PMID:Methionine synthase (MTR) 2756 (A --> G) polymorphism, double heterozygosity methionine synthase 2756 AG/methionine synthase reductase (MTRR) 66 AG, and elevated homocysteinemia are three risk factors for having a child with Down syndrome. 1292 61

Epidemiological studies indicated a role for polymorphisms in genes of folate and homocysteine (Hcy) metabolism in the etiology of neurodegenerative disease, congenital defects and coronary artery disease (CAD). This study investigated the effect of several polymorphisms [C677 T, A1298C of methylenetetrahydrofolate reductase (MTHFR) and A66G of methionine synthase reductase (MTRR) genes] on Hcy levels and DNA damage in 68 patients who underwent coronary angiography. Plasma Hcy concentrations were higher in patients with multivessel disease with respect to monovessel disease and no-CAD patients (19.4+/-2.6 vs 11.6+/-1.2 and 13.7+/-1.4 micromol/l, respectively; P=0.03). 677TT patients had higher Hcy levels than those with 677CC or 677CT genotypes (26.2+/-4.3 vs 13.1+/-1.4 and 13.0+/-1.4 micromol/l, respectively; P=0.0006). No significant associations were found between A1298C and A66G polymorphisms and plasma Hcy levels. Among patients with 677CC genotype, 66GG individuals tended to have higher levels of Hcy than 66AA homozygotes (14.5+/-1.9 vs 8.9+/-0.7 micromol/l, P=0.06). Multivessel disease patients showed an increased frequency of DNA damage, measured by the micronucleus (MN) frequency, as compared to monovessel disease and no-CAD subjects (12.5+/-1.1 vs 8.5+/-0.8 and 8.2+/-0.9, respectively; P=0.006). The MN were positively correlated with Hcy levels (r=0.33, P=0.006) and were significantly higher in subjects with the 677TT genotype compared with the 677CC or 677CT genotypes (14.4+/-2.0 vs 8.8+/-1.2 and 9.5+/-0.7, respectively; P=0.006). A1298C and A66G polymorphisms had no effect on MN frequency. However, among 677TT patients, 66GG subjects tended to have higher levels of MN than those 66AG and 66AA (18.2+/-3.6 vs 13.8+/-4.0 and 10.3+/-1.7, respectively; P=NS). Our results indicate that genetic instability may be associated with increased risk for multiple Hcy-related diseases.
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PMID:Genetic polymorphisms in folate and homocysteine metabolism as risk factors for DNA damage. 1293 53

Linxian, a rural county in North Central China, has among the highest rates of esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA) in the world. Its inhabitants have documented chronic nutritional inadequacies, including folate and vitamin B(12) deficiencies. Using a cohort we have been studying in Linxian since 1985, we examined the relationship between incident ESCC and GCA cancers and three polymorphisms in two genes that code for enzymes that require folate and B(12) as cofactors: methionine synthase reductase (MTRR) A66G and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C. We conducted a case-cohort study among 4005 individuals in our cohort who were alive and cancer free in 1991 and had blood samples adequate for DNA extraction. Polymorphisms were measured on all 219 incident cancers (129 ESCCs and 90 GCAs) that developed through May 1996 and on 398 controls. Cox proportional hazard models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs). Individuals with the MTHFR 677TT genotype had significantly higher combined ESCC/GCA risks (RR, 1.45; 95% CI, 1.02-2.05) than those with CC or CT genotypes. The only subjects to have MTHFR 1298CC were three ESCC cases (P = 0.03). Compared with subjects with the MTRR 66AA genotype, subjects with the AG or GG genotypes had significantly higher risk of ESCC (RR, 1.59; 95% CI, 1.04-2.42). No association was observed for GCA. Our results suggest that the MTHFR C677T and MTRR A66G polymorphisms influence the risk of ESCC and GCA in this population.
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PMID:Esophageal and gastric cardia cancer risk and folate- and vitamin B(12)-related polymorphisms in Linxian, China. 1465 85

One-carbon metabolism is under the influence of folate, vitamin B12 and genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR 677 C --> T and 1298 A --> C), of methionine synthase (MTR 2756 C --> G), methionine synthase reductase (MTRR 66 A --> G) and transcobalamin (TCN 776 C --> G). The pathogenesis of neural tube defect (NTD) may be related to this metabolism. The influence of the MTHFR 677 C --> T polymorphism reported in The Netherlands and Ireland can be questioned in southern Italy, France and Great Britain. MTRR, combined with a low level of vitamin B12, increases the risk of NTD and of having a child with NTD in Canada, while TCN 776 GG and MTRR 66 GG mutated genotypes associated with the MTHFR 677 CC wild-type are predictors of NTD cases in Sicily. Down syndrome (DS) is due to a failure of normal chromosomal segregation during meiosis, possibly related to one-carbon metabolism. MTHFR 677 C --> T and MTRR 66 A --> G polymorphisms are associated with a greater risk of having a child with DS in North America, Ireland and The Netherlands. In contrast, MTHFR 677 C --> T has no influence on DS risk in France and Sicily, while homocysteine and MTR 2756 AG/GG genotypes are predictors of DS risk in Sicily. In conclusion, NTD and DS are influenced by the same genetic determinants of one-carbon metabolism. The distinct data produced in different geographical areas may be explained by differences in the nutritional environment and genetic characteristics of the populations.
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PMID:Genetic determinants of folate and vitamin B12 metabolism: a common pathway in neural tube defect and Down syndrome? 1465 28

Epidemiologic and mechanistic evidence suggests that folate is involved in colorectal neoplasia. Some polymorphic genes involved in folate metabolism--methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), methionine synthase (MTR A2756G), methionine synthase reductase (MTRR A66G), cystathionine beta-synthase (CBS exon 8, 68-base-pair insertion), and thymidylate synthase (TS enhancer region and 3' untranslated region)--have been investigated in colorectal neoplasia. For MTHFR C677T and A1298C, the variant allele is associated with reduced enzyme activity in vitro. For the other polymorphisms, functional data are limited and/or inconsistent. Genotype frequencies for all of the polymorphisms show marked ethnic and geographic variation. In most studies, MTHFR 677TT (10 studies, >4,000 cases) and 1298CC (four studies, >1,500 cases) are associated with moderately reduced colorectal cancer risk. In four of five genotype-diet interaction studies, 677TT subjects who had higher folate levels (or a "high-methyl diet") had the lowest cancer risk. In two studies, 677TT homozygote subjects with the highest alcohol intake had the highest cancer risk. Findings from six studies of MTHFR C677T and adenomatous polyps are inconsistent. There have been only one or two studies of the other polymorphisms; replication is needed. Overall, the roles of folate-pathway genes, folate, and related dietary factors in colorectal neoplasia are complex. Research priorities are suggested.
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PMID:Polymorphisms in genes involved in folate metabolism and colorectal neoplasia: a HuGE review. 1497 39

Folate and methionine metabolism is involved in DNA synthesis and methylation processes. Polymorphisms in the genes of folate metabolism enzymes have been associated with some forms of cancer. In a case-control study, we evaluated whether four common polymorphisms in methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), methionine synthase (MS A2756G), and methionine synthase reductase (MTRR A66G) genes may have a role in altering susceptibility to adult acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). We analyzed DNA of 120 adult ALL, 200 NHL, and 257 healthy control subjects. Individual carrying the MTHFR 677TT genotype showed a 3.6-fold decreased ALL risk [odds ratio (OR) 0.28, 95% confidence interval (95% CI) 0.12-0.72] than wild-types. Similarly, MS 2756GG individuals showed a 5.0-fold decreased ALL risk (OR 0.20, 95% CI 0.02-1.45) than wild-types. In combined results, subjects with the MTHFR 677CT/TT and MS 2756AG/GG genotypes revealed a 3.6-fold ALL risk reduction (OR 0.28, 95% CI 0.14-0.58) and those with the MTHFR 677TT and MTRR 66AG genotypes revealed a 4.2-fold ALL risk reduction (OR 0.24, 95% CI 0.06-0.81). Finally, those with the MS 2756AG/GG and MTRR 66AG/GG genotypes revealed a 2.2-fold ALL risk reduction (OR 0.45, 95% CI 0.10-0.85). Single analysis for NHL did not show any significant difference for all the polymorphisms investigated, but in the low-grade NHL subgroup, we found a 2.0-fold risk reduction for the MTRR 66GG homozygous genotype (OR 0.50, 95% CI 0.25-0.99), which was higher (OR 0.37, 95% CI 0.14-0.85) when analyzed in combination with MS 2756AA genotype. These data are in accordance with the hypothesis that polymorphisms in the genes for folate and methionine metabolism might play a greater role in the occurrence of ALL than NHL by influencing DNA synthesis and/or DNA methylation.
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PMID:Common gene polymorphisms in the metabolic folate and methylation pathway and the risk of acute lymphoblastic leukemia and non-Hodgkin's lymphoma in adults. 1515 11

Hyperhomocysteinemia is a risk factor for thrombosis, and methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) polymorphisms, folate, and B12 levels could contribute to plasma homocysteine (Hcy) variation. Although well established in adults, few studies have been performed in childhood. In this study, we investigated association of polymorphisms C677T and A1298C in the MTHFR gene and A66G in the MTRR gene with Hcy levels in children. These polymorphisms, as well as Hcy, folate, and vitamin B12 levels were investigated in 220 normal children with ages ranging from 1 to 8 years. Plasma Hcy, folate, and vitamin B12 levels were normal in all children. None of the polymorphisms could be considered an independent risk factor for hyperhomocysteinemia during childhood. The median Hcy levels in 37 children (17%) doubly heterozygous for C677T and A1298C mutations in the MTHFR gene were not different from the other genotypes. However, the association of the different genotypes with Hcy, folate, and vitamin B12 levels demonstrated significant P-values. The folate levels demonstrated a statistically significant decrease (P = 0.0477) from the C677T mutation in the MTHFR gene (TT genotype) when compared to the other groups. Folate was the only independent risk factor for hyperhomocysteinemia. Thus, monitoring the concentrations of folate would be more helpful for evaluating hyperhomocysteinemia and for preventing cardiovascular disease.
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PMID:Polymorphisms in the methylenetetrahydrofolate reductase and methionine synthase reductase genes and homocysteine levels in Brazilian children. 1521 46


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