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      Association of MTHFR C677T and A1298C polymorphisms with non-Hodgkin lymphoma susceptibility: Evidence from a meta-analysis

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          Abstract

          Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism and DNA synthesis. A number of studies have examined the association of MTHFR C677T and A1298C polymorphisms with non-Hodgkin lymphoma (NHL) susceptibility; however, the conclusions were contradictory. We searched available publications assessing the polymorphisms of MTHFR and NHL susceptibility from MEDLINE, EMBASE and CBM. Genotype-based mRNA expression analysis was performed using data from 270 individuals with three different ethnicities. Ultimately, a total of 7448 cases and 11146 controls from 25 studies were included for the C677T polymorphism, 6173 cases and 9725 controls from 19 studies for the A1298C polymorphism. Pooled results indicated that neither C677T nor A1298C polymorphism was associated with NHL susceptibility. However, C677T polymorphism showed a statistically significantly increased risk for Caucasians, but a decreased risk for Asians in the subgroup analysis by ethnicity. The same variants may confer increased susceptibility to develop follicular lymphoma (FL). Moreover, A1298C polymorphism was associated with increased NHL risk for Asians. This meta-analysis indicated that C677T polymorphism was associated with altered NHL susceptibility for Caucasians, Asians and FL. Increased NHL risk was also shown for A1298C among Asians. These findings warrant validation in large and well-designed prospective studies.

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          Most cited references47

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          A second common mutation in the methylenetetrahydrofolate reductase gene: an additional risk factor for neural-tube defects?

          Recently, we showed that homozygosity for the common 677(C-->T) mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, causing thermolability of the enzyme, is a risk factor for neural-tube defects (NTDs). We now report on another mutation in the same gene, the 1298(A-->C) mutation, which changes a glutamate into an alanine residue. This mutation destroys an MboII recognition site and has an allele frequency of .33. This 1298(A-->C) mutation results in decreased MTHFR activity (one-way analysis of variance [ANOVA] P T) mutation. However, there appears to be an interaction between these two common mutations. When compared with heterozygosity for either the 677(C-->T) or 1298(A-->C) mutations, the combined heterozygosity for the 1298(A-->C) and 677(C-->T) mutations was associated with reduced MTHFR specific activity (ANOVA P T) mutation. This combined heterozygosity was observed in 28% (n =86) of the NTD patients compared with 20% (n =403) among controls, resulting in an odds ratio of 2.04 (95% confidence interval: .9-4.7). These data suggest that the combined heterozygosity for the two MTHFR common mutations accounts for a proportion of folate-related NTDs, which is not explained by homozygosity for the 677(C-->T) mutation, and can be an additional genetic risk factor for NTDs.
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            A common mutation in the 5,10-methylenetetrahydrofolate reductase gene affects genomic DNA methylation through an interaction with folate status.

            DNA methylation, an essential epigenetic feature of DNA that modulates gene expression and genomic integrity, is catalyzed by methyltransferases that use the universal methyl donor S-adenosyl-l-methionine. Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of 5-methyltetrahydrofolate (5-methylTHF), the methyl donor for synthesis of methionine from homocysteine and precursor of S-adenosyl-l-methionine. In the present study we sought to determine the effect of folate status on genomic DNA methylation with an emphasis on the interaction with the common C677T mutation in the MTHFR gene. A liquid chromatography/MS method for the analysis of nucleotide bases was used to assess genomic DNA methylation in peripheral blood mononuclear cell DNA from 105 subjects homozygous for this mutation (T/T) and 187 homozygous for the wild-type (C/C) MTHFR genotype. The results show that genomic DNA methylation directly correlates with folate status and inversely with plasma homocysteine (tHcy) levels (P < 0.01). T/T genotypes had a diminished level of DNA methylation compared with those with the C/C wild-type (32.23 vs.62.24 ng 5-methylcytosine/microg DNA, P < 0.0001). When analyzed according to folate status, however, only the T/T subjects with low levels of folate accounted for the diminished DNA methylation (P < 0.0001). Moreover, in T/T subjects DNA methylation status correlated with the methylated proportion of red blood cell folate and was inversely related to the formylated proportion of red blood cell folates (P < 0.03) that is known to be solely represented in those individuals. These results indicate that the MTHFR C677T polymorphism influences DNA methylation status through an interaction with folate status.
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              Polymorphisms in the XPG gene and risk of gastric cancer in Chinese populations.

              DNA repair genes play an important role in maintaining stability and integrity of genomic DNA. Polymorphisms in nucleotide excision repair genes may cause variations in DNA repair capacity phenotype and thus contribute to cancer risk. In this case-control study of 1,125 gastric cancer cases and 1,196 cancer-free controls, we investigated the association between three functional single nucleotide polymorphisms (SNPs, rs2296147T > C, rs2094258C > T and rs873601G > A) in the xeroderma pigmentosum group G (XPG) gene and gastric cancer risk. We used the Taqman assays to genotype these three SNPs and logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). We found that only the rs873601A variant genotypes were associated with a significant higher risk for gastric adenocarcinoma (adjusted OR = 1.30, 95% CI = 1.03-1.64 for AA vs. GG and adjusted OR = 1.23, 95% CI = 1.01-1.49 for AA vs. GG/AG). Stratification analysis indicated that this risk was more pronounced in subgroups of older age (>59 years), males, ever-smokers, and patients with NGCA. All these were not found for the other two SNPs (rs2296147T > C and rs2094258C > T). We then performed expression analysis using gastric cancer adjacent normal tissues from 141 patients and found that the A variant allele was associated with non-significantly reduced expression of XPG mRNA (P(trend) = 0.107). Further analysis using mRNA expression data from the HapMap suggested that the A allele was associated with significantly reduced expression of XPG mRNA in normal cell lines for 45 Chinese (P(trend) = 0.003) as well as for 261 subjects with different ethnicities (P(trend) = 0.001). These support the hypothesis that functional XPG variants may contribute to the risk of gastric cancer. Larger studies with different ethnic populations are warranted to validate our findings.
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                Author and article information

                Journal
                Sci Rep
                Sci Rep
                Scientific Reports
                Nature Publishing Group
                2045-2322
                22 August 2014
                2014
                : 4
                : 6159
                Affiliations
                [1 ]State Key Laboratory of Oncology in South China, Department of Experimental Research, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center , Guangzhou, Guangdong 510060, China
                [2 ]Molecular Epidemiology Laboratory and Laboratory Medicine, Harbin Medical University Cancer Hospital , Harbin, Heilongjiang 150040, China
                [3 ]Department of Radiation Oncology, The First Affiliated Hospital, Sun Yat-Sen University , Guangzhou, Guangdong 510080, China
                [4 ]Department of Neurosurgery, The Second Affiliated Hospital, Sun Yat-Sen University , Guangzhou, Guangdong 510120, China
                Author notes
                Article
                srep06159
                10.1038/srep06159
                5381410
                25146845
                3b39d058-6af1-4bc9-ab6f-c87784aea4d4
                Copyright © 2014, Macmillan Publishers Limited. All rights reserved

                This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

                History
                : 11 March 2014
                : 07 July 2014
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