Methylenetetrahydrofolate Reductase Gene Variants Research Articles

Analysis of 9 patients with adolescence-onset methylenetetrahydrofolate reductase deficiency

Objective: To explore the diagnosis and treatment of adolescence-onset methylenetetrahydrofolate reductase (MTHFR) deficiency. Methods: This was a retrospective case study. Nine patients with adolescence-onset MTHFR deficiency were diagnosed at Peking University First Hospital from January 2016 to December 2022, and followed up for more than 1 year. Their general information, clinical manifestations, laboratory tests, cranial images, MTHFR gene variants, diagnosis, treatment, and outcome were analyzed retrospectively. Results: The 9 patients came from 8 families. They had symptoms at age of 8.0 years to 17.0 years and diagnosed at 9.0 years to 17.5 years. Eight were male and 1 was female. Two patients were brothers, the elder brother developed abnormal gait at 17.0 years; and the younger brother was then diagnosed at 15.0 years of age and treated at the asymptomatic stage, who was 18.0 years old with normal condition during this study. The main manifestations of the 8 symptomatic patients included progressive dyskinesia and spastic paralysis of the lower limbs, with or without intellectual decline, cognitive impairment and behavioral abnormalities. Totally, 15 variants of MTHFR gene were identified in the 9 patients, including 8 novel variants. Five patients had brain image abnormalities. Increased plasma total homocysteine level (65-221 μmol/L) was found in all patients, and decreased to 20-70 μmol/L after treatment with betaine and calcium folinate. Besides, the 8 symptomatic patients had their behavior and cognitive problems significantly improved, with a legacy of lower limb motor disorders. Conclusions: Late-onset MTHFR deficiency can occur in adolescence. The diagnosis is usually delayed because of non-specific clinical symptoms. The test of blood total homocysteine could be used as a selective screening test. Eight novel varients of MTHFR gene were identified. Timely treatment can improve clinical condition significantly, and pre-symptomatic treatment may prevent brain damage.

Association of methylenetetrahydrofolate reductase gene variant C677T and folate levels in non-syndromic cleft lip/palate among Sindhi, Pakistani population.

The object ives of this study were to determine the association of methylenetetrahydrofolate reduc tase (MTHFR) gene variant C67 7 T with non -syndromic cl eft lip/palate (NSCLP) in Pakistani population and compare the m aternal serum foli c acid levels in NSCLP-affected and healthy group. A c om parative cross sec ti onal study was conducted between 2017 and 2019 at Liaquat U niversity of Medi cal and Health Science s, Jamshoro. Sixty motherinfant dy ads were recruited (n=120), inc luding NSCLP-affected and healthy infants alo ng with t heir mother s. The MTHFR C677T vari ant exhibited si gnificant association with NSCLP in dominant and over-domi nant models. No differences in maternal serum folic acid levels were obse rved between both th e groups; however, the folic acid intake during pre-conception period was associated w ith decreased risk for NSC LP. Our stu dy suggested that MTHFR 677 CT genotype was related with decreased risk for NSCLP in Sindhi, Pakistani, population. Pre -conception folic acid may decrease the ri sk for ora l clefts.

Association between COVID-19 Infection or Vaccination Outcomes and Methylenetetrahydrofolate Reductase Gene Polymorphism: A Systematic Review of the Literature.

Thrombosis is a detrimental sequala of COVID-19 infection; thus, prophylactic anti-coagulant therapy has been deemed mandatory in treatment unless serious contraindications are present. Susceptibility to thromboembolic events in COVID-19, or following COVID-19 vaccination, is likely attributable to an interplay of factors, including a patient's baseline clinical status and comorbidities, alongside genetic risk factors. In Europe, 8-20% of the population are homozygous for the MTHFR (methylene tetrahydrofolate reductase) variant, which compromises folate metabolism and elevates homocysteine levels. While heightened homocysteine levels are considered a risk factor for thromboembolic events, the precise clinical significance remains a contentious issue. However, recent research suggests elevated homocysteine levels may predict the course and severity of COVID-19 infection. Given the lack of reliable biomarkers predictive of COVID-19 thrombotic risk existing in practice, and the accessibility of MTHFR screening, we established two main outcomes for this study: (1) to determine the association between hereditary MTHFR mutations and COVID-19 severity and thromboembolic events and (2) to determine the link between MTHFR variants and adverse thrombotic events following COVID-19 vaccination. The review was conducted in accordance with PRISMA guidelines. Medline, Scopus, and Web of Science databases were searched from pandemic inception (11 March 2020) to 30 October 2023. Eligibility criteria were applied, and data extraction performed. From 63 citations identified, a total of 14 articles met the full inclusion criteria (8 of which were cross-sectional or observational studies, and 6 were case studies or reports). Among the eight observational and cross-sectional studies evaluating the relationship between MTHFR variants (C667T; A1298C) and thromboembolic events in COVID-19 infection, four studies established a connection (n = 2200), while the remaining four studies failed to demonstrate any significant association (n = 38). This systematic review demonstrated a possible association between the MTHFR gene variants and COVID-19 severity, thromboembolic events, and adverse events following vaccination. However, the paucity of robust data precluded any firm conclusions being drawn. Further prospective trials are required to determine the connection between the MTHFR gene variant and COVID-19 infection and vaccination outcomes.

Associations of LRP5 and MTHFR Gene Variants with Osteoarthritis Prevalence in Elderly Women: A Japanese Cohort Survey Randomly Sampled from a Basic Resident Registry.

ObjectiveOsteoarthritis (OA) is a common and degenerative joint disorder in the elderly. A greater importance of understanding the relationship between genetic factors and OA prevalence has emerged with population aging. We therefore investigated the associations of several bone disease-related genetic variants with the prevalence of OA and osteoporosis in Japanese elderly women from the Obuse study cohort, which was randomly sampled from a basic town resident registry.Methods and ResultsIn total, 206 female participants (mean ± standard deviation age: 69.7 ± 11.0 years) who completed OA, bone mineral density, and genotype assessments were included. The number of patients diagnosed as having knee/hip OA and osteoporosis was 59 (28.6%) and 30 (14.6%), respectively. Fisher’s exact testing revealed significant relationships between the minor T allele of LDL receptor related protein 5 (LRP5) rs3736228 and the prevalence of knee/hip OA and osteoporosis. The respective odds ratios (ORs) of the TT genotype for knee/hip OA and osteoporosis were 7.28 (95% confidence interval [CI] 2.22–28.08) and 5.24 (95% CI 0.95–26.98). An additional subgroup analysis for knee OA revealed that the frequency of the common C allele of methylenetetrahydrofolate reductase (MTHFR) rs1801133 had a statistically significant protective association with the prevalence of knee OA (OR 0.58, 95% CI 0.35–0.97).ConclusionIn sum, the present study demonstrated significant associations of LRP5 rs3736228 and MTHFR rs1801133 with knee/hip OA and osteoporosis prevalences and knee OA prevalence, respectively, in Japanese elderly women. These results will help further the understanding of OA pathogenesis and related genetic risk factors.

A COMPARATIVE STUDY ON RISK OF OSTEOPOROSIS ASSOCIATED WITH THE USE OF VALPROATE VERSUS LEVETIRACETAM IN EPILEPTIC PATIENTS AND ITS RELATIONSHIP WITH METHYLENE TETRA-HYDRO FOLATE REDUCTASE GENOTYPES

Objective: The study objects at assessing and comparing the intensity of the effect of valproate (VPA) and levetiracetam (LV) on the bone mass in young adult epileptic patients while distinguishing their methylene tetra-hydro folate reductase (MTHFR) genotypes and correlating MTHFR polymorphism and antiepileptic drugs (AEDs) usage with the risk of development of osteoporosis.
 Methods: The study design was a comparative, prospective, and observational study. It was conducted at Princess Esra Hospital (PEH), Hyderabad and genotype testing was carried out at Salar-e-Millat Research lab (PEH). The consent was obtained from total 70 subjects, divided into three groups:
 Group 1: 18 patients receiving sodium VPA monotherapy
 Group 2: 17 patients receiving LV monotherapy
 Group 3: 35 healthy control subjects from general population.
 Patients of either gender within age group of 15–40 years, experiencing generalized tonic-clonic seizures or focal seizures, receiving the AED for duration of time ≥2 years were included in the study.
 Results: Our study showed significant correlation between the AEDs treatment and MTHFR polymorphism in predisposing osteoporosis.
 Conclusion: The variants of MTHFR gene (C677T) are prone to develop increased levels of homocysteine as a result of decreased activity of the enzyme in their bodies which are further increased in patients receiving AEDs. Monitoring of homocysteine levels in epileptic patients especially in the mutants of MTHFR gene along with their periodic testing of bone mineral density levels is recommended. Treatment for low folate and calcium levels is recommended in these patients to correct their deficiencies.

Venous thromboembolism associated with hyperhomocysteinemia, homozygosity for the methylenetetrahydrofolate reductase 677C>T gene variant, and secondary polycythemia.

: The development of pulmonary embolism/deep vein thrombosis (DVT) in the extremities is influenced by various risk factors. Hyperhomocysteinemia is one such risk factor, which may be associated with vitamin B12/folate deficiency, or the methylenetetrahydrofolate reductase gene variant, 677C>T. Here, we report a 47-year-old male who developed pulmonary embolism/DVT, associated with hyperhomocysteinemia (plasma homocysteine: 71.9 nmol/ml; reference range: 6.3-18.9 nmol/ml) and was homozygous (T/T) for the methylenetetrahydrofolate reductase variant. Serum levels of vitamin B12 and folate were within the normal range, while secondary polycythemia (hemoglobin: 18.2 g/dl and hematocrit: 50.8%) may have acted as an additional trigger for the thromboembolism. The pulmonary embolism/DVT was successfully managed and the patient has been doing well for longer than 3 years.

Methylenetetrahydrofolate Reductase Gene Variants Confer Potential Vulnerability to Autism Spectrum Disorder in a Saudi Community.

PurposeSeveral interacting genes or single nucleotide polymorphisms (SNPs) are vulnerable to the risk of autism spectrum disorder (ASD). Here we explored associations between SNPs in the methylenetetrahydrofolate reductase (MTHFR) gene or combined genotypes and the risk of ASD in a Saudi community.Subjects and methodsASD severity symptoms were assessed according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria and scores on the childhood autism rating scale (CARS). Genomic DNA from buccal cells was analyzed for 112 cases and 104 healthy controls using TaqMan genotyping assays of 677C>T rs1801133 and 1298A>C rs1801131 SNPs in the MTHFR gene. SNPStats software was utilized to determine the best interactive model of inheritance of genotypic data.ResultsControls were consistent with Hardy-Weinberg equilibrium in the examined SNPs. Our data showed associations between the 677C>T and 1298A>C SNPs and ASD risk (odds ratio [OR]= 5.2; 95% confidence interval [CI], 3.1–9.8 and OR= 22.2; 95% CI, 7.9–62.3, respectively). Genotype associations of 677C>T and 1298A>C were identified in cases compared with controls (P= 0.0012 and P= 0.0008, respectively). The examined SNPs were significantly associated with ASD cases having ≥37 scores (codominant and recessive models; P= 0.001 and P= 0.0005, respectively). Six combined genotypes—C/C-A/A (42.9%), C/T-A/A (17.9%), C/T-C/C (14.5%), C/T-A/C (10.9%), T/T-C/C (10.9%), and T/T-A/A (3.6%)—were found in ASD cases. Global haplotype analysis showed a significant difference in haplotype distribution between cases and controls (P= 0.00057). The two SNPs were found to be in relatively strong linkage disequilibrium (D`= 0.63, r2= 0.260).ConclusionOur findings suggest that the 677C>T and 1298A>C SNPs add to each other for potential vulnerability to increase the risk of ASD, particularly if they can be confirmed in larger cohorts along with other genetic/environmental factors. Our study could create reference data for future genetic association studies in the Saudi population and for use by government and health experts to develop regional health management programs.

Association between the methylenetetrahydrofolate reductase (MTHFR) gene 677C>T and 1298A>C polymorphisms and the risk of diabetic nephropathy; a meta-analysis

Methylenetetrahydrofolate reductase (MTHFR) is involved in the homocysteine metabolism. Two common variants of MTHFR gene (677C>T and 1298A>C), have been reported to reduce the MTHFR enzyme activity and leading to plasma hyperhomocysteinemia. There are a number of recent case-control studies that investigated the association between the MTHFR polymorphism and diabetic nephropathy (DN), albeit with inconsistent results. The aim of this meta-analysis is to evaluate the associations between the genetic polymorphisms of MTHFR with susceptibility to DN. A literature search was conducted on PubMed, Embase and Google scholar from inception till March 18, 2019. For MTHFR 677C>T analysis, a total of 23 studies including DM controls (3095 cases and 3187 DM controls) and 12 studies including non-DM controls (1590 cases and 2052 nonDM controls) were taken. For MTHFR 1298A>C analysis, a total of 7 studies using DM controls (959 cases and 1209 DM controls) and 3 studies using non-DM controls (400 cases and 802 nonDM controls) were taken. Meta-analysis showed that mutant genotypes of the 677C>T (OR: 1.58; 95%CI: 1.16-2.14) and 1298A>C (OR: 1.38; 95%CI: 1.16-1.65) polymorphisms in the MTHFR gene were associated with increased risk of DN (diabetic kidney disease). MTHFR 677C>T and 1298A>C polymorphisms revealed significant heterogeneity between studies. Further, there was no evidence for publication bias for these polymorphisms. In conclusion, this meta-analysis provides strong evidence that MTHFR 677C>T and 1298A>C polymorphisms may be associated with increased risks of DN. However, further studies are still needed to accurately determine whether MTHFR genetic polymorphisms are associated with susceptibility to DN.

Study of C677T variant of methylene tetrahydrofolate reductase gene in autistic spectrum disorder Egyptian children.

Autism spectrum disorders (ASD) is a heterogeneous neurodevelopmental disease, various articles reported that dysfunctional folate-methionine pathway enzymes might assume a paramount part in the pathophysiology of autism. Methylene tetrahydrofolate reductase (MTHFR) is a basic catalyst for this pathway, also MTHFR gene C677T variant accounted as a risk factor of autism. The present study aimed to investigate the association of MTHFR gene rs1801133(C677T) variant among Egyptian autistic children. The study included 78 autistic children, and 80 matched healthy control children. Full clinical and radiological examinations were conducted. MTHFR genetic variant, rs1801133(C677T) was studied by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods followed by direct sequencing technique. MTHFR (C677T) allele frequency was found to be higher significantly in ASD cases compared with nonautistic children. Also, we had a higher distribution of combined CT + TT genotypes among autistic patients with consanguinity and family history of psychological disease. In Gastrointestinal tract (GIT) and sleep disorders showed a higher distribution of hetero CT genotype as well as combined CT + TT genotypes. This study demonstrated a role of MTHFR gene (C667T) variant with the increased risk for ASD.

Lack of association between methylenetetrahydrofolate reductase gene variants & essential tremor in Han Chinese

Lack of association between methylenetetrahydrofolate reductase gene variants & essential tremor in Han Chinese

Relevance of methylenetetrahydrofolate reductase gene variants C677T and A1298C with response to fluoropyrimidine-based chemotherapy in colorectal cancer: a systematic review and meta-analysis.

Methylenetetrahydrofolate reductase (MTHFR) is a critical enzyme influencing the metabolism of fluoropyrimidines. The relevance of MTHFR polymorphisms with the clinical response to fluoropyrimidine-based chemotherapy has been explored, but the results remain controversial. Thus, a meta-analysis was performed to provide a comprehensive estimate in this account. Relevant studies were identified through PubMed, Embase and Web of Science databases from inception up to May 2017. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were applied to assess the strength of association. A total of 2118 colorectal cancer patients from 21 studies were included in the meta-analysis. Overall, there was no significant association between MTHFR C677T (rs1801133) or A1298C (rs1801131) polymorphisms and the clinical response to fluoropyrimidine-based chemotherapy under all of the three genetic models (allele model, dominant model, and recessive model) and stratification analysis, except for the retrospective study subgroup in the dominant model of MTHFR C677T and the “5-Fu + FA” treatment group in the allele contrast of MTHFR A1298C. No or moderate heterogeneity was observed in all genetic models. This meta-analysis suggested that MTHFR polymorphisms could not be considered as reliable factors for predicting the clinical response to fluoropyrimidine-based chemotherapy in colorectal cancer patients.

Contribution of MTHFR gene variants in lupus related subclinical atherosclerosis

ObjectiveElevated concentrations of homocysteine have been previously identified as an independent risk factor for subclinical atherosclerosis in patients with systemic lupus erythematosus (SLE). Given that heightened homocysteine levels are known to be strongly influenced by genetic factors, in the current study we investigated the contribution of high homocysteine levels as well as of functional polymorphisms of the gene encoding for the enzyme 5, 10- methylenetetrahydrofolate reductase (MTHFR) to atherosclerotic disease characterizing SLE patients. MethodsPeripheral DNA samples from 150 SLE patients, 214 rheumatoid arthritis (RA) patients and 561 age/sex matched apparently healthy volunteers (HC) were genotyped by PCR-based assays for the detection of the MTHFR gene polymorphisms (c. 677C > T and c. 1298A > C). All SLE patients and 30 age sex matched RA patients underwent assessment for subclinical atherosclerosis [ultrasound measurement of intima-media thickness scores (IMT) and detection of carotid and/or femoral (C/F) plaque] and complete clinical and laboratory evaluation including serum homocysteine levels. Data were analyzed using univariate and multivariate models (SPSS 21.0). ResultsHyperhomocysteinemia was detected in 26.0% of SLE patients compared to 6.7% of age/sex matched RA controls (p = 0.02). Higher serum B12 levels and decreased frequency of the MTHFR 677TT variant in RA patients could potentially account for the observed differences between the groups. In SLE patients, both hyperhomocysteinemia and MTHFR 677TT genotype were identified as independent contributors for plaque formation, following adjustment for traditional cardiovascular risk factors and disease related features, including age, sex, BMI, cholesterol and triglyceride levels, presence of arterial hypertension, smoking (pack/years), disease duration and total steroid dose [OR 95% (CI): 5.8 (1.0–35.8) and 5.2 (1.1–24.0), respectively]. MTHFR 677TT genotype, but not hyperhomocysteinemia was also found to confer increased risk for arterial wall thickening, after the above confounders were taken into account [OR (95%) CI: 4.9 (1.2–20.6)]. ConclusionsHyperhomocysteinemia and MTHFR 677TT genetic variant emerged as independent risk factors for subclinical atherosclerosis in SLE patients, implying genetic influences as potential contributors to the increased burden of atherosclerotic disease characterizing SLE.

The Methylene Tetrahydrofolate Reductase Gene Variant C677T is not Associated with Migraine in Twelve Sudanese Pedigrees with Migraine

The Methylene Tetrahydrofolate Reductase Gene Variant C677T is not Associated with Migraine in Twelve Sudanese Pedigrees with Migraine

104 - Analysis of Cigarette Smoke Exposure and Single Nucleotide Variants of Genes Associated with Folate Metabolism (MTHFR) and Oxidative Stress (SOD2, GPX1) in Pregnant Women with Obstetric risk of Colombia: A case controlled pilot study

Introduction Genetic and environmental risk factors are involved with adverse obstetric outcomes. Maternal folate and homocysteine metabolism, mainly influenced by methylenetetrahydrofolate reductase (MTHFR) activity, play a key role in pregnancy risk. Oxidative stress and exposure to cigarette smoke are also well known factors amply associated with obstetric complications. Objective To study the association of cigarette smoke exposure and the influence of MTHFR C677T, superoxide dismutase 2 (SOD2) A16V and glutathione peroxidase 1 (GPX1) P197L gene variants in women with obstetric risk of Risaralda, Colombia. Methods The study population was composed of 237 pregnant women, including 152 subjects with obstetric risk and 89 healthy controls. Data of cigarette smoke exposure were extracted from standardized questionnaires. Genotypes were determined by real-time PCR using TaqMan probes. Results There was no between-group difference in genotype distribution of any of the polymorphisms analyzed. We found neither an association of the MTHFR or the oxidative stress-related genotype frequencies with an obstetric risk. Pregnant women with previous cigarette smoke use (OR=2.47, 95% CI, 1.16-5.24) or exposure to second hand smoke (OR=2.14, 95% CI 1.15-3.99) were significantly associated to gynecological risk. Conclusions Our preliminary results did not show a direct genetic association of the MTHFR or H2O2-related gene variants with an obstetrical risk in the Colombian population under study. Former active and passive cigarette smoke exposure remained as a considerable health problem to pregnant women. These data highlight the importance to health care providers to reinforce programs to reduce cigarette smoke exposure in pregnancy.

MTHFR gene variants and non-MALT lymphoma development in primary Sjogren\u2019s syndrome

Primary Sjogren’s syndrome (pSS) confers increased risk for non-Hodgkin lymphoma (NHL) development. Two common polymorphisms, the c. 677C > T and c. 1298A > C, of the methylene-tetrahydrofolate reductase (MTHFR) gene, an enzyme essential in DNA synthesis and methylation, have been associated with susceptibility to NHL. Herein, we tested the hypothesis that MTHFR variants contribute to pSS-related lymphomagenesis. 356 pSS patients, of whom 75 had MALT and 19 non-MALT NHL and 600 healthy controls were genotyped for the detection of MTHFR polymorphisms. DNA methylation levels were assessed by pyrosequencing of the LINE-1 retroelement promoter in DNA from 55 salivary gland tissues from pSS patients. DNA double-strand breaks were determined in peripheral blood mononuclear cells from 13 pSS patients, using comet assay. Αnalysis according to lymphoma subtype revealed increased frequency of c. 677C > T TT genotype and T allele, as well as reduced prevalence of the c. 1298A > C C allele in the pSS non-MALT group compared to controls and patients without NHL. MTHFR c. 677C > T TT genotype was associated with reduced DNA methylation levels, while MTHFR c. 1298A > C AC genotype with reduced DNA double-strand breaks levels. MTHFR variants may be involved in SS non-MALT NHL development, through contribution to defective DNA methylation and genomic instability.

A duplex polymerase chain reaction-restriction fragment length polymorphism for rapid screening of methylenetetrahydrofolate reductase gene variants: Genotyping in acute leukemia.

Methylenetetrahydrofolate reductase (MTHFR; NM_005957.4) is the key enzyme for folate metabolism which plays in DNA biosynthesis and the epigenetic process of DNA methylation. MTHFR gene polymorphisms, the c. 677C>T and c.1298A>C have been implicated as risk factors for several types of cancers as the acute leukemia. We have optimized a duplex polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP) for the simultaneous detection of both variants in acute leukemia patients, from Tunisia. Genomic DNA was extracted from EDTA-anticoagulant blood samples from a total of 50 patients suffering from acute leukemia (AL). After DNA extraction, the polymerase chain reaction using specific primers, designed using Primer 3 Software. Restriction Fragment Length Polymorphism (RFLP) was performed in two separate tubes followed by agarose gel electrophoresis. This new method has proved to be a rapid, simple, and reliable method that should facilitate high throughput genotyping of MTHFR polymorphisms in acute leukemia.

Chronic postsurgical pain in the Evaluation of Nitrous Oxide in the Gas Mixture for Anaesthesia (ENIGMA)-II trial

BackgroundPrevious animal and clinical studies showed that nitrous oxide may produce long-term analgesia. The aim of this study was to evaluate the effect of nitrous oxide in preventing chronic postsurgical pain. We also explored whether methylenetetrahydrofolate reductase gene polymorphisms (1298A>C, 667C>T) would enhance nitrous oxide analgesia. MethodsWe conducted a telephone interview at 12 months after surgery on 2924 (41.1%) patients enrolled in the Evaluation of Nitrous Oxide in the Gas Mixture for Anaesthesia-II trial. Pain at the wound site was recorded using the modified brief pain inventory and the neuropathic pain questionnaire. General health status was measured using the EQ-5D questionnaire. Genotyping was performed in a subset of 674 Asian patients in Hong Kong. ResultsAt 12 months after surgery, 356 (12.2%) patients reported chronic postsurgical pain at the wound site and 112 (3.8%) patients had severe pain and required regular analgesic interventions. Nitrous oxide did not affect the rate of chronic postsurgical pain (11.8% nitrous oxide group; 12.5% no nitrous oxide group), relative risk (95% confidence intervals): 0.94 (0.75–1.17), P=0.57. However, in a planned subgroup analysis, nitrous oxide reduced the risk of chronic postsurgical pain in Asian patients, relative risk (95% confidence intervals): 0.70 (0.50–0.98), P=0.031. Patients who were homozygous for either gene polymorphism and who received nitrous oxide during surgery were less likely to report chronic postsurgical pain. ConclusionsNitrous oxide administration had no impact on chronic postsurgical pain, but benefits may still be possible in Asian patients and patients with variants in methylenetetrahydrofolate reductase gene. Clinical trial registrationNCT00430989.

Heterogenous Distribution of MTHFR Gene Variants among Mestizos and Diverse Amerindian Groups from Mexico.

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in folate metabolism. Folate deficiency has been related to several conditions, including neural tube defects (NTDs) and cardiovascular diseases. Hence, MTHFR genetic variants have been studied worldwide, particularly the C677T and A1298C. We genotyped the C677T and A1298C MTHFR polymorphisms in Mexican Amerindians (MAs), from the largest sample included in a genetic study (n = 2026, from 62 ethnic groups), and in a geographically-matched Mexican Mestizo population (MEZ, n = 638). The 677T allele was most frequent in Mexican individuals, particularly in MAs. The frequency of this allele in both MAs and MEZs was clearly enriched in the South region of the country, followed by the Central East and South East regions. In contrast, the frequency of the 1298C risk allele in Mexicans was one of the lowest in the world. Both in MAs and MEZs the variants 677T and 1298C displayed opposite allele frequency gradients from southern to northern Mexico. Our findings suggest that in Mestizos the 677T allele was derived from Amerindians while the 1298C allele was a European contribution. Some subgroups showed an allele frequency distribution that highlighted their genetic diversity. Notably, the distribution of the frequency of the 677T allele was consistent with that of the high incidence of NTDs reported in MEZ.

Role of methylenetetrahydrofolate reductase 677C→T polymorphism in the development of myocardial infarction: evidence from an original study and updated meta-analysis

The methylenetetrahydrofolate reductase (MTHFR) gene variant 677C→T is considered a risk factor for myocardial infarction (MI) in Caucasians, but it remains unclear whether this applies to Chinese or other Asian populations. A total of 551 controls and 304 age-matched Chinese MI patients were recruited. MTHFR genotypes were determined. A subsequent meta-analysis was performed to determine the association between MTHFR and MI in Asia. Conventional risk factors such as hypertension, diabetes mellitus and low-density lipoprotein exhibited no significant differences between the two groups. Genotype frequencies among cases and controls were compatible with Hardy–Weinberg equilibrium. The frequencies of CC, CT and TT genotypes were 28, 46 and 26 % for patients with MI and 31, 52 and 17 % for the matched control group (p = 0.006). T-allele frequency in MI patients was higher than in controls (49 vs. 43 %, odds ratio = 0.785, 95 % confidence interval = 0.644–0.958, p = 0.017). A total of 16 studies including ours were identified, involving 4053 patients and 6791 controls. A recessive genotype model of MTHFR 677C→T polymorphism, but not a dominant genotype model, was significantly associated with greater MI risk in Asians. MI risk increased 48, 37 and 47 % for the TT homozygote compared with the CC wild type, CT heterozygote and the combination of CT and CC. Thus, we conclude that the MTHFR gene variant 677C→T is a risk factor for MI in the Chinese population and the TT genotype is associated with a significant increase in MI risk in Asia.

Associations of Polymorphisms in MTHFR Gene with the Risk of Age-Related Cataract in Chinese Han Population: A Genotype-Phenotype Analysis.

Homocysteine (Hcy) is a potential risk factor for age-related cataract (ARC). Methylenetetrahydrofolate reductase (MTHFR) is the key enzyme for Hcy metabolism, and variants of MTHFR may affect MTHFR enzyme activity. This study mainly evaluated the associations between variants in MTHFR gene, plasma MTHFR enzyme activity, total Hcy (tHcy) levels and ARC risk in Chinese population. Four single nucleotide polymorphisms (SNPs) in MTHFR gene were genotyped using the high-resolution melting (HRM) method in 502 ARC patients (mean age, 70.2 [SD, 9.0], 46.0% male) and 890 healthy controls (mean age, 67.1 [SD, 11.1], 47.6% male). The plasma MTHFR activity, folic acid (FA), vitamins B12 and B6 levels were detected by enzyme-linked immunosorbent assays (ELISA). The plasma tHcy levels were measured by an automated enzymatic assay. After the Bonferroni correction, the minor allele T of SNP rs1801133 showed a significant association with an increased risk of overall ARC (OR = 1.26, P = 0.003). Consistent association was also found between SNP rs1801133 and cortical ARC risk (OR = 1.44, P = 0.003). Haplotype analyses revealed an adverse effect of the haplotype "C-A-T-C" (alleles in order of SNPs rs3737967, rs1801131, rs1801133 and rs9651118) on ARC risk (OR = 1.55, P = 0.003). Moreover, in a joint analysis of SNPs rs9651118 and rs1801133, subjects with two unfavorable genotypes had a 1.76-fold increased risk of ARC compared with the reference group, and a statistically significant dose-response trend (Ptrend = 0.001) was also observed. Further, in healthy controls and patients with cortical ARC, the allele T of SNP rs1801133 and the increasing number of unfavorable genotypes were significantly correlated with decreased MTHFR activity as well as increased tHcy levels. However, there was no significant association between FA, vitamins B12, B6 levels and MTHFR variants. Our data indicated that variants in MTHFR gene might individually and jointly influence susceptibility to ARC by affecting MTHFR enzyme activity and tHcy levels.