MTHFR、MTRR和MTR基因多态性与唐氏综合征发生的相关性研究

应用PCR-RFLP方法分析31例唐氏综合征（Down＇s syndrome, DS）患儿母亲和68例正常生育女性叶酸代谢相关基因：MTHFR 677C〉T、MTRR 66A〉G和MTR 2756A〉G多态性,探讨其与唐氏综合征DS发生的关系。采用Pearson χ^2 检验基因和基因型频率分布,并分析各基因之间的相互作用,计算比值比评价相对危险度。MTHFR基因T等位基因频率在病例组和对照组中具有显著性差异（P〈0.05）,而MTRR和MTR基因G等位基因频率在病例组和对照组中的差异无显著性。MTHFR TT基因型母亲生育DS风险显著增加（OR=3.51,95 %CI=1.04-11.85,P〈0.05）。MTRR GG基因型生育DS的风险增加3.57倍（OR=3.57,95 %CI=1.19-10.73,P〈0.05）。MTR突变基因型AG和GG与生育DS的风险无显著关系。MTHFR （CT＋TT）/MTRR GG、MTHFR （CT＋TT）/MTR AA和MTRR GG/MTR AA联合基因型与DS发生风险显著相关。结果表明,MTHFR 677C〉T、MTRR 66A〉G位点变异是生育DS的独立风险因子,尚不能认为MTR 2756A〉G多态与DS发生相关。基因与基因多态位点之间存在交互和修饰效应。     

Association between MTR A2756G and MTRR A66G polymorphisms and maternal risk for neural tube defects: A meta-analysis

Background

Methionine synthase (MTR) and methionine synthase reductase (MTRR) genes have been considered to be implicated in the development of neural tube defects (NTDs). However, the results are inconsistent. Accordingly, we conducted a meta-analysis to further investigate such an association.

Methods

Published literature from PubMed and Embase databases was retrieved. All studies evaluating the association between MTR A2756G or MTRR A66G polymorphism and maternal risk for NTDs were included. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using the fixed- or random-effects model.

Results

A total of 11 studies (1005 cases and 2098 controls) on MTR A2756G polymorphism and 10 studies (1211 cases and 2003 controls) on MTRR A66G polymorphism were included. Overall, this meta-analysis revealed no significant association between maternal MTR A2756G polymorphism and NTD susceptibility in either genetic model. A significant association between MTRR A66G polymorphism and maternal risk for NTDs was observed for GG vs. AA (OR = 1.31, 95% CI 1.03–1.67) among Caucasians.

Conclusion

The present meta-analysis indicated that MTRR A66G polymorphism, but not MTR A2756G, is significantly associated with maternal risk for NTDs in Caucasians.     

年轻母亲叶酸代谢基因多态性与唐氏综合征发生的关系

为探讨年轻母亲叶酸代谢相关基因MTHFR 677C>T、MTRR 66A>G、RFC-1 80G>A和MTR 2756A>G多态性与唐氏综合征(Down syndrome, DS)发生的关系, 采用随机病例-对照研究设计, 应用PCR-RFLP方法检测60例DS患儿的母亲与68例正常生育女性的基因型。经χ² 检验, MTHFR基因T等位基因频率在病例组和对照组中差异有统计学意义(P<0.05), 而MTRR、MTR和 RFC-1等位基因频率差异无统计学意义。Logistic回归分析显示: 携带MTHFR TT基因型的母亲孕育DS患儿的风险显著增加(OR=3.51, 95% CI=1.30~9.46, P<0.05), 而杂合子CT以及CT合并TT基因型与DS发生风险无显著关联; 携带MTRR GG基因型的母亲孕育DS患儿的风险增加3.16倍(OR=3.16, 95% CI=1.20~8.35, P<0.05), 而RFC-1和MTR突变基因型与DS发生风险无显著关联; MTHFR(CT+TT)/MTRR GG、MTHFR (CT+TT)/ RFC-1 AA、MTHFR CC / MTR (AG +GG)、 MTHFR (CT+TT)/MTR AA、MTRR GG/MTR AA和RFC-1 AA / MTR AA联合基因型与DS发生风险显著相关。结果表明, 年轻女性MTHFR 677C>T、MTRR 66A>G位点变异是孕育DS患儿的独立风险因子, 尚不能认为RFC-1 80G>A、MTR 2756A>G多态性与DS发生相关, 而基因与基因多态位点之间存在交互和修饰效应。     

Allelic polymorphism of MTHFR, MTR and MTRR genes in patients with cleft lip and/or palate and their mothers

The frequency of common MTHFR, MTR and MTRR genes polymorphisms was evaluated among patients with non-syndromic cleft lip and/or palate (CL/P), their mothers and healthy persons from West-Ukrainian region. MTHFR 677TT genotype was shown to increase more than three-fold risk of CL/P and for mothers the risk of having CL/P children may increase two-fold compared with homozygous carriers of MTHFR 677CC genotype (OR = 3.3, OR = 1.92, respectively). The heterozygous MTR 2756AG genotype was associated with 1.5-fold increased risk of CL/P compared with the AA genotype (OR = 1.48). The heterozygous genotype MTRR 66AG was associated with the 5.56-fold increased CL/P risk (OR = 5.56) and for mothers with 2.6-fold increased risk of delivering a CL/P offspring (OR = 2.6). The results showed that MTRR 66G allele is more prevalent than MTRR 66A (wild type) and the MTRR 66GG genotype frequency was significantly lower among CL/P patients and their mothers than in control group among Western Ukrainian inhabitants.     

Three genetic polymorphisms of homocysteine-metabolizing enzymes and risk of coronary heart disease: a meta-analysis based on 23 case-control studies

Many epidemiological studies have explored the relationships between three genetic polymorphisms of genes encoding homocysteine-metabolizing enzymes (methionine synthase [MTR] A2756G, methionine synthase reductase [MTRR] A66G, and N(5),N(10)-methylenetetrahydrofolate reductase [MTHFR] A1298C) and risk of coronary heart disease (CHD), but no conclusive results were obtained. Therefore, we performed a meta-analysis of 23 case-control studies. Odds ratio (OR) and 95% confidence interval (95% CI) were used to examine the strength of the associations. Among those primary studies, 22 studies were for Europeans, and one study focused on the MTR A2756G polymorphism in Asians. The results of combined analyses of the MTR A2756G polymorphism suggested that the G allele was associated with increased risk of CHD and myocardial infarction (MI) especially for Europeans (GG vs. AA for CHD: OR [95% CI]=1.63 [1.18-2.25], p(z)(-test)=0.001, p(heterogeneity)=0.274; GG+AG vs. AA for MI: OR [95% CI]=1.44 [1.08-1.93], p(z)(-test)=0.014, p(heterogeneity)=0.611). In addition, the G allele was also associated with higher risk CHD based on population-based case-control studies (PCC) (GG vs. AA: OR [95% CI]=1.75 [1.24-2.49], p(z)(-test)=0.002, p(heterogeneity)=0.316). The results suggested that the MTRR A66G polymorphism was not associated with risk of CHD for Europeans (AA vs. GG: OR [95% CI]=1.07 [0.59-1.94], p(z)(-test)=0.831, p(heterogeneity)<0.01). The results suggested that the C allele of the MTHFR A1298C polymorphism might be associated with the increased risk of MI for Europeans (CC vs. CA+AA: OR [95% CI]=1.37 [1.03-1.84], p(z)(-test)=0.033, p(heterogeneity)=0.668). However, when subgroup analyses for sources of controls were performed, conflicting results were obtained. The results suggested that the C allele was associated with decreased risk of CHD based on hospital-based case-control studies, but associated with increased risk of CHD based on PCC. This meta-analysis suggests that MTR A2756G polymorphism, but not MTRR A66G and MTHFR A1298C, is associated with risk of CHD for Europeans. Because of limitations and potential bias, more well-designed studies with larger sample size, especially focused on Asians and Africans, should be performed in the future.     

MTHFR C677T and A1298C polymorphisms and cervical carcinoma susceptibility: meta-analyses based on 4421 individuals

MTHFR polymorphisms have been implicated as risk factors for several cancers. Studies have conducted on the associations of MTHFR polymorphisms with cervical carcinoma risk and have generated inconclusive results. The aim of the present study was to increase power demonstrating the possible relations. Meta-analyses examining the association between MTHFR C677T and A1298C polymorphisms and cervical carcinoma risk were performed. Separate analyses on ethnicity and source of controls were also implemented. Eligible studies were identified for the period up to Dec 2011. Eleven case-control studies containing 1859 cases and 2562 controls regarding MTHFR C677T polymorphisms were selected, of which four studies containing 461 cases and 832 controls described A1298C polymorphisms. For the overall data, no associations of MTHFR C677T polymorphisms with cervical carcinoma were observed (TT vs CC: OR = 1.07; 95 %CI = 0.73-1.58; dominant model: OR = 0.89; 95 %CI = 0.66-1.18; recessive model: OR = 1.13; 95 %CI = 0.84-1.52). In the subgroup analysis by ethnicity, MTHFR 677T allele was associated with decreased cervical cancer susceptibility among Caucasians (TT vs CC: OR = 0.65; 95 %CI = 0.45-0.93; dominant model: OR = 0.70; 95 %CI = 0.58-0.86) but not Asians. As for A1298C polymorphism, no marked associations of A1298C genetic variation with cervical cancer risk were observed (CC vs AA: OR = 1.01; 95 %CI = 0.60-1.73; dominant model: OR = 1.17; 95 %CI = 0.91-1.49; recessive model: OR = 0.99; 95 %CI = 0.60-1.63). Collectively, the results of the present study suggest that MTHFR 677T allele might play a preventive role for cervical carcinoma among Caucasians. A1298C polymorphisms might exert little effect on cervical cancerigenesis.     

Association of MTHFR, MTR, MTRR, RFC1, and DHFR gene polymorphisms with susceptibility to sporadic colon cancer

Altered folate levels may play an important role in colon carcinogenesis. The aim of this study was to investigate the association of polymorphisms in key folate-metabolizing genes with susceptibility to sporadic colon cancer. Six common polymorphisms (two in MTHFR and one each in MTR, MTRR, RFC1, and DHFR genes) were genotyped in 300 healthy subjects and 300 colon cancer patients from Croatia. Obtained results indicate possible protective role of MTRR 66 AA in sporadic colon cancer (OR=0.655; 95% CI=0.441-0.973; p=0.04). Maximum-likelihood analysis of haplotypes revealed a linkage disequilibrium (LD) between the two investigated polymorphisms of the MTHFR gene (C677T and A1298C), both in the control and patient groups (p<0.01 for both). LD was also detected between MTRR A66G and MTHFR A1298C polymorphisms but only in a group of patients (p<0.01). A haplotype of A66G and A1298C polymorphisms, A/A, proved to be protective (OR=0.775; 95% CI=0.603-0.996; p=0.04), whereas haplotype A/G was a risk factor for colon cancer (OR=1.270; 95% CI=1.007-1.602; p=0.04). Contrary to some previous studies, single-locus analyses identified no polymorphisms associated with risk for colon cancer, but demonstrated a possible protective effect of MTRR 66 AA genotype. The detected significant LD between two loci (MTHFR A1298C and MTRR A66G) located on different chromosomes indicates a strong selective force as a mechanism for the maintenance of their linkage. Specific combinations of alleles of these two polymorphisms showed a protective but also a risk effect on colon cancer susceptibility.     

Methylenetetrahydrofolate reductase C677T and methionine synthase A2756G polymorphisms influence on leukocyte genomic DNA methylation level

Methionine synthase (MTR) and methylenetetrahydrofolate reductase (MTHFR) enzymes are involved in the metabolism of methyl groups, and thus have an important role in the maintenance of proper DNA methylation level. In our study we aimed to evaluate the effect of the polymorphism A2756G (rs1805087) in the MTR gene on the level of human leukocyte genomic DNA methylation. Since the well-studied polymorphism C677T (rs1801133) in the MTHFR gene has already been shown to affect DNA methylation, we aimed to analyze the effect of MTR A2756G independently of the MTHFR C677T polymorphism. For this purpose, we collected the groups of 80 subjects with the MTR 2756AA genotype and 80 subjects with the MTR 2756GG genotype, having equal numbers of individuals with the MTHFR 677CC and the MTHFR 677TT genotypes, and determined the level of DNA methylation in each group. Individuals homozygous for the mutant MTR 2756G allele showed higher DNA methylation level than those harboring the MTR 2756AA genotype (5.061 ± 1.761% vs. 4.501 ± 1.621%, P = 0.0391). Individuals with wild-type MTHFR 677СC genotype displayed higher DNA methylation level than the subjects with mutant MTHFR 677TT genotype (5.103 ± 1.767% vs. 4.323 ± 1.525%, P = 0.0034). Our data provide evidence that the MTR A2756G polymorphism increases the level of DNA methylation and confirm the previous reports that the MTHFR C677T polymorphism is associated with DNA hypomethylation.     

Methylenetetrahydrofolate reductase gene polymorphisms in patients with nonalcoholic steatohepatitis (NASH)

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of abnormal hepatic steatosis in the absence of a history of alcohol use. Nonalcoholic steatohepatitis (NASH) is the progressive form of NAFLD. Hyperhomocysteinemia causes steatosis, and the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms result in hyperhomocysteinemia. To examine whether the C677T and A1298C polymorphisms of the MTHFR gene were associated with NASH, we analysed the allele and genotype distribution of the MTHFR C677T and A1298C polymorphisms in 57 well-diagnosed NASH patients, 324 healthy controls in a case-control study of Turkish subjects of Caucasian origin. The diagnosis of the NASH patients was based on liver biopsy. The method used in the analysis of genotypes was PCR-RFLP. The MTHFR A1298C polymorphism was significantly associated with NASH (chi(2) = 8.439; p = 0.015) in the total NASH patients compared with healthy controls. The MTHFR 1298C allele (odds ratio (OR) = 2.480; 95%CI = 1.286-4.782; chi(2) = 7.703; df = 1; p = 0.006) was significantly associated with NASH in the total NASH patients. The MTHFR C677C/A1298C compound genotype (OR = 2.218; 95%CI = 1.003-4.906; chi(2) = 3.998; df = 1; p = 0.046) in men patients was also significantly associated with NASH. Likewise the MTHFR C1298C genotype was significantly associated with NASH in women patients with NASH (OR = 2.979; 95%CI = 1.027-8.641; chi(2) = 4.343; df = 1; p = 0.037). In conclusion, the MTHFR 1298C allele in all NASH patients, C1298C genotype, C677C/C1298C compound genotype in women NASH patients and C677C/A1298C compound genotype in men NASH patients were genetic risk factors for NASH.     

Methylenetetrahydrofolate reductase genotypes and haplotypes associated with susceptibility to colorectal cancer in an eastern Chinese Han population

Methylenetetrahydrofolate reductase (MTHFR) plays an important role in folate metabolism and is involved in DNA synthesis, DNA repair and DNA methylation. The two common functional polymorphisms of MTHFR, C677T and A1298C have been associated with several diseases, including cancer. We made a case-control study to analyze a possible association of MTHFR gene polymorphisms C677T and A1298C with risk for colorectal cancer in an eastern Chinese Han population of 137 patients with a confirmed histopathological diagnosis of CRC and 145 age- and gender-matched controls with no history of cancer. DNA was isolated from peripheral blood samples and the genotypes were determined by PCR-RFLP. The concentrations of folate in plasma were measured by chemiluminescence immunoassay. The MTHFR 677TT genotype had a protective effect against colorectal cancer, with an odds ratio (OR) = 0.467 (95% confidence interval (CI) = 0.225-0.966). The 1298CC genotype was significantly correlated with a reduced risk of colorectal cancer (OR = 0.192; 95%CI = 0.040-0.916). 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). MTHFR 677TT+CT genotypes had a significantly lower plasma folate concentration than those with the MTHFR 677CC genotype. MTHFR 1298AC+CC genotypes had a lower plasma folate concentration than those with the MTHFR 1298AA genotype (P < 0.05). In conclusion, subjects with the MTHFR 677TT and MTHFR 1298CC genotypes appeared to have a significantly lower risk for colorectal cancer. MTHFR haplotypes 677CC/1298CC and 677TT/1298AC were less common in cases than in controls. These haplotypes, when compared to the most common haplotype 677CC/1298AA, were associated with a decreased risk for colorectal cancer. We conclude that plasma folate level is influenced by MTHFR genotypes.     

Analysis of methionine synthase reductase polymorphism (A66G) in Indian Muslim population

BACKGROUND AND OBJECTIVES:

Methionine synthase reductase (MTRR) is a vital enzyme of homocysteine/methionine metabolic pathway and is required for the conversion of inactive form of methionine synthase (MTR) to its active form. A clinically important allelic variant of MTRR A66G, with less enzymatic activity is reported with worldwide prevalence rate of ~ 30%. The present study was designed to determine the frequency of MTRR A66G polymorphism in rural Sunni Muslim population of Eastern Uttar Pradesh.

MATERIALS AND METHODS:

Total 56 subjects were analyzed for MTRR A66G polymorphism. A66G mutation analysis was carried out according to the polymerase chain reaction-restriction fragment length polymorphism method of Wilson et al. [1] amplification with MTRR specific primers followed by amplicon digestion with NdeI enzyme was used for the identification of different MTRR genotypes in subjects.

RESULTS AND DISCUSSION:

The AA genotype was found in 5 subjects, AG in 23 subjects, and GG genotype in 28 subjects. Genotype frequencies of AA, AG, and GG were 0.089, 0.41, and 0.5 respectively. The allele frequency of A allele was found to be 0.298 and G allele was 0.705.

CONCLUSION:

It is evident from the present study that the percentage of homozygous genotype GG and frequency of G allele is high in the target Muslim population.     

A polymorphism of the methionine synthase reductase gene increases chromosomal damage in peripheral lymphocytes in smokers

The cytogenetic effects of cigarette smoke has been evaluated as one of many potential confounders in a large number of biomonitoring studies of occupationally or environmentally exposed populations and control subjects. Despite the well-known presence of carcinogens in the cigarette smoke, the results in the scientific literature linking smoking habits to micronuclei (MN) frequency, one of the cytogenetic markers, are rather controversial. Here, we investigated the relationships among MN frequency, smoking habits and five folate metabolic enzyme gene polymorphisms (MTHFR C677T and A1298C, MTR A2756G, MTRR A66G and TYMS 3'UTR) in 132 healthy Japanese men who were non-habitual drinkers. In never- and former-smokers, no statistically significant differences in the mean MN frequencies were observed according to the five folate metabolic enzyme gene polymorphisms. In current-smokers, however, subjects with the AA genotype for MTRR had a significantly higher mean MN frequency than the AG genotypes for MTRR (p<0.05). Furthermore, among subjects with the AA genotype for MTRR, current-smokers were found to have a significantly higher mean MN frequency than never- and former-smokers (p<0.05). To further characterize this association, we stratified the smoking status into five groups: non-smokers (never-smokers and former-smokers), 1-10 cigarettes/day, 11-20 cigarettes/day, 21-30 cigarettes/day and >or=31 cigarettes/day. There was an overall trend for the mean MN frequency in subjects with the MTRR AA genotype to increase as the number of cigarettes smoked per day increased (p<0.01, Jonckheere-Terpstra test). The results of our preliminary study suggest that the MTRR AA genotype acts to increase the MN frequency resulting from cigarette smoking. Therefore, studies on human genotoxicity based on cytogenetic markers of MN should take into account both the MTRR polymorphism and the potential confounding effect of smoking, although these preliminary findings need to be validated in larger populations because of the relatively small sample size.     

MTHFR 677 CT/MTHFR 1298 CC genotypes are associated with increased risk of hypertension in Indians

The goals of our present study were to measure plasma homocysteine levels and determine their association with methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms (C677T and A1298C) in essential hypertensive subjects. Plasma total homocysteine and folic acid levels were measured in essential hypertensive patients (n = 153) before and after oral supplementation with either 5 mg folic acid tablet/day or 5 mg placebo/day for 4 weeks and compared with age and sex matched normotensive controls (n = 133). MTHFR gene polymorphisms (C677T and A1298C) were studied by restriction fragment length polymorphism and correlated with plasma homocysteine levels. Homocysteine levels were significantly higher in hypertensive patients as compared to controls and showed a negative correlation with plasma folate levels. Folic acid supplementation (5 mg/day) for 4 weeks resulted in a significant decrease in plasma homocysteine concentrations in these patients. Patients carrying MTHFR 677T allele (OR = 1.90; 95%CI: 1.14–3.19) or MTHFR 1298C (OR = 2.6, 95%CI: 1.55–4.40) allele were at increased risk of hypertension. The frequency of co-occurrence of MTHFR 677 CT/1298 CC genotypes was significantly higher in the patients compared to controls (P < 0.05) and was associated with increased risk of hypertension (OR = 3.54, 95%CI: 0.37–4.30). Subjects with MTHFR 1298 CC genotype had significantly higher homocysteine levels compared to those with MTHFR 1298 AA genotype (P < 0.05). Our results indicate that MTHFR 677T and 1298C alleles and co-occurrence of MTHFR 677 CT/MTHFR 1298 CC genotypes are associated with increased risk of hypertension and MTHFR 1298 CC genotype is associated with higher homocysteine levels in our subjects.     

Allelic polymorphisms in the <Emphasis Type="Italic">MTHFR</Emphasis>, <Emphasis Type="Italic">MTR</Emphasis> and <Emphasis Type="Italic">MTRR</Emphasis> genes in patients with cleft lip and/or palate and their mothers

The distribution of polymorphic variants in the MTHFR, MTR and MTRR genes in the contingents of patients with nonsyndromic cleft lip and/or palate (NSCL/P), their mothers, and healthy individuals from Ukraine’s western region was evaluated. It was shown that the presence of the homozygous MTHFR 677TT genotype might lead to a threefold increase in the risk of CL/P; mothers carrying the MTHFR 677TT genotype had a twofold increase in the risk of giving birth to a child with CL/P compared to homozygous carriers of MTHFR 677CC (OR = 3.3 and OR = 1.92, respectively). The presence of the heterozygous genotype MTR 2756AG can lead to a 1.5-fold increase in the risk of CL/P compared to the 2765AA genotype (OR = 1.48). The heterozygous genotype MTRR 66AG is associated with a 5-fold risk of CL/P (OR = 5.56); mothers carrying this genotype had a 2.6-fold increase in the risk of giving birth to a child with CL/P (OR = 2.6). The prevalence of the MTRR 66G allelic variant among inhabitants of Ukraine’s western region was higher compared to the MTRR 66A allelic variant (wild type); and the MTRR 66GG genotype frequency among CL/P patients was significantly lower compared to the control group.     

Methionine synthase A2756G polymorphism and breast cancer risk: An up-to-date meta-analysis

The methionine synthase (MTR) gene polymorphism A2756G has been linked to the risk of developing breast cancer, but the available results were inconsistent and underpowered. To derive a more precise estimation of the association between A2756G and breast cancer risk, an updated meta-analysis of 16 available studies with 9866 cases and 11,702 controls estimating the association between MTR A2756G and breast cancer risk was conducted. The quality of these studies was generally good except 2 studies with a lowest score 4 according to the Newcastle–Ottawa Scale (NOS). The results suggested that there is no significant association between A2756G and breast cancer risk in overall results. In the stratified analysis by ethnicity, source of controls (population or hospital-based), Hardy–Weinberg equilibrium (HWE) in controls, sample size (≥ 1000 and < 1000 subjects), and menopausal status, the 2756G allele was associated with a decreased risk in Caucasians, PB (population-based) subgroup, and large studies. But the associations disappeared after removing the studies not in HWE. On the contrary, an increased risk was found in small studies. In conclusion, the findings suggest that MTR A2756G polymorphism is not associated with altered susceptibility to breast cancer, while the observed decreased risk in Caucasians, PB subgroup, and large studies and increased risk in small studies may be due to selection bias or other unknown factors.     

MTHFR and MTRR genotype and haplotype analysis and colorectal cancer susceptibility in a case-control study from the Czech Republic

Polymorphic variants in genes involved in one-carbon metabolism, in particular of dietary folate, may modulate the risk for colorectal cancer through aberrant DNA-methylation and altered nucleotide synthesis and repair. In the present study, we have assessed the association of six polymorphisms and relative haplotypes in the MTHFR gene (rs1801133 and rs1801131) and in the MTRR gene (rs1801394, rs1532268, rs162036, and rs10380) with the risk for colorectal cancer in 666 patients and 1377 controls from the Czech Republic. We found that the 677 C>T polymorphism in the MTHFR gene significantly decreased the risk for colorectal cancer in homozygous carriers of the variant allele (OR, 0.58; 95% CI, 0.39-0.87). Also, we noted a significantly different distribution of genotypes between cases and controls for the 66A>G polymorphism in the MTRR gene. In particular, homozygous carriers of the G-containing allele of this polymorphism were at an increased risk for colorectal cancer (OR, 1.39; 95% CI, 1.04-1.85). Haplotype analysis of the two MTHFR polymorphisms showed a moderate difference in the distribution of the TA haplotype between cases and controls. In comparison to the most common haplotype (CA), the TA haplotype was associated with a decreased risk for colorectal cancer (OR, 0.84; 95% CI, 0.71-0.99). No difference in the distribution between cases and controls was observed for the haplotypes based on the four polymorphisms in the MTRR gene. The present study suggests that the 677TT genotype and the TA haplotype in the MTHFR gene may also have a role in colorectal cancer risk in the Czech population, indicating the importance of genes involved in folate metabolism with respect to cancer risk. For MTRR, additional studies on larger populations are needed to clarify the possible role of variation in this gene in colorectal carcinogenesis.     

Thrombophilic gene polymorphism studies in G6PD deficient individuals from Saudi population

We performed a study to evaluate the role of three single nucleotide polymorphisms (SNPs), factor V Leiden G1691A (FVL), prothrombin gene mutation G20210A (PRT or FII-G20210A) and methylenotetrahydrofolate reductase variant C677T (MTHFRC677T), as risk factors for G6PD in Saudi populations. Our results did not show any association with the three Thrombophilic genes with FVL gene, no statistical analysis have shown any association with either allele or genotype frequencies OR=0.566, p=.0.667, (95% CI=0.014-22.48) and OR=0.569, p=0.251¸ (95% CI=0.014-22.96).In PRT gene G20210A for G Vs A, p=0.774; OR=0.566 (95%CI; 0.011-29.6); AA+GA Vs GG; p=0.502; OR=0.569 (95%CI=0.010-2969). G and A allele frequencies were similar between cases and controls with no statistical significance. In the MTHFR gene none of the genotypes or allele frequency cannot show any association OR=1.281, p=.0.667, (95% CI=0.414-3.958) and OR=1.1.172, p=0.800¸ (95% CI=0.343-4.008). Similarly, the difference of T allele frequencies between patients and controls was not found any association. In conclusion, our finding indicates that the prevalence of G1691A, G20210A and C677T mutations in G6PD deficient individuals is not statistically different compared to normal subjects and G6PD is not associated with these thrombophilic mutations in Saudi population.     

Polymorphisms of 5,10-methylenetetralydrofolate reductase (MTHFR), fruit and vegetable intake, and the risk of stomach cancer

Stomach cancer is a serious public health problem in China. 5,10-Methylenetetralydrofolate reductase (MTHFR) may be involved in both DNA methylation and DNA synthesis. Folate deficiency is associated with cancer risk that may be modulated by a genetic variation in the MTHFR gene in folate metabolism. The main goal of this study was to evaluate the association between polymorphisms of the MTHFR gene and the risk of stomach cancer. This study also explored the modification effects of fruit and vegetable intake (one of the main constituents is folate) on the risk of this disease. A population-based case-control study was conducted in Taixing, China, consisting of 206 newly diagnosed cases with primary stomach cancer and 415 healthy population controls. Polymorphisms of MTHFR C677T and A1298C were assayed by polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) techniques. The data were analysed using the logistic regression model. No obvious association between the MTHFR A1298C polymorphism and the risk of stomach cancer was observed in this study. The frequencies of 677 C/C, C/T, and T/T were 34.5, 50.9, and 14.6%, respectively, in controls. The frequency of the MTHFR 677 wild homozygotic genotype was 25.8% in cases, which was lower than that in controls (34.5%). The adjusted odds ratio (OR) for the MTHFR 677 any T genotype was 2.05 (95% confidence interval (CI), 1.26-3.34) when compared with the C/C genotype. In the low fruit and vegetable intake group an increasing trend was observed with the T allele exposure, p=0.0056. The adjusted ORs were 1.68 (95% CI = 0.86-3.29) for the C/T genotype and 3.58 (95% CI = 1.46-8.75) for the T/T genotype, respectively. The MTHFR 677 any T genotype was associated with an increased risk of primary stomach cancer among the Chinese population. Folate deficiency might modify the MTHFR gene polymorphism and influence the risk of stomach cancer.     

Mutation incidence in folate metabolism genes and regulatory genes in Polish families with neural tube defects

Neural tube defects (NTDs) are a common cause of disability or death of new-borns, but the aetiology and genetic background of this disease are still poorly understood. Therefore, it was decided to determine the conditions for the identification of several polymorphisms and to perform a preliminary study on Polish NTD patients and their parents. According to the results of this study, the genetic predisposition to NTD can be correlated with the 677TT genotype in the MTHFR gene, 677CT/1298AC haplotype (the MTHFR gene), 2756G allele in the MTR gene, 66AG variant and minisatellite sequence with 5 or 10 repeats in intron 6 of the MTRR gene. The 530GG and TIVS7-2/TIVS7-2 genotypes in the T gene could also be considered as a risk factor for NTD. The analysis also revealed no correlation between neurulation disturbances and A4956G and A1186G mutations in the BRCA1 gene and the 844ins68bp in CBS gene. Although a correlation was found of some molecular markers with NTD, an additional examination should be conducted on more numerous groups to obtain statistically significant results.     

Interleukin-10 gene polymorphisms and chronic/aggressive periodontitis susceptibility: A meta-analysis based on 14 case-control studies

Interleukin-10 (IL-10) has been described as an anti-inflammatory cytokine and IL-10 gene polymorphisms was associated with altered interleukin-10 levels, therefore, we aimed to conduct a meta-analysis assessing the association of IL-10 genetic polymorphisms with the risk of both chronic periodontitis (CP) and aggressive periodontitis (AgP). Electronic databases were acquired from PubMed, Embase, the Sinomed and WANFANG. Fourteen studies with 1438 patients and 1303 control subjects investigated the association of the three single-nucleotide polymorphisms (SNPs) of IL-10 (-1082A>G, -819C>T, -592C>A) and chronic/aggressive periodontitis risk were brought into this study. We found that there was no association between IL-10 -1082 gene polymorphism and periodontitis risk (either CP or AgP), even when we separately investigated sub-group analysis among Caucasians. The -819 polymorphism seemed to be a genetic risk factor to CP among Caucasians (T allele vs. C allele: OR=1.55, 95%CI=1.07-2.24; CT vs. CC: OR=1.64, 95%CI=1.00-2.67). When excluding one study deviated from HWE, the results showed that the T allele carriers had a significantly risk of CP in overall population (T allele vs. C allele: OR=1.23, 95%CI=1.03-1.48). Furthermore, the results of this meta-analysis showed that -592 polymorphism was associated with a significantly increased risk of CP (A allele vs. C allele: OR=1.38, 95%CI=1.04-1.85; AA vs. CA+CC: OR=1.39, 95%CI=1.05-1.85 for overall analysis; A allele vs. C allele: OR=1.97, 95%CI=1.36-3.86; AA vs. CC: OR=3.70, 95%CI=1.32-10.39; CA vs. CC: OR=2.22, 95%CI=1.36-3.64, AA+CA vs. CC: OR=2.35, 95%CI=1.46-3.79 for Caucasian descent analysis). This meta-analysis suggested that IL-10 -819 and -592 gene polymorphisms were associated with CP, especially among Caucasians. Further research is needed to assess possible gene-gene or gene-environment-lifestyle interactions on periodontal disease..