Genetic polymorphisms and folate status

Moderate hyperhomocysteinemia-induced low folate status is an independent risk factor for cardiovascular disease, dementia, and depression. Folate is an essential cofactor in the one-carbon metabolism pathway and is necessary in amino acid metabolism, purine and thymidylate synthesis, and DNA methylation. In the folate cycle and homocysteine metabolism, folate, vitamin B12, vitamin B6, and vitamin B2 are important cofactors. Many enzymes are involved in folate transport and uptake, the folate pathway, and homocysteine (Hcy) metabolism, and various polymorphisms have been documented in these enzymes. Serum folate and total Hcy (tHcy) levels are influenced by folate intake and genetic polymorphisms in 5,10-methylenetertahydrofolate reductase (MTHFR) such as C677T. The prevalence of the MTHFR 677TT genotype varies across ethnic groups and regions, with a frequency of approximately 15% in Japanese populations. Individuals with the TT genotype have significantly higher tHcy levels and lower folate levels in serum than those with the CT and TT genotypes. However, administration of folic acid has been shown to eliminate these differences. Moreover, data have suggested that interventions based on genotype may be effective for motivating individuals to change their lifestyle and improve their nutrition status. Accordingly, in this review, we discuss the effects of MTHFR C677T polymorphisms on serum tHcy and folate levels with folic acid intervention and evaluate approaches for overcoming folic acid deficiency and related symptoms.

Methylenetetrahydrofolate reductase C677T polymorphism and the risks of polycystic ovary syndrome: an updated meta-analysis of 14 studies

Some studies have reported an association between the Methylenetetrahydrofolate reductase (MTHFR) C667T genetic variant and risk of polycystic ovary syndrome (PCOS), although the results remain controversial. A systematic search was conducted on PubMed, Web of Science, EMBASE, Ovid, Chinese National Knowledge Databases and WanFang databases with relevant keywords. Fourteen studies of sixteen distinct populations involving 1478 PCOS cases and used to conduct a meta-analysis. The T allele was not significantly associated with increased risk of PCOS [OR: 1.08; 95% CI: 0.96–1.21]. In the stratified analysis by ethnicity, the T allele significantly increases risks for the Asian [OR = 1.31; 95% CI: 1.09–1.58] population. No significant associations were detected for the Middle Eastern population [OR = 1.26; 95% CI: 0.96–1.67] and the T allele was found to be protective in the Caucasian population [OR = 0.82; 95% CI: 0.68–0.99]. In conclusion, this meta-analysis suggests that MTHFR C667T variant can increase, decrease, or have no effect on the risks of PCOS depending on the ethnicity.

Studying the association between methylenetetrahydrofolate reductase (MTHFR) 677 gene polymorphism, cardiovascular risk and lichen planus

BACKGROUND

There is a reported relation between hyperhomocysteinemia and lichen planus (LP). An increase in homocysteine (Hcy) and the risk of cardiovascular disease (CVD) in patients with methylenetetrahydrofolate reductase (MTHFR) mutation has been described.

OBJECTIVE

To detect MTHFR (C677T) gene polymorphism, and to find its association with CVD risk, Hcy and folic acid levels in patients with LP.

METHODS

This hospital-based case-control study included 110 patients with LP: 70 with cutaneous LP (CLP) and 40 with oral LP (OLP). A total of 120 age- and sex-matched healthy subjects were used as controls. Three millilitre venous blood sample was taken for detection of MTHFR gene polymorphism by PCR-RFLP technique and for measurement of the lipid profile. Hcy and folic acid were measured by ELISA. Hypertension was evaluated.

RESULTS

There were significantly higher prevalence of hypertension with higher Hcy, triglycerides and cholesterol levels and lower folic acid and HDL levels among patients' groups. Hypertension with higher Hcy and cholesterol levels together with lower folic acid and HDL levels have been found in OLP when compared to CLP. Patients showed a significant higher percentage of the MTHFR 677 TT genotype (P=.003) and of the MTHFR 677 T allele (P=.042) compared to controls. Moreover, there was a higher prevalence of MTHFR 677 T allele in patients with CLP.

CONCLUSION

MTHFR 677 gene polymorphism may be a risk factor for the development of the LP, and to predispose these patients to higher risk of CVD.

MTHFR gene C677T and A1298C variants are associated with FMF risk in a Turkish cohort

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) is a crucial enzyme in homocysteine (Hcy) metabolism. We aimed to evaluate a possible relationship between MTHFR gene C677T (rs 1801133), A1298C (rs 1801131) variants and susceptibility to FMF in a Turkish cohort.

MATERIAL-METHODS

This case-control study included 198 Turkish FMF patients and 100 healthy subjects as controls. MTHFR C677T and A1298C were analyzed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) methods.

RESULTS

The genotype distribution and allele frequency of the MTHFR C677T were statistically different between the patients and the control group (P=.006, P=.001, respectively). The frequency of the TT genotype and T allele of MTHFR C677T was significantly higher in the patients than in the controls. The genotype distribution of MTHFR A1298C variant did not show any statistically significant difference between the patients and the controls (P›.05). The patients had statistically different frequencies in allele C of MTHFR A1298C variant compared with the control (P=.032). We also examined the risk associated with inheriting the combined genotypes for the two MTHFR variants. According to these results, individuals who were CC homozygous at C677T locus and AA homozygous at A1298C locus have a lower risk of developing FMF (P=.002). Individuals who were TT homozygous at C677T locus and AC heterozygous at A1298C locus have higher risk of developing FMF (P=.033).

CONCLUSION

Our findings clearly showed there was an association the MTHFR C677T/A1298C variants and susceptibility to FMF in the Turkish sample.

New insights in orofacial cleft: epidemiological and genetic studies on italian samples

Cleft of the lip and/or palate (CL±P) is the most common congenital craniofacial anomaly affecting around 1 in 700 live births worldwide. Clefts of the human face can be classified anatomically as cleft lip only (CL), cleft palate only (CP), cleft lip and palate (CLP) or a combined group of cleft lip with or without cleft palate (CL±P), based on differences in embryologic development. CL±P has a genetic base and several linkage and association analyses have been performed in order to obtain important information about the role of candidate genes in its onset; not less important are gene-environment interactions that play an increasing role in its aetiology. In CL±P, several loci have been seen associated with the malformation, and, in some cases, a specific gene mapping in a locus has also been identified as susceptibility factor. In CP, one gene has been found, but many more are probably involved. In this short review the genetic studies carried out on CL±P, and the interaction with environmental factors (alcohol, smoking, drugs) are discussed.

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

BACKGROUND

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.

AIM

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.

METHODS

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.

CONCLUSION

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.

Methylenetetrahydrofolate reductase A1298C genetic variant& risk of schizophrenia: A meta-analysis

BACKGROUND & OBJECTIVES

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme of folate metabolism, whose role in schizophrenia is debatable. Numerous case-control studies have investigated the association of MTHFR A1298C polymorphism with schizophrenia, but results are controversial. The aim of the present study was to find the association between MTHFR A1298C gene polymorphism and schizophrenia.

METHODS

PubMed, Google Scholar, Science Direct and Springer link databases were searched for case-control association studies in which MTHFR A1298C polymorphism was investigated as a risk factor for schizophrenia. In all, 19 studies with 4049 cases and 5488 controls were included in this meta-analysis. Odds ratios (ORs) with 95 per cent confidence intervals (CIs) were used as an association measure.

RESULTS

The results of meta-analysis reported a significant association between A1298C polymorphism and schizophrenia risk in overall comparisons in all genetic models (C vs. A: OR=1.13, 95% CI=1.01-1.27, P=0.02; CC vs. AA: OR=1.20, 95% CI=1.03-1.39, P=0.02; AC vs. AA: OR=1.13, 95% CI=1.03-1.23, P=0.009; AC+CC vs. AA: OR=1.14, 95% CI=1.02-1.24, P=0.002; CC vs. AA+AC: OR=1.17, 95% CI=1.01-1.35, P=0.04).

INTERPRETATION & CONCLUSIONS

MTHFR A1298C polymorphism was found to be a risk factor for schizophrenia and might have played a significant role in the pathogenesis of schizophrenia.

Geographical and ethnic distribution of MTHFR gene polymorphisms and their associations with diseases among Chinese population

Numerous studies have investigated the distribution of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms and their associations with diseases in China. In this study we conducted a systematic review and meta-analysis of these studies (715 eligible studies in total).Results revealed that the frequencies of the MTHFR C677T and A1298C polymorphisms varied markedly in different areas and ethnicities, and even showed geographical gradients. The MTHFR C677T polymorphism was significantly associated with 42 clinical disorders (p < 0.05), mostly relating to the diseases of circulatory system, birth defects and cancers. The association of the A1298C polymorphism with three diseases (coronary heart disease, breast cancer and neural tube defects fathers) was statistically significant (p < 0.05). However, according to the Venice criteria, only the associations of the C677T polymorphism with breast and ovarian cancers were assessed as having strong epidemiological credibility. This is the first study to provide a comprehensive assessment of the current status and gaps in genetic epidemiological study of the two polymorphisms in China, and its findings may be useful for medical and public health practices. Future studies are warranted to focus on the interactions of MTHFR genes with environmental exposure and with other genes, and to improve their methodological quality and reporting of findings.

Riboflavin Deficiency in Rats Decreases de novo Formate Production but Does Not Affect Plasma Formate Concentration

Background: The one-carbon metabolism pathway is highly dependent on a number of B vitamins in order to provide one-carbon units for purine and thymidylate biosynthesis as well as homocysteine remethylation. Previous studies have examined folate and vitamin B-12 deficiency and their effects on formate metabolism; as of yet, to our knowledge, no studies on the effects of riboflavin deficiency on formate metabolism have been published.Objective: Our objective was to determine the effects of riboflavin deficiency on formate metabolism.Methods: Weanling male rats were randomly assigned either to control, riboflavin-replete (RR) or to experimental, riboflavin-deficient (RD) versions of the AIN-93G diet for 13 d, at which time a constant infusion of [¹³C]-formate was carried out to ascertain the effects of deficiency on formate production. Gas chromatography-mass spectrometry was used to measure plasma formate concentration and [¹³C]-formate enrichment. HPLC, LC-mass spectrometry (MS)/MS, and enzymatic assays were used for the measurement of one-carbon precursors and other metabolites.Results: RD rats had significantly lower rates of formate production (15%) as well as significantly reduced hepatic methylenetetrahydrofolate reductase activity (69%) and protein concentration (54%) compared with RR rats. There was no difference in plasma formate concentrations between the groups. Plasma serine, a potential one-carbon precursor, was significantly higher in RD rats (467 ± 73 μM) than in RR rats (368 ± 52 μM).Conclusions: Although deficiencies in folate and vitamin B-12 lead to major changes in plasma formate concentrations, riboflavin deficiency results in no significant difference; this disagrees with the prediction of a published mathematical model. Our observation of a lower rate of formate production is consistent with a role for flavoproteins in this process.

Shared Genetic Risk Factors for Late-Life Depression and Alzheimer's Disease

BACKGROUND

Considerable evidence has been reported for the comorbidity between late-life depression (LLD) and Alzheimer's disease (AD), both of which are very common in the general elderly population and represent a large burden on the health of the elderly. The pathophysiological mechanisms underlying the link between LLD and AD are poorly understood. Because both LLD and AD can be heritable and are influenced by multiple risk genes, shared genetic risk factors between LLD and AD may exist.

OBJECTIVE

The objective is to review the existing evidence for genetic risk factors that are common to LLD and AD and to outline the biological substrates proposed to mediate this association.

METHODS

A literature review was performed.

RESULTS

Genetic polymorphisms of brain-derived neurotrophic factor, apolipoprotein E, interleukin 1-beta, and methylenetetrahydrofolate reductase have been demonstrated to confer increased risk to both LLD and AD by studies examining either LLD or AD patients. These results contribute to the understanding of pathophysiological mechanisms that are common to both of these disorders, including deficits in nerve growth factors, inflammatory changes, and dysregulation mechanisms involving lipoprotein and folate. Other conflicting results have also been reviewed, and few studies have investigated the effects of the described polymorphisms on both LLD and AD.

CONCLUSION

The findings suggest that common genetic pathways may underlie LLD and AD comorbidity. Studies to evaluate the genetic relationship between LLD and AD may provide insights into the molecular mechanisms that trigger disease progression as the population ages.

Genetic Variation in One-Carbon Metabolism and Changes in Metabolic Parameters in First-Episode Schizophrenia Patients

BACKGROUND

In this study, we aimed to investigate the effects of polymorphisms in genes encoding 1-carbon metabolism enzymes on differential development of metabolic parameters during 12 weeks of treatment with second-generation antipsychotics in first-episode schizophrenia patients.

METHODS

The following polymorphisms in 1-carbon metabolism genes were genotyped: MTHFR (C677T and A1298C), MTHFD1 (G1958A), MTRR (A66G), and BHMT (G742A). A broad panel of metabolic parameters including body mass index, waist circumference, total cholesterol low and high density lipoproteins, triglycerides, homocysteine, folate, and vitamin B12 was determined.

RESULTS

There was a significant effect of the interaction between the MTHFR C677T polymorphism and time on body mass index and waist circumference in the allelic and genotype analyses. Indeed, patients with the MTHFR 677CC genotype had higher increase in body mass index and waist circumference compared with other corresponding genotypes or the MTHFR 677T allele carriers (CT and TT genotypes). In addition, patients with the MTHFR 677TT genotype had higher waist circumference in all time points. Similarly, patients with the MTHFR 677TT genotype had higher body mass index in all time points, but this effect was not significant after correction for multiple testing.

CONCLUSIONS

Our results indicate that the MTHFR C677T polymorphism may predict antipsychotic-induced weight gain. Effects of the MTHFR C677T polymorphism might be different in initial exposure to antipsychotics compared with long-term perspective.

Prognostic Relevance of Methylenetetrahydrofolate Reductase Polymorphisms for Prostate Cancer

Folate metabolism has been associated with cancers via alterations in nucleotide synthesis, DNA methylation, and DNA repair. We hypothesized that genetic variants in methylenetetrahydrofolate reductase (MTHFR), a key enzyme of folate metabolism, would affect the prognosis of prostate cancer. Three haplotype-tagging single-nucleotide polymorphisms (SNPs) across the MTHFR gene region were genotyped in a cohort of 458 patients with clinically localized prostate cancer treated with radical prostatectomy. One SNP, rs9651118, was associated with disease recurrence, and the association persisted after multivariate analyses adjusting for known risk factors. Public dataset analyses suggested that rs9651118 affects MTHFR expression. Quantitative real-time polymerase chain reaction analysis revealed that MTHFR expression is significantly upregulated in prostate tumor tissues when compared with adjacent normal tissues. Furthermore, overexpression of MTHFR correlates with cancer recurrence and death in two independent publicly available prostate cancer datasets. In conclusion, our data provide rationale to further validate the clinical utility of MTHFR rs9651118 as a biomarker for prognosis in prostate cancer.

A study on the correlation between MTHFR promoter methylation and diabetic nephropathy

OBJECTIVE

In order to observe the relationship between MTHFR promoter and DN, the determinations on MTHFR promoter methylation level and expression of HCY from DN patients have been carried out.

METHODS

According to the Diabetes diagnosis and classification standard from WHO in 1999, 85 patients with DM diagnosed by Endocrinology and 30 healthy participants from our medical examination center were chosen as control specimen to study in this paper. All this specimen were divided into A, B, C and D four groups , which are corresponding simple diabetes mellitus group (SDM), early diabetic nephropathy group (EDN), clinical diabetic nephropathy group (CDN) and normal control group. And then, all common materials and clinical experiments data have been collected respectively. (1) Extracted the peripheral blood DNA of each group and determinate the methylation status of MTHFR gene promoter by PCR (MSP). (2) Determinated the serum HCY protein expression of each group.

RESULTS

(1) The MTHFR promoter methylation of SDM and diabetic nephropathy group are wear off comparied with normal control group. And MTHFR promoter was in demethylation state in normal control group, a slightly weak in SDN, a obviously weak in early diabetic nephropathy group; the MTHFR promoter was in methylation state in clinical diabetic nephropathy group. (2) The HCY protein of simple diabetes mellitus group, early diabetic nephropathy group and clinical diabetic nephropathy group are Pitch with normal control group. HCY protein level of each group are as 7.41±1.61 umol/L, 10.34±2.89 umol/L, 10.95±5.89 umol/L and 13.03±6.14 umol/L corresponding normal control group, simple diabetes mellitus group, early diabetic nephropathy group and clinical diabetic nephropathy group. And there is no statistical significance about the differences among four groups.

CONCLUSION

The demethylation state of MTHFR promoter was obviously weaker in clinical diabetic nephropathy group than in SDM. The level of serum HCY was obviously higher in clinical diabetic nephropathy group than in SDM. It suggested that MTHFR promoter demethylation may be involoed in the pathogenesis of DN.

Moderate folic acid supplementation and MTHFD1-synthetase deficiency in mice, a model for the R653Q variant, result in embryonic defects and abnormal placental development

BACKGROUND

Moderately high folic acid intake in pregnant women has led to concerns about deleterious effects on the mother and fetus. Common polymorphisms in folate genes, such as methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase (MTHFD1) R653Q, may modulate the effects of elevated folic acid intake.

OBJECTIVES

We investigated the effects of moderate folic acid supplementation on reproductive outcomes and assessed the potential interaction of the supplemented diet with MTHFD1-synthetase (Mthfd1S) deficiency in mice, which is a model for the R653Q variant.

DESIGN

Female Mthfd1S^+/+ and Mthfd1S^+/- mice were fed a folic acid-supplemented diet (FASD) (5-fold higher than recommended) or control diets before mating and during pregnancy. Embryos and placentas were assessed for developmental defects at embryonic day 10.5 (E10.5). Maternal folate and choline metabolites and gene expression in folate-related pathways were examined.

RESULTS

The combination of FASD and maternal MTHFD1-synthetase deficiency led to a greater incidence of defects in E10.5 embryos (diet × maternal genotype, P = 0.0016; diet × embryonic genotype, P = 0.054). The methylenetetrahydrofolate reductase (MTHFR) protein and methylation potential [ratio of S-adenosylmethionine (major methyl donor):S-adenosylhomocysteine) were reduced in maternal liver. Although 5-methyltetrahydrofolate (methylTHF) was higher in maternal circulation, the methylation potential was lower in embryos. The presence of developmental delays and defects in Mthfd1S^+/- embryos was associated with placental defects (P = 0.003). The labyrinth layer failed to form properly in the majority of abnormal placentas, which compromised the integration of the maternal and fetal circulation and presumably the transfer of methylTHF and other nutrients.

CONCLUSIONS

Moderately higher folate intake and MTHFD1-synthetase deficiency in pregnant mice result in a lower methylation potential in maternal liver and embryos and a greater incidence of defects in embryos. Although maternal circulating methylTHF was higher, it may not have reached the embryos because of abnormal placental development; abnormal placentas were observed predominantly in abnormally developed embryos. These findings have implications for women with high folate intakes, particularly if they are polymorphic for MTHFD1 R653Q.

Combined genotype and haplotype distributions of MTHFR C677T and A1298C polymorphisms: A cross-sectional descriptive study of 13,473 Chinese adult women

Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms are, independently and/or in combination, associated with many disorders. However, data on the combined genotype and haplotype distributions of the 2 polymorphisms in Chinese population were limited.We recruited 13,473 adult women from 9 Chinese provinces, collected buccal cell samples, and determined genotypes, to estimate the combined genotype and haplotype distributions of the MTHFR C677T and A1298C polymorphisms.In the total sample, the 6 common combined genotypes were CT/AA (29.5%), TT/AA (21.9%), CC/AA (15.4%), CC/AC (14.9%), CT/AC (13.7%), and CC/CC (3.4%); the 3 frequent haplotypes were 677T-1298A (43.6%), 677C-1298A (37.9%), and 677C-1298C (17.6%). Importantly, we observed that there were 51 (0.4%) individuals with the CT/CC genotype, 92 (0.7%) with the TT/AC genotype, 17 (0.1%) with the TT/CC genotype, and that the frequency of the 677T-1298C haplotype was 0.9%. In addition, the prevalence of some combined genotypes and haplotypes varied among populations residing in different areas and even showed apparent geographical gradients. Further linkage disequilibrium analysis showed that the D' and r values were 0.883 and 0.143, respectively.In summary, the findings of our study provide further strong evidence that the MTHFR C677T and A1298C polymorphisms are usually in trans and occasionally in cis configurations. The frequencies of mutant genotype combinations were relatively higher in Chinese population than other populations, and showed geographical variations. These baseline data would be useful for future related studies and for developing health management programs.

Polymorphisms in the MTHFR gene are associated with recurrence risk in lymph node-positive breast cancer patients

Purpose

The aim of this study is to clarify the relationship between recurrence risk of breast cancer and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms.

Patients and methods

Breast cancer patients who had undergone surgery in Gaziantep University Oncology Hospital between June 2005 and June 2012 were followed-up and retrospectively enrolled in this study. Blood samples were collected from all patients to assess MTHFR C677T polymorphisms. Stage according to tumor–node–metastasis system, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 status, grade of disease, menopausal status, and administered chemotherapy or hormonal therapy were recorded. Effects of these parameters on recurrence risk were evaluated using univariate analysis and multivariate binary logistic regression model.

Results

Association of MTHFR C677T polymorphisms with recurrence risk was evaluated in 298 patients whose median age was 47 years (range: 21–79 years). In all patients, age (odds ratio [OR] =0.953, P=0.005) and N3 lymph node status (OR =6.293, P=0.001) were found to affect the recurrence risk. While MTHFR homozygote genotype did not have an effect on recurrence risk in all patients, increased risk was observed in lymph node-positive subgroup (OR =4.271; 95% CI 1.515–12.023; P=0.006). Adjusting for age, tumor size (T), and node status (N), MTHFR homozygote genotype had more statistically significant risk for recurrence (OR =3.255; 95% CI 1.047–10.125; P=0.041).

Conclusion

MTHFR TT genotype was found to be associated with increased recurrence risk in patients with lymph node-positive breast cancer.

Association between MTHFR C677T polymorphism and diabetic nephropathy in the Chinese population: An updated meta-analysis and review

To clarify the effects of MTHFR C677T polymorphism on the risk of diabetic nephropathy (DN) in the Chinese population, an updated meta-analysis was performed. Related studies were identified from PubMed, Springer Link, Ovid and Chinese Databases up to 24 February 2015. A total of 15 studies including 1227 DN cases, 586 healthy controls and 1277 diabetes mellitus (DM) controls were involved in this meta-analysis. Overall, a significantly elevated risk of DN was associated with all variants of MTHFR C677T when compared with the healthy group (T vs C, odds ratio (OR) = 2.22, 95% confidence interval (CI) = 1.88-2.61; TT vs CC, OR = 4.22, 95% CI = 3.02-5.90; TT + CT vs CC, OR = 2.62, 95% CI = 2.07-3.31; TT vs CC + CT, OR = 2.81, 95% CI = 2.08-3.81) or DM (T vs C, OR = 1.78, 95% CI = 1.59-2.00; TT vs CC, OR = 2.95, 95% CI = 2.33-3.73; TT + CT vs CC, OR = 1.93, 95% CI = 1.63-2.29; TT vs CC + CT, OR = 2.31, 95% CI = 1.87-2.84). In subgroup analyses stratified by ethnicity and geographic areas, it revealed the significant results in Chinese Han, in North and South China. The risk conferred by MTHFR C677T polymorphism is higher in North China than in South China. This meta-analysis showed that the MTHFR C677T variants may influence DN risk in Chinese, and further studies with gene-gene and gene-environment interactions are required for definite conclusions.

Association between MTHFR C677T polymorphism and abdominal aortic aneurysm risk: A comprehensive meta-analysis with 10,123 participants involved

BACKGROUND

Abdominal aortic aneurysm (AAA) is a life-threatening condition. A number of studies reported the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and AAA risk, but substantial controversial findings were observed and the strength of the association remains unclear.

OBJECTIVE

The aim of this study was to investigate the aforementioned association in the overall population and different subgroups.

METHODS

PUBMED and EMBASE databases were searched until March 2016 to identify eligible studies, restricted to humans and articles published in English. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the susceptibility to AAA. Subgroup meta-analyses were conducted on features of the population, such as ethnicity, sex of the participants, and study design (source of control).

RESULTS

Twelve case-control studies on MTHFR C677T polymorphism and AAA risk, including 3555 cases and 6568 case-free controls were identified. The results revealed no significant association between the MTHFR C677T polymorphism and AAA risk in the overall population and within Caucasian or Asian subpopulations in all 5 genetic models. Further subgroup meta-analysis indicated that significantly increased risks were observed among cases with a mean age <70 years (OR = 1.73, 95% CI = 1.10-2.12, P = 0.02), cases with prevalence of smoking <60% (OR = 1.39, 95% CI = 1.02-1.90, P = 0.04), and cases with aneurysm diameter ≥55 mm (OR = 1.55, 95% CI = 1.07-2.24, P = 0.02) in the dominant genetic model. No publication bias was detected in the present study.

CONCLUSION

In conclusion, our comprehensive meta-analysis suggests that the MTHFR C677T polymorphism may play an important role in AAA susceptibility, especially in younger, non-smoking, larger AAA-diameter subgroups of patients.

Methylenetetrahydrofolate reductase gene polymorphism in endometrial cancer: A systematic review and meta-analysis

OBJECTIVE

We conducted a meta-analysis of case-controlled prospective or retrospective studies to assess the effect of MTHFR polymorphisms on the risk of developing endometrial cancer.

MATERIALS AND METHODS

PubMed, Cochrane, EMBASE, and ISI Web of Knowledge were searched (up to March 2014) for prospective or retrospective case-controlled studies that investigated the association of three MTHFR polymorphisms (rs180113 [C677T], rs1801131 [A1289C], and rs2274976 [G1793A]) with endometrial cancer.

RESULTS

The patient population included subjects from three separate countries: China, Spain, and the USA. Only one study reported quantitative findings for MTHFR G1793A and, consequently, this polymorphism was not evaluated in our analysis. There were no significant associations of any MTHFR C677T or MTHFR A1298C alleles or genotypes with endometrial cancer (all p > 0.300).

CONCLUSION

This meta-analysis does not support the association of endometrial cancer with two common MTHFR polymorphisms from this patient population.

The effect of parental 5,10-methylenetetrahydrofolate reductase 677C/T and 1298A/C gene polymorphisms on response to single-dose methotrexate in tubal ectopic pregnancy

OBJECT

The aim of this study was to assess the effect of parental 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms (677C/T and 1298A/C) on response to single-dose methotrexate (MTX) treatment in tubal ectopic pregnancy (TEP).

MATERIALS AND METHODS

In this prospective cohort study, cases with unruptured TEPs were grouped into two according to their response to single-dose MTX treatment (Group 1: responsive, n:88; Group 2: unresponsive, n:21). The groups were compared with regard to baseline demographic and clinical parameters. As a main outcome measure, the independent effects of parental MTHFR gene polymorphisms on response to single dose MTX treatment were evaluated.

RESULTS

One hundred and nine unruptured TEP were included in the final analysis. The mean maternal age was 29.30 ± 5.21 years, gravity 2 (min-max: 1-5), parity 1 (min-max: 0-4). The median serum beta-human chorionic gonadotropin (β-hCG) was 1403.35 MI/I (Q₁-Q₃: 517-2564). The overall response rate was 81% (88/109). The groups were similar with respect to basic baseline demographic data and serum β-hCG level. Binary logistic regression analysis showed that the presence of parental MTHFR677C/T and 1298A/C polymorphism were not independent factor predicting treatment success (p > 0.05). The only independent factor for resistance to single dose MTX was the previous TEP (OR: 4.47 (1.18-16.9)).

CONCLUSION

Parental MTHFR 677C/T and 1298A/C mutations do not predict the outcome of single dose intramuscular MTX treatment in unruptured TEP.

Methylenetetrahydrofolate Reductase C677T: Hypoplastic Left Heart and Thrombosis

The incidence of congenital heart defects is higher in infants with mutation of methylenetetrahydrofolate reductase (MTHFR) gene. The MTHFR C677T gene decreases the bioavailability of folate and increases plasma homocysteine, a risk factor for thrombosis. There have been no reported cases in the literature on the clinical implications of this procoagulable state in the setting of cyanotic heart disease, which itself has prothrombotic predisposition. Two patients with hypoplastic left heart syndrome developed postoperative thrombotic complications, both were homozygous for MTHFR C677T. We present these cases and highlight the implications of MTHFR mutation in the management of complex congenital heart disease.

Genetic and epigenetic variation in the DNMT3B and MTHFR genes and colorectal adenoma risk

Polymorphisms in DNMT3B and MTHFR have been implicated in cancer etiology; however, it is increasingly clear that gene-specific DNA methylation also affects gene expression. A cross-sectional study (N = 272) investigated the main and joint effects of polymorphisms and DNA methylation in DNMT3B and MTHFR on colorectal adenoma risk. Polymorphisms examined included DNMT3B c.-6-1045G > T, and MTHFR c.665C > T and c.1286A > C. DNA methylation of 66 and 28 CpG sites in DNMT3B and MTHFR, respectively, was quantified in blood leukocytes using Sequenom EpiTYPER®. DNA methylation was conceptualized using two approaches: (1) average methylation and (2) unsupervised principal component analysis to identify variables that represented methylation around the transcription start site and the gene coding area of both genes. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) associated with the main and joint effects of polymorphisms and DNA methylation. DNA methyltransferase 3B (DNMT3B) TT versus GG/GT genotypes was associated with increased colorectal adenoma risk (OR = 2.12; 95% CI: 1.03-4.34). In addition, increasing DNA methylation in the gene-coding area of DNMT3B was associated with higher risk of colorectal adenomas (OR = 1.34; 95% CI: 1.01-1.79 per SD). In joint effect analyses, synergistic effects were observed among those with both the DNMT3B TT genotype and higher DNMT3B methylation levels compared to those with GT/GG genotypes and lower methylation levels (OR = 4.19; 95% CI: 1.45-12.13 for average methylation; OR = 4.26; 95%CI: 1.31-13.87 for methylation in the transcription start site). This research provides novel evidence that genetic and epigenetic variations contribute to colorectal adenoma risk, precursor to the majority of colorectal cancer (CRC).

Association of Homozygous Thrombophilia Polymorphisms and Venous Thromboembolism in Shahrekord, Iran

BACKGROUND

Venous thromboembolism (VTE) is a major cause of mortality. Factor V Leiden (FVL), methylenetetrahydrofolate reductase (MTHFR) C677T, and prothrombin (FII) G20210A polymorphisms are the main inherited risk factors for VTE. Since evidence is limited on homozygotes, the aim of this study was to investigate the association between homozygous variants of these polymorphisms and VTE in Shahrekord, southwest Iran.

MATERIALS AND METHODS

In this case-control study, blood samples of 72 VTE patients admitted to Hajar Hospital, Shahrekord and 306 sex- and age-matched healthy volunteers as controls were taken in EDTA Vacutainers. The polymorphisms of FVL, MTHFR C677T, and FIIG20210A were investigated by PCR-RFLP. The data were analyzed by descriptive statistics and independent t-test.

RESULTS

The frequency of all homozygous polymorphisms was found to be 16.77% in patients and 4.90% in controls with a significant difference (P=0.004). Homozygous FVL mutation was more frequent in patients than in controls with no significant difference. Regarding the frequency of homozygous MTHFR C677T, a significant difference was noted between patients and controls (P=0.03). There was no significant difference in homozygous FIIG20210A and heterozygous variants of the above-mentioned polymorphisms between the patients and controls.

CONCLUSION

Homozygous MTHFR C677T polymorphism is associated with VTE in Shahrekord. Control of the acquired risk factors may be necessary in homozygous form of this polymorphism. VTE patients with this polymorphism may need to be managed differently.

Factor V Leiden, factor V Cambridge, factor II GA20210, and methylenetetrahydrofolate reductase in cerebral venous and sinus thrombosis: A case-control study

Background:

Factor V G1691A (FV Leiden), FII GA20210, and methylenetetrahydrofolate reductase (MTHFR) C677T mutations are the most common genetic risk factors for thromboembolism in the Western countries. However, there is rare data in Iran about cerebral venous and sinus thrombosis (CVST) patients. The aim of this study was to evaluate the frequency of common genetic thrombophilic factors in CVST patients.

Materials and Methods:

Forty consequently CVST patients from two University Hospital in Isfahan University of Medical Sciences aged more than 15 years from January 2009 to January 2011 were recruited. In parallel, 51 healthy subjects with the same age and race from similar population selected as controls. FV Leiden, FII GA20210, MTHFR C677T, and FV Cambridge gene mutations by polymerase chain reaction technique were evaluated in case and control groups.

Results:

FV Leiden, FII GA20210, and FV Cambridge gene mutations had very low prevalence in both case (5%, 2%, 0%) and control (2.5%, 0%, 0%) and were not found any significant difference between groups. MTHFR C677T mutations was in 22 (55%) of patients in case group and 18 (35.5%) of control group (P = 0.09).

Conclusion:

This study showed that the prevalence of FV Leiden, FII GA20210, and FV Cambridge were low. Laboratory investigations of these mutations as a routine test for all patients with CVST may not be cost benefit.

Association study of methylenetetrahydrofolate reductase A1298C mutation with cerebral venous thrombosis risk in an Iranian population

BACKGROUND

Cerebral venous thrombosis (CVT) is an uncommon condition characterized by severe clinical manifestations and high mortality rate. There is limited data on the role of methylenetetrahydrofolate reductase (MTHFR) A1298C mutation as a risk factor for CVT development in Iranians.

AIM

The aim was to investigate a possible association between fasting plasma homocysteine (Hcy) levels, MTHFR A1298C mutation, and CVT in Iranian population.

MATERIALS AND METHODS

The study population consisted of 50 patients with a diagnosis of CVT (20-63 years old) and 75 healthy subjects (18-65 years old) as control. Genotyping of the MTHFR A1298C mutation and Hcy measurement was carried out by polymerase chain reaction-restriction fragment length polymorphism technique and enzyme immunoassay method, respectively.

RESULTS

Fasting plasma total Hcy levels were significantly higher in CVT patients than controls (P = 0.015). No significant differences were observed in the MTHFR A1298C genotypes frequency between CVT patients and controls (P > 0.05). The frequency of the 1298C allele was 36% and 37.5% in CVT patients and controls, respectively and did not differ significantly between the two groups (P = 0.16).

CONCLUSIONS

Our study demonstrated that MTHFR A1298Cmutation is not a significant risk factor for CVT.

Methylenetetrahydrofolate reductase C677T and A1298C gene polymorphisms in oral squamous cell carcinoma in south-east Iran

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) gene encodes an essential enzyme involving in folate metabolism. Due to the role of folate in DNA integrity, polymorphisms of MTHFR are interesting targets for cancer risk studies. Our goal was to evaluate the prevalence of MTHFR C677T and A1298T single nucleotide polymorphisms in oral squamous cell carcinoma (OSCC).

METHODS

The study was conducted on 57 OSCC patients diagnosed within 2004-2013 along with 62 non-OSCC subjects. DNA was extracted by standard kit protocol. Subsequently, tetra-ARMS (amplification refractory mutation system)-PCR was applied to identify the selected polymorphisms.

RESULTS

Data showed that CT and TT genotypes of C677T polymorphisms significantly increased the risk of OSCC [odds ratio (OR) = 2.2, 95% CI: 1-5, P = 0.04]. Although allelic distribution was not significantly different between patients and controls, T allele of C677T polymorphism was closely associated with the risk of OSCC (OR = 2.5; 95% CI: 0.9-6.9; P = 0.07). Results indicated that C677T/A1298C: CC/AC and C677T/A1298C: CC/AA haplotypes were the most common combinations in OSCC patient and control groups, respectively. (OR = 1.5, 95% CI: 0.6-3.8, P > 0.05).

CONCLUSION

Our results highlight the possible impact of C677T polymorphism in increasing the risk of OSCC development.

Incidence Assessment of MTHFR C677T and A1298C Polymorphisms in Iranian Non-syndromic Cleft Lip and/or Palate Patients

Background and aims. The aim of the present study is to determine the incidence of MTHFR C677 T and A1298C muta-tions in Iranian patients with cleft lip and/or cleft palate. Materials and methods. We screened 61 Iranian patients with cleft lip and/or cleft palate for mutations in the two alleles of MTHFR gene associated with cleft lip and/or palate: A1298C and C677T, using Polymerase Chain Reaction following by RFLP. Results. The 677T and 1298C homozygote genotypes showed a frequency of 36.1% and 11.4%, respectively. Combined genotype frequencies in newborns having oral clefts showed that the highest genotype was 677TT/1298AA (22.9%) and 677TT/1298CC genotypes were not observed. Conclusion. The results showed that 65.6% of all patients had at least one T mutant allele in C677T and 58.9% C mutant allele for A1298C. According to the frequencies of homozygosity of mutant alleles, it could be said that MTHFR genotype of 677TT shows a greater role in having oral clefts.

Association between the MTHFR C677T polymorphism and gastric cancer susceptibility: A meta-analysis of 5,757 cases and 8,501 controls

Current data regarding the association between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of developing gastric cancer are insufficient to draw definite conclusions. Therefore, the present meta-analysis was conducted to achieve a more precise estimation of the association. MEDLINE, EMBASE and Wanfang database searches resulted in the identification of 28 eligible studies describing 5,757 cases and 8,501 controls. The strength of the association between the MTHFR C677T polymorphism and gastric cancer risk were evaluated using crude odds ratios (ORs), with 95% confidence intervals (CIs). The pooled ORs were determined using homozygous (TT vs. CC), heterozygous (CT vs. CC), dominant (TT+CT vs. CC) and recessive (TT vs. CC+CT) models. When all studies were pooled into the meta-analysis, significant associations were identified between the MTHFR C677T polymorphism and the risk of gastric cancer (homozygous model: OR, 1.39; 95% CI, 1.20-1.62; heterozygous model: OR, 1.18; 95% CI, 1.05-1.32; dominant model: OR, 1.23; 95% CI, 1.10-1.38; recessive model: OR, 1.26; 95% CI, 1.12-1.42). Stratification of the data by ethnicity identified a statistically significantly elevated risk of gastric cancer in Asian MTHFR C677T polymorphism populations (homozygous model: OR, 1.64; 95% CI, 1.43-1.90; heterozygous model: OR, 1.30; 95% CI, 1.16-1.45; dominant model: OR, 1.39; 95% CI, 1.25-1.54; recessive model: OR, 1.41; 95% CI, 1.25-1.51), but not in Caucasian populations (homozygous model: OR, 1.15; 95% CI, 0.89-1.48; heterozygous model: OR, 1.03; 95% CI, 0.84-1.25; dominant model: OR, 1.05; 95% CI, 0.86-1.28; recessive model: OR, 1.09; 95% CI, 0.91-1.31). Following adjustment for heterogeneity, the current meta-analysis demonstrated that the MTHFR C677T polymorphism was not associated with the risk of gastric cancer in Caucasian individuals. Furthermore, no evidence of publication bias was observed. Thus, the current meta-analysis indicates that the MTHFR C677T allele may be a low-penetrant risk factor for the development of gastric cancer in Asian populations.

Genetic variation associated with hypersensitivity to mercury

Objectives:

Very little is known about mechanisms of idiosyncratic sensitivity to the damaging effects of mercury (Hg); however, there is likely a genetic component. The aim of the present study was to search for genetic variation in genes thought to be involved in Hg metabolism and transport in a group of individuals identified as having elevated Hg sensitivity compared to a normal control group.

Materials and Methods:

Survivors of pink disease (PD; infantile acrodynia) are a population of clinically identifiable individuals who are Hg sensitive. In the present study, single nucleotide polymorphisms in genes thought to be involved in Hg transport and metabolism were compared across two groups: (i) PD survivors (n = 25); and (ii) age- and sex-matched healthy controls (n = 25).

Results:

Analyses revealed significant differences between groups in genotype frequencies for rs662 in the gene encoding paraoxanase 1 (PON1) and rs1801131 in the gene encoding methylenetetrahydrofolate reductase (MTHFR).

Conclusions:

We have identified two genetic polymorphisms associated with increased sensitivity to Hg. Genetic variation in MTHFR and PON1 significantly differentiated a group formerly diagnosed with PD (a condition of Hg hypersensitivity) with age- and gender-matched healthy controls.

High folic acid consumption leads to pseudo-MTHFR deficiency, altered lipid metabolism, and liver injury in mice

BACKGROUND

Increased consumption of folic acid is prevalent, leading to concerns about negative consequences. The effects of folic acid on the liver, the primary organ for folate metabolism, are largely unknown. Methylenetetrahydrofolate reductase (MTHFR) provides methyl donors for S-adenosylmethionine (SAM) synthesis and methylation reactions.

OBJECTIVE

Our goal was to investigate the impact of high folic acid intake on liver disease and methyl metabolism.

DESIGN

Folic acid-supplemented diet (FASD, 10-fold higher than recommended) and control diet were fed to male Mthfr(+/+) and Mthfr(+/-) mice for 6 mo to assess gene-nutrient interactions. Liver pathology, folate and choline metabolites, and gene expression in folate and lipid pathways were examined.

RESULTS

Liver and spleen weights were higher and hematologic profiles were altered in FASD-fed mice. Liver histology revealed unusually large, degenerating cells in FASD Mthfr(+/-) mice, consistent with nonalcoholic fatty liver disease. High folic acid inhibited MTHFR activity in vitro, and MTHFR protein was reduced in FASD-fed mice. 5-Methyltetrahydrofolate, SAM, and SAM/S-adenosylhomocysteine ratios were lower in FASD and Mthfr(+/-) livers. Choline metabolites, including phosphatidylcholine, were reduced due to genotype and/or diet in an attempt to restore methylation capacity through choline/betaine-dependent SAM synthesis. Expression changes in genes of one-carbon and lipid metabolism were particularly significant in FASD Mthfr(+/-) mice. The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile.

CONCLUSIONS

We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency. This deficiency results in hepatocyte degeneration, suggesting a 2-hit mechanism whereby mutant hepatocytes cannot accommodate the lipid disturbances and altered membrane integrity arising from changes in phospholipid/lipid metabolism. These preliminary findings may have clinical implications for individuals consuming high-dose folic acid supplements, particularly those who are MTHFR deficient.

Association between folate metabolism-related polymorphisms and colorectal cancer risk

Folate has essential roles in DNA synthesis, repair and methylation. Folate metabolism-related gene variants may modulate the levels of this vitamin and affect the cancer risk. Thus, whether these polymorphisms play an important role in carcinogenesis, particularly colorectal cancer (CRC) development, has been a subject interest. The present study investigated the association between polymorphisms in the methylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS) and the reduced folate carrier 1 (RFC1) genes and CRC risk. Polymorphisms in MTHFR (677C>T and 1298A>C), TS [1494del6 and the TS enhancer region (TSER)] and RFC1 (-43T>C, 80G>A and 696C>T) were characterized using polymerase chain reaction-restriction fragment length polymorphism in 477 CRC cases and 514 controls. Although no polymorphisms were significantly associated with the CRC risk in the overall sample, significant associations between folate metabolism-related polymorphisms and CRC risk were identified in the stratified analyses. The MTHFR 677CT/1298AC and MTHFR 1298AC+CC/TSER 2R3R genotypes in the presence of plasma folate levels ≤4.12 ng/ml were associated with significantly increased CRC risk. In addition, individuals with the MTHFR 677TT/TSER 3R3R or MTHFR 677/TSER 3R3R/TS 1494 0bp6bp+6bp6bp genotypes and diabetes mellitus (DM) were at an increased risk for CRC. Therefore, the data suggest that i) MTHFR polymorphisms combined with low plasma folate levels and ii) polymorphisms in folate metabolism-related genes combined with metabolic syndrome risk factors (hypertension and DM) increase the odds of developing CRC.

The maize brown midrib4 (bm4) gene encodes a functional folylpolyglutamate synthase

Mutations in the brown midrib4 (bm4) gene affect the accumulation and composition of lignin in maize. Fine-mapping analysis of bm4 narrowed the candidate region to an approximately 105 kb interval on chromosome 9 containing six genes. Only one of these six genes, GRMZM2G393334, showed decreased expression in mutants. At least four of 10 Mu-induced bm4 mutant alleles contain a Mu insertion in the GRMZM2G393334 gene. Based on these results, we concluded that GRMZM2G393334 is the bm4 gene. GRMZM2G393334 encodes a putative folylpolyglutamate synthase (FPGS), which functions in one-carbon (C1) metabolism to polyglutamylate substrates of folate-dependent enzymes. Yeast complementation experiments demonstrated that expression of the maize bm4 gene in FPGS-deficient met7 yeast is able to rescue the yeast mutant phenotype, thus demonstrating that bm4 encodes a functional FPGS. Consistent with earlier studies, bm4 mutants exhibit a modest decrease in lignin concentration and an overall increase in the S:G lignin ratio relative to wild-type. Orthologs of bm4 include at least one paralogous gene in maize and various homologs in other grasses and dicots. Discovery of the gene underlying the bm4 maize phenotype illustrates a role for FPGS in lignin biosynthesis.

Methylenetetrahydrofolate reductase polymorphism is not risk factor for Down syndrome in North India

BACKGROUND

Down syndrome (DS) is the most common cause of mental retardation of genetic etiology with the prevalence rate of 1/700 to 1/1000 live births worldwide. Several polymorphisms in folate/homocysteine metabolism pathways genes have been reported as a risk factor in women for bearing DS child, but very few studies investigated these polymorphisms in DS cases whether there are a risk factor for being DS or not.

OBJECTIVE

We have investigated the association of methylenetetrahydrofolate reductase (MTHFR) with the occurrence of DS in Indian population. MTHFR is one of the key regulatory enzymes involved in the metabolic pathway of homocysteine responsible for the reduction of methyltetrahydrofolate. A total of 32 DS cases and 64 age, sex matched controls were genotyped for MTHFR C677T polymorphism by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The observed genotype frequencies were CC = 0.81; CT = 0.17 and TT = 0.02 in controls and CC = 0.81 and CT = 0.19 in DS cases. Frequency of T allele in DS and controls were 0.09 and 0.1, respectively. Significant difference in the distribution of mutant 677T allele was not observed between DS cases and controls (odds ratio = 0.915; 95% confidence intervals: 0.331-2.53; P = 0.864).

CONCLUSION

Results of this study indicate that MTHFR C677T polymorphism is not risk factor for DS.

Folic acid supplementation and methylenetetrahydrofolate reductase (MTHFR) gene variations in relation to in vitro fertilization pregnancy outcome

OBJECTIVE

To study folic acid intake, folate status and pregnancy outcome after infertility treatment in women with different infertility diagnoses in relation to methylenetetrahydrofolate reductase (MTHFR) 677C>T, 1298A>C and 1793G>A polymorphisms. Also the use of folic acid supplements, folate status and the frequency of different gene variations were studied in women undergoing infertility treatment and fertile women.

DESIGN

Observational study.

SETTING

University hospital.

POPULATION

Women undergoing infertility treatment and healthy, fertile, non-pregnant women.

METHODS

A questionnaire was used to assess general background data and use of dietary supplements. Blood samples were taken to determine plasma folate and homocysteine levels, and for genomic DNA extraction. A comparison of four studies was performed to assess pregnancy outcome in relation to MTHFR 677 TT vs. CC, and 1298 CC vs. AA polymorphisms.

MAIN OUTCOME MEASURES

Folic acid supplement intake, and plasma folate, homocysteine and genomic assays.

RESULTS

Women in the infertility group used significantly more folic acid supplements and had better folate status than fertile women, but pregnancy outcome after fertility treatment was not dependent on folic acid intake, folate status or MTHFR gene variations.

CONCLUSION

High folic acid intakes and MTHFR gene variations seem not to be associated with helping women to achieve pregnancy during or after fertility treatment.

Intergenotypic variation of Vitamin B12 and Folate in AD: In north indian population

OBJECTIVES

Changes in lifestyle habits such as diet modification or supplementation have been indicated as probable protective factors for a number of chronic conditions including Alzheimer's disease (AD). With this background, we aim to hypothesize that whether C677T polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene contributes towards the risk of developing AD and its association with vitamin B12 and folate levels.

MATERIALS AND METHODS

A case-control study comprising of total 200 subjects, within the age group of 50-85 years. Their blood samples were analyzed for serum folate, vitamin B12 levels, and MTHFR C677T polymorphism by restriction fragment length polymorphism (RFLP).

RESULTS

The mean plasma levels of vitamin B12 and folate were significantly lower in study group when compared to the control group (P < 0.001). Genotypic and allelic frequency of MTHFR gene in both groups was found to be significant (P < 0.05). The intergenotypic variations of vitamin B12 and folate were found to be significant (P < 0.001).

CONCLUSION

We concluded that the subjects with homozygous mutated alleles are more prone to AD and also pointed out the influence of presence/absence of MTHFR T allelic variants on serum folate and vitamin B12 levels.

Methylenetetrahydrofolate reductase C677T gene polymorphism and essential hypertension: A meta-analysis of 10,415 subjects

The methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism has been suggested to be associated with the risk of essential hypertension (EH), however, results remain inconclusive. To investigate this association, the present meta-analysis of 27 studies including 5,418 cases and 4,997 controls was performed. The pooled odds ratio (OR) and its corresponding 95% confidence interval were calculated using the random-effects model. A significant association between the MTHFR C677T gene polymorphism and EH was found under the allelic (OR, 1.32; 95% CI, 1.20-1.45; P=0.000), dominant (OR, 1.39; 95% CI, 1.25-1.55; P=0.000), recessive (OR, 1.38; 95% CI, 1.18-1.62; P=0.000), homozygote (OR, 1.59; 95% CI, 1.32-1.92; P=0.000), and heterozygote (OR, 1.32; 95% CI, 1.20-1.45; P=0.000) genetic models. A strong association was also revealed in subgroups, including Asian, Caucasian and Chinese. The Japanese subgroup did not show any significant association under all models. Meta-regression analyses suggested that the study design was a potential source of heterogeneity, whereas the subgroup analysis additionally indicated that the population origin may also be an explanation. Another subgroup analysis revealed that hospital-based studies have a stronger association than population-based studies, however, the former suffered a greater heterogeneity. Funnel plot and Egger's test manifested no evidence of publication bias. In conclusion, the present study supports the evidence for the association between the MTHFR C677T gene polymorphism and EH in the whole population, as well as in subgroups, such as Asian, Caucasian and Chinese. The carriers of the 677T allele are susceptible to EH.

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism among Gaddi tribe of Indian state of Himachal Pradesh

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism has been suggested to be positively associated with several disorders. Distribution of the mutant T-allele varies in ethnic and geographical populations of the world.

AIM

The aim of the present study was to investigate the distribution of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in a transhumant (Gaddi) tribal population of Himachal Pradesh dwelling at high and middle altitude and exposed to strong ultraviolet radiation.

METHOD AND RESULTS

A total of 486 samples (141 males and 345 females) were randomly enrolled from the individuals aged 25-75 years who were unrelated up to first cousin. Among Gaddis, genotype frequencies of CC, CT and TT were 67.90%, 27.78% and 4.32%, respectively. Among males and females distribution of genotype frequencies also followed a similar trend. The studied population was in Hardy-Weinberg equilibrium (χ(2 )= 2.213, df = 1, p = 0.136). Frequency of mutant T-allele in the Gaddi population was found to be 0.183, which might be due to European ancestry, endogamous nature and selection.

Association analysis of the catechol-O-methyltransferase /methylenetetrahydrofolate reductase genes and cognition in late-onset depression

AIMS

Increasing evidence suggests that the catechol-O-methyltransferase (COMT) gene might be associated with cognition in patients with mental disorders and healthy people. The metabolic pathways of COMT and methylenetetrahydrofolate reductase (MTHFR) are closely interconnected. In this study, we aimed to examine whether the COMT-MTHFR genotype interacted with cognitive function in late-onset depression (LOD) patients and COMT Val/Val homozygous individuals who also carried the MTHFR T allele and had poor neuropsychological test performance.

METHODS

Ninety-seven unrelated LOD patients who met DSM-IV criteria for major depressive disorder were recruited for the study and 103 normal controls were recruited from the local community. All of these patients and 44 normal controls completed a series of neuropsychological tests. Patients and normal controls were genotyped for COMT (rs4680) and MTHFR (rs1801133) variants using polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

There were no significant differences in the frequencies of the single alleles and genotypes of two polymorphisms between LOD patients and normal controls. No main effects of COMT or MTHFR genotype on any neuropsychological test performance were observed. There was a significant interactive effect of COMT Val158Met and MTHFR C677T polymorphisms on the Symbol Digit Modalities Test independent of diagnosis (P < 0.05). After controlling for covariates, the subjects with COMT Met/ Met and MTHFR C/C genotype had better Symbol Digit Modalities Test performance.

CONCLUSIONS

The results suggest no major effect of COMT or MTHFR on cognitive function alone. However, an interaction of COMT Val158Met and MTHFR C677T polymorphisms may be associated with cognitive function. Further studies in a large sample are needed to replicate the genetic role in the LOD patients.

Lack of association between MTHFR Ala222Val and Glu429Ala polymorphisms and bladder cancer risk: A meta-analysis of case-control studies

Bladder cancer is a commom malignancy in the urinary tract that is influenced by genetic and environmental factors. The role of functional polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene with bladder cancer risk remains to be determined. This meta-analysis was performed to derive a more precise estimation of MTHFR Ala222Val and Glu429Ala polymorphisms and bladder cancer risk. Data were collected with the last report up to September 2013. A total of 3,463 cases and 3,927 controls for Ala222Val, and 3,177 cases and 3,502 controls for Glu429Ala were analyzed. The pooled odds ratios (ORs) and 95% confidence interval (CI) were estimated for the association with bladder cancer risk. Overall, no significant associations of Ala222Val and Glu429Ala polymorphisms with bladder cancer risk were found (for Ala222Val: Val/Val vs. Ala/Ala: OR, 1.02; 95% CI: 0.80–1.29; Val/Ala vs. Ala/Ala: OR, 1.02; 95% CI: 0.92–1.12; dominant model: OR, 1.01; 95% CI: 0.87–1.17; recessive model: OR, 1.00; 95% CI: 0.87–1.15; and for Glu429Ala: Ala/Ala vs. Glu/Glu: OR, 1.11; 95% CI: 0.78–1.58; Ala/Glu vs. Glu/Glu: OR, 1.16; 95% CI: 0.95–1.40; dominant model: OR, 1.15; 95% CI: 0.94–1.41; recessive model: OR, 0.96; 95% CI: 0.79–1.15). In stratified analyses by ethnicity, significant associations were observed for Glu429Ala polymorphism in individuals of Middle Eastern descent (Ala/Glu vs. Glu/Glu: OR, 2.11; 95% CI: 1.26–3.53; dominant model: OR, 2.16; 95% CI: 1.16–4.01; recessive model: OR, 1.82; 95% CI: 1.11–3.01). This meta-analysis demonstrated that overall there was no association of MTHFR Ala222Val and Glu429Ala polymorphisms with bladder cancer risk. However, in the stratified analysis by ethnicity the MTHFR Glu429Ala polymorphism was significantly associated with increased bladder cancer risk in individuals of Middle Eastern descent.

Prevalence of methylenetetrahydrofolate reductase 677 C-T polymorphism among mothers of Down syndrome children

INTRODUCTION:

The relationship between chromosomal non-disjunction leading to aneuploidy and folate metabolism has drawn attention in the recent years. In this study, we examined the polymorphism in the gene encoding the folate metabolizing enzyme methylenetetrahydrofolate reductase (MTHFR), namely, 677 C-T in women having Down syndrome (DS) children.

MATERIALS AND METHODS:

The prevalence of these variant genotypes (MTHFR 677 C-T polymorphism) in women having DS children (case mothers) (n = 110) was compared with controls (n = 111) from Punjab. Genotyping was done using the polymerase chain reaction method followed by restriction fragment length polymorphism.

RESULTS:

In the present study, 1.8% of case mothers had TT genotype while none of the control mothers showed this genotype. T allele frequency among cases was 0.13 and 0.11 in controls. The Chi-square value showed a non-significant difference between cases and controls.

CONCLUSION:

No association has been observed between 677 C-T polymorphism and risk of non-disjunction in case mothers. Detection of polymorphisms in more genes of folate pathway is required to find out the exact cause of non-disjunction.

C677T mutation in methylenetetrahydrofolate reductase gene and neural tube defects: should Japanese women undergo gene screening before pregnancy?

We analyzed the role of maternal C677T mutation in methylenetetrahydrofolate reductase (MTHFR) gene on spina bifida development in newborns. A total of 115 mothers who had given birth to a spina bifida child (SB mothers) gave 10 mL of blood together with written informed consent. The genotype distribution of C677T mutation was assessed and compared with that of the 4517 control individuals. The prevalence of the homozygous genotype (TT) among SB mothers was not significantly different from that among the controls (odds ratio [OR] = 0.65; 95% confidence interval [CI] = 0.31-1.25; P = 0.182), suggesting that MTHFR 677TT genotype in Japan is not associated with spina bifida development in newborns. The T allele frequency was not increased in SB mothers (34.8%) as compared to that of the control individuals (38.2%). Further, the internationally reported association between the two groups was found to be similar in all 15 countries studied except the Netherlands, where the TT genotype was found to be a genetic risk factor for spina bifida. For the prevention of affected pregnancy every woman planning to conceive has to take folic acid supplements 400 μg a day and the government is asked to take action in implementing food fortification with folic acid in the near future. In conclusion, it is not necessary for Japanese women to undergo genetic screening C677T mutation of the MTHFR gene as a predictive marker for spina bifida prior to pregnancy, because the TT genotype is not a risk factor for having an affected infant.

Methylenetetrahydrofolate reductase polymorphisms and breast cancer risk in Chinese population: a meta-analysis of 22 case-control studies

The association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and breast cancer risk in the Chinese population has been widely reported, but results were inconsistent. In order to derive a more precise estimation of the relationship, a meta-analysis was performed. Eligible articles were identified through search of databases including Medline, PubMed, Web of Science, Embase, Chinese Biomedical Literature Database (CBM, Chinese), China National Knowledge Infrastructure (CNKI, Chinese), and Wangfang Database (Chinese). The association between the MTHFR polymorphism and breast cancer risk was conducted using odds ratios (ORs) and 95 % confidence intervals (95 % CIs). Finally, a total of 22 studies with 6,103 cases and 7,913 controls were included in our meta-analysis: 13 studies with 3,273 cases and 4,419 controls for C677T polymorphism and 9 studies with 2,830 cases and 3,494 controls for A1298C polymorphism. With regard to C677T polymorphism, significant association was found with breast cancer risk under three models (T vs. C: OR = 1.12, 95 % CI = 1.02-1.23, P = 0.015; TT vs. CC: OR = 1.35, 95 % CI = 1.10-1.67, P = 0.005; TT vs.

CC/CT

OR = 1.37, 95 % CI = 1.11-1.70, P = 0.004). There was no significant association found between A1298C polymorphism and breast cancer risk under all genetic models (C vs. A: OR = 0.96, 95 % CI = 0.89-1.03, P = 0.268; CC vs. AA: OR = 0.98, 95 % CI = 0.77-1.26, P = 0.899; AC vs. AA: OR = 0.95, 95 % CI = 0.88-1.02, P = 0.174; CC vs. AC/AA: OR = 1.00, 95 % CI = 0.78-1.28, P = 0.996, CC/AC vs. AA: OR = 0.96, 95 % CI = 0.89-1.02, P = 0.196). In summary, during this meta-analysis, we found that MTHFR C677T polymorphism was significantly associated with breast cancer risk in the Chinese population. Meanwhile, MTHFR A1298C polymorphism was not associated with breast cancer risk in the Chinese population.

Variation of types of alcoholism: review and subtypes identified in Han Chinese

Alcoholism, as it has been hypothesized, is caused by a highly heterogeneous genetic load. Since 1960, many reports have used the bio-psycho-social approach to subtype alcoholism; however, no subtypes have been genetically validated. We reviewed and compared the major single-gene, multiple-gene, and gene-to-gene interaction studies on alcoholism published during the past quarter-century, including many recent studies that have made contributions to the subtyping of alcoholism. Four subtypes of alcoholism have been reported: [1] pure alcoholism, [2] anxiety/depression alcoholism, [3] antisocial alcoholism, and [4] mixed alcoholism. Most of the important studies focused on three genes: DRD2, MAOA, and ALDH2. Therefore, our review focuses on these three genes.

Spinal cord demyelination combined with hyperhomocysteinemia: a case report

Hyperhomocysteinemia (HHcy) has been recognized as an independent risk factor for atherosclerotic vascular disease. Here we report a patient who suffered from spinal cord demyelination combined with HHcy. The patient was admitted to our hospital with a diagnosis of acute myelitis. However, hormone therapy was ineffective. Further investigations revealed that he had HHcy and a homozygous mutation of the gene encoding methylenetetrahydrofolate reductase (MTHFR) c.677C>T, which is a key enzyme involved in homocysteine metabolism. In view of these findings, we treated the patient with B vitamins and his symptoms gradually improved. Spinal magnetic resonance imaging performed 3 months after onset showed near recovery of the lesion. To our knowledge, similar reports are rare.

Contribution of GSTM1, GSTT1, and MTHFR polymorphisms to end-stage renal disease of unknown etiology in Mexicans

Oxidative stress is increased in chronic kidney disease, owing to an imbalance between the oxidative and antioxidant pathways as well as a state of persistent hyperhomocysteinemia. The enzymes glutathione S-transferases (GSTs) and methylenetetrahydrofolate reductase (MTHFR) are implicated in the regulation of these pathways. This study investigates the association between polymorphisms in the Glutathione S-transferase Mu 1 (GSTM1), glutathione S-transferase theta 1 (GSTT1), and MTHFR genes and end-stage renal disease (ESRD) of unknown etiology in patients in Mexico. A Case-control study included 110 ESRD patients and 125 healthy individuals. GSTM1 and GSTT1 genotypes were determined using the multiplex polymerase chain reaction (PCR). The MTHFR C677T polymorphism was studied using a PCR/restriction fragment length polymorphism method. In ESRD patients, GSTM1 and GSTT1 null genotype frequencies were 61% and 7% respectively. GSTM1 genotype frequencies differed significantly between groups, showing that homozygous deletion of the GSTM1 gene was associated with susceptibility to ESRD of unknown etiology (P = 0.007, odds ratios = 2.05, 95% confidence interval 1.21-3.45). The MTHFR C677T polymorphism genotype and allele distributions were similar in both groups (P > 0.05), and the CT genotype was the most common genotype in both groups (45.5% and 46.6%). Our findings suggest that the GSTM1 null polymorphism appears to be associated with the ESRD of unknown etiology in patients in Mexico.

A magnetic nanoparticles-based method for DNA extraction from the saliva of stroke patients

C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene is a risk factor for stroke, suggesting that widespread detection could help to prevent stroke. DNA from 70 stroke patients and 70 healthy controls was extracted from saliva using a magnetic nanoparticles-based method and from blood using conventional methods. Real-time PCR results revealed that the C677T polymorphism was genotyped by PCR using DNA extracted from both saliva and blood samples. The genotype results were confirmed by gene sequencing, and results for saliva and blood samples were consistent. The mutation TT genotype frequency was significantly higher in the stroke group than in controls. Homocysteine levels were significantly higher than controls in both TT genotype groups. Therefore, this noninvasive magnetic nanoparticles-based method using saliva samples could be used to screen for the MTHFR C677T polymorphism in target populations.

High prevalence of cerebral venous sinus thrombosis (CVST) as presentation of cystathionine beta-synthase deficiency in childhood: molecular and clinical findings of Turkish probands

Classical homocystinuria is the most commonly inherited disorder of sulfur metabolism, caused by the genetic alterations in human cystathionine beta-synthase (CBS) gene. In this study, we present comprehensive clinical findings and the genetic basis of homocystinuria in a cohort of Turkish patients. Excluding some CBS mutations, detailed genotype-phenotype correlation for different CBS mutations has not been established in literature. We aimed to make clinical subgroups according to main clinical symptoms and discussed these data together with mutational analysis results from our patients. Totally, 16 different mutations were identified; twelve of which had already been reported, and four are novel (p.N93Y, p.L251P, p.D281V and c.829-2A>T). The probands were classified into three major groups according to the clinical symptoms caused by these mutations. A psychomotor delay was the most common diagnostic symptom (n=12, 46.2% neurological presentation), followed by thromboembolic events (n=6, 23.1% vascular presentation) and lens ectopia, myopia or marfanoid features (n=5, 19.2% connective tissue presentation). Pyridoxine responsiveness was 7.7%; however, with partial responsive probands, the ratio was 53.9%. In addition, five thrombophilic nucleotide changes including MTHFR c.677 C>T and c.1298 A>C, Factor V c.1691 G>A, Factor II c.20210 G>A, and SERPINE1 4G/5G were investigated to assess their contributions to the clinical spectrum. We suggest that the effect of these polymorphisms on clinical phenotype of CBS is not very clear since the distribution of thrombophilic polymorphisms does not differ among specific groups. This study provides molecular findings of 26 Turkish probands with homocystinuria and discusses the clinical presentations and putative effects of the CBS mutations.

Is green tea a potential trigger for autoimmune hepatitis?

A case of autoimmune liver hepatitis is reported: the onset was triggered by consumption of green tea infusion in a patient taking oral contraceptives and irbesartan. We hypothesize that our patient, carrying genetic variant of hepatic metabolism making her particularly susceptible to oxidative stress, developed an abnormal response to a mild toxic insult, afforded by a combination of agents (oral contraceptives+irbesartan+green tea) that normally would not be able to cause damage. Her particular hepatic metabolism further increased the drugs' concentration, favoring the haptenization of liver proteins, eventually leading to the development of an autoimmune hepatitis.

Methylenetetrahydrofolate reductase C677T and methionine synthase A2756G polymorphisms influence on leukocyte genomic DNA methylation level

Methionine synthase (MTR) and methylenetetrahydrofolate reductase (MTHFR) enzymes are involved in the metabolism of methyl groups, and thus have an important role in the maintenance of proper DNA methylation level. In our study we aimed to evaluate the effect of the polymorphism A2756G (rs1805087) in the MTR gene on the level of human leukocyte genomic DNA methylation. Since the well-studied polymorphism C677T (rs1801133) in the MTHFR gene has already been shown to affect DNA methylation, we aimed to analyze the effect of MTR A2756G independently of the MTHFR C677T polymorphism. For this purpose, we collected the groups of 80 subjects with the MTR 2756AA genotype and 80 subjects with the MTR 2756GG genotype, having equal numbers of individuals with the MTHFR 677CC and the MTHFR 677TT genotypes, and determined the level of DNA methylation in each group. Individuals homozygous for the mutant MTR 2756G allele showed higher DNA methylation level than those harboring the MTR 2756AA genotype (5.061 ± 1.761% vs. 4.501 ± 1.621%, P=0.0391). Individuals with wild-type MTHFR 677СC genotype displayed higher DNA methylation level than the subjects with mutant MTHFR 677TT genotype (5.103 ± 1.767% vs. 4.323 ± 1.525%, P=0.0034). Our data provide evidence that the MTR A2756G polymorphism increases the level of DNA methylation and confirm the previous reports that the MTHFR C677T polymorphism is associated with DNA hypomethylation.