Methylenetetrahydrofolate Reductase C677T Mutation Research Articles

Role of Genetic and Acquired Prothrombotic Risk Factors in Genesis of Sudden Sensorineural Hearing Loss

The methylenetetrahydrofolate reductase C677T mutation, factor V G1691A (factor V Leiden) mutation, prothrombin G20210A mutation and 8 other laboratory values associated with increased thrombotic risk were analyzed in 40 patients with sudden sensorineural hearing loss (SSHL). The results were compared with those obtained from 120 controls not affected by SSHL. We found a statistically significant higher frequency of hyperhomocysteinemia in the SSHL group compared with controls, and that this was also associated with the presence of homozygosity for the MTHFR C677T mutation. The study results suggest that SSHL might be caused, among other factors, by a combination of these 2 variables. We suggest that this analysis of the MTHFR C677T mutation should be further investigated to establish the etiology of SSHL, and that the same analysis should be taken into account in those patients with high levels of homocysteine.

The association between methylene-tetrahydrofolate reductase gene polymorphism and lung cancer risk

This study aimed to determine the relation between methylene-tetrahydrofolate reductase (MTHFR) gene polymorphism and lung cancer risk and the frequency of this polymorphism. The study involved 64 lung cancer patients (the study group) with definitive diagnosis and 61 noncancerous subjects (the control group). MTHFR C677T and A1298C mutation analysis was made using DNA isolated from peripheric blood and multiplex PCR and reverse hybridization strip test. Eighty-four percent of the patients were male. The age, gender, and history of alcohol use of the patients and control group were statistically similar. While MTHFR 677T and 677C allele frequency was 0.33 and 0.67 in the patients respectively, it was 0.29 and 0.71 in the control group. The frequencies of MTHFR 1298C and 1298A were 0.33 and 0.67 in the patients, and it was 0.31 and 0.69 in the control group respectively. When MTHFR 677TT and 677CT genotypes were compared with 677CC genotype, lung cancer risk was 2.4 times higher in the 677TT genotype. When MTHFR 1298AC and 1298CC genotypes were compared with 1298AA genotype, lung cancer risk was 1.5 times higher in 1298CC genotype. According to the results, allele frequency of homozygote T and C was high in lung cancer patients. It was 3.05 and 1.29 times higher in smokers than in non-smokers, and 3.05 and 1.64 times higher in males than in females; 3.0 and 2.44 times higher in those with non-small cell lung cancer than in those with small-cell lung cancer.

Methylenetetrahydrofolate reductase C677T gene mutation as risk factor for sudden sensorineural hearing loss: association with plasma homocysteine, folate and cholesterol concentrations

Impaired cochlear perfusion appears to be the most important event in the development of sudden sensorineural hearing loss. Methylenetetrahydrofolate reductase gene mutations at nucleotide 677 cause reduced methylenetetrahydrofolate reductase enzyme activity, resulting in vascular impairment. Thirty-three patients and 68 control subjects underwent audiological and haematological investigation. No statistically significant association was found between sudden sensorineural hearing loss and the methylenetetrahydrofolate reductase C677T gene mutation. Mean homocysteine and cholesterol concentrations were significantly higher in patients than in controls. Mean folate levels were significantly lower in patients than in controls. Amongst patients with sudden sensorineural hearing loss, no significant differences in mean cholesterol, homocysteine or folate concentration were found, comparing patients with methylenetetrahydrofolate reductase C677T mutation genotypes with those without. No statistically significant association was found between the methylenetetrahydrofolate reductase C677T gene mutation and sudden sensorineural hearing loss. There was a statistically significant difference between the homocysteine, folate and cholesterol concentrations of sudden sensorineural hearing loss patients, compared with controls. However, there was no statistically significant difference in these levels, comparing patients with and without the methylenetetrahydrofolate reductase C677T mutation.

SUBACUTE METHOTREXATE NEUROTOXICITY AND CEREBRAL VENOUS SINUS THROMBOSIS IN A 12-YEAR OLD WITH ACUTE LYMPHOBLASTIC LEUKEMIA AND METHYLENETETRAHYDROFOLATE REDUCTASE (MTHFR) C677T POLYMORPHISM: Homocysteine-Mediated Methotrexate Neurotoxicity via Direct Endothelial Injury

From as early as the 1970s methotrexate has been associated with disseminated necrotizing leukoencephalopathy and other neurotoxic sequelae. Yet, a clear mechanism for methotrexate-induced neurotoxicity has not been established. The authors describe the case of a 12-year-old male with acute lymphoblastic leukemia and a homozygous methylenetetrahydrofolate reductase C677T mutation, who developed subacute methotrexate-induced toxicity and cerebral venous thrombosis after receiving intrathecal methotrexate. The role of homocysteine as a possible mediator in methotrexate-induced neurotoxicity via direct endothelial injury is discussed.

Hyperhomocysteinemia and C677T Polymorphism of Methylenetetrahydrofolate Reductase Gene in Patients with Cardiovascular Disease

Abstract The aim of the present study was to explore the influence of age and gender, on the association between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and plasma total homocysteine (tHcy) concentrations in patients with cardiovascular disease (CVD). Fasting tHcy and the MTHFR C677T mutation were evaluated in 98 patients with CVD, 46 were men and 52 women (aged 20-96 years). There was a significant elevation of plasma tHcy with age (<45 yr: 33.9 μmol/L vs. >75 yr: 43.6 μmol/L; p <0.01). The mean tHcy concentration increased significantly with age in men (<55 yr: 33.4 μmol/L vs. >55yr: 42.45 μmol/L; p 0.01). However, the plasma tHcy was not increased with older age in women. The frequency of the TT genotype was 19.6% in the younger patients group (>55 yr) compared with 4.7% in the older patients group (>55 yr; p <0.01). In conclusion, the data presented here are consistent with genetic factors that influence tHcy levels being more prominent in old patients (>55 yr). Then, the MTHFR mutation does not seem to be associated with either high tHcy or the occurrence of CVD.

Hypercoagulability and ischemic stroke in young patients

Introduction Hypercoagulable states have been reported as an established risk factor for cerebral venous thrombosis, but they have also been proposed as a predisposing factor for cerebral ischemia of arterial origin, especially among young patients. This may have implications on therapeutic management and secondary prevention. We have studied the frequency of prothrombotic abnormalities in young patients with ischaemic stroke, as other classic risk factors are less common in this group. Materials and methods Observational study with sequential inclusion of patients under 55 with stroke or transient ischaemic attack (TIA) admitted to the Stroke Unit from January 2005 through December 2007. We analysed demographic data, severity and subtype of stroke, risk factors, including the presence of hypercoagulable states, and outcome. Results We included 100 patients, of whom 65 were men. The mean age was 42.6 ± 8.9 years, 46% with a hypercoagulable state, and no sex differences. Acquired hyperhomocysteinemia was the most common abnormality (18%), followed by protein C or S deficiency (8%), factor V Leiden mutation (5%) and methylenetetrahydrofolate reductase (MTHFR) C677T mutation (5%). Other findings included anticardiolipin antibodies (3%), presence of lupus anticoagulant (2%), thrombocytosis (3%) and G20210A prothrombin gene mutation (3%). No association was found between these states and the presence of other vascular risk factors, or more severe stroke or worse outcomes. There was an increased presence of these abnormalities in patients who were classified as atherothrombotic stroke (p = 0.04). Conclusions The hypercoagulable states are common in young patients with ischaemic stroke, being present in up to 46% of them.

ABO Blood Groups and Genetic Risk Factors for Thrombosis in Croatian Population

To assess the association between ABO blood group genotypes and genetic risk factors for thrombosis (FV Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations) in the Croatian population and to determine whether genetic predisposition to thrombotic risk is higher in non-OO blood group genotypes than in OO blood group genotypes. The study included 154 patients with thrombosis and 200 asymptomatic blood donors as a control group. Genotyping to 5 common alleles of ABO blood groups was performed by polymerase chain reaction with sequence specific primers (PCR-SSP). FV Leiden was determined by PCR-SSP, while prothrombin and methylenetetrahydrofolate reductase were determined by PCR and restriction fragment length polymorphism (PCR-RFLP). There was an association between non-OO blood group genotypes and the risk of thrombosis (odds ratio [OR] 2.08, 95% confidence interval [CI], 1.32-3.27). The strongest association with thrombotic risk was recorded for A1B/A2B blood group genotypes (OR, 2.73; 95% CI, 1.10-6.74), followed by BB/O1B/O2B (OR, 2.29; 95% CI, 1.25-4.21) and O1A1/O2A1 (OR, 1.95; 95% CI, 1.15-3.31). FV Leiden increased the risk of thrombosis 31-fold in the group of OO carriers and fourfold in the group of non-OO carriers. There was no significant difference in the risk of thrombosis between OO and non-OO blood groups associated with prothrombin mutation. Non-OO carriers positive for methylenetetrahydrofolate reductase had a 5.7 times greater risk of thrombosis than that recorded in OO carriers negative for methylenetetrahydrofolate reductase. Study results confirmed the association of non-OO blood group genotypes with an increased risk of thrombosis in Croatia.

The prevalence of factor V Leiden (G1691A), prothrombin G20210A and methylenetetrahydrofolate reductase C677T mutations in Jordanian patients with β-thalassemia major

One hundred beta-thalassemia major (beta-TM) patients and 100 individuals as control were included. Factor V Leiden and prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) gene mutations were genotyped by PCR and allele-specific restriction enzyme techniques. The prevalence of factor V Leiden G1691A, MTHFR C677T and prothrombin G20210A in patients was insignificantly higher than controls. Patients with beta-TM have insignificantly higher frequencies of mutant A allele in factor V Leiden G1691A (11.5 vs. 10.5%), mutant T allele in MTHFR C677T (21.5 vs. 21%) and mutant A allele in prothrombin G20210A (3 vs. 2.5%) than controls. Double heterozygosity for two of the three mutations discussed in this study was found in (10 vs. 8%, P = 0.62) in beta-TM patients and controls. The prevalence of factor V Leiden G1691A, prothrombin G20210A and MTHFR C677T mutations was slightly but insignificantly higher in beta-TM patients than controls. beta-TM is a chronic hypercoagulable condition independent of predisposing genetic factors.

Folate, homocysteine, interleukin-6, and tumor necrosis factor alfa levels, but not the methylenetetrahydrofolate reductase C677T polymorphism, are risk factors for schizophrenia

The methylenetetrahydrofolate reductase ( MTHFR) C677T mutation has been associated to high homocysteine levels and schizophrenia. Since cytokines are altered in schizophrenia and increments of homocysteine could promote an inflammatory response, it was investigated whether interleukin-6 (IL-6) and tumor necrosis factor alfa (TNFα) levels are modulated by the MTHFR genotype. Serum levels of TNFα, IL-6, B 12, homocysteine, folate and red blood cell (RBC) folate as well as the MTHFR genotype were determined in a group of schizophrenic patients and compared to those of a control group. RBC folate levels were reduced and homocysteine and the two cytokines’ concentrations were elevated in all patients as compared to controls. RBC folate in both heterozygous (CT) and homozygous (TT) patients was significantly different to that of their respective control groups. Homocysteine levels found in patients were significantly higher than those found in controls, only in individuals carrying the TT genotype. Cytokine levels were augmented in the group of patients irrespective of the genotype, and significant differences were found in all cases, except for TNFα levels in those subjects carrying the CC genotype. After adjusting for sex, low levels of RBC folate, high levels of homocysteine, both medium and high levels of TNFα and high IL-6 levels were associated with schizophrenia. MTHFR genotype was not a risk factor for developing the disease, although a larger sample is required to confirm this finding.

Hypercoagulable State and Methylenetetra- hydrofolate Reductase (MTHFR) C677T Mutation in Patients with Beta-Thalassemia Major in Kuwait

Introduction: Patients with thalassemia major often present with a hypercoagulable state, the pathogenesis of which is still not understood. Materials and Methods: This study evaluates the risk factors for hypercoagulability in 50 β-thalassemia major patients and 50 healthy controls. Fasting total homocysteine, protein C (PC), protein S (PS), antithrombin (AT), activated protein C resistance (APCR) and lupus anticoagulant (LA) were assessed. MTHFR C677T mutation was determined. Results: Significant reductions in PC, PS and AT were noted in patients. Only 4% of the patients had hyperhomocysteinemia. Thirty-two percent of the patients were heterozygous and 4% were homozygous for MTHFR C677T mutation. Conclusion: The natural coagulation inhibitors PC, PS and AT were significantly reduced in patients with β-thalassemia major and were thus important risk factors for the hypercoagulable state, but hyperhomocysteinemia and MTHFR mutation do not seem to be significant risk factors for thromboembolic events.

Live Term Birth and Two Ongoing Viable Pregnancies with Therapeutic Enoxaparin and Aspirin After Failure of Prophylactic Enoxaparin and Aspirin in Two Women with Thrombophilia and Recurrent Pregnancy Loss.

Abstract 4184The combination of prophylactic heparin and low-dose aspirin was shown in the 1990s to improve pregnancy outcome in patients with antiphospholipid antibodies and recurrent pregnancy loss (RPL). Antiphospholipid antibodies induce placental thrombosis. When associations between hereditary thrombophilias and RPL were reported in the early 2000s, we and other physicians (Rodger MA J Obstr Gyn Canada 2002) began empirically prescribing prophylactic low molecular weight heparin, low-dose aspirin, or the combination to pregnant women with thrombophilia and unexplained RPL. We observed high live birth rates. Data emerged showing live birth rates of 70.2-94% in pregnant women with RPL treated with low-dose low molecular weight heparin and/or low-dose aspirin. Only one report has addressed treatment after failure of low-dose low molecular weight heparin: Brenner and colleagues (Thromb Haemost 2000) treated 3 pregnant women with multiple thrombophilic defects with enoxaparin 60 mg x 2/day after failure of enoxaparin 40 mg x 2/day; all 3 pregnancies yielded live births. We report cases of a live term birth and two ongoing viable pregnancies with therapeutic enoxaparin,1.5 mg/kg SC, (TEP) and aspirin after failure of prophylactic enoxaparin, 40 mg SC, (PEP) and aspirin in two women with thrombophilia and RPL.A 33 year-old woman with a history of 2 unexplained miscarriages at 6 weeks (Patient 1) and a 42 year-old woman with a history of 3 unexplained miscarriages at 8 weeks (Patient 2) presented in April 2006 and in August 2007 respectively. Uterine malformations, acquired uterine defects, and hormonal abnormalities were ruled out. Parental karyotypes were normal. Thrombophilia evaluation included: factor V Leiden, prothrombin gene mutation, methylene tetrahydrofolate reductase (MTHFR) gene mutation, fasting homocysteine, protein C, protein S, antithrombin, IgG anticardiolipin antibody, IgM anticardiolipin antibody, lupus anticoagulant, plasminogen activator inhibitor-1 (PAI-1), and PAI-1 4G/5G polymorphism. Positive results were: one copy each of the C677T and A1298C MTHFR mutations in Patient 1 and Patient 2; PAI-1 120 ng/mL and PAI-1 4G/4G polymorphism in Patient 2. The following describes the clinical course in both patients.Patient 1 was started on aspirin 81 mg daily and on clomiphene citrate to improve fertility. She conceived but miscarried at 7 weeks in June 2006. She underwent in vitro fertilization (IVF) in December 2006 while continuing on aspirin. She started on PEP daily within 24 hours of egg retrieval. She miscarried twins at 6 and 8&1/2 weeks. In May 2007, she conceived through IVF while continuing on aspirin. She started on TEP daily within 24 hours of egg retrieval. Anti-Xa level was monitored monthly. Enoxaparin was adjusted to maintain the anti-Xa level between 0.6 and 1.2 ui/mL. She delivered a healthy term baby on January 10, 2008. She continued to take aspirin daily. She conceived naturally in February 2009. She started on TEP daily with monthly anti-Xa monitoring when her pregnancy was confirmed. She currently has a live 24-week gestation.Patient 2 was started on aspirin 81 mg daily. She conceived through IVF in May 2008. She started on PEP daily within 24 hours of egg retrieval. She miscarried in a few weeks. She conceived through IVF in October 2008 while continuing on aspirin. She started on PEP daily within 24 hours of egg retrieval. After two weeks when her pregnancy was confirmed PEP was increased to TEP. She miscarried in a few weeks. She conceived in May 2009 through IVF while continuing on aspirin. TEP with monthly anti-Xa monitoring was started prior to IVF when she started her ovarian stimulation medications. She currently has a live 16-week gestation.Our report corroborates the findings by Brenner and colleagues of a benefit of an increased enoxaparin dose after failure of a low dose. It is possible that the higher dose leads to better control of a placental thrombotic state. While the timing of initiation of thromboprophylaxis has been established for natural pregnancies (aspirin is started pre-conception; enoxaparin is started at pregnancy confirmation or at detection of the fetal heartbeat), optimal time for initiation of thromboprophylaxis in IVF pregnancies has not been determined. Ovarian stimulation for IVF leads to a hyperestrogenic state which increases thrombotic risk. It is possible that starting TEP at the time of initiation of ovarian stimulation in Patient 2 enabled her ongoing viable second-trimester pregnancy by optimizing placental conditions. Disclosures:Off Label Use: Aspirin and enoxaparin during pregnancy to prevent recurrent fetal loss.

Hyperhomocysteinaemia, Low Folate Concentrations and Methylene Tetrahydrofolate Reductase C677T Mutation in Acute Mesenteric Venous Thrombosis

Objectives Acute mesenteric venous thrombosis (AMVT) was first reported by Fagge and was recognised as a distinct clinical entity by Warreen in 1935. However, its pathogenesis is still unclear. Elevated plasma levels of homocysteine (Hcy) are associated with an increased risk of deep vein thrombosis. This case-control study examines the potential association among hyperhomocysteinaemia (hyper-Hcy), low serum folate and vitamin B 12 levels and the common C677T mutation of the MTHFR gene in patients with AMVT. Materials and methods Sixty-three patients with AMVT and 75 sex- and age-matched healthy controls were recruited, and their plasma Hcy, folate and vitamin B 12 levels were measured by high performance liquid chromatography (HPLC) and immunological assays. The polymorphism of MTHFR C677T was detected by PCR-RFLP. Results The mean plasma Hcy levels were significantly higher in patients with AVMT compared with controls (23.5 standard deviation (S.D.) 8.8 vs. 12.6 ± 6.6 μmol l −1, P < 0.01). The fasting Hcy correlated negatively with folate (AMVT: r = −0.42, P < 0.01; Control: r = −0.40, P < 0.01). The frequency of homozygous (TT) genotype in MTHFR C677T mutation was significantly higher in patients with AMVT than that in control subjects (33% vs. 17%; chi square (χ 2) = 6.31, P < 0.05; odds ratio (OR) = 2.80; 95% confidence interval (CI): 1.25–6.25). Compared with the control subjects, the mean serum vitamin B 12 levels were lower in patients, but it was not statistically significant (365 ± 88 pmol l −1 vs. 408 ± 108 pmol l −1, P > 0.05). Conclusions Hyper-Hcy and low serum folate levels were associated with an increased risk of AMVT. The homozygous (TT) genotype of MTHFR gene mutation may be a crucial hereditary risk factor in the development of AMVT for a Chinese population.

Prevalence of methylenetetrahydrofolate gene (MTHFR) C677T polymorphism among chronic hemodialysis patients and its association with cardiovascular disease: a cross-sectional analysis

Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in end stage renal disease (ESDR) patients. A common C-T mutation at nucleotide position 677 (C677T) has been identified in the gene coding for methylenetetrahydrofolate reductase (MTHFR), which is involved in the remethylation of homocysteine (Hcy). The C677T mutation decreases MTHFR activity, tends to increase Hcy concentrations in individuals who are homozygous for the T/T genotype, and may predispose to CVD. Recent reports suggested that the T/T genotype may predispose type 2 diabetic and hypertensive patients to the development of progressive renal insufficiency. The aim of this cross-sectional study is to analyze the prevalence of the MTHFR C677T gene polymorphism among a group of chronic dialysis patients in comparison to age- and gender-matched controls. We also examined the possible association between CVD and MTHFR gene mutation in this group of patients. Fifty chronic hemodialysis patients were included in the study. They were 29 males and 21 females with a mean age of 41.57 +/- 11.76 years. Three patients (6%) were diabetic (type 2). Mean duration of dialysis was 6.4 +/- 3.2 years (range 1-15 years). CVD was defined as being present if there was a medical history of coronary artery disease, cerebrovascular stroke or transient ischemic attacks. MTHFR C677T gene polymorphism was analyzed by PCR in order to discriminate between homozygous (C/C and T/T) and heterozygous (C/T) genotypes. We also measured serum vitamin B(12), folate, total plasma Hcy (tHcy), lipid profile and serum albumin concentrations in the study group. Thirty healthy subjects (16 males and 14 females with mean age of 37.42 +/- 7.63 years) served as healthy controls. Thirteen patients (26%) experienced at least one cardiovascular event: two (4%) had a history of ischemic cerebrovascular disease, 13 (26%) had coronary artery disease, and one patient (2%) had myocardial infarction. The C677T mutation of MTHFR was not found to be different in hemodialysis patients and healthy controls. Thirty dialysis patients (60%) and 19 healthy subjects (63.33%) had only the wild-type allele (C/C), 16 dialysis patients (32%) and nine healthy controls (30%) had one T allele (C/T), and four dialysis patients (8%) and two healthy controls (6.67%) had two copies (T/T) of the T allele. There were no differences between patients with the three different MTHFR genotypes (C/C, C/T, T/T) regarding cardiovascular events or cardiovascular risk factors. Age, gender, percentages of diabetic and hypertensive patients, serum folate, vitamin B(12), lipid profile, and tHcy levels were not significantly different between the three groups (P > 0.05). Hemodialysis patients with CVD were significantly older compared to those without CVD (P = 0.02). Diabetes status was significantly associated with cardiovascular events (P = 0.01). In the dialysis population that we studied, MTHFR C677T gene polymorphism occurred in a pattern similar to that seen for age- and gender-matched healthy controls. No significant association was detected between the T/T genotype and CVD in dialysis patients. Plasma total homocysteine levels were not affected by mutation of the gene coding for MTHFR, and this may be explained by the normal serum folate and vitamin B(12) levels found in the study group.

Renal venous thrombosis in a newborn with prothrombotic risk factors

Renal venous thrombosis (RVT) is a rare but a well recognized entity in children and neonates. The clinical signs of neonatal RVT include hypertension, enlarged kidney(s), hematuria, renal insufficiency, proteinuria, thrombocytopenia, or all. Persisting impairment of kidney function and hypertension are serious and common complications in patients with RVT. Risk factors for the development of RVT include maternal diabetes mellitus, pathologic states associated with thrombosis (e.g., shock, dehydration, perinatal asphyxia, polycythemia), and sepsis. Inherited prothrombotic abnormalities have been described in some reports of RVT. We report the case of a male newborn with left RVT and associated homozygosity for both factor V Leiden (G1691A) and methylenetetrahydrofolate reductase C677T mutations in addition to elevated serum lipoprotein (a). The patient was treated with heparin. We believe our case to be the first reported case in the English medical literature of such an association between neonatal RVT and homozygosity for both factor V Leiden and methylenetetrahydrofolate reductase. This case and other studies clearly demonstrate that neonatal RVT should be evaluated for thrombophilia conditions.

Case-control Study of Methylenetetrahydrofolate Reductase Mutations and Hyperhomocysteinemia and Risk of Stroke

The association of factor V-Leiden and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C mutations with stroke was investigated in 118 patients with stroke and 120 control subjects. MTHFR 677TT (P < .001) and 1298CC (P < .001), but not factor V-Leiden (P = .179), genotypes were associated with stroke. The C677T but not A1298C MTHFR mutation was associated with elevated homocysteine levels in patients and control subjects. In addition to hypertension, the significant predictors for stroke were MTHFR 677CT and TT and A1298CC genotypes, together with hyperhomocysteinemia, indicating a synergistic effect of MTHFR mutations with elevated homocysteine and other risk factors in pathogenesis of stroke.

Inherited Thrombophilia and Preeclampsia Within a Multicenter Cohort: The Montreal Preeclampsia Study

Previous studies have suggested that inherited thrombophilia (hypercoagulability) may be associated with preeclampsia. Most of these studies were retrospective and showed positive associations between preeclampsia and several inherited thrombophilia polymorphisms. This prospective, multicenter case―control study investigated the association between inherited thrombophilia and preeclampsia among a cohort of 5337 pregnant women who were participants in the Montreal Preeclampsia Study, a large multicenter study of causal pathways of preterm birth. Of the 5165 woman followed up to delivery, 113 women (2.2%) developed preeclampsia and became the study group; 443 women who did not develop preeclampsia or nonproteinuric gestational hypertension became the control group. Prenatal blood samples were analyzed for the presence of 3 inherited thrombophilia polymorphisms (factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations), and homocysteine and folate levels were measured. The frequency of placental underperfusion (infarction, decidual vasculopathy, or syncytial knotting) was determined by pathological examination in all participants. Inherited thrombophilias were not more frequent in the study group than in the control group (14% vs. 21%, respectively); the adjusted odds ratio was 0.6, with a 95% confidence interval, of 0.3 to 1.3. Similar results were found for each individual thrombophilia, and were unchanged when the analysis was restricted to patients with early onset or severe preeclampsia. Homocysteine levels were higher in the control group than the study group. Placental underperfusion was found more frequently in the study group than in control group (63.2% vs. 46.2%, P < 0.0001) and among women with folate levels in the lowest quartile of control values (P = 0.04). There was no association, however, between placental underperfusion and thrombophilia either collectively or by individual mutation. These findings do not indicate an increased risk of preeclampsia among women with any of 3 inherited thrombophilias. The increase in placental underperfusion among women with preeclampsia seems to be associated with low plasma folate levels but not with the 3 thrombophilias examined.

Genetic Thrombophilias and Intrauterine Growth Restriction

To estimate the relationship between inherited thrombophilias and intrauterine growth restriction (IUGR) using meta-analytic techniques. A literature review identified case-control and cohort studies evaluating the relationship between IUGR and the following thrombophilias: homozygous or heterozygous factor V Leiden or prothrombin (PT) G20210A mutations and homozygous methylenetetrahydrofolate reductase (MTHFR) C677T mutation. Using mixed effects and random-effects models, the association between thrombophilias and IUGR was explored. Publication bias was assessed with funnel plots and corrected for with Duval and Tweedie's trim-and-fill method. The following number of related studies were found: studies evaluating relationships between factor V Leiden mutation and IUGR, 12 case-control and four cohort; between PT mutation and IUGR, 11 case-control and 0 cohort; and between MTHFR C677T homozygosity and IUGR, 10 case-control and two cohort. The overall summary odds ratio (OR) for the association between factor V Leiden and IUGR was significant (OR 1.23, 95% confidence interval [CI] 1.04-1.44); however, this was mainly driven by the positive association seen in the case-control studies (OR 1.91, 95% CI 1.17-3.12). The association between PT and IUGR was only explored in case-control studies yielding a summary OR that was not significant (OR 1.52, 95% CI 0.98-2.35). The overall summary OR for the association between MTHFR and IUGR was not significant (OR 1.01, 95% CI 0.88-1.17), but was significant for the case-control studies alone (OR 1.35, 95% CI 1.04-1.75). For both factor V Leiden and MTHFR mutations, a funnel-plot analysis of the case-control studies suggests publication bias. When the trim-and fill-method was used to correct for the publication bias, these summary estimates were no longer significant. The association between inherited thrombophilias and IUGR can only be discerned in case-control studies and seems to be largely because of publication bias. III.

The methylenetetrahydrofolate reductase C677T mutation induces cell‐specific changes in genomic DNA methylation and uracil misincorporation: A possible molecular basis for the site‐specific cancer risk modification

The C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with a decreased risk of colon cancer although it may increase the risk of breast cancer. This polymorphism is associated with changes in intracellular folate cofactors, which may affect DNA methylation and synthesis via altered one-carbon transfer reactions. We investigated the effect of this mutation on DNA methylation and uracil misincorporation and its interaction with exogenous folate in further modulating these biomarkers of one-carbon transfer reactions in an in vitro model of the MTHFR 677T mutation in HCT116 colon and MDA-MB-435 breast adenocarcinoma cells. In HCT116 cells, the MTHFR 677T mutation was associated with significantly increased genomic DNA methylation when folate supply was adequate or high; however, in the setting of folate insufficiency, this mutation was associated with significantly decreased genomic DNA methylation. In contrast, in MDA-MB-435 cells, the MTHFR 677T mutation was associated with significantly decreased genomic DNA methylation when folate supply was adequate or high and with no effect when folate supply was low. The MTHFR 677T mutation was associated with a nonsignificant trend toward decreased and increased uracil misincorporation in HCT116 and MDA-MB-435 cells, respectively. Our data demonstrate for the first time a functional consequence of changes in intracellular folate cofactors resulting from the MTHFR 677T mutation in cells derived from the target organs of interest, thus providing a plausible cellular mechanism that may partly explain the site-specific modification of colon and breast cancer risks associated with the MTHFR C677T mutation.

Peripheral arterial disease and methylenetetrahydrofolate reductase (MTHFR) C677T mutations: A case-control study and meta-analysis

Hyperhomocysteinaemia is associated with peripheral arterial disease (PAD). There are inter-individual variations in the metabolism of homocysteine because of genetic polymorphisms. This study analyzed the role of one polymorphism that is associated with raised homocysteine, as a risk factor for PAD. This study considered the association of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms with the incidence of PAD by performing a case-control study and a cross sectional study of homocysteine levels. We recruited 133 patients with PAD in Norfolk and compared the MTHFR allele distribution with 457 healthy individuals. We also carried out a meta-analysis to place our data within the context of other published studies. We searched Medline, Embase, and Cochrane databases up to March 2008 for any studies on the association between MTHFR C677T polymorphism and PAD. The MTHFR C677T allele frequencies in the cases and controls were 0.37 and 0.33, and the odds ratios for the association of the 677 T allele or TT genotype with PAD were 1.18 (95% Confidence Interval [CI] 0.89, 1.58) and 1.99 (95% CI 1.09, 3.63). Homozygotes for the MTHFR C677T mutation had higher concentrations of plasma total homocysteine, odds ratio 2.82 (95% CI 1.03, 7.77) compared to homozygotes for the MTHFR 677 CC genotype. Twelve of 72 articles retrieved from the database search reported the prevalence of mutations in PAD patients. A meta-analysis of 9 appropriate studies, including our own, showed that being homozygous for the C677T allele was associated with an increased risk of PAD, pooled odds ratio 1.36 (95% CI 1.09, 1.68). We have found a strong association between raised homocysteine, the TT genotype, and PAD.

Methylenetetrahydrofolate reductase C677T polymorphism in Iraqi patients with ischemic stroke

Data are conflicting concerning the association between ischemic stroke and methylenetetrahydrofolate reductase (MTHFR) C677T mutation. Studies addressing this matter in developing countries are limited. This study was undertaken to evaluate MTHFR C677T gene polymorphism as a possible risk factor in patients with ischemic stroke in Iraq. A case-control study in a major teaching hospital in Northern Iraq. Study population included 70 patients with ischemic stroke diagnosed by computed tomography (CT) or magnetic resonance imaging (MRI) and 50 controls matched by age and sex. All the patients and controls had detailed neurologic examination and blood sugar, lipid profile, total homocysteine, as well as, MTHFR gene analysis. The MTHFR C677T mutation status was detected in the amplified products using reverse hybridization to specific mutant and wild oligonucleotide probes by a colorimetric microwell plate method. Mann-Whitney U test and Chi-square tests were used to find the significance. The median age of the patients was 60 years and 54% were males. The MTHFR C677T gene analysis detected TT genotype in 20% of patients and in 6% of controls and CC genotype in 37% of the patients and in 54% of the controls. The calculated risk of ischemic stroke in the subjects with TT genotype was 4.85 times more than the subjects with CC genotype (P = 0.03). Serum homocysteine level was significantly higher in the patients than the controls (P = 0.02). The serum homocysteine levels were significantly higher in those with TT and CT genotypes when compared to those with CC genotype (P < 0.001 and P = 0.04, respectively). In the Iraq population studied MTHFR C677T TT genotype was a significant risk factor for ischemic stroke and it was related to the increased total homocysteine levels and the risk for ischemic stroke was graded with increasing MTHFR 677T allele dose.