Study of C677T Methylene Tetrahydrofolate Reductase Gene Polymorphism as a Risk Factor for Neural Tube Defects

Introduction

Various genetic and environmental factors contribute to the development of neural tube defects (NTDs) which are a group of neurulation defects resulting from failure of closure of embryonic neural tube. Among genetic factors is polymorphism in methylene tetrahydrofolate reductase (MTHFR) gene, giving rise to a gene variant or mutant. However, in most studies directed at finding an association between MTHFR variants and NTD, there is no clear evidence of a cause-and-effect relationship.

Materials and Methods

Forty diagnosed cases of NTDs and forty healthy individuals were investigated in a case-control study for presence of C677T MTHFR gene polymorphism. Serum folate and Vitamin B12 levels were estimated and MTHFR gene polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism.

Results

It was found that 32 cases were homozygous with CC genotype and eight were heterozygous with CT genotype, whereas 35 controls had CC genotype and five had CT genotype. TT genotype was absent in both the groups. There was no statistically significant difference between both the groups. No evidence of association between MTHFR C677T polymorphism and NTDs was found.

Conclusion

Although there was no evidence of association between MTHFR C677T polymorphism and NTDs, our study does not rule out the impact of MTHFR gene mutation on folate metabolism. The reason for absence of TT genotype and no association could be a small sample size. Larger, comprehensive, and well-designed multicentric but feasible studies involving proper subjects and appropriate and adequate controls from several hospitals may provide more meaningful data.

MTHFR C677T and A1298C variants in Mexican Mestizo infants with neural tube defects from Western Mexico

Our study investigated the role of MTHFR C677T and A1298C variants in infants with neural tube defects (NTDs) from western Mexico. Using TaqMan allelic discrimination assay, we genotyped 101 live-born patients with NTDs (cases) and 247 controls. Our findings do not support that homozygosity or heterozygosity for the variants C677T and A1298C in the MTHFR gene are associated with NTDs in infants. However, since we have the highest worldwide frequency of homozygotes for the MTHFR C677T variant, we cannot rule out that our propensity for NTDs may be related to how such gene variant interacts with other factors, mainly with our secular patterns of inappropriate folate intake.

Folic Acid and Autism: A Systematic Review of the Current State of Knowledge

Folic acid has been identified to be integral in rapid tissue growth and cell division during fetal development. Different studies indicate folic acid’s importance in improving childhood behavioral outcomes and underline its role as a modifiable risk factor for autism spectrum disorders. The aim of this systematic review is to both elucidate the potential role of folic acid in autism spectrum disorders and to investigate the mechanisms involved. Studies have pointed out a potential beneficial effect of prenatal folic acid maternal supplementation (600 µg) on the risk of autism spectrum disorder onset, but opposite results have been reported as well. Folic acid and/or folinic acid supplementation in autism spectrum disorder diagnosed children has led to improvements, both in some neurologic and behavioral symptoms and in the concentration of one-carbon metabolites. Several authors report an increased frequency of serum auto-antibodies against folate receptor alpha (FRAA) in autism spectrum disorder children. Furthermore, methylene tetrahydrofolate reductase (MTHFR) polymorphisms showed a significant influence on ASD risk. More clinical trials, with a clear study design, with larger sample sizes and longer observation periods are necessary to be carried out to better evaluate the potential protective role of folic acid in autism spectrum disorder risk.

Associations Among Methylene Tetrahydrofolate Reductase rs1801133 C677T Gene Variant, Food Groups, and Non-alcoholic Fatty Liver Disease Risk in the Chinese Population

Objectives

To investigate the associations among the methylene tetrahydrofolate reductase rs1801133 C677T gene variant, food groups, and the risk of non-alcoholic fatty liver disease in the Chinese population.

Methods

A study of gene polymorphism was conducted using the polymerase chain reaction method. A total of 4,049 adults participated in the study, and all underwent physical examination and genotyping. Participants filled out a dietary questionnaire to enable us to assess the frequency and quantity of food consumption.

Results

The important variables identified as risk factors of non-alcoholic fatty liver disease were age, smoking, sex, body mass index, hyperlipidemia, diabetes, and methylene tetrahydrofolate reductase genotype (T – allele carriers). The homocysteine content was higher in the non-alcoholic fatty liver disease group than in the control group, and was higher in the T- allele than C- allele carriers. The homocysteine content was the highest in the T- allele carriers. Additionally, certain food groups such as milk and beans were associated with a lower risk of non-alcoholic fatty liver disease. Food groups such as meat, were associated with a higher risk of non-alcoholic fatty liver disease. Fresh fruit and vegetables, salted and smoked foods, desserts, cereals, fish, and eggs were not associated with the risk of non-alcoholic fatty liver disease. However, the influence of salted and smoked foods on non-alcoholic fatty liver disease was different in the C-allele and T-allele carriers of methylene tetrahydrofolate reductase (CT + TT vs. CC, OR = 1.196, P = 0.041 for 1–4 times food per week, OR = 1.580, P = 0.004 for 5–7 times per week). Similarly, salted and smoked foods were also a risk factor for the development of non-alcoholic steatohepatitis in patients with non-alcoholic fatty liver disease.

Conclusion

This study found that the T-allele of the C677T variant of methylene tetrahydrofolate reductase was a risk factor for non-alcoholic fatty liver disease among Chinese people. These results can likely aid the development of novel approaches for managing non-alcoholic fatty liver disease risk.

Methylene tetrahydrofolate reductase (MTHFR) and vascular endothelial growth factor (VEGF) polymorphisms in Brazilian patients with Hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC)

OBJECTIVE

The folate pathway is involved in hepatic carcinogenesis and angiogenesis. Polymorphisms in genes related to such processes, including methylene tetrahydrofolate reductase (MTHFR) and vascular endothelial growth factor (VEGF)] may play an important role in the development of hepatocellular carcinoma (HCC). The objective of this study was to evaluate MTHFR and VEGF polymorphisms in Brazilian patients with hepatitis C virus (HCV)-related HCC.

METHODS

A total of 119 patients diagnosed with confirmed HCC and HCV were included in the study. SNP genotyping assays were performed using real-time PCR. VEGFA (rs2010963, rs3025039, and rs833061) and MTHFRC677T (rs1801133, rs1801131) polymorphisms were evaluated.

RESULTS

The C alleles of MTHFR (rs1801131) and VEGF (rs2010963) were associated with protection against the development of multinodular HCC, while the T allele of MTHFR (rs1801133) was associated with a higher risk of multinodular presentation [p=0.04 OR 1.835 CI (1.022-3.297)]. Multivariate analysis revealed that the GG/GC genotypes of VEGF rs2010963 were independently associated with multinodular tumors at diagnosis (p=0.013; OR 4.78 CI (1.38-16.67)].

CONCLUSION

Our results suggest that these polymorphisms may increase the risk of rapid tumor progression in patients with HCV infection. This subgroup of patients with HCC and who present polymorphism is more likely to be diagnosed with multinodular disease and not be amenable to receiving curative treatments. These data must be validated in larger cohorts, and the screening intervals can be customized based on genetic history.

Prevalence of the methylenetetrahydrofolate reductase 677C>T polymorphism in the pregnant women of Yunnan Province, China

Mutations in the methylenetetrahydrofolate reductase (MTHFR) gene can result in a reduced ability to utilize folic acid. The MTHFR 677C>T polymorphism in particular has been linked to both birth defects and pregnancy-associated diseases. This study aimed to evaluate the prevalence of the MTHFR 677C>T mutation among pregnant women in Yunnan Province so as to collect baseline data that may be utilized to guide folic acid supplementation efforts and to support related disease prevention programs. We retrospectively reviewed 3387 pregnant women from Yunnan Province. The MTHFR 677C>T polymorphism was identified using polymerase chain reaction (PCR) and DNA sequencing. In total, 1350 (39.9%) subjects were homozygous for the C allele (CC), 1540 (45.4%) subjects were heterozygous (CT), and 497 (14.7%) subjects were homozygous for the T allele (TT). The MTHFR 677C>T polymorphism was found to be present within the studied population, with ∼60% of these patients being either heterozygous or homozygous for the mutant allele and with an overall T allele frequency of 0.37. The frequency of the T allele was significantly higher among pregnant women with complications relative to women with healthy pregnancies, particularly among women <30 years old. As such, the maternal MTHFR 677C>T polymorphism may be a genetic risk factor associated with pregnancy complications and may help identify pregnant women at a high risk of such complications.

A hidden cause of infertility in hypothyroid patients

Methylene tetrahydrofolate reductase (MTHFR) gene mutations could be the cause of infertility in hypothyroid patients. Hence, it is worthy to screen for MTHFR gene mutations in infertile hypothyroid females and their partners if infertility persists after optimizing thyroid function.

Contribution of genetic polymorphism of methylene tetrahydrofolate reductase on the effect of methotrexate in ectopic pregnancy patients

Background

Methotrexate (MTX) is the prior drug in ectopic pregnancy (EP). However, approximately 10% of patients suffer from failure by MTX therapy. Reduced folate carrier 1 (RFC1), methylene tetrahydrofolate reductase (MTHFR), and dihydrofolate reductase (DHFR) are involved in the transport and effects of MTX in vivo. In the present study, we aim to investigate the relationship between the genetic polymorphisms of RFC1, MTHFR, and DHFR and the clinical efficacy of MTX in tubal pregnancies.

Methods

100 patients of EP were enrolled in this study. Polymorphisms of RFC1 G80A, MTHFR C677T, and DHFR A‐317G were genotyped. β‐hCG level was detected in day 0, 4, and 7 after MTX injection. Association of MTX efficacy and genetic polymorphisms was analyzed.

Results

Methylene tetrahydrofolate reductase C677T was associated with MTX treatment (P = .017). The success rate of first MTX injection was superior in patients with harboring mutation allele of MTHFR gene than that in patients with wild‐type gene (P = .001). However, there was no significant association between the polymorphisms of RFC1 G80A, DHFR A‐317G, and surgical treatment (P = .709 and .476, respectively). In addition, β‐hCG level decrement was not significantly changed by MTX injection with different polymorphisms of RFC1, MTHFR, and DHFR on either day 4 (P = .214, 0.197 and 0.270, respectively) or day 7 (P = .172, .554, and .726, respectively).

Conclusion

Our results suggested that the reliable indicator was polymorphism of MTHFR C677T in failure by MTX injection.

Coexpression of Methyltransferase Gene dmt50 and Methylene Tetrahydrofolate Reductase Gene Increases Arabidopsis thaliana Dicamba Resistance

Dicamba, a broad-spectrum and highly efficient herbicide, is an excellent target herbicide for the engineering of herbicide-resistant crops. In this study, a new tetrahydrofolate (THF)-dependent dicamba methyltransferase gene, dmt50, was cloned from the dicamba-degrading strain Rhizorhabdus dicambivorans Ndbn-20. Dmt50 catalyzed the methyl transfer from dicamba to THF, generating the herbicidally inactive product 3,6-dichlorosalicylic acid (3,6-DCSA) and 5-methyl-THF. A dmt50 transgenic Arabidopsis thaliana clearly showed dicamba resistance (560 g/ha, the normal field application rate). However, Dmt50 demethylation activity was inhibited by the product 5-methyl-THF. Mthfr66, encoded by the 5,10-methylene-THF reductase gene mthfr66 could relieve the inhibition by removing 5-methyl-THF in vitro. Compared with expression of dmt50 alone, simultaneous expression of dmt50 and mthfr66 further improved the dicamba resistance (1120 g/ha) of transgenic A. thaliana. This study provides new genes for dicamba detoxification and a strategy for the engineering of dicamba-resistant crops.

Biochemical and genetic predictors and correlates of response to lamotrigine and folic acid in bipolar depression: Analysis of the CEQUEL clinical trial

OBJECTIVES

CEQUEL (Comparative Evaluation of QUEtiapine plus Lamotrigine combination versus quetiapine monotherapy [and folic acid versus placebo] in bipolar depression) was a double-blind, randomized, placebo-controlled, parallel group, 2×2 factorial trial that examined the effect of adding lamotrigine and/or folic acid (FA) to quetiapine in bipolar depression. Lamotrigine improved depression, but its effectiveness was reduced by FA. We investigated the baseline predictors and correlates of clinical response, and the possible basis of the interaction.

METHODS

The main outcome was change in depressive symptoms at 12 weeks, measured using the Quick Inventory for Depressive Symptoms-self report version 16 (QIDS-SR16). We examined the relationship between symptoms and lamotrigine levels, and biochemical measures of one-carbon metabolism and functional polymorphisms in catechol-O-methyltransferase (COMT), methylene tetrahydrofolate reductase (MTHFR) and folate hydrolase 1 (FOLH1).

RESULTS

Lamotrigine levels were unaffected by FA and did not differ between those participants who achieved remission and those with persisting symptoms. When participants with subtherapeutic serum levels were excluded, there was a main effect of lamotrigine on the main outcome, although this remained limited to those randomized to FA placebo. None of the biochemical measures correlated with clinical outcome. The negative impact of FA on lamotrigine response was limited to COMT Met carriers. FOLH1 and MTHFR had no effect.

CONCLUSIONS

Our results clarify that FA's inhibition of lamotrigine's efficacy is not a pharmacokinetic effect, and that low serum lamotrigine levels contributed to lamotrigine's lack of a main effect at 12 weeks. We were unable to explain the lamotrigine-FA interaction, but our finding that it is modulated by the COMT genotype provides a starting point for follow-on neurobiological investigations. More broadly, our results highlight the value of including biochemical and genetic indices in randomized clinical trials.

Association of MTHFR genetic polymorphisms with venous thromboembolism in Uyghur population in Xinjiang, China

BACKGROUND

The aim of this study was to reveal the association between Methylene tetrahydrofolate reductase (MTHFR) gene mutations (C677T, A1298C and C1317T) and risk of venous thromboembolism (VTE) in Han and Uyghur population in Xinjiang.

MATERIAL AND METHOD

We conducted a case control study composed of 246 cases, including 86 Uyghur and 160 Han ethnic diagnosed VTE were admitted in the First Affiliated Hospital of Xinjiang Medical University between January 2008 to December 2012, and 292 population including 122 Uyghur ethnic and 170 Han ethnic were studied as controls. To detect the polymorphism of MTHFR gene C677T, A1298T, and C1317T, Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was applied. Fluorescence polarization immunoassay was adopted to determine the plasma levels Homocysteine (Hcy), folic acid and vitaminB12 (VitB12). The association of the polymorphism of MTHFR and levels Hcy, folic acid and VitB12 with VTE was analyzed.

RESULTS

The MTHFR gene C677T genotypes distribution in Uyghur VTE patients and control groups were: TT (27.91% vs. 12.29%), CT (41.86% vs. 52.46%) and CC (30.23% vs. 35.25%), respectively; and in Han VTE patients and control groups were: TT (27.49% vs. 14.71%), CT (44.38% vs. 53.53%) and CC (28.13% vs. 31.76%), respectively, and there were significant differences in TT genotype of MTHFRC677T between VTE patients and controls in both Uyghur and Han ethnic (Uyghur: x(2)=8.070, P=0.005; Han: x(2)=8.159, P=0.004). However, there were no significant differences in the MTHFR gene A1298T and C1317T genotyping distribution frequency in Uygur and Han ethnic between VTE patients and controls (P>0.05). Plasma levels of Hcy in MTHFR gene TT genotype were statistically higher than CT and CC genotype (P<0.05). After adjusting for age, gender, smoking, hypertension, hyperlipidemia, diabetes and MTHFR genotype for plasma Hcy levels, multifactor logistic regression analysis showed (OR=1.025, 95% CI 1.003-1.046, P=0.024) and obesity (OR=4.660, 95% CI 1.417-15.324, P=0.011) were independent risk factors for Uygur ethnic with VTE while plasma Hcy levels (OR=1.020, 95% CI 1.006-1.034, P=0.004) and smoking (OR=2.867, 95% CI 1.062-6.586, P=0.024) were independent risk factors for Han ethnic with VTE.

CONCLUSIONS

Our finding supports significant role of MTHFR gene in VTE and evidence of genetically determined HHcy contribute a risk for VTE, and a smoker with tHcy has positive association with a risk of VTE.

Has prenatal folate supplementation established an at-risk population for age-related cognitive decline?

Nutrition exerts a pervasive impact on normal and pathological conditions of the nervous system throughout life. Maternal folate supplementation during pregnancy has reduced developmental disorders of the nervous system, but may have also fostered an increase in individuals harboring genetic polymorphisms that compromise folate usage. Such individuals may harbor a lifetime requirement for additional dietary folate, often not met beyond peri/postnatal periods. An increased association of such polymorphisms has been detected in individuals with autism. Prenatal nutritional supplementation may have inadvertently established latent conditions that, in the absence of continued supplementation, may lead to age-related cognitive decline.

Pharmacogenomics of fluorouracil -based chemotherapy toxicity

INTRODUCTION

5- fluorouracil (5-FU), alone or in combination, is the most prevalent and effective chemotherapeutic agent for the treatment of cancers of the head and neck, breast, pancreas and gastrointestinal tract.

AREAS COVERED

Three rare DPYD mutations, a splice mutation in intron 14 (c.1905+1G>A) and two nonsynonymous coding variants (c.1679T>G, c.2846A>T), have consistently been associated with severe 5-FU toxicity. A relatively common haplotype, hapB3, containing three intronic polymorphisms (c.483+18G>A; c.680+139G>A; c.959-51T>C) and a synonymous mutation c.1236G>A linked to c.1129-5923C>G, is a major contributor to early onset severe toxicity. TYMS VNTR 2R and TYMS-3'-UTR 6-bp ins-del variants were associated with global toxicity in capecitabine-treated patients. A candidate gene study of capecitabine-related toxicity reported that the s12132152 were strongly associated with hand-foot syndrome (HFS), whereas rs7548189 was associated with diarrhea. The rs2612091 and rs2741171, which are downstream of TYMS and intronic for ENOSF1, were associated with increased global toxicity and HFS.

EXPERT OPINION

Sex-dependent differences, ethnicity, cancer types and 5-FU-based chemotherapy regimens might affect the heterogeneity of genetic variants for predictive 5-FU-related toxicity. Future approaches using genome-wide association analyses may help in identifying additional candidate genes causally involved in the path mechanisms of 5-FU-related toxicity.

Joint effects between urinary selenium and polymorphisms in methylation related genes on breast cancer risk

The aim of this study was to explore the associations of urinary selenium and polymorphisms in methylation related genes with breast cancer risk and the interactions on the risk. The present study involved in 240 female patients with incident breast cancer and 246 age-matched controls in two affiliated hospitals of Sun Yat-sen University in Guangzhou, China, from October 2009 to July 2010. DNMT1 rs2228611, MTHFR rs1801133, and MTR rs1805087 were genotyped using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry platform. Urinary concentration of selenium was measured by inductively coupled plasma mass spectrometry. Women with urinary selenium in the second tertile had a significant reduced breast cancer risk compared to those with urinary selenium in the lowest tertile [OR (95%CI): 0.50 (0.30, 0.81)]. DNMT1 rs2228611, MTHFR rs1801133, and MTR rs1805087 were not associated with breast cancer risk. Women with the third tertile of urinary selenium had a significant reduced breast cancer risk compared to those with the lowest tertile among women only with CC genotype [OR (95%CI): 0.55 (0.30, 1.00)] but not CT/TT genotypes [OR (95%CI): 1.58 (0.73, 3.42)] of MTHFR rs1801133 (P for interaction=0.044). Our results suggested that selenium was associated with a decreased risk of breast cancer and this beneficial effect was limited to women with CC genotype of MTHFR rs1801133.

Pharmacogenetic evaluation of ABCB1, Cyp2C9, Cyp2C19 and methylene tetrahydrofolate reductase polymorphisms in teratogenicity of anti-epileptic drugs in women with epilepsy

Aim:

Pregnancy in women with epilepsy (WWE) who are on anti-epileptic drugs (AEDs) has two- to three-fold increased risk of fetal malformations. AEDs are mostly metabolized by Cyp2C9, Cyp2C19 and Cyp3A4 and transported by ABCB1. Patients on AED therapy can have folate deficiency. We hypothesize that the polymorphisms in ABCB1, Cyp2C9, Cyp2C19 and methylene tetrahydrofolate reductase (MTHFR) might result in differential expression resulting in differential drug transport, drug metabolism and folate metabolism, which in turn may contribute to the teratogenic impact of AEDs.

Materials and Methods:

The ABCB1, Cyp2C9, Cyp2C19 and MTHFR polymorphisms were genotyped for their role in teratogenic potential and the nature of teratogenecity in response to AED treatment in WWE. The allelic, genotypic associations were tested in 266 WWE comprising of 143 WWE who had given birth to babies with WWE-malformation (WWE-M) and 123 WWE who had normal offsprings (WWE-N).

Results:

In WWE-M, CC genotype of Ex07 + 139C/T was overrepresented (P = 0.0032) whereas the poor metabolizer allele *2 and *2 *2 genotype of CYP2C219 was significantly higher in comparison to WWE-N group (P = 0.007 and P = 0.005, respectively). All these observations were independent of the nature of malformation (cardiac vs. non cardiac malformations).

Conclusion:

Our study indicates the possibility that ABCB1 and Cyp2C19 may play a pivotal role in the AED induced teratogenesis, which is independent of nature of malformation. This is one of the first reports indicating the pharmacogenetic role of Cyp2C19 and ABCB1 in teratogenesis of AED in pregnant WWE.

Hyperhomocysteinaemia, low folate concentrations and MTHFR C677T mutation in abdominal aortic aneurysm

BACKGROUND

Homocysteine (Hcy) has been implicated in abdominal aortic aneurysm (AAA). However, the association of Hcy, vitamin B12, and folate in patients with AAA has not been studied in China. This study was conducted with the aim to evaluate the relationship of vitamin B12, folic acid, and Hcy levels in AAA.

PATIENTS AND METHODS

463 patients who had AAA were included in this study. 463 control subjects were age- and sex-matched with the patients. In all of the subjects, we evaluated total plasma levels Hcy, vitamin B12, folic acid and the distribution of the C677T methylenetetrahydrofolate reductase (MTHFR) gene mutation.

RESULTS

The mean plasma Hcy levels were significantly higher in patients with AAA compared with controls (18.37 ± 6.97 vs. 12.89 ± 4.08 μmol/L, P < 0.001). The frequency of homozygous (TT) genotype in MTHFR C677T mutation was significantly higher in patients with AAA than that in control subjects (19.4 % vs. 11.9 %, P = 0.002). The fasting Hcy correlated negatively with folate (AAA: r = - 0.311, P < 0.01;

CONTROL

r = - 0.348, P < 0.01). The aneurysm size was significantly greater (P < 0.001) in patients with hyperhomocysteinemia than that in patients with normal Hcy plasma levels. The size of the AAA had a linear correlation with the plasma Hcy level (r = 0.286; P< 0.001).

CONCLUSIONS

Serum folate deficiency and hyperhomocysteinemia were associated with an increased risk of AAA in Northeast China. The homozygous (TT) genotype of MTHFR gene mutation may be a crucial hereditary risk factor in AAA.

Epigenetic modulation of RFC1, MHC2TA and HLA-DR in systemic lupus erythematosus: association with serological markers and six functional polymorphisms of one-carbon metabolic pathway

The current study was conducted to elucidate the effect of genetic variations in one-carbon metabolism on the epigenetic regulation of major histocompatibility complex II transactivator (MHC2TA), reduced folate carrier 1 (RFC1/SLC19A1) and human leukocyte antigen (HLA)-DR in systemic lupus erythematosus (SLE). PCR-RFLP/AFLP, bisulfite-sequencing and real-time PCR approaches were used for genetic, epigenetic and expression analysis respectively. SLE cases exhibited elevated plasma homocysteine levels compared to healthy controls (24.93 ± 1.3 vs. 11.67 ± 0.48 μmol/l), while plasma folate levels showed no association (7.10 ± 2.49 vs. 7.64 ± 2.09 ng/ml). The RFC1 80G>A polymorphism showed 1.32-fold risk (95% CI: 1.02-1.72) for SLE, while glutamate carboxypeptidase II (GCPII) 1561C>T showed reduced risk (OR: 0.47, 95% CI: 0.24-0.90). The expression of RFC1 (0.37 ± 0.09 vs. 0.60 ± 0.17) and HLA-DR (0.68 ± 0.17 vs. 0.98 ± 0.02) was down regulated in the SLE cases. The hypermethylation of RFC1 as observed in the current study may contribute for its down regulation. Plasma folate and thymidylate synthase (TYMS) 5'-UTR 28 bp tandem repeat showed an inverse association with methylation of RFC1 and MHC2TA. SLE cases with hypocomplementemia showed hypermethylation of RFC1, hypomethylation/up regulation of MHC2TA and down regulation of HLA-DR. The hypermethylation of MHC2TA and down regulation of RFC1, MHC2TA and HLA-DR were observed in anti-cardiolipin antibody positive SLE cases. The up regulation of RFC1 and HLA-DR was observed in anti-dsDNA antibody positive SLE cases. The hypomethylation/upregulation of RFC1 and MHC2TA was observed in anti-RNP antibody positive cases. To conclude, one-carbon genetic variants influence epigenetic of MHC2TA and RFC1, thus contributing to phenotypic heterogeneity of SLE.

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.

Homocysteine induces cerebral endothelial cell death by activating the acid sphingomyelinase ceramide pathway

Homocysteine (Hcy) levels may rise after a stroke, but the mechanism of Hcy-induced cerebral endothelial cell (CEC) dysfunction has not been explored. In this study we examined the role of the acid sphingomyelinase (Asm)-ceramide pathway in the molecular mechanism of Hcy-induced CEC dysfunction. Murine CECs were prepared from fresh mouse brains. CECs were treated with 50-500 μM Hcy and 30-100 μM C2-ceramide for 48 h. Sphingomyelinase assays were performed to determine Asm activity. Quantitative assessments of cell survival and death by the MTT reduction and LDH release were conducted. Treatment of murine CECs with Hcy and ceramide caused cell death in a dose-dependent manner as determined by LDH and MTT assays. 250 μM Hcy and 50 μM C2-ceramide caused 50% cell death. Hcy induced murine CEC death also occurred in a time-dependant manner with substantial cell death noted as early as 24h after Hcy exposure. C2-ceramide-induced murine CEC death occurred earlier than Hcy-induced cell death by about 18h. Hcy treatment increased Asm activity and intracellular ceramide accumulation. This study demonstrated that Hcy and C2-ceramide can cause murine CEC death. Hcy induces CEC death possibly by activating the Asm-ceramide pathway.

5,10-methylene tetrahydrofolate reductase C677T gene polymorphism, homocysteine concentration and the extent of premature coronary artery disease in southern Iran

Elevated level of plasma homocysteine (Hcy) has been identified as an independent risk factor for coronary artery disease (CAD). Furthermore, numerous studies have documented the influences of a common polymorphism (C677T) of methylenetetrahydrofolate reductase (MTHFR) on homocysteine levels. However the relationship between this mutation and cardiovascular diseases (CVD) has remained as a controversial issue. The present study was undertaken to investigate the relationship between C677T polymorphism of MTHFR gene, plasma total Hcy levels and the number of affected vessels as a criterion for the extent of CAD. MTHFR genotypes and plasma homocysteine (HCY) concentrations were examined in 231 patients and 300 healthy subjects who underwent diagnostic coronary angiography. A multiple linear regression analysis was performed to identify the predictors of Hcy levels whereas logistic regression model was built to determine the association of Hcy quartiles with the risk of CAD adjusted for risk factors. The prevalence of MTHFR genotypes was similar between CAD patients and non-CAD individuals while the geometric mean of Hcy values was significantly higher in patient group (14.13 ± 4.11 μmol/l) than in control group (10.19 ± 3.52 μmol/l) (P < 0.001). Moreover, unlike the MTHFR polymorphism, Hcy concentration increased with increasing number of stenosed vessels and the CAD risk increased about 2 folds in the top two Hcy quartiles (≥ 17.03 and 13.20-17.02 μmol/l) compared with the lowest quartile (≤ 9.92 μmol/l) after controlling for conventional risk factors (P<0.001 for both). Our data suggest that hyperhomocysteinaemia (HHcy) is significantly associated to CAD risk increase as well as to the extent of coronary atherosclerosis.

Prevalence of MTHFR C677T and MS A2756G polymorphisms in major depressive disorder, and their impact on response to fluoxetine treatment

OBJECTIVE

To examine the prevalence of the C677T polymorphism of the methylene tetrahydrofolate reductase (MTHFR) gene and the A2756G polymorphism of methionine synthase (MS), and their impact on antidepressant response.

METHODS

We screened 224 subjects (52% female, mean age 39 ± 11 years) with SCID-diagnosed major depressive disorder (MDD), and obtained 194 genetic samples. 49 subjects (49% female, mean age 36 ± 11 years) participated in a 12-week open clinical trial of fluoxetine 20-60 mg/day. Association between clinical response and C677T and A2756G polymorphisms, folate, B12, and homocysteine was examined.

RESULTS

Prevalence of the C677T and A2756G polymorphisms was consistent with previous reports (C/C = 41%, C/T = 47%, T/T = 11%, A/A = 66%, A/G = 29%, G/G = 4%). In the fluoxetine-treated subsample (n = 49), intent-to-treat (ITT) response rates were 47% for C/C subjects and 46% for pooled C/T and T/T subjects (nonsignificant). ITT response rates were 38% for A/A subjects and 60% for A/G subjects (nonsignificant), with no subjects exhibiting the G/G homozygote. Mean baseline plasma B12 was significantly lower in A/G subjects compared to A/A, but folate and homocysteine levels were not affected by genetic status. Plasma folate was negatively associated with treatment response.

CONCLUSION

The C677T and A2756G polymorphisms did not significantly affect antidepressant response. These preliminary findings require replication in larger samples.