A common mutation in the methylenetetrahydrofolate reductase gene is a determinant of hyperhomocysteinemia in epileptic patients receiving anticonvulsants.

Hyperhomocysteinemia is a condition caused by both genetic and nongenetic factors. To determine whether a common methylenetetrahydrofolate reductase (MTHFR) variant is related to elevated homocysteine concentrations in epileptic patients receiving anticonvulsants, we investigated the plasma total homocysteine (tHcy) level, folate level, and MTHFR 677 C --> T mutation using a polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis with HinfI digestion in 103 patients with epilepsy and 103 normal controls. The prevalence of hyperhomocysteinemia (> or = 11.4 micromol/L, 90th percentile of control group) was higher in patients than in controls (25% v 10.0%, P = .007). The homozygosity for the 677 C --> T mutation of MTHFR was associated with elevated tHcy and low folate levels. The magnitude of hyperhomocysteinemia in MTHFR TT homozygotes was more pronounced in epileptic patients than in controls (18.2 +/- 1.6 v 9.1 +/- 1.2 micromol/L, P = .04). In epileptic patients, hyperhomocysteinemia was more frequent in MTHFR TT genotypes versus CT or CC genotypes (58% v 17% and 16%, P < .001). Multiple logistic regression analysis showed that MTHFR TT genotype was an independent predictor of hyperhomocysteinemia in epileptic patients receiving anticonvulsants (phenytoin and carbamazepine but not valproic acid), suggesting that gene-drug interactions induce hyperhomocysteinemia. These findings indicate that epileptic patients receiving anticonvulsants may have a higher folate requirement to maintain a normal tHcy level, especially homozygotes for MTHFR 677 C --> T mutation.     

Factor V G1691A,Prothrombin G20210A,and Methylenetetrahydrofolate Reductase [MTHFR] C677T Gene Polymorphism in Angiographically Documented Coronary Artery Disease

BACKGROUND: Single point mutations in the genes coding for factor V [G1691A; Leiden], prothrombin [PRT; G20210A], and methylenetetrahydrofolate reductase [MTHFR, C677T] were shown to be major inherited predisposing factors for venous thromboembolism. However, their contribution in the development of coronary artery disease [CAD] remains controversial. The aim of the study was to examine the association of these mutations in CAD. METHODS: A total of 96 patients with angiographically-demonstrated CAD [mean age 55.3 +/- 11.3], and 404 healthy subjects [mean age 50.7 +/- 8.9] were recruited into the study. Fasting plasma homocysteine was determined by HPLC, and genotype analysis was assessed by PCR-RFLP. RESULTS: The carrier frequency of factor V-Leiden (14.6% vs. 15.1%, p = 0.617) and PRT G20210A (3.1% vs. 3.0%; p = 0.936) were similar between patients and controls, respectively. In contrast, the frequency of the MTHFR variant C677T was 71.9% among patients compared with 45.5% in controls (p < 0.001), of which the T/T genotype was significantly higher among patients (31.3%) than controls (4.5%; p < 0.001). Significantly higher homocysteine levels were seen among T/T genotype in both groups compared to non-T/T carriers (p < 0.05), and among patients compared with controls (18.47 +/- 3.73 micromol/L vs. 16.28 +/- 4.16 micromol/L). In addition, the coexistence of MTHFR C677T with FV-Leiden was seen in 10.4% of CAD patients compared 6.9% of controls (p = 0.001). CONCLUSION: While results from this study clearly demonstrate a strong association of hyperhomocysteinemia and homozygosity of the MTHFR C677T, but not FV-Leiden or PRT G20210A, mutations with confirmed CAD, they also suggest a potential role for factor V-Leiden in MTHFR C677T carriers.     

Prevalence of methylenetetrahydrofolate reductase C677T and its association with arterial and venous thrombosis in the Chinese population

Moderate hyperhomocysteinaemia (MHH) is associated with arterial and venous thrombosis. A main genetic defect related to MHH is a C to T substitution at nucleotide 677 of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. A prothrombin 20210A mutation was recently identified as a risk factor for arterial and venous thrombosis. However, studies on the prevalence of mutant MTHFR C677T and prothrombin G20210A and their association with thrombosis were controversial and seldom reported in the Chinese population. We investigated the prevalence of MTHFR C677T and prothrombin G20210A genotypes by polymerase chain reaction (PCR) followed by restriction enzyme digestion in 420 Chinese subjects: 53 with deep venous thrombosis (DVT); 145 with cerebrovascular disease [115 cerebral infarction, 30 cerebral haemorrhage (CH)]; 100 with coronary artery disease (CAD); and 122 control subjects. The prevalence of the mutated MTHFR 677TT genotype and the 677T allele in normal controls was 12.3% and 30.7% respectively, similar to that in Caucasians and Japanese. The mutant 677T homozygotes and alleles were more frequent in patients with DVT than in controls (18.9% vs. 12.3%, 0.01 < P < 0. 025; 48.1% vs. 30.7%, P < 0.005). The relative risk of DVT among the carriers of 677TT and 677T were significantly increased [odds ratios: 3.4, 95% confidence interval (CI) 1.3-9.5, and 3.6, 95% CI 1. 7-7.7, respectively). The mutant MTHFR heterozygous 677C/T carriers were increased in patients with cerebral infarction compared with controls (53.9% vs. 36.9%, 0.01 < P < 0.025). Relative risk of cerebral infarction was 0.96 (95% CI 0.4-2.3) for 677TT homozygotes and 1.99 (95% CI 1.2-3.4) for 677C/T heterozygotes. However, the distribution of the MTHFR TT genotype was less frequent in patients with CAD with coronary artery stenosis of > 50% than in controls (2. 8% vs. 12.3%, 0.025 < P < 0.05). Relative risk of CAD was not increased among the carriers of 677TT and 677T (odds ratios: 0.2, 95% CI 0-1.1, and 0.97, 95% CI 0.5-1.8, respectively). There were no differences in the distribution of the MTHFR genotypes among CH, CAD with coronary artery stenosis of < 50% and controls. The prothrombin 20210A mutation was not found in any patients or controls. These results demonstrated that MTHFR 677T was associated with DVT and cerebral infarction but was less associated with CAD in the Chinese population.     

Genetic risk factors in young adults with 'cryptogenic' ischemic cerebrovascular disease.

Mutations such as factor V Leiden G1691A (FVL), prothrombin G20210A (FIIM), methylenetetrahydrofolate reductase (MTHFR) C677T, cystathionine beta-synthase (CBS) 844ins68 and endothelial cell protein C receptor (EPCR) 4031ins23 are risk factors for thromboembolism. To assess the role of these mutations in young adults with cerebral ischemia of otherwise undetermined etiology, 93 patients younger than 50 years old with thromboembolic strokes or transient ischemic attacks were studied. One hundred and eighty-six healthy age-matched and sex-matched blood donors served as controls. The FVL mutation was detected in 15/93 patients and 13/186 controls. After adjustment for smoking, arterial hypertension, and hyperlipidemia, the association of the FVL mutation with cerebral ischemia [odds ratio (OR), 3.19; 95% confidence interval (CI), 1.38-7.39] remained significant. One of 93 patients and 6/186 controls were carriers of FIIM (OR, 0.33; 95% CI, 0.04-2.75). We detected the MTHFR TT677 genotype in 9/93 patients and 26/186 controls (OR, 0.66; 95% CI, 0.30-1.47), a CBS 844ins68 mutation in 12/93 patients and 19/186 controls (OR, 1.30; 95% CI, 0.60-2.81), and an EPCR 4031ins23 mutation in 1/93 patients and in no control individual (P = 0.33). In conclusion, in younger adults the FVL mutation is a risk factor for cerebrovascular disease. FIIM, the MTHFR TT677 genotype and the CBS 844ins68 mutation did not contribute to the risk in this group of patients. The EPCR 4031ins23 mutation is very rare, its possible role needs further investigation.     

Hyperhomocysteinemia increases the risk of venous thrombosis independent of the C677T mutation of the methylenetetrahydrofolate reductase gene in selected Brazilian patients.

Fasting total homocysteine (tHcy) and the methylenetetrahydrofolate reductase (MTHFR) C677T mutation were evaluated in 91 patients with venous thromboembolism and without acquired thrombophilia, and in 91 age-matched and sex-matched controls. Hyperhomocysteinemia was detected in 11 patients (12.1%) and in two controls (2.2%), yielding an odds ratio (OR) for venous thrombosis of 6.1 [95% confidence interval (CI), 1.3-28.4]. After excluding 21 patients and four controls with other known genetic risk factors for venous thrombosis, the OR was not substantially changed (7.0; 95% CI, 1.5-33.1). The prevalence of the MTHFR 677TT genotype was not significantly different in patients (9.9%) and in controls (5.5%), with an OR for venous thrombosis of 1.8 (95% CI, 0.6-5.8). Subjects with the MTHFR 677TT genotype showed higher levels of tHcy compared with the 677CC genotype in patients (P = 0.010) and in controls (P = 0.030). In conclusion, we found that fasting hyperhomocysteinemia is a risk factor for venous thrombosis in patients without known acquired thrombophilia and other genetic risk factors for venous thrombosis. Although tHcy levels are significantly higher in those homozygous for the MTHFR C677T mutation, this genotype does not increase the thrombotic risk in our study population.     

Associations of plasma homocysteine and the methylenetetrahydrofolate reductase C677T polymorphism with carotid intima media thickness among South Asian, Chinese and European Canadians

BACKGROUND: Few studies have evaluated the associations of plasma homocysteine concentration, the methylenetetrahydrofolate reductase (MTHFR) C677T genotype and B vitamin concentration with intima media thickness (IMT) in multiethnic populations. METHODS: In the Study of Health Assessment and Risk in Ethnic groups (SHARE), we measured carotid IMT, fasting serum folate, serum B12, plasma pyridoxal-5'-phosphate (PLP) and plasma homocysteine and determined the MTHFR C677T genotype in a cross-sectional study of 818 South Asian, Chinese and European Canadians without previous history of CVD, cancer or diabetes during 1996-1998. RESULTS: Plasma homocysteine was inversely related to serum folate, serum B12, plasma PLP, B vitamin supplement use and Chinese ethnicity, and was positively associated with hypertension, smoking, IMT, MTHFR 677T/T genotype and South Asian ethnicity. Although ethnicity was not a statistically significant modifier, among carriers of the MTHFR 677T/T genotype with serum folate < or =14 nmol/L compared to >14 nmol/L, plasma homocysteine was significantly higher among South Asians (50.9% increase, P < 0.001) and Europeans (52.4% increase, P < 0.001) but not Chinese (11.0% increase, P > 0.05). Plasma homocysteine > 11.7 micromol/L was associated with a 5.9% (95% CI: 1.9%, 10.0%) increase in IMT (approximately 0.04 mm) in the pooled-data analyses with similar increases noted in the ethnic-specific analyses. The 677T/T genotype was not associated with a significant change in IMT in the pooled-data analyses (2.7%; 95% CI: -1.7%, 7.2%) nor in ethnic-specific analyses compared to other genotypes, although there were only 63 677T/T homozygotes. CONCLUSION: The combination of lower serum folate and the MTHFR 677T/T genotype is associated with increased plasma homocysteine among South Asians and Europeans, but the association is not evident among Chinese possibly because their serum folate may not have been low enough to compromise MTHFR activity. Plasma homocysteine > 11.7 micromol/L appears to be associated with a clinically important increase in IMT.     

A second mutation in the methylenetetrahydrofolate reductase gene and the risk of venous thrombotic disease

We assessed the effect of a recently described mutation in the MTHFR gene (1298 A --> C) on the risk of deep venous thrombosis (DVT) by determining its prevalence in 190 patients with verified DVT and in age-, race- and gender-matched controls. MTHFR 1298 A --> C was found in 42.1% of patients and in 41.1% of controls. The OR for venous thrombosis was 1.07 (95% CI 0.70-1.65) for heterozygotes and 0.83 (95% CI 0.33-2.08) for homozygotes. The OR for the factor V Leiden (FVL) mutation was 3.40 (95% CI 1.22-9.48), for FII 20210 G --> A was 5.22 (95% CI 1.12-24.2) and for MTHFR 677 C --> T, 1.24 (95% CI 0.82-1.87). No significant increased risk for venous thrombosis was found when MTHFR 1298 A --> C was coinherited with FVL (OR 2.85, 95% CI 0.88-9.23), FII 20210 G --> A (OR 7.19, 95% CI 0.87-59.4) or MTHFR 677 C --> T (OR 1.44, 95% CI 0.71-2.92). These data do not support a critical role of MTHFR 1298 A --> C in the predisposition to DVT.     

风湿性疾病中高同型半胱氨酸血症的临床研究

目的　分析多种风湿性疾病患者血浆中同型半胱氨酸(Hcy)水平及其相关因素。方法脊柱关节病(uSpA)患者和 62例正常对照的Hcy、VitB12、叶酸的水平和亚甲基四氢叶酸还原酶(MTHFR)基因 677位的多态性。结果　(1)各疾病组Hcy水平分别为:SLE组 (19 04±6 86)μmol/L,RA组(19 07±7 43)μmol/L,AS组(16 47±6 50)μmol/L,uSpA组(16 59±6 72)μmol/L,对照组(12 24±3 58)μmol/L,各疾病组Hcy水平明显较对照组高,其差异有统计学意义 (P<0 01 ); ( 2 )Hcy与VitB12、叶酸呈负相关,相关系数分别为-0 701和-0 443,P<0 01; (3)MTHFR基因 677位C→T的突变使Hcy水平升高, CC型 ( 13 41±5 78 )μmol/L,CT型 ( 16 81±4 22 )μmol/L,TT型(20 88±6 60)μmol/L,P<0 01;TT基因型是高Hcy血症的易感基因 (OR=84 46,P<0 05);TT基因型还是SLE的易感基因(OR=7 56,P<0 05)。结论　(1)SLE、RA、AS、uSpA4种疾病患者普遍存在高Hcy血症。(2)导致高Hcy血症的原因可能有叶酸、VitB12的水平降低和MTHFR基因的突变。(3)TT型基因是Hcy异常升高的易感基因,也是SLE的易感基因。     

Methylenetetrahydrofolate reductase homozygosis and low-density lipoproteins in patients with genotype 1 chronic hepatitis C

Methylenetetrahydrofolate reductase status, homocysteine and lipoproteins levels have been associated with severity of disease and both rapid and sustained virological response (SVR) in patients with genotype 1 chronic hepatitis C (CHC). We aimed to assess the association of homocysteine and MTHFR status with serum cholesterol levels and their potential links to both histological findings and virological response, in patients with genotype 1 hepatitis C virus (HCV). A total of 119 consecutive patients were evaluated by biopsy and metabolic measurements. A total of 103 healthy blood donors were used as controls. Serum homocysteine and MTHFR C677T mutation were also evaluated. All patients underwent antiviral therapy with PEG-IFN alfa-2a plus ribavirin. HCV-RNA was assessed at baseline, week 4, week 12, at the end of therapy and after 6 months of follow-up. Mean serum values of homocysteine were higher in patients than in controls (15.8 ± 5.8 μg/L vs 12.5 ± 5.8 μg/L; P < 0.001), with a similar CC, CT and TT MTHFR distribution (23.6%, 48.7% and 27.7% in G1-CHC vs 34%, 48.5% and 17.5% in controls; P = 0.14). In genotype 1, HCV MTHFR TT homozygosis was independently linked to higher LDL (OR 1.016; CI 1.002-1.031; P = 0.03), but not to homocysteine. No association were found between homocysteine, MTHFR and histological features or both rapid virological response (RVR) and SVR. Low cholesterol (OR 0.988, 95%CI 0.975-0.999, P = 0.04) was independently linked to severe fibrosis, and high LDL was the only independent positive predictors of both RVR and SVR (OR 1.036; 95%CI 1.017-1.055; P < 0.001; and OR 1.016; 95%CI 1.001-1.031; P = 0.04 respectively). In patients with genotype 1 hepatitis C, showing higher homocysteine serum levels than controls, MTHFR C677T homozygosis, via modulating cholesterol levels, could interfere with liver fibrosis and response to antiviral therapy.     

The effect of methylenetetrahydrofolate reductase C677T common variant on hypertensive risk is not solely explained by increased plasma homocysteine values

The C677T transition of methylenetetrahydrofolate reductase (MTHFR) gene causes a moderate increase in total plasma homocysteine (tHcy). We studied the effect of MTHFR TT homozygosity and mild hyperhomocysteinemia on arterial hypertension. Normotensive controls (n = 223) and hypertensive subjects (n = 235) were matched for age, gender, and history of cardiovascular disease. Homocysteine levels were measured by a polarization immunoassay method. Methylenetetrahydrofolate reductase we determined by polymerase chain reaction and restriction fragment analysis. Hypertensives showed elevated tHcy compared to normotensive group in men (P = 0.039). Homocysteine values higher than 15 micromol/L were associated with increased hypertensive risk in the male population [odds ratios (OR) = 1.63; 95% confidence interval (CI) = 1.06-2.52; P = 0.027]. In multivariate analysis, TT genotype was associated with an increased risk of hypertension in males (OR = 2.27; 95% CI = 1.12-4.60; P = 0.022) An increased hypertensive risk was observed in those TT males with tHcy levels higher than 15 micromol/L (OR = 2.78; 95% CI = 1.05-7.3; P = 0.032) but not in those non-TT males with tHcy levels higher than 15 micromol/L (P = 0.33). Our findings do not support the possibility that mild hyperhomocysteinemia my solely account for the hypertensive risk associated to the TT genotype.     

Methylenetetrahydrofolate Reductase C677T Mutation and Nonalcoholic Fatty Liver Disease

A mutation in the methylenetetrahydrofolate reductase (MTHFR) gene is known as one of the causes of hyperhomocyteinemia. The oxidation products of homocysteine can initiate lipid peroxidation, which has a central role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). We aimed to assess the possible role of the MTHFR C677T mutation in the progression of simple steatosis to an advanced form of NAFLD. Thirty-four patients with NAFLD diagnosed by histologic analysis and 282 healthy controls were included in the study. The discrimination of nonalcoholic steatohepatitis (NASH) from another NAFLD was made by NAFLD activity score (NAS), and a NAS≥5 was considered NASH. Patients with either NASH or nonalcoholic fatty liver (NAFL) and controls were evaluated for frequency of the MTHFR C677T mutation. The frequency of the MTHFR C677T mutation was 53.5% (CT, 44.7%; TT, 8.9%) in controls and 41.5% (CT, 37.7%; TT, 3.8%) in patients (odds ratio [OR], 0.62; 95% confidence interval [CI], 0.34–1.12). There was no statistical difference in the frequency of this genotype between patients with NAFL and those with NASH (36% [CT, 28%; TT, 8%] vs 46.4% [CT, 46.4; TT, 0%]; OR, 0.65; 95% CI, 0.22–1.96). According to this study, the MTHFR C677T mutation does not seem to be a risk factor for the progression of NAFL to NASH.     

Lipoprotein (a) and genetic polymorphisms of clotting factor V, prothrombin, and methylenetetrahydrofolate reductase are risk factors of spontaneous ischemic stroke in childhood

Ischemic stroke is a rare event in childhood. In approximately one third of cases no obvious underlying cause or disorder can be detected. We investigated the importance of genetic risk factors of venous thromboembolism in childhood or stroke in adulthood as risk factors for spontaneous ischemic stroke in children. One hundred forty-eight Caucasian infants and children (aged 0.5 to 16 years) with stroke and 296 age-matched controls from the same geographic areas as the patients were analyzed for increased lipoprotein (a) [Lp(a)] levels >30 mg/dL; for the presence of the factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, and the TT677 genotype of methylenetetrahydrofolate reductase (MTHFR); and deficiencies of protein C, protein S, and antithrombin. The following frequencies (patients v controls), odds ratios (ORs), and confidence intervals (CIs) of single risk factors were found: Lp(a) >30 mg/dL (26.4% v 4.7%; OR/CI, 7.2/3.8 to 13.8; P <.0001), FV G1691A (20.2% v 4%; OR/CI, 6/2.97 to 12.1; P <.0001), protein C deficiency (6% v 0.67%; OR/CI, 9.5/2 to 44.6; P =.001), PT G20210A (6% v 1.3%; OR/CI, 4.7/1.4 to 15.6; P =.01), and the MTHFR TT677 genotype (23.6% v 10.4%; OR/CI, 2.4/1.53 to 4.5; P <.0001). A combination of the heterozygous FV G1691A mutation with increased Lp(a) (n = 11) or the MTHFR TT677 genotype (n = 5) was found in 10. 8% of cases, but only 0.3% of controls (OR/CI, 35.75/4.7 to 272; P <. 0001). Increased Lp (a) levels, the FV G1691A mutation, protein C deficiency, the prothrombin G20210A variant, and the MTHFR TT677 are important risk factors for spontaneous ischemic stroke in childhood.     

Impact of plasma homocysteine and prothrombin G20210 A on primary antiphospholipid syndrome.

The prevalence of prothrombin (PT) G20210A and methylenetetrahydrofolate reductase (MTHFR) C677 <-- T was assessed in 40 patients with primary antiphospholipid syndrome (APS) (14 male, 26 female; mean age, 37 +/- 14 years) and in 27 persistent carriers of antiphospholipid antibodies (aPL) (five male, 22 female; mean age, 40 +/- 16 years) without underlying diseases. Non-APS thrombotic patients (n = 100; 47 female, 53 male; mean age, 40 +/- 10 years) and healthy subjects (n = 100; 46 female, 54 male; mean age, 56 +/- 16 years) served as control groups. Plasma homocysteine (HC) (enzyme-linked immunosorbent assay) was measured in all aPL patients and in 51 subjects from the healthy control group (mean age, 38 +/- 16 years). Heterozygous prothrombin PT G20210A was more frequent in the thrombotic group without APS (18%) than in the control (4%), APS (12%) or aPL (11%) groups, whereas homozygous MTHFR C677 <-- T was equally distributed. After genotype sub-grouping, plasma HC was higher in APS patients with homozygous MTHFR C677 <-- T compared with non-homozygous APS patients (22 +/- 5.4 versus 11 +/- 1.3 micromol/l; P < 0.01) and with homozygous MTHFR C677 <-- T controls (22 +/- 5.4 versus 15 +/- 2.0 micromol/l). In the APS group, mean age at first event was lower in homozygous MTHFR C677 <-- T patients than in non-homozygous patients (26 +/- 7.5 versus 36 +/- 13 years; P = 0.008). In the same group, homozygous MTHFR C677 <-- T patients suffered an increased average number of events per person than non-homozygous patients (1.9 versus 1.3; P = 0.04). Heterozygous PT G20210A contributes little to the thrombotic tendency of primary APS whereas plasma HC may influence age at first event and number of events. Measurement of plasma HC in aPL subjects may identify patients at increased thrombotic risk requiring HC lowering.     

MTHFR C677T polymorphism and its relation to ischemic stroke in the Black Sea Turkish population

The MTHFR C677T mutation has been shown to be associated with venous thrombosis. The role of this mutation in ischemic stroke is unclear. We investigated whether the MTHFR mutation is a risk factor for patients with ischemic stroke in the Black Sea Turkish population or not. We analyzed 30 patients (19 male, 11 female) [median age: 50 years (range: 28-78)] with ischemic stroke who had no known predisposition factors for stroke and 242 (182 male, 60 female) healthy controls [median age: 42 years (range: 18-65)]. Detection of the MTHFR C677T mutation was performed by using commercially available allele-specific PCR-ELISA kits. Prevalence of the MTHFR C677T genotype was 49.1% (CT, 45.8%; TT, 3.3%) in controls and 50% (CT, 43.3%; TT, 6.6%) in patients [OR: 1.03, 95% CI (0.45-2.35]). The prevalence of homozygous gene mutation for MTHFR was higher among patients with stroke than control subjects, but this difference was not statistically significant. The MTHFR gene mutation is not a risk factor for ischemic stroke formation in patients from the Black Sea region in Turkey.     

The association between 5, 10 – methylenetetrahydrofolate reductase and the risk of unexplained recurrent pregnancy loss in China: A Meta-analysis

Backgroud:To analyze the correlation between gene polymorphisms of 5,10- methylenetetrahydrofolate reductase (MTHFR) and risk of unexplained recurrent pregnancy loss (URPL) in Chinese women.Methods:Eligible studies were searched in Pubmed, Embase, Web of Science, Wanfang, and China National Knowledge Infrastructure (CNKI) databases. Established inclusion criteria were used to screening articles, subsequently evaluate the quality of the included studies, Stata 16.0 PM and RevMan 5.3 software were conducted for meta-analysis. The pooled odds ratio (OR) with 95% confidence interval (CI) was determined to assess the relationship between MTHFR and risk of URPL in Chinese women.Results:For MTHFR C677T, fifty studies were included, involving 6677 URPL cases and 8111 controls. The overall results showed that MTHFR C677T was significantly correlated with URPL risk, especially in the homozygous model (TT vs CC; OR 3.06; 95% CI 2.56–3.66). For MTHFR A1298C, twenty-first studies were included, involving 3439 URPL cases and 3155 controls. The results showed that MTHFR A1298C was also significantly correlated with URPL risk in recessive (CC vs AC + AA; OR 1.55; 95% CI 1.25–1.93) and homozygous (CC vs AA; OR 1.53; 95% CI 1.22–1.91) models. In addition, sub-group results showed that no significant difference between north and south China populations in the MTHFR gene polymorphisms and URPL risk. Of note, the patients carrying MTHFR C677T and MTHFR A1298C joint mutants had no synergistic effect (OR 2.71; 95% CI 0.84–8.70) on the occurrence of URPL compared with the wild-type homozygous genotype (MTHFR 677CC/ MTHFR 1298AA).Conclusion:Studies included in this meta-analysis suggested that MTHFR 677T allele and 677TT genotype and MTHFR 1298CC genotype were both associated with URPL; testing MTHFR C677T gene polymorphism was a more appropriate target compared with other mutations in the prediction of URPL.     

Methylenetetrahydrofolate reductase C677T polymorphism and predisposition towards esophageal squamous cell carcinoma in a German Caucasian and a northern Chinese population

Purpose Folate deficiency is considered to increase the risk of developing esophageal cancer. Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme involved in folate metabolism. A single C T substitution at nucleotide 677 of the MTHFR cDNA influences enzyme activity. The purpose of this study is to compare the association of the MTHFR C677T polymorphism with susceptibility to esophageal squamous cell carcinoma (ESCC).Methods Using real-time PCR and melting curve analysis, the MTHFR C677T genotypes were determined in 430 patients with ESCC (241 German Caucasians and 189 northern Chinese) and 397 unrelated healthy controls (256 German Caucasians and 141 northern Chinese).Results A significant difference in MTHFR C677T genotype distribution was observed between German Caucasian controls (C/C, 41.8%, C/T, 44.9%, T/T, 13.3%) and northern Chinese controls (C/C, 17.7%, C/T, 38.3%, T/T, 44.0%) (²=52.19, P<0.001). The distribution of the MTHFR C677T genotypes among German ESCC patients (C/C, 39.0%, C/T, 48.1%, T/T, 12.9%) was not significantly different from that among healthy controls (²=0.531, P=0.767). In contrast, the frequency of the C/C genotype among Chinese ESCC patients (8.5%) was significantly lower than among Chinese healthy controls (17.7%) (²=6.37, P=0.012). The C/C genotype was correlated with a significantly reduced risk for the development of ESCC as compared to the combination of C/T and T/T genotypes (adjusted OR=0.38, 95% CI=0.16–0.88).Conclusions Our results suggest that, in contrast to German Caucasians, the MTHFR 677CC homozygous wild-type plays a protective role in the development of ESCC in the northern Chinese population.Abbreviations CI Confidence interval - ESCC Esophageal squamous cell carcinoma - MTHFR Methylenetetrahydrofolate reductase - OR Odds ratio - PCR Polymerase chain reaction     

亚甲基四氢叶酸还原酶基因C677T多态与肝细胞癌遗传易感性的相关性研究

目的探讨亚甲基四氢叶酸还原酶（MTHFR）基因C677T多态与中国人肝细胞癌（Hcc）遗传易感性的关系。方法采用聚合酶链反应一限制性片段长度多态性（PCR—RFLP）方法，检测508例Hcc与543例对照的MTHFR C677T基因型分布及其差异。结果HCc和对照两组人群的MTHFR C677T基因型分布差异无统计学意义。但与C等位基因携带者（C／C和C／T基因型）相比，T／T基因型携带者患HCC的风险增加0．66倍（95％可信区间为1．08～2．54，P〈0．05）。性别因素分层分析结果显示：T／T基因型女性携带者其HCC的风险是C等位基因女性携带者的2．64倍（95％可信区间为1．19～5．88，P〈0．05）；而男性T／T基因型与C等位基因携带者其HCC的风险差异无统计学意义。结论MTHFR基因C677T多态可能是中国女性患HCC的一个遗传易感因素，而男性HCC发病风险与该多态无明显关系。     

MTHFR gene polymorphism is susceptible to diabetic retinopathy but not to diabetic nephropathy in Japanese type 2 diabetic patients

AIMS: Previously, we have proposed that methylenetetrahydrofolate reductase (MTHFR) gene polymorphism (C677T) could be a risk factor for diabetic retinopathy. To support our suggestion, we examined in detail the association of MTHFR polymorphism with diabetic retinopathy and nephropathy in Japanese type 2 diabetic patients. METHODS: Subjects (n=190) were free of cardiovascular diseases and were not on hemodialysis. Retinopathy was assessed according to fundamental differentiation; nephropathy was determined according to urinary albumin level; and MTHFR genotype was determined by polymerase chain reaction-restriction fragment length polymorphism. We also analyzed how hyperglycemia affected these three conditions in 131 patients with glycosylated hemoglobin > or =6.5% and fasting blood sugar > or =110 mg/dl. RESULTS: The frequency of 677T/677T homozygous subjects with retinopathy was higher than the frequencies of the other two genotypes, and a significant difference was observed in the distribution of the genotypes (677C/677C, 41.9%; 677C/677T, 31.1%; 677T/677T, 61.5%; P<.05). The susceptibility of 677T/677T homozygote to retinopathy approached significance [odds ratio (OR)=2.17; 95% confidence interval (95% CI)=0.87-5.42]. However, in the population with hyperglycemia, the 677T/677T homozygote modified the risk for retinopathy (OR=4.30; 95% CI=1.42-13.1), especially the risk for nonproliferative retinopathy. In contrast, the 677T/677T homozygote did not affect the risk for nephropathy (OR=1.17; 95% CI=0.45-3.05), even in subjects with hyperglycemia (OR=1.50; 95% CI=0.50-4.48). CONCLUSIONS: Our results are highly suggestive of an important role for MTHFR genotype in susceptibility to retinopathy under hyperglycemia, but not to nephropathy. Preventive therapies based on MTHFR polymorphism could delay the onset of retinopathy in type 2 diabetic patients.     

Genetic polymorphisms in methylenetetrahydrofolate reductase and thymidylate synthase and risk of pancreatic cancer.

BACKGROUND & AIMS: Human pancreatic cancer might be associated with folate deficiency and impaired metabolism. We tested this hypothesis by examining the contribution of functional polymorphisms in methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TS) to risk of cancer. METHODS: DNA from 163 pancreatic cancer patients and 337 control subjects was genotyped for MTHFR (677C > T and 1298A > C) and TS (5'-untranslated region tandem repeat and G/C). Association with risk of pancreatic cancer was estimated by logistic regression. All statistical tests were two-sided. RESULTS: We observed an increased risk of pancreatic cancer associated with the MTHFR 677CT (odds ratio [OR], 2.60; 95% confidence interval [CI], 1.61-4.29; P = .0005) or 677TT (OR, 5.12; 95% CI, 2.94-9.10; P < .0001) genotype compared with the MTHFR CC genotype. An increased risk of pancreatic cancer was also associated with the TS 3Rc/3Rc genotype (OR, 2.19, 95% CI, 1.13-4.31; P = .022) compared with the TS 3Rg/3Rg genotype. Joint effect between MTHFR C677T polymorphism and smoking or drinking increased risk of pancreatic cancer in a super-multiplicative manner. The ORs for smoking, the polymorphism, and both factors combined were 0.70 (95% CI, 0.30-1.63), 2.17 (95% CI, 1.17-4.21), and 3.10 (95% CI, 1.54-6.51), respectively. This joint effect was much stronger in heavy smokers (OR, 6.69; 95% CI, 3.39-13.63; P < .0001). The ORs for drinking, the polymorphism, and both factors combined were 0.98 (95% CI, 0.40-2.30), 2.81 (95% CI, 1.65-4.98), and 4.39 (95% CI, 2.25-8.78), respectively. CONCLUSION: The MTHFR and TS polymorphisms are genetic determinants for developing pancreatic cancer.     

Infant methylenetetrahydrofolate reductase 677TT genotype is a risk factor for congenital heart disease

OBJECTIVE: Recently, an association between the homozygous C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in infants with congenital neural tube defects or congenital oral clefts has been shown. However, no data are available so far with respect to the MTHFR 677TT genotype in children with underlying structural congenital heart disease (CHD). METHODS: We investigated the MTHFR genotype in 114 Caucasian CHD patients aged newborn to 16 years (median 0.6 years; 53% male) and in 228 age- and sex-matched healthy controls. RESULTS: In childhood patients with CHD the homozygous MTHFR 677TT genotype was found in 21 out of 114 subjects (18.4%) compared with 21 out of 228 controls (9.2%; odds ratio (OR) 2.2, 95%-confidence interval (CI) 1.2-4.3; P=0.027). In patients with pulmonary valve stenosis, hypoplastic left heart syndrome, coarctation of the aorta, aortic valve stenosis or subaortic stenosis the frequency of the TT genotype varied between 38 and 67% with corresponding ORs from 6.1 (CI, 1.4-27.5; P=0.034) to 20.4 (CI, 1.8-235.0; P=0.025), whereas in other structural CHD the frequency of this genotype was not significantly different from the controls. CONCLUSIONS: With the present study we can show for the first time that the embryonal MTHFR 677TT genotype is significantly associated with the development of structural congenital heart malformations during early pregnancy. It remains to be clarified, whether this genotype is at least a risk marker or a risk factor for structural congenital heart malformations.