Methylenetetrahydrofolate Reductase C677T Mutation Research Articles

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.

Two siblings with a homozygous MTHFR C677T (G80A-RFC1) mutation and stroke

Stroke is a rare disorder in childhood; among its risk factors, C677T mutations in the methylenetetrahydrofolate reductase (MTHFR) gene with secondary hyperhomocysteinemia are considered. We report on a family in which two brothers had arterial ischemic stroke (AIS). One of these siblings came to our observation at the age of 4 years because of decreased motility of the right arm, mild hypotrophy of the right limbs, and frequent falls: brain magnetic resonance imaging revealed a large left AIS. Family history revealed that his older brother had died at the age of 7 due to AIS. An extensive metabolic investigation revealed a homozygous C677T [G80A-reduced folate carrier 1 (RFC1)] mutation in the MTHFR gene in both the affected siblings and in their healthy older brother and heterozygous mutations in the parents. None of these family members presented hyperhomocysteinemia. To the best of our knowledge, this is the first family with multiple AIS patients harboring homozygous MTHFR gene C677T (G80A-RFC1) mutations without associated hyperhomocysteinemia (the latter factor is usually considered as effector of vascular damage in patients with MTHFR C677T mutations). The pathogenic hypotheses of stroke in this family are considered.

Genetic Polymorphisms in Venous Thrombosis and Pulmonary Embolism After Total Hip Arthroplasty: A Pilot Study

Deep venous thrombosis (DVT) after major orthopaedic surgery is a substantial concern. We asked whether the single or combined presence of thrombophilic genetic polymorphisms might further increase the already high risk for venous thrombosis and pulmonary embolism (PE) after THA. We therefore compared the prevalence of factor V Leiden, prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, and plasminogen activator inhibitor 4G/5G polymorphisms between 50 patients with symptomatic DVT within 3 weeks after elective THA and an asymptomatic control group of 85 patients. We found no major difference for the presence of a single mutation between the groups. Factor V Leiden and homozygous MTHFR C667T mutations were of borderline significance with odds ratios (95% confidence intervals) of 3.73 (0.89-15.63) and 2.93 (0.92-9.29), respectively. Patients with homozygous or combined heterozygous status of MTHFR C677T and A1298C mutation had a higher frequency of DVT after elective THA (odds ratio, 2.86; 95% confidence interval, 1.32-6.35) than those with wild-type. The presence of a single mutation may not further increase the already high risk for symptomatic DVT after THA, whereas combinations of mutations of distinct polymorphisms might be important. However, prospective studies with a larger number of patients are needed before we would recommend preoperative screening. Level III, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Acute myocardial infarction, ischemic cerebrovascular disease and variceal bleeding due to portal vein thrombosis in a patient with hereditary thrombophilia

We report on a 43-year-old female patient with multiple thrombotic risk factors who, in a few months, developed acute myocardial infarction, an ischemic cerebrovascular event and variceal bleeding due to portal vein thrombosis. The factor V Leiden mutation was carried in heterozygous form, homocysteine was elevated at 19.6 micromol/l, and methylenetetrahydrofolate reductase C677T mutation was carried in homozygous form. Moderately increased plasma homocysteine level and a reduced protein S activity were evident. Anticardiolipin IgG antibodies were mildly positive. We conclude that the presence of multiple genetic and environmental risk factors greatly amplifies the risk of clinical thrombotic events.

Predictive Factors of Cardiovascular Disease in Patients on Maintenance Hemodialysis

AbstractOBJECTIVEThe purpose of this study was to identify the role of the methylenetetrahydrofolate reductase (MTHFR) gene mutation and other predictive factors of cardiovascular disease (CVD) in patients on maintenance hemodialysis.METHODSA total of 144 patients with end‐stage renal disease (ESRD) undergoing maintenance hemodialysis for at least 6 months were recruited. The mean age of patients was 44.84 ± 16.23 years. Serum folate, vitamin B12, homocysteine (tHcy), albumin, lipids, MTHFR C677T mutation, and smoking habits were analyzed relative to the presence of CVD.RESULTSForty‐two of the 144 patients (29.1%) had CVD. Mean age, duration of dialysis, body mass index, CRP, Kt/V, male sex, diabetes mellitus, and currently smoking were found to be significantly higher in patients with CVD than in those without CVD (p &lt; 0.05). The means of serum folate, vitamin B12, tHcy, albumin, and percentage of past smokers were not significant (p &gt; 0.05). MTHFR C677T mutation was not found to be associated with CVD risk factors. The mean differences in tHcy levels between the TT and CC and the CT and CC genotype allele groups were significant.CONCLUSIONWe recommend that duration of ESRD and CRP predictors with traditional risk factors be taken into account when examining CVD. We suggest that if patients with ESRD have normal B12 and folate levels, abnormal tHcy level and tHcy metabolism are not risk factors for CVD in patients with ESRD. We do not recommend evaluation of the MTHFR C677T mutation and tHcy level in maintenance hemodialysis patients. The discriminative ability of risk predictors in CVD found in the study present new ideas for researchers studying this subject.

The Association Between Common C677T Mutation in Methylenetetrahydrofolate Reductase Gene and the Risk of Venous Thrombosis in an Iranian Population

Background: Venous thrombosis is a multicausal disease involving acquired and genetic factors. The prevalence of methylenetetrahydrofolate reductase (MTHFR) C677T genotypes and its association with venous thrombosis is not established in the Iranian population. In this study we investigated a possible association between fasting hyperhomocysteinemia and C677T mutation in the MTHFR gene with venous thrombosis. Materials and Methods: We studied 200 venous thrombotic patients and 100 healthy controls, of similar age and sex. Mutation analysis was carried out by PCR-RFLP, and the homocysteine level was measured by EIA. Results: No significant differences in the frequency of C677T genotypes were observed between patients and controls (P=0.2). The frequency of the T allele was 21% and 27.2% in controls and patients, respectively (odds ratio, 1.27; 95% CI, 0.83–1.94, P=0.15). Fasting homocysteine level was significantly higher in patients than controls (P=0.001). Conclusions: We concluded that hyperhomocysteinemia, but not MTHFR C677T mutation, is a significant risk factor for venous thrombosis in the Iranian population, and measuring the level of homocysteine is less expensive and more useful than the genetic test for the MTHFR mutation.

Study on Homocysteine Levels and Methylenetetrahydrofolate Reductase Gene Variant (C677T) in a Population of Buenos Aires City

The substitution of cytosine (C) by thymine (T) at nucleotide 677 of the methylenetetrahydrofolate reductase (MTHFR) gene, which converts an alanine to a valine residue, is a frequent polymorphism with reduced specific activity, associated with moderate increase in plasma homocysteine levels (tHcy) and risk of vascular diseases. Objectives. This study was designed to investigate an association of this polymorphism with tHcy and vascular risk factors. Methods. We used a cross-sectional study on subjects affiliated to three health centers from Buenos Aires city. The diagnosis of hypertension was ascertained by patients' clinical history. Only subjects under long-term antihypertensive treatment were included. Results. Samples from 138 physically active individuals (44 men and 94 women) randomly selected were included. The mean tHcy was significantly higher amongst hypertensives (HT) than normotensives (NT). The risk of hypertension was compared in subjects with CC genotype and the combined number of subjects with at least one T allele (CT/TT). There was no significant difference regarding the risk of hypertension between NT and HT groups in the overall sample. However, as obesity is considered a risk factor for hypertension development, when only HT (n = 29) and NT (n = 66) subjects with body mass index below 30 kg/m2 (BMI<30) were compared, subjects bearing CT/TT presented a significantly higher risk of hypertension than those bearing the CC genotype and significantly higher concentration of tHcy. Conclusions. Our results indicate an association of hyper-tHcy and MTHFR C677T mutation with hypertension. MTHFR C677T mutation may contribute to hypertension or affect the development of hypertension through hyperhomocysteinemia.

Arterial thrombosis associated with factor V Leiden and methylenetetrahydrofolate reductase C677T mutation in childhood membranous glomerulonephritis

Acquired abnormalities of coagulation and fibrinolysis in nephrotic syndrome have been implicated in the pathogenesis of deep-vein and arterial thrombosis. A mutation in the factor V and methylenetetrahydrofolate reductase (MTHFR) gene, the commonest inherited risk factor for venous thrombosis, may contribute to the risk of both arterial and deep-vein thrombosis in patients with nephrotic syndrome. Here, we report on an arterial thrombosis in a young girl with idiopathic membranous glomerulonephritis associated with heterozygous factor V Leiden and homozygous MTHFR C677T mutation. We postulate that screening for factors such as factor V Leiden and MTHFR C677T mutation may be beneficial to patients associated with thromboembolism and idiopathic nephrotic syndrome.

Hyperhomocysteinemia, Deep Vein Thrombosis and Vitamin B12 Deficiency in a Metformin-treated Diabetic Patient

Vitamin B12 deficiency may be induced by long-term use of metformin, which may in turn lead to hyperhomocysteinemia. Thus, hyperhomocysteinemia may increase the risk of vascular thrombosis in diabetic patients, when metformin is used and a homozygous methylenetetrahydrofolate reductase (MTHFR) C677T mutation is present. We report a 65-year-old Taiwanese diabetic woman who was treated with metformin for 6 years and who had suffered from swelling of the left lower extremity for 3 months. Ascending venography confirmed the diagnosis of proximal deep vein thrombosis, while hyperhomocysteinemia, megaloblastic anemia caused by vitamin B12 deficiency, and a homozygous C677T mutation of the MTHFR gene were also found. She had no identifiable venous thrombotic risk factors other than hyperhomocysteinemia, which seemed to be caused by both MTHFR C677T homozygous mutation and vitamin B12 deficiency. With the substitution of insulin injection for metformin, short-term supplement of vitamin B12, and anticoagulant therapy for the deep vein thrombosis, her anemia and hyperhomocysteinemia recovered rapidly. The deep vein thrombosis also responded well. Our findings highly suggested the role of metformin in causing vitamin B12 deficiency, which may serve as an additional risk factor for venous thrombosis in diabetic patients. Our report also highlights the need to check vitamin B12 levels during metformin treatment.

Two Cousins With Neonatal Stroke, PAI-1 4G Variant and MTHFR A1298C Mutation

The authors describe 2 female cousins with neonatal stroke. One was heterozygous for the plasminogen activator inhibitor-1 4G variant and compound heterozygous for the A1298C and C677T methylenetetrahydrofolate reductase mutations. Her cousin was homozygous for the plasminogen activator inhibitor-1 4G variant and heterozygous for the methylenetetrahydrofolate reductase A1298C and factor V Leiden mutations.

High frequency of vitamin B12 deficiency in asymptomatic individuals homozygous to MTHFR C677T mutation is associated with endothelial dysfunction and homocysteinemia

The aim of this study was to examine the association of homozygosity for the methylenetetrahydrofolate reductase (MTHFR) C677T mutation and vitamin B12 deficiency in 360 asymptomatic individuals and to investigate forearm endothelial function in C677T homozygotes. MTHFR C677T mutation and levels of vitamin B12, folic acid, and homocysteine were measured in study participants. Frequency of homozygosity for the C677T mutation was 67/360 (18.6%). Homocysteine levels were elevated in homozygous compared with heterozygous subjects or those without the mutation (20.6 +/- 18.8 vs. 9.4 +/- 3.2 mumol/l; P < 0.0001). The number of subjects with vitamin B12 deficiency (<150 pmol/l) was significantly higher among the homozygote than the heterozygote subjects or subjects without mutation [20/67 (29.8%) vs. 27/293 (9.2%); P < 0.0001]. Homozygote subjects had 4.2 times higher probability of having B12 deficiency (95% confidence interval = 2.1-8.3). Forearm endothelial function was assessed in 33 homozygote and 12 control subjects. Abnormal endothelial function was observed in homozygous subjects and was worse in homozygote subjects with vitamin B12 deficiency. Endothelial function was normalized after B12 and folic acid treatment. We found that homozygosity for the C677T mutation is strongly associated with B12 deficiency. Coexistence of homozygosity for the C677T mutation and B12 deficiency is associated with endothelial dysfunction and can be corrected with vitamin B12 and folic acid treatment.

The Frequency of Factor V Leiden and Concomitance of Factor V Leiden With Prothrombin G20210A Mutation and Methylene Tetrahydrofolate Reductase C677T Gene Mutation in Healthy Population of Denizli, Aegean Region of Turkey

Factor V Leiden causing activated protein C resistance is the most common inherited form of thrombophilia leading to thrombosis. Its frequency shows great ethnic and geographic variations. The aim of this study was to determine the frequency of FV Leiden and coinheritance of FV Leiden with two other frequent hereditary thrombophilia causes, namely, prothrombin G20210A and methylene-tetrahydrofolate reductase (MTHFR) C677T mutation in the Aegean region of Turkey. The study population consisted of 1030 (500 men and 530 women) apparently healthy subjects. Functional resistance to activated protein C (APC) was measured by using the test kit STA staclot APC-R ((Diagnostica Stago, Asnieres, France, Cat. No. 00721). In subjects with APC resistance, molecular analyses of FV Leiden and of prothrombin G20210A and MTHFR C677T mutation were performed by using FV-PTH-MTHFR StripA (Vienna Lab, Labordiagnostika GmbH, Austria) kit, which was based on hybridization of polymerase chain reaction (PCR) amplified DNA products with mutation-specific oligonucleotide probes. Functional APC resistance was present in 93 subjects (9%). FV Leiden mutation was found in 87 of 93 subjects with APC resistance by PCR method. The FV Leiden carrier frequency was found to be 8.4% (87/1030). Seventy-six individuals were heterozygous (7.3%), and 11 were homozygous (1.06%). Among the 87 subjects with FV Leiden mutation, 45 subjects had MTHFR C677T gene mutation (7 homozygous, 38 heterozygous) and 4 subjects had heterozygote prothrombin G20210A gene mutation. A combination of FV Leiden and prothrombin G20210A and MTHFR C677T gene mutation was detected in 3 subjects. The results indicate that FV Leiden prevalence is quite high and coexistence of FV Leiden with other hereditary causes of thrombosis such as prothrombin G20210A mutation and MTHFR enzyme defect is not rare in healthy population of Aegean region of Turkey.

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>or=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.

Sex-Specific Effect of the Thermolabile C677T Mutation in the Methylenetetrahydrofolate Reductase Gene on Angiographically Assessed Coronary Artery Disease in Brazilians

Hyperhomocysteinemia is associated with increased coronary artery disease (CAD) risk. Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the metabolism of homocysteine and presents a common mutation (C677T) that leads to a thermolabile enzyme, mild hyperhomocysteinemia, and increased CAD risk. The C677T MTHFR mutation was studied in 772 subjects (480 Caucasian Brazilians and 292 African Brazilians) who underwent coronary angiography at the hemodynamic center of the Santa Izabel Hospital in Salvador, Bahia State, Brazil. The 677T allele frequency was increased in Caucasian Brazilians (28.1%) compared to the frequency observed in African Brazilians (18.3%; p < 0.001). In Caucasian Brazilians the frequency of the 677T homozygous genotype was increased in CAD cases (10.4%) compared to control subjects (1.4%; p = 0.014) in males but not in females. In African Brazilians the mutation was not associated with CAD in either sex. The multivariate logistic regression analysis of all the samples shows that the 677T homozygous interaction with sex was a significant CAD predictor, independent of other classical risk factors and ethnic group. The odds ratio associated with male 677T homozygotes was increased 9.2-fold (p = 0.021) compared to the 677C carriers. The present study suggests that the C677T MTHFR mutation is associated with increased CAD risk in a sex-dependent manner in Brazilians.

Plasma homocysteine cutoff values for venous thrombosis

Hyperhomocysteinemia is considered an independent risk factor for vascular occlusive diseases. To date, there is no general agreement on hyperhomocysteinemia cutoff values. To establish a homocysteine cutoff value, we performed a case-control study in 118 patients suffering from venous thrombosis and in 115 healthy subjects. We calculated odds ratios at different cutoff points and considered hyperhomocysteinemia as homocysteine levels above which the risk of venous thrombosis was increased. Initially we used the 97.5th percentiles for fasting homocysteine levels in the control group to calculate odds ratios (95% CI) of 9.5 (2.6-35.3), 3.7 (0.8-17.9) and 4.5 (1.7-123.8) for the total population, women and men, respectively. When individuals with well-known thrombotic risk factors were excluded (selected population), odds ratios were 10.5 (2.7- 41.1), 6.5 (1.3-32.1) and 11.2 (1.2-103.1), respectively, confirming hyperhomocysteinemia as an independent risk factor for venous thrombosis. We did not find any association of venous thrombosis with the homozygous methylenetetrahydrofolate reductase C677T mutation. When the hyperhomocysteinemia cutoff was set at other arbitrary points, odds ratios for the selected population were statistically significant only at >12 micromol/L. Based on our results, we propose 12 micromol/L as the hyperhomocysteinemia cutoff value.

The 5, 10 methylenetetrahydrofolate reductase C677T mutation and risk of fetal loss: a case series and review of the literature

BackgroundThe true relationship between methylenetetrahydrofolate reductase C677T homozygosity and risk of recurrent spontaneous abortion is unknown, and it is unclear if women with these mutations should be anticoagulated during pregnancy.ObjectivesWe report a series of 8 patients with this issue and review the current literature.Methods8 patients (3 of whom were actively pregnant) were referred with histories of spontaneous fetal loss; hypercoaguability work-ups revealed each were homozygous for the MTHFR C677T mutation without other thrombophilias.ResultsIn the 3 women who have conceived, treatment with LMW heparin during pregnancy led to two full-term births and one additional pregnancy without complication. For the 5 who have not, we recommended treatment with LMW heparin upon conception.ConclusionWe provide evidence to support the relationship between MTHFR C677T mutations and recurrent fetal loss, and to suggest that anticoagulation of these patients during pregnancy can lead to a successful pregnancy outcome.

Congenital Prothrombotic Disorders in Children with Peripheral Venous and Arterial Thromboses

Aims: To evaluate the prevalence of congenital prothrombotic disorders in children with peripheral venous and arterial thromboses. Methods: Deficiencies in antithrombin (AT), proteins C (PC) and S (PS), and increased lipoprotein (a), and the presence of factor V (FV) G1691A, prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) mutations were investigated. Results: Forty-eight patients (mean age, 3.4 years) were investigated. Of these patients, 23 had venous thrombosis, 22 had arterial thrombosis, and 3 had both. No patients had AT, PC or PS deficiency. FV G1691A mutation was present in 2 (7.6%) and 3 (12%) patients with venous and arterial thromboses, respectively. The prothrombin G20210A mutation was present in 1 (4%) patient with arterial thrombosis. Homozygous MTHFR C677T mutation was detected in 4 (18%) and 2 (9%) patients with venous and arterial thromboses, respectively. Increased lipoprotein (a) was present in 2 (10%) and 1 (4.5%) patients with venous and arterial thromboses, respectively. Regarding acquired risk factors, 79% of all thrombotic events were related to catheter usage. An underlying disease was present in 96% of the patients. Conclusions: Compared to acquired risk factors, congenital prothrombotic disorders are rarely present in children with peripheral venous and arterial thromboses. These results do not support general screening of children with venous and arterial thromboses for congenital prothrombotic disorders.

High frequency of methylenetetrahydrofolate reductase 677TT genotype in Hungarian HELLP syndrome patients determined by quantitative real-time PCR

Our aim was to determine the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in hypertensive disorders during pregnancy. We conducted our experiments on isolated DNA samples of 73 healthy pregnant, 101 severe pre-eclamptic and 63 HELLP syndrome women in this study. The MTHFR C677T polymorphism was determined by quantitative real-time PCR method. A significantly higher number of the TT genotype (25.4%) was found in the HELLP syndrome group compared to the healthy (8.2%) and severe pre-eclamptics group (8.9%) (P=0.03). The frequency of the mutant T allele was found to be 45.2% of HELLP syndrome, whereas it was 32.2% of the healthy pregnant (P=0.03) and 30.2% (P=0.008) of the severe pre-eclamptic patients. In the HELLP group a high frequency of eclampsia was observed (12.6%) and among them 75% had the MTHFR C677T mutation.

Is Homozygosity for the MTHFR C677T Mutation a Risk Factor for Miscarriage? — Likely.

Various hereditary thrombophilias such as activated protein C resistance, the factor V leiden mutation, the prothrombin G20210A mutation, protein S deficiency, hyperhomocysteinemia, or combinations of the above disorders have been linked to pregnancy loss at varying stages of gestation (Robertson L, et al. Thrombophilia in pregnancy: a systematic review. Br J Haematol 2006; 132(2):171–96; Seligsohn U, et al. Genetic susceptibility to venous thrombosis. N Engl J Med 2001; 344(16):1222–31). The literature regarding methylenetetrahydrofolate reductase (MTHFR) mutations is confusing. Much of the evidence supporting a causal relationship between MTHFR mutations and early fetal loss comes from individual case reports with little outcome data. Three recent meta-analyses of thrombophilia in pregnancy concluded that although there may be a trend toward higher risk, the relationship between MTHFR mutations and spontaneous abortions is not truly significant (Robertson L, et al. Thrombophilia in pregnancy: a systematic review. Br J Haematol 2006; 132(2):171–96; Nelen WL, et al. Hyperhomocysteinemia and recurrent early pregnancy loss: a meta-analysis. Fertil Steril 2000; 74(6):1196–9; Rey E, et al. Thrombophilic disorders and fetal loss: a meta-analysis. Lancet 2003; 361(9361):901–8). In contrast, a study supporting the role of MTHFR mutations in recurrent unexplained abortions found a 2–3 fold increased risk of early fetal loss among Caucasian females homozygous for the C677T mutation versus normal controls (Nelen WL, et al. Genetic risk factor for unexplained recurrent early pregnancy loss. Lancet 1997; 350(9081):861). We present 5 patients with this genetic defect who presented consecutively to our clinic for decision making for future pregnancies. Each had strong histories of miscarriages after the 8th week of gestation. The clinical features of these patients are reported in the table below. [Display omitted] Each woman is Caucasian, and is homozygous for the MTHFR C677T mutation with no other acquired or hereditary thrombophilias. Homocysteine levels were also in normal range for each patient. Our case series of 5 Caucasian women gives support to the theory of a causal relationship between MTHFR mutations and fetal loss. We recommended anticoagulation with low-molecular weight or unfractionated heparin for each patient as a therapeutic intervention to reduce the risk of recurrent abortion in future pregnancies.

Methylenetetrahydrofolate reductase C677T polymorphism and the risk of unexplained recurrent pregnancy loss: A meta-analysis

To investigate the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of unexplained recurrent pregnancy loss (URPL). Meta-analysis of published case-control studies of the MTHFR C677T variant and URPL risk. A research institution in China. Women with URPL. None. Odds ratios (ORs) and 95% confidence intervals (CIs) for TT versus CC genotype, CT versus CC genotype, TT versus CT and CC genotype combined, and for T versus C allele. Twenty-six studies with 2120 URPL cases and 2949 controls were included. Overall random-effects ORs of 1.49 (95% CI, 1.12-2.00) for TT versus CC genotype, 1.40 (95% CI, 1.11-1.77) for TT versus CT and CC genotype combined, and 1.21 (95%CI, 1.04-1.40) for T versus C allele were found. Stratified analysis showed that significant strong associations between MTHFR C677T polymorphism and URPL were present only in the five Chinese studies (OR = 2.96 for TT versus CC genotype; OR = 2.30 for TT versus CT+CC genotype; OR = 1.73 for T versus C allele), but not in any other studies, including the studies conducted in the European countries. The MTHFR C677T mutation is not a genetic risk factor for URPL except in a Chinese population.