Mild hyperhomocysteinemia and the common C677T polymorphism of methylene tetrahydrofolate reductase gene are not associated with the metabolic syndrome in Type 2 diabetes

Associations of MTRR and TSER polymorphisms related to folate metabolism with susceptibility to metabolic syndrome

BACKGROUND

Hyperhomocysteinemia is a potential risk factor for the development of metabolic syndrome (MetS). Among genes involved in homocysteine metabolism, polymorphisms of methylenetetrahydrofolate reductase (MTHFR) gene are known to be associated with MetS incidence. However, effects of polymorphisms of other folate metabolism-related genes on MetS susceptibility are not well known yet.

OBJECTIVE

This study was to determine whether methionine synthase (MTR) 2756A > G, methionine synthase reductase (MTRR) 66A > G, and thymidylate synthase enhancer region (TSER) 2R/3R polymorphisms might be associated with risks of MetS development in the Korean population.

METHODS

Genotype analysis of the three polymorphisms was performed for a total of 483 subjects including 236 MetS patients and 247 unrelated healthy controls using polymerase chain reaction-restriction fragment length polymorphism technique.

RESULTS

The present study revealed that MTRR and TSER polymorphisms were associated with susceptibility to MetS. Several genotypes and allele combinations from the three polymorphisms were also related to the MetS prevalence. When polymorphism data were stratified according to the risk components of MetS, MTR polymorphism was significantly associated with an increased risk of MetS in subjects with systolic blood pressure < 132.7 mmHg (AOR 1.842, 95% CI 1.039-3.266, P = 0.037) and fasting blood glucose level < 106.3 mg/dL (AOR 1.772, 95% CI 1.069-2.937, P = 0.027). MTRR polymorphism was significantly associated with a decreased risk of MetS in subjects with triglyceride level < 216.3 mg/dL (AOR 0.616, 95% CI 0.399-0.951, P = 0.029). To the best of our knowledge, this is the first to provide reliable evidence about the association of other folate metabolism-related gene polymorphisms besides MTHFR with MetS susceptibility and its risk factors.

CONCLUSION

Results of this study suggest that MTRR and TSER polymorphisms might be potential genetic markers for the risk of MetS development in Korean population.

A Genetic Association Study of MTHFR C677T Polymorphism with Risk of Metabolic Syndrome: A Systematic Review and Meta-Analysis

Methylenetetrahydrofolate reductase (MTHFR) is an enzyme that plays a crucial role as a methyl-group donor in demethylation of homocysteine. The aim of this systematic review and meta-analysis was to study the relationship between MTHFR gene polymorphism and metabolic syndrome (MS). We used search engines and databases such as Science Direct, Google Scholar, Embase, Cochrane Library, and PubMed to identify eligible studies up to 2018. The articles were studied based on keywords including MTHFR, mutation, variant, and polymorphism in combination with MS. Data was analyzed using Comprehensive Meta-Analysis version 2.2.064 software. After extracting the data from seven articles, the total number of subjects was 1280 in the patient group and 1374 in the control group. The odds ratio was estimated to be 1.078 for the allele model of T vs. C (95% confidence interval [CI]: 1.626-0.715), 1.157 for the allele model of CC vs. CT (95% CI: 0.829-1.615), 1.020 for the allele model of CT + TT vs. CC (95% CI: 1.611-0.646) and 0.799 for the allele model of TT vs. CC + CT (95% CI: 1.185- 0.539). As well, the results showed no statistically significant correlation between polymorphism genotypes of the MTHFR gene and MS (P<0.05). In general, this study showed that the presence of C677T polymorphism in the MTHFR gene has no effect on the incidence of MS.

MTHFR - Ala222Val Effects on Metabolic Syndrome Progression

Objective: Methylene-tetrahydrofolate reductase (MTHFR) is involved in adapting metabolism to environmental challenges by various mechanisms, including the control of gene expression by epigenetic and post-translational changes of transcription factors. Though a metabolic syndrome candidate gene, association studies of its common polymorphism rs1801133 (MTHFR-Ala222Val) remain inconclusive with important ethnic differences, and the effect on disease progression was not addressed.

Methods: 307 middle-aged metabolic syndrome patients in a central Romanian hospital setting were investigated metabolically, and genotyped by PCR-RFLP. Disease progression was assessed by the age of onset of metabolic components, as well as development of non-alcoholic fatty liver disease and atherosclerotic complications.

Results: The minor allele frequency of rs1801133 was 30.13%. Metabolic parameters showed no statistically significant differences according to genotype, but variant carriers developed dysglycemia and dyslipidemia earlier (53.28±10.8 vs 59.44±9.31 years, p<0.05 and 58.57±11.31 vs 64.72±10.6 years, p<0.1).While the polymorphism did not influence hepatic complications, an inverse association was found for manifest atherosclerosis (OR=0.49, p=0.006, 95%CI:0.29-0.81), which may be folate-status dependent, and needs further investigations. Simultaneous analysis with transcription factor polymorphisms (rs1801282, rs8192678) showed that the more protective genotypes were present the later metabolic disturbances developed, and in the presence of the other two variants the apparent protective cardiovascular effect disappeared.

Conclusions: The common functional polymorphism rs1801133 may influence metabolic syndrome progression, the age of onset of components and development of atherosclerotic complications. Besides simple additive effects, complex mitigating and aggravating variant interactions may exist, and the protective or predisposing outcome may depend on modifiable environmental factors.

Associations of MTHFR C677T and MTRR A66G gene polymorphisms with metabolic syndrome: a case-control study in Northern China

Prior evidence indicates that homocysteine plays a role in the development of metabolic syndrome (MetS). Methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase reductase (MTRR) A66G polymorphisms are common genetic determinants of homocysteine levels. To investigate the associations of the MTHFR C677T and MTRR A66G polymorphisms with MetS, 692 Chinese Han subjects with MetS and 878 controls were recruited. The component traits of MetS and the MTHFR C677T and MTRR A66G genotypes were determined. A significant association was observed between the MTHFR 677T allele and increased risk of MetS, high fasting blood glucose, high waist circumference, and increasing number of MetS components. The MTRR A66G polymorphism was associated with an increased risk of MetS when combined with the MTHFR 677TT genotype, although there was no association found between MetS and MTRR A66G alone. Furthermore, the MTRR 66GG genotype was associated with high fasting blood glucose and triglycerides. Our data suggest that the MTHFR 677T allele may contribute to an increased risk of MetS in the northern Chinese Han population. The MTRR A66G polymorphism is not associated with MetS. However, it may exacerbate the effect of the MTHFR C677T variant alone. Further large prospective population-based studies are required to confirm our findings.

Association of genetic polymorphism of PPARγ-2, ACE, MTHFR, FABP-2 and FTO genes in risk prediction of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a non-autoimmune, complex, heterogeneous and polygenic metabolic disease condition characterized by persistent elevated blood glucose levels (hyperglycemia). India as said to be the diabetic capital of the world is likely to experience the largest increase in T2DM and a greater number of diabetic individuals in the world by the year 2030. Identification of specific genetic variations in a particular ethnic group has a critical role in understanding the risk of developing T2DM in a much efficient way in future. These genetic variations include numerous types of polymorphisms among which single nucleotide polymorphisms (SNPs) is the most frequent. SNPs are basically located within the regulatory elements of several gene sequences. There are scores of genes interacting with various environmental factors affecting various pathways and sometimes even the whole signalling network that cause diseases like T2DM. This review discusses the biomarkers for early risk prediction of T2DM. Such predictions could be used in order to understand the pathogenesis of T2DM and to better diagnostics, treatment, and eventually prevention.

Nutritional models of foetal programming and nutrigenomic and epigenomic dysregulations of fatty acid metabolism in the liver and heart

Barker's concept of 'foetal programming' proposes that intrauterine growth restriction (IUGR) predicts complex metabolic diseases through relationships that may be further modified by the postnatal environment. Dietary restriction and deficit in methyl donors, folate, vitamin B12, and choline are used as experimental conditions of foetal programming as they lead to IUGR and decreased birth weight. Overfeeding and deficit in methyl donors increase central fat mass and lead to a dramatic increase of plasma free fatty acids (FFA) in offspring. Conversely, supplementing the mothers under protein restriction with folic acid reverses metabolic and epigenomic phenotypes of offspring. High-fat diet or methyl donor deficiency (MDD) during pregnancy and lactation produce liver steatosis and myocardium hypertrophy that result from increased import of FFA and impaired fatty acid β-oxidation, respectively. The underlying molecular mechanisms show dysregulations related with similar decreased expression and activity of sirtuin 1 (SIRT1) and hyperacetylation of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α). High-fat diet and overfeeding impair AMPK-dependent phosphorylation of PGC-1α, while MDD decreases PGC-1α methylation through decreased expression of PRMT1 and cellular level of S-adenosyl methionine. The visceral manifestations of metabolic syndrome are under the influence of endoplasmic reticulum (ER) stress in overnourished animal models. These mechanisms should also deserve attention in the foetal programming effects of MDD since vitamin B12 influences ER stress through impaired SIRT1 deacetylation of HSF1. Taken together, similarities and synergies of high-fat diet and MDD suggest, therefore, considering their consecutive or contemporary influence in the mechanisms of complex metabolic diseases.

Folate and fetal programming: a play in epigenomics?

Folate plays a key role in the interactions between nutrition, fetal programming, and epigenomics. Maternal folate status influences DNA methylation, inheritance of the agouti phenotype, expression of imprinting genes, and the effects of mycotoxin FB1 on heterochromatin assembly in rodent offspring. Deficiency in folate and other methyl donors increases birth defects and produces visceral manifestations of fetal programming, including liver and heart steatosis, through imbalanced methylation and acetylation of PGC1-α and decreased SIRT1 expression, and produces persistent cognitive and learning disabilities through impaired plasticity and hippocampal atrophy. Maternal folate supplementation also produces long-term epigenomic effects in offspring, some beneficial and others negative. Deciphering these mechanisms will help understanding the discordances between experimental models and population studies of folate deficiency and supplementation.

The multidimensional nature of metabolic syndrome in schizophrenia: lessons from studies of one-carbon metabolism and DNA methylation

Large data sets indicate that the prevalence of metabolic syndrome (MetS) is significantly higher in patients with schizophrenia in comparison with the general population. Given that interactions between genes and the environment may underlie the etiology of MetS in subjects with schizophrenia, it is feasible that epigenetic phenomena can serve as the etiological consensus between genetic and environmental factors. However, there is still a striking scarcity of studies aimed at investigating the role of aberrant DNA methylation in the development of MetS in this group of patients. This article provides an update on the epigenetics of schizophrenia and reviews studies on the role of one-carbon metabolism and aberrant DNA methylation in the development of MetS.

Association of MTHFR C677T and A1298C gene polymorphisms with hypertension

OBJECTIVES

To check for the association of genetic polymorphisms related to the methylenetetrahydrofolate reductase (MTHFR) gene namely C677T and A1298C with hypertension in Saudi affected subjects from Qassim region.

SUBJECTS AND METHODS

Participants included 123 Saudi hypertensive cases (83 males and 40 females) in addition to 250 (142 males and 108 females) unrelated healthy controls from the same locality. Their age mean ±SD was 50.93 ± 15.43 years. For all subjects, DNA was extracted followed by real-time PCR amplifications for characterization of genotypes and alleles related to MTHFR C677T and A1298C gene polymorphisms

RESULTS

Total cases showed significantly higher carriage rate for the mutant allele 677T compared to controls (40.7% vs. 26%, OR=1.9, 95% CI= 1.2-3.1) with a lower frequency of the wild type 677CC genotype (59.3% vs. 74%, p=0.004). The same was observed among cases-subgroups of hypertension associated with obesity with a notably higher odds ratio (OR=2.6, 95% CI=1.3-5.01, p=0.004). Total cases showed also significantly higher frequency of mutant 1298 C allele carriage rate compared to controls (59.3% vs. 42.4%, OR=1.98, 95% CI= 1.3-3.1) with a lower frequency of the normal AA genotype (40.7% vs. 57.6%, p=0.003). The same was observed among cases-subgroups of hypertension associated with both diabetes and obesity and among cases of hypertension with obesity, also with higher odds ratio (OR=2.6 and 2.2 respectively).

CONCLUSION

This work showed that genetic polymorphisms related to the MTHFR gene are associated with the risk of hypertension particularly when accompanied with obesity and diabetes among Saudi subjects.

Methylenetetrahydrofolate reductase gene polymorphism in diabetes and obesity

Methylenetetrahydrofolate reductase (MTHFR) polymorphism may play an important role in the pathophysiology of obesity and diabetes accompanied by obesity due to its influence on plasma homocysteine levels. There are significant and sometimes very strong relationship between levels of homocysteine and several multi-system diseases including CHD and CVA. To examine the association between MTHFR gene C677T polymorphism in diabetes and obesity with serum homocysteine levels. A total of 682 subjects were recruited in four groups (Normal, obese, diabetic and obese and diabetics). MTHFR gene C677T polymorphism was detected using PCR-RFLP technique. Serum homocysteine levels were measured using HPLC. There was a significant increase in the mean serum homocysteine levels in subjects carrying TT genotype (34.6 +/- 26.5) compared to subjects carrying CC (15.1 +/- 8) or CT genotype (16.4 +/- 7.8) (P < 0.000). We found no significant differences for MTHFR allele and genotype frequencies between different groups. Our data have confirmed the association between serum homocysteine levels and MTHFR C677T genotype reported in other populations.

LG839: anti-obesity effects and polymorphic gene correlates of reward deficiency syndrome

INTRODUCTION

This study systematically assessed the weight management effects of a novel experimental DNA-customized nutraceutical, LG839 (LifeGen, Inc., La Jolla, CA, USA).

METHODS

A total of 1058 subjects who participated in the overall D.I.E.T. study were genotyped and administered an LG839 variant based on polymorphic outcomes. A subset of 27 self-identified obese subjects of Dutch descent, having the same DNA pattern of four out of the five candidate genes tested (chi-square analysis) as the entire data set, was subsequently evaluated. Simple t tests comparing a number of weight management parameters before and after 80 days of treatment with LG839 were performed.

RESULTS

Significant results were observed for weight loss, sugar craving reduction, appetite suppression, snack reduction, reduction of late night eating (all P<0.01), increased perception of overeating, enhanced quality of sleep, increased happiness (all P<0.05), and increased energy (P<0.001). Polymorphic correlates were obtained for a number of genes (LEP, PPAR-gamma2, MTHFR, 5-HT2A, and DRD2 genes) with positive clinical parameters tested in this study. Of all the outcomes and gene polymorphisms, only the DRD2 gene polymorphism (A1 allele) had a significant Pearson correlation with days on treatment (r=0.42, P=0.045).

CONCLUSION

If these results are confirmed in additional rigorous, controlled studies, we carefully suggest that DNA-directed targeting of certain regulator genes, along with customized nutraceutical intervention, provides a unique framework and strategic modality to combat obesity.

The methylenetetrahydrofolate reductase C677T genotype and the risk of obesity in three large population-based cohorts

OBJECTIVE

Epidemiological studies have shown that low folate levels are associated with a high body mass index (BMI). These findings have potentially important health implications and warrant further investigation to determine whether a causal relationship exists and the direction of this relationship. The methylenetetrahydrofolate reductase (MTHFR) C677T TT genotype is associated with reduced folate availability and may be a surrogate for measuring folate levels. We sought to determine whether MTHFR C677T genotype was associated with obesity.

DESIGN

We carried out our study on four populations from three longitudinal studies based in the UK and Denmark in which DNA for genotyping was obtained along with measures of obesity.

METHODS

Our subjects were taken from the British Women's Heart and Health Study (BWHHS), the Avon Longitudinal Study of Parents and Children (two populations: mothers and children) and the Copenhagen City Heart Study. We performed analyses separately by population, and then carried out a meta-analysis, combining similar populations.

RESULTS

Initial findings in the BWHHS suggested that the TT genotype may be associated with an increased risk of obesity BMI > or =30, however, no association was found with BMI or central adiposity in this cohort. This genotype was not associated with obesity in our other cohorts.

CONCLUSIONS

Our results suggest that the initial positive finding with obesity in the BWHHS was a chance finding. Our findings do not support a causal effect of low folate on obesity.