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)

The mutations in homocysteine (Hcy) metabolism-related enzyme genes including methylenetetrahydrofolate reductase (MTHFR) C677T, cystathionine beta-synthase (CBS) 844ins68, and methionine synthase (MS) A2756G have been identified as genetic risk factors for thromboembolic events. It has been noticed that these gene mutations have heterogeneous distributions among different ethnic groups or geographic areas. The data on the prevalence of the gene mutations in Chinese population is not yet available. In the present study, we have investigated the frequency of the MTHFR C677T, CBS 844ins68, and MS A2756G mutations in 102 patients with ischemic stroke (IS), 73 patients with myocardial infarction (MI) and 100 healthy controls. The distributive frequencies of the gene variations are as follows: In the IS, MI and control groups, the mutant homozygote for MTHFR C677T is 15 (14.7%), 8 (11.7%) and 16 (16.0%), respectively, and the T allele frequency is 37.7%, 33.6% and 39.5%, respectively; the heterozygote for CBS 844ins68 is 1 (1.0%), 1 (1.4%) and 5 (5.0%), respectively; the heterozygote for MS A2756G is 18 (17.6%), 14 (19.2%) and 17 (17.0%), and the G allele frequency is 8.8%, 11.0% and 9.5%, respectively. The carrier of both MS A2756G and MTHFR C677T (combined mutations) is 14 (12.7%), 8(11.0%) and 12(12.0%), respectively. There is no statistically significant difference between the patient groups and the control group in the frequencies of these single mutation or combined mutations. The heterozygosity of CBS 844ins68 yields an odds ratio (OR) of 0.19 (95% confidence interval (CI) 0.02-1.43) for IS and 0.26 (95% CI 0.03-2.31) for MI. The T allele of MTHFR C677T yields an OR of 0.93 for IS (95% CI 0.62-1.39) and 0.77 for MI (95% CI 0.50-1.21). The G allele of MS A2756G yields an OR of 0.92(95% CI 0.47-1.81) for IS and 1.17 (95% CI 0.58-2.37) for MI. Our results suggest that neither single mutation nor combined mutations in MTHFR C677T, CBS 844ins68 and MS A2756G represent an independent risk factor for increasing IS and coronary artery disease risks in Chinese population. However, CBS 844ins68 may be a protective factor against vascular thromboembolic disease. The prevalence of CBS 844ins68 and MS A2756G in Chinese population is obviously lower than in Western Caucasian population.
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PMID:Gene polymorphisms of homocysteine metabolism-related enzymes in Chinese patients with occlusive coronary artery or cerebral vascular diseases. 1167 61

Ischemic stroke in young adults is a well-known disease, but despite extensive clinical and laboratory investigations, its etiology remains unclear in approximately half of the cases. We examined the prevalence of factor V Leiden, the prothrombin G20210A genotype, and the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in 100 patients (51 males and 49 females) who survived an ischemic stroke without a cardiac embolic source at an age < or = 45 years, and in 238 healthy control subjects from the same geographic area. The patients were selected for study only if the diagnosis of stroke was documented by computed tomography scan or nuclear magnetic resonance (NMR) of the brain, or both. Heterozygosity for the FV Leiden mutation was found in 3 patients (3.0%) and in 10 control subjects (4.2%). Two patients (2.0%) and five control subjects (2.1%) were heterozygous for the prothrombin G20210A mutation. The frequencies of the MTHFR 677TT, CT, and CC genotypes in the patient group were 12%, 37%, and 51%, respectively, and were not significantly different from those in control subjects (11%, 40%, and 49%, respectively). In conclusion, our results indicate that FV Leiden mutation, prothrombin G20210A genotype, and homozygosity for the C677T mutation in the MTHFR gene are not associated with an increased risk for ischemic stroke in young adults.
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PMID:Factor V Leiden, prothrombin gene G20210A variant, and methylenetetrahydrofolate reductase C677T genotype in young adults with ischemic stroke. 1169 22

Moderately elevated plasma homocysteine levels have been established as independent risk factors in vascular disease, including ischemic stroke. Recently, a common mutation (C677T) in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene reducing the activity of MTHFR and increasing homocysteine levels in plasma was reported. The C677T MTHFR mutation may be a risk factor for ischemic stroke, but the results of previous studies have been conflicting. One possible explanation is that the association with the MTHFR genotype may be different according to gender. To investigate the association for ischemic stroke, we conducted a case-control study of 77 hospital cases (49 men and 28 women) with ischemic stroke and 229 (120 men and 109 women) control subjects in Japanese. The prevalence of conventional vascular risk factors and MTHFR genotypes were determined in case and controls. After adjustment by multiple analysis in all there was no statistical significance in MTHFR genotypes. The conventional vascular risk factors such as diabetes mellitus (adjusted odds ratio [OR], 17.21), hypertension (adjusted OR, 4.67), smoking habit (adjusted OR, 4.70), and hyperlipidemia (adjusted OR, 2.73) were identified independently associated with ischemic stroke. With a separate sex analysis it was identified that the relationship of the MTHFR T/T gneotype was statisticaly significant in women (adjusted OR, 9.49; 95% CI, 1.75-51.47, P=0.0091). The relevance of the MTHFR T/T mutation appears to be restricted to women, suggesting a role of female hormones in the resistance to elevated homocysteine levels due to the MTHFR T/T mutation.
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PMID:Methylenetetrahydrofolate reductase gene polymorphism and ischemic stroke: sex difference in Japanese. 1187 Mar 35

Plasma homocysteine levels result from the effect of genetic and environmental factors. We investigated the hypothesis of familial association between folates, methylenetetrahydrofolate reductase (MTHFR) and hyperhomocysteinemia with acute events, studying three families through pedigree analysis and log-linear graphical models. In 43 subjects, 13 had homocysteine levels of >15 micromol/l. In Family A, premature venous and arterial events occurred in father and son, respectively. In Family B, several arterial premature events occurred and very high homocysteine level was found in a healthy 18-year-old nephew. In Family C, stroke occurred at the age of 16 in a boy. In all three families, all subjects with premature cardiovascular events had high homocysteine level as well as MTHFR mutation, either homozygous or heterozygous. The present results underline that hyperhomocysteinemia has a direct conditional association with cardiovascular events. Moreover, homocysteine level is a variable that links the indirect association of folates, MTHFR mutation and cardiovascular event.
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PMID:Premature arterial and venous events in three families. Effect of folate levels and MTHFR mutation mediated by family/generation and homocysteine levels. 1195

It has been known for decades that babies born to women that have a dietary deficiency in folic acid (folate) are at increased risk for birth defects, and that the nervous system is particularly susceptible to such defects. Folate deficiency in adults can increase risk of coronary artery disease, stroke, several types of cancer, and possibly Alzheimer's and Parkinson's diseases. Recent findings have begun to reveal the cellular and molecular mechanisms whereby folate counteracts age-related disease. An increase in homocysteine levels is a major consequence of folate deficiency that may have adverse effects on multiple organ systems during aging. Humans with inherited defects in enzymes involved in homocysteine metabolism, including cystathionine beta-synthase and 5,10-methylenetetrahydrofolate reductase, exhibit features of accelerated aging and a marked propensity for several age-related diseases. Homocysteine enhances accumulation of DNA damage by inducing a methyl donor deficiency state and impairing DNA repair. In mitotic cells such DNA damage can lead to cancer, while in postmitotic cells such as neurons it promotes cell death. The emerging data strongly suggest that elevated homocysteine levels increase the risk of multiple age-related diseases, and point to dietary supplementation with folate as a primary means of normalizing homocysteine levels and increasing healthspan.
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PMID:Folic acid and homocysteine in age-related disease. 1203 51

In the present study, the determinants of fasting plasma homocysteine in diabetic subjects were examined; whether plasma homocysteine and vascular disease are related and the influence of the C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene on serum and erythrocyte folate, plasma homocysteine and vascular disease. Diabetic clinic subjects (Type I, n=354; Type II, n=392) were recalled for a cross-sectional survey. Standard methods were used to measure biochemical variables and to characterize vascular disease and MTHFR genotype. Plasma homocysteine was significantly and directly related to age, male sex and serum urea, and inversely related to serum folate and vitamin B12, independently in stepwise regression. When corrected for age and sex, homocysteine was significantly related to hard end points of coronary artery disease and stroke (each P<0.01), remaining significant when additionally adjusted for serum folate (P=0.043 and P=0.019 respectively). Serum folate was not clearly related to these events, although there was a trend to associate with the lower quintile of serum folate. The MTHFR genotype was not a determinant of plasma homocysteine, even in those in the lowest quintile of serum folate, nor of vascular disease. TT homozygosity at residue 677 was associated with elevation of total erythrocyte folate compared with both other genotypes (P<0.0001), almost certainly due to the diversion of 5,10-methylenetetrahydrofolate into derivates subsequent to the partial metabolic block that results from the MTHFR enzyme defect. In conclusion, in this clinic cohort of people with diabetes, vascular disease is related to plasma homocysteine, which is correlated with serum folate. The MTHFR genotype does not significantly influence either plasma homocysteine or vascular disease, despite it being a determinant of erythrocyte folate, which reflects its effect on folate metabolism.
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PMID:Homocysteine, folate, methylene tetrahydrofolate reductase genotype and vascular morbidity in diabetic subjects. 1204 16

The aim of this study was to identify hereditary and acquired risk-factors as they are related to the occurrence of stroke in children. We identified 21 children with stroke. A search of the Factor V Leiden mutation, the Factor II G20210A variant, and the thermolabile variant of methylenetetrahydrofolate reductase was performed in patients and in a control group (n = 115). We identified risk factors of acquired and/or hereditary nature for stroke in 19 of 21 children. Eleven children had three or more risk factors, seven had two risk factors, and one child had only one risk factor. We found three carriers (14.3%) of the Factor V Leiden mutation, two carriers (9.5%) of the Factor II G20210A variant, eleven (52.4%) thermolabile variant of methylenetetrahydrofolate reductase heterozygote carriers, and one (4.8%) homozygotes for this variant. Frequencies of the Factor V Leiden mutation and the Factor II variant were higher in patients than in controls, suggesting that these variants are associated with an increased risk of stroke in childhood. Homozygosity for the thermolabile variant of methylenetetrahydrofolate reductase was equally frequent amongst patients and controls. Our study confirms that stroke in children is commonly associated with a combination of multiple risk factors, both genetic and acquired, and that the Factor V Leiden mutation and the Factor II G20210A variant are predisposing factors for this situation.
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PMID:Inherited and acquired risk factors and their combined effects in pediatric stroke. 1269 65

Arterial thrombosis is a complex disorder that involves multiple genetic and environmental factors interacting to produce the characteristic phenotype. In the past decades, investigators have focused on the molecular genetics of arterial vascular disorders and have identified numerous polymorphisms and mutations in genes related to the hemostatic system and to enzymes involved in the synthesis and bioavailability of nitric oxide (NO); however, the relation between most polymorphisms and the risk of coronary artery disease, ischemic stroke, and peripheral vascular disease remains highly controversial. In this review, we describe the most common genetic variations involved in the pathogenesis of arterial thrombosis, their functional implications, and their association with disease risk. Specifically, we consider polymorphisms in coagulation factors (fibrinogen, prothrombin, FV Leiden, FVII, and FXIII); fibrinolytic factors (tissue-type plasminogen activator, plasminogen activator inhibitor-1, and thrombin-activatable fibrinolysis inhibitor); platelet surface receptors; methylenetetrahydrofolate reductase; endothelial NO synthase; and the antioxidant enzymes paraoxonase and plasma glutathione peroxidase. Overall, there seems to be a modest contribution of individual genetic variants in the hemostatic and antioxidant systems to the risk of arterial thrombosis. Thus, future research ought to focus on identifying novel genetic determinants and on the interaction of these genetic risk factors with each other and the environment to understand better the pathobiology and susceptibility to arterial thrombotic disease.
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PMID:Genetic determinants of arterial thrombosis. 1461 95

Twin and family-based studies indicate that genetic factors might be involved in the risk of transient ischemic attack (TIA) and ischemic stroke (IS). Identification of genetic risk factors for new vascular events after cerebral ischemia may target secondary prevention. The overall aim of POLARIS is to study which polymorphisms predispose to new vascular events after TIA/IS and to assess their predictive value. Patients who have had a TIA or IS of presumed arterial origin are included. The study design is twofold. In part one the prevalences of polymorphisms will be compared between 300 long-term survivors of the Dutch TIA Trial (average follow-up 10 years) and 820 patients with recent TIA/IS. In part two a cohort of 820 patients with recent TIA/IS will be followed for the occurrence of vascular events for an average of 3.5 years. Several polymorphisms of interest will be genotyped, including factor V Leiden, prothrombin 20210A, 5,10-methylenetetrahydrofolate reductase, HR2 haplotype factor V and factor XIII Val34Leu.
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PMID:Polymorphisms and Risk of Ischemic Stroke (POLARIS) study: rationale and design. 1463 Nov 27

Diamond-Blackfan anemia is a congenital hypoproliferative anemia known to be associated with diverse physical anomalies affecting the thumb, craniofacial bones, urogenital system, and heart; prematurity; and fetal demise. We report the case of a 16-month-old boy with Diamond-Blackfan anemia noted to have decreased use of his right side since birth. Magnetic resonance imaging demonstrated a large area of encephalomalacia in the left middle cerebral artery territory. Magnetic resonance angiography showed marked attenuation of the left middle cerebral artery, suggesting a remote thromboembolic event. The laboratory results were remarkable for a decreased hemogolobin of 9.5 g/dL and increased platelets of 591,000/microL. He was heterozygous for the methylenetetrahydrofolate reductase gene C677T mutation. An echocardiogram demonstrated a patent foramen ovale versus an atrial septal defect with left to right shunting. Perinatal stroke may be a rare complication of Diamond-Blackfan anemia in the setting of other risk factors.
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PMID:A child with Diamond-Blackfan anemia, methylenetetrahydrofolate reductase mutation, and perinatal stroke. 1469 10


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