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)

Recent genetic studies have led to the characterization of molecular determinants contributing to the pathogenesis of hyperhomocysteinemia. In this article we summarize the current insights into the molecular genetics of severe, moderate and mild hyperhomocysteinemia. We will consider deficiencies of the trans-sulfuration enzyme cystathionine beta-synthase (gene symbol: CBS), and the disturbances of the remethylation enzymes 5, 10-methylenetetrahydrofolate reductase (gene symbol: MTHFR), methionine synthase (gene symbol: MTR), and the recently identified methionine synthase reductase (gene symbol: MTRR). Furthermore, we will focus on clinically important genetic polymorphisms which are highly prevalent and thus of potential general interest.
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PMID:Molecular genetics of homocysteine metabolism. 1068 51

Homocysteine is associated with atherosclerosis and enhanced cardiovascular risk. In previous studies, treatment with folic acid up to 15 mg/d failed to correct hyperhomocysteinemia in the majority of end-stage renal disease patients. A dose of 30 or 60 mg of folic acid per day was compared with 15 mg/d in an attempt to normalize hyperhomocysteinemia in 150 hemodialysis patients. In a randomized, double-blind, multicenter study, 144 patients completed the 4-wk treatment period and 121 patients completed the 6-mo follow-up. Total homocysteine plasma levels were reduced by 32.1% (15 mg/d), 29. 9% (30 mg/d), or 37.8% (60 mg/d) with no significant differences found between the three treatment groups. Baseline total homocysteine plasma concentration was an independent predictor of the response to folic acid therapy (P = 0.0001), whereas the 5, 10-methylenetetrahydrofolate reductase polymorphisms (MTHFR 677C --> T and 1298A --> C) had no influence. Nevertheless, patients with the MTHFR 677TT genotype more frequently attained normal total homocysteine plasma levels than patients with the CC or CT genotype (P = 0.025). In response to 60 mg of folic acid per day, TT genotype patients had lower folate plasma levels compared to CC or CT genotype patients (P = 0.016). After completion of the 4-wk treatment period with 30 or 60 mg of folic acid per day, there was a marked rebound of total homocysteine plasma levels at the end of the follow-up in patients with the MTHFR 677TT genotype, which even exceeded baseline values in several patients (P = 0.0001). This study clearly demonstrates that doses of 30 or 60 mg of folic acid per day are not more effective than 15 mg/d in reducing hyperhomocysteinemia in regular hemodialysis patients. Patients with the MTHFR 677TT genotype are more likely to realize normal total homocysteine plasma levels. Folic acid at 30 or 60 mg/d but not 15 mg/d results in a rebound of total homocysteine plasma concentrations when treatment is stopped.
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PMID:Effect of high dose folic acid therapy on hyperhomocysteinemia in hemodialysis patients: results of the Vienna multicenter study. 1082 Jan 75

The specific aim of the current study of 133 women with at least 1 pregnancy and measures of hypofibrinolytic and thrombophilic gene mutations was to determine retrospectively whether the mutations were associated with adverse pregnancy outcomes including prematurity, miscarriage, stillbirth, intrauterine growth retardation (IUGR), eclampsia, and abruptio placentae. Four gene mutations (factor V Leiden, methylenetetrahydrofolate reductase [MTHFR], prothrombin, and 4G/5G polymorphism of the plasminogen activator inhibitor type 1 [PAI-1] gene) were assessed by polymerase chain reaction (PCR). One hundred twenty-two women were genotyped for all 4 genes and divided into gene mutation (n = 68) and non-gene (n = 54) groups. The gene mutation group included those with at least 1 thrombophilic mutation (heterozygous for factor V Leiden, heterozygous for prothrombin, and homozygous for MTHFR), or hypofibrinolysis with homozygosity for the 4G polymorphism of the PAI-1 gene. The non-gene mutation group included those with no mutation for all 4 genes (wild-type normal) or who were wild-type normal for the prothrombin and factor V Leiden mutations and heterozygous for MTHFR and/or 4G/5G for the PAI-1 gene, neither heterozygosity associated with coagulation abnormalities. The 68 women with gene mutations, versus 54 in the non-gene mutation group, has more prematurity (10% v 4%, chi2 = 5.4, P = .021), more IUGR (3% v 0%, P = .035), and more total complications of pregnancy (37% v 21%, chi2 = 11.6, P = .001). The number of pregnancies (P = .0001) and 4G/4G polymorphism of the PAI-1 gene (P = .029) were positively associated with complications of pregnancy by stepwise logistic regression when the age, number of pregnancies, and all 4 gene mutations were the explanatory variables. Heritable hypofibrinolysis, mediated by 4G/4G homozygosity for the PAI-1 gene, is an independent significant, potentially reversible risk factor for pregnancy complications, probably acting through thrombotic induction of placental insufficiency.
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PMID:The 4G/4G polymorphism of the hypofibrinolytic plasminogen activator inhibitor type 1 gene: an independent risk factor for serious pregnancy complications. 1090 93

Diagnosis of inherited diseases or cancer predispositions frequently involves determination of specific mutations or polymorphisms. The number of characterized monogenetic and polygenetic diseases is significantly rising every year. As a result, an increasing number of patient samples with a rising complexity of genetic diseases require molecular diagnostics. In order to apply genetic analyses to large groups of patients or population screening, automation of a sensitive and precise method is highly desirable. Capillary electrophoresis (CE) facilitates the development of methods which can rapidly process large number of patient samples in an automated fashion. In contrast, conventional techniques including Southern blotting, sequencing or standard gel electrophoresis are time consuming, cost ineffective and require substantial amounts of each specimen. Robustness, ease of operation, good reproducibility and low cost are the main advantages of CE. Currently, most protocols adapted to automated CE represent (i) analyses of DNA fragment length or DNA restriction patterns (RFLP), (ii) analyses of single-strand conformation polymorphism (SSCP) and (iii) microsatellite analyses. Recently, automated detection of variations in the FRAXA (CGG)n region (fragile X syndrome), LDL receptor gene, p53 gene, MTHFR (methylenetetrahydrofolate reductase) gene, HFE gene and others has been established on CE systems. These applications clearly demonstrate the suitability of CE for high throughput screening in medical applications.
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PMID:Use of capillary electrophoresis for high throughput screening in biomedical applications. A minireview. 1112 15

The homocysteine plasma level is determined by non-genetic and genetic factors. In recent years evidence has accumulated that the total homocysteine plasma level of patients under different forms of renal replacement therapy is influenced by a common mutation at nucleotide position 677 of the gene coding for 5,10-methylenetetrahydrofolate reductase (MTHFR 677C-->T). Furthermore, compound heterozygosity for the 677T allele and a novel A-->C polymorphism at nucleotide position 1298 of MTHFR is suggested to correlate with a decrease of folate plasma concentrations. Because polymorphisms of genes coding for proteins involved in the metabolism of homocysteine may contribute to elevated total homocysteine plasma concentrations, molecular genetic analyses of the homocysteine pathways experienced a drift towards screening for candidate genes with a putative relationship to total homocysteine plasma levels. One example is the cloning of the FOLR1 gene coding for the folate-binding protein (Folbp1), which has recently been inactivated in mice, thus representing an elegant model to investigate the consequence on the homocysteine metabolism. Furthermore, the recent characterization of the CUBN gene encoding the intrinsic factor-vitamin B12 receptor (cubilin) provides a basis to identify the causative mutations in patients suffering from a hereditary syndrome of hyperhomocysteinemia that presents with megaloblastic anemia and proteinuria. This review focuses on recent insights into the molecular genetics of MTHFR, FOLR1, and CUBN, and their relationships to the metabolism of the amino acid homocysteine.
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PMID:Recent insights into the molecular genetics of the homocysteine metabolism. 1116 18

In this study of 118 children (median age 5.1 years; range 6 months to 17 years) with ischaemic stroke or transient ischaemic attack (TIA), 22 children (19%) were homozygous for the thermolabile variant of the methylenetetrahydrofolate reductase allele (t-MTHFR), compared with nine of 78 (12%) of a reference population (p=0.18, OR 1.76, 95% CI 0.76 to 4.04). Of those with cerebrovascular disease (CVD), 17 of 84 were homozygous for the t-MTHFR allele (p=0.13 compared with the reference population (OR 1.95, 95% CI 0.81 to 4.65). There was a significant (p<0.025) increment of plasma total homocysteine concentration in homozygotes for the t-MTHFR allele compared with heterozygotes, negatives for the t-MTHFR allele, and control children with no history of stroke. In four of 12 homozygotes for the t-MTHFR allele, plasma homocysteine levels were raised, compared with three of 38 of those who were negative or heterozygous (p=0.047; OR 5.8, 95% CI 1.1 to 31.2). Homozygotes for the t-MTHFR allele were significantly more likely to have a recurrent event than those who were negative or heterozygous (Cox regression p=0.031, hazard ratio 2.18, 95% CI 1.08 to 4.42). These data suggest that homozygosity for the t-MTHFR allele is associated with raised homocysteine levels in children and is a risk factor for primary and secondary stroke and TIA.
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PMID:Homozygous thermolabile variant of the methylenetetrahydrofolate reductase gene: a potential risk factor for hyperhomocysteinaemia, CVD, and stroke in childhood. 1130 98

Venous thromboembolism is a complex disease resulting from the interaction of a multitude of both genetic and environmental factors that can affect the cascade of biochemical reactions involved. Single-nucleotide polymorphisms in the genes that code for coagulation factors V (factor V Leiden) and II (prothrombin G20210A), as well as the methylenetetrahydrofolate reductase (MTHFR C677T) gene, have been implicated in the majority of cases of hereditary thrombophilia. In this study the authors evaluated the coexistence of the MTHFR polymorphism in 96 patients with a clinical suspicion for thrombosis who also have either the factor V Leiden polymorphism or the prothrombin G20210A polymorphism. Results indicate that the frequency of the MTHFR polymorphism was similar between the study and control groups with respect to heterozygosity (36.5% vs. 55.3%) and homozygosity (20.8% vs. 14.9%). These data suggest that the MTHFR polymorphism is not associated preferentially with patients who have had or who are at risk of developing a thrombotic event. In this study, patients with the factor V Leiden polymorphism or the prothrombin G20210A polymorphism were considered to be at risk.
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PMID:Coexistence of the methylenetetrahydrofolate reductase single-nucleotide polymorphism (C677T) in patients with the factor V Leiden or prothrombin G20210A polymorphisms. 1138 20

Currently, the established risk factors for cardiovascular disease (CVD) are largely environmental in nature. Conflicting studies have suggested that mutations in specific coagulation genes may also provide a genetic basis for CVD risk. We reviewed clinical studies that examined the role of single nucleotide polymorphisms in coagulation and platelet factors, and a biochemical factor to determine if specific genotypes are correlated with patients with a history of arterial thrombotic diseases (acute coronary syndromes or stroke). A meta-analysis was performed on studies for factors II (G20210A variant), V Leiden (G1691A), VII (R353Q), glycoprotein (GP) IIIa receptor (PI(A1/A2)), and methylenetetrahydrofolate reductase (MTHFR, C677T). There was no correlation for factor II or factor V polymorphisms to coronary artery disease (CAD) in 5,607 and 5,431 patients studied, respectively. There was also no correlation for factor II variants and stroke in 3,451 patients studied. For factor V, statistical significance was achieved for the G1691A variant on 3,399 patients with stroke (odds ratio [OR] 1.43, 95% confidence intervals [CI] 1.03 to 1.97). The GP IIIa PI(A1/A2) genotype was associated with increased risk for CAD in 7,920 patients (OR 1.12, 95% CI 1.01 to 1.24), but not for 1,855 patients who had a stroke (OR 0.80, 95% CI 0.62 to 1.04). The combined RQ and RR genotypes of factor VII R353Q were correlated to a reduced risk for CVD in 2,574 patients (OR 0.78, 95% CI 0.65 to 0.93), whereas the QQ genotype had offered more protection (OR 0.53, 95% CI 0.27 to 1.03). The TT homozygous variant of MTHFR was associated with CAD risk in 5,644 patients studied (OR 1.30, 95% CI 1.11 to 1.52) but not for 3,075 patients with stroke. This study shows that for some genes, further studies are unnecessary, whereas for others, no more enrollments are needed. The impact of certain genotypes must be examined in relation to other established risk factors and potentially new therapeutic strategies.
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PMID:Correlation of polymorphisms to coagulation and biochemical risk factors for cardiovascular diseases. 1139 54

Homocysteine represents a risk factor for coronary artery disease determined not only by nutritional habits, but also by the genetic polymorphism of the enzymes involved in its metabolism (i.e. methylenetetrahydrofolate reductase - MTHFR). However, recent prospective studies questioned the initial evidence of a clear epidemiological and pathogenetic link between homocysteine levels and coronary artery disease. Moreover, the relationships between MTHFR polymorphism and coronary artery disease remain unclear. In this paper, the recent literature analyzing the role of homocysteine and MTHFR polymorphism as a risk factor for coronary artery disease has been reviewed.
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PMID:[Familial predisposition to ischemic cardiopathy: role of homocysteine and genetic polymorphism of methylenetetrahydrofolate reductase]. 1150 92

BACKGROUND: Women may be at increased risk for venous thromboembolism (VTE) as compared with men. We studied the effects of genetic and biochemical markers of thrombophilia in women, in conjunction with other established risk factors for VTE. METHOD: The present retrospective case-control study was conducted in a thrombosis treatment programme at a large Toronto hospital. The cases were 129 women aged 16-79 years with objectively confirmed VTE. Age-matched control individuals were women who were free of venous thrombosis. Neither cases nor control individuals had known cardiovascular disease. Participants were interviewed regarding personal risk factors for VTE, including smoking, history of malignancy, pregnancy, and oestrogen or oral contraceptive use. Blood specimens were analyzed for common single nucleotide polymorphisms of prothrombin, factor V and methylenetetrahydrofolate reductase (MTHFR; C677T, A1298C and T1317C), and the A66G polymorphism for methionine synthase reductase (MTRR).Fasting plasma homocysteine was also analyzed. RESULTS: Women with VTE were significantly more likely than female control individuals to carry the prothrombin polymorphism and the factor V polymorphism, or to have fasting hyperhomocysteinaemia. Homozygosity for the C677T MTHFR gene was not a significant risk factor for VTE, or were the A1298C or T1317C MTHFR homozygous variants. Also, the A66G MTRR homozygous state did not confer an increased risk for VTE. CONCLUSION: Prothrombin and factor V polymorphisms increased the risk for VTE in women, independent from other established risk factors. Although hyperhomocysteinaemia also heightens this risk, common polymorphisms in two genes that are responsible for homocysteine remethylation do not. These findings are consistent with previous studies that included both men and women.
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PMID:Genetics University of Toronto Thrombophilia Study in Women (GUTTSI): genetic and other risk factors for venous thromboembolism in women. 1180 87


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