MTR) And Methionine Synthase Reductase Research Articles

Level of homocysteine and polymorphism of genes involved in folate metabolism in women with polycystic ovary syndrome

Background. Polycystic ovary syndrome (PCOS) is a multifactorial disease in the development of which gene polymorphism plays an important role. In recent years, data on the role of homocysteine (Hcy) in the formation of PCOS have appeared, and hyperhomocysteinemia is even considered one of the main symptoms of this disease. The causes of an impaired Hcy metabolism are varied and mainly depend on the condition of the genes encoding enzymes of the folate cycle. At the same time, available data on the effect of the 5,10-methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) gene polymorphisms on the development of hyperhomocysteinemia and the risk of PCOS are few and contradictory. The purpose of the study was to investigate the polymorphisms of the main genes encoding enzymes of the folate cycle (MTHFR, MTR, MTRR) and to reveal their relationship with the level of Hcy in PCOS. Material and methods. One hundred and twenty-nine women aged 20–28 years were examined: the main group — 98 patients with PCOS, the control group — 31 healthy women. The serum content of Hcy was evaluated and a molecular genetic study was conducted to identify the MTHFR, MTR, and MTRR genes. Results. Polymorphic variants of genes involved in folate metabolism were found in both patients with PCOS and in healthy women. However, serum concentration of Hcy was significantly higher in PCOS. Analysis of the MTHFR C677T polymorphism gene showed that the presence of the mutant T allele was associated with an increased Hcy level (12.9 ± 0.2 μmol/l) and the risk of PCOS (odds ratio (OR) = 1.19; 95% confidence interval (CI) 0.52–2.71). In the presence of two T alleles, the level of Hcy (14.6 ± 0.3 µmol/L) and the risk of deve­loping PCOS (OR = 7.69; 95% CI 0.98–59.87) increased even further compared to the functionally “normal” C677C genotype. There was also an association between the MTHFR gene polymorphism at locus 1298 and PCOS whose strength depended on the number of pathological C alleles and was mediated by Hcy content, although this mutation was accompanied by a less significant increase in the level of Hcy than the mutation at locus 677. Compared to carriers of the homozygous A1298A genotype, the risk of developing PCOS was 5.7 times higher in patients with one C allele, and 7.3 times higher in the presence of two C alleles. The MTRR A66A and A66G genotypes were associated with a significant increase in the level of Hcy compared to that of the control group and were associated with an increased risk of PCOS. The mutant homozygous G66G genotype was more common in the control group and had no significant effect on Hcy concentration. It is not proved that the MTR gene is a candidate gene for the development of PCOS, and its polymorphic variants have a negative effect on the level of Hcy. The combination of MTHFR C677T and A1298C, MTHFR C677T and MTR A2756G, MTR A2756G and MTRR A66G gene mutations are associated with a greater increase in Hcy and the risk of developing PCOS compared to any individual monomutation. Conclusions. The MTHFR gene polymorphism and the synergistic effect of the MTHFR, MTR, MTRR gene mutations can be important genetic determinants for homocysteine levels and the risk of PCOS.

Vitamin B Mitigates Thoracic Aortic Dilation in Marfan Syndrome Mice by Restoring the Canonical TGF-β Pathway.

Thoracic aortic aneurysm (TAA) formation is a multifactorial process that results in diverse clinical manifestations and drug responses. Identifying the critical factors and their functions in Marfan syndrome (MFS) pathogenesis is important for exploring personalized medicine for MFS. Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) polymorphisms have been correlated with TAA severity in MFS patients. However, the detailed relationship between the folate-methionine cycle and MFS pathogenesis remains unclear. Fbn1C1039G/+ mice were reported to be a disease model of MFS. To study the role of the folate-methionine cycle in MFS, Fbn1C1039G/+ mice were treated orally with methionine or vitamin B mixture (VITB), including vitamins B6, B9, and B12, for 20 weeks. VITB reduced the heart rate and circumference of the ascending aorta in Fbn1C1039G/+ mice. Our data showed that the Mtr and Smad4 genes were suppressed in Fbn1C1039G/+ mice, while VITB treatment restored the expression of these genes to normal levels. Additionally, VITB restored canonical transforming-growth factor β (TGF-β) signaling and promoted Loxl1-mediated collagen maturation in aortic media. This study provides a potential method to attenuate the pathogenesis of MFS that may have a synergistic effect with drug treatments for MFS patients.

Association of Three Single Nucleotide Polymorphisms in MTR and MTRR Genes with Lung Cancer in a Turkish Population.

Folate metabolism plays a critical role in DNA methylation and synthesis. Polymorphisms in folate metabolism may affect enzyme activities and thereby affect the cancer risk. Methionine synthase (MTR) and methionine synthase reductase (MTRR) are critical enzymes for the folate cycle. In this study, possible associations between genetic variabilities in MTR and MTRR and susceptibility to lung cancer (LC) were investigated in a Turkish population. A case-control study with 193 LC cases and 199 noncancerous controls was conducted. DNA was extracted from leukocytes using the high pure polymerase chain reaction (PCR) template preparation kit. The MTR 2756 A>G (rs1805087), MTRR 524 C > T (rs1532268), and MTRR 66 A>G (rs1801394) genotypes were determined using PCR-restriction fragment length polymorphism (PCR-RFLP) assays. The genotype and haplotype analyses of these polymorphisms were performed using SPSS 21 and Haploview 4.2, respectively. An association between the MTRR A66G polymorphism and LC (p = 0.042) was found. In addition, this allele was observed more frequently in smokers compared to nonsmokers (p = 0.030). In contrast, the distribution of the MTR 2756 A>G and the MTRR 524 C > T allele frequencies were similar in the subject cases and controls. In conclusion, the present study suggests an association between the MTRR 66 A>G gene polymorphisms and LC risk in a Turkish population.

The polymorphisms of methionine synthase (MTR) and methionine synthase reductase (MTRR) genes in pathogenesis of preeclampsia

Purpose: The aim of the study was to determine the MTR (methionine synthase) and MTRR (mehionine synthase reductase) polymorphisms in pregnant women with preeclampsia (PE).Materials and methods: The group of 98 women with PE and the group of 120 healthy pregnant women were analyzed. Determination of MTR 2756A > G and MTRR 66A > G polymorphisms was performed using polymerase chain reaction (PCR)/restriction fragment length polymorphism (RFLP) method.Results: The study did not show any statistically significant differences in frequency of genotypes and alleles of MTR 2756A > G polymorphism between PE group and controls. Higher frequency of 66GG genotype and 66G allele of MTRR 66A > G polymorphism was observed in the women with PE compared to control group. Moreover, the 66GG genotype correlated with higher doses of methyldopa, lower birth weight and higher placenta weight in women with PE.Conclusions: The obtained results for 66A > G polymorphism of MTRR gene suggest the predisposition to PE in carriers of mutated 66GG genotype and – 66G allele.

A Polymorphism in the MTRR Gene Is Associated with Early Childhood Caries and Underweight

Polymorphisms in genes encoding the enzymes involved in the metabolism of homocysteine, such as methionine synthase (MTR) and methionine synthase reductase (MTRR), play an important function in the metabolism of folic acid and vitamin B₁₂. The present study aimed to evaluate the association of polymorphisms in genes MTR (rs1805087) and MTRR (rs1801394) with susceptibility of early childhood caries (ECC) and with body mass index alterations. A cross-sectional study was performed in 488 children aged from 2 to 6 years from 25 public day care centers in Rio de Janeiro, Brazil. Demographic data and oral health habits were obtained through a questionnaire. Anthropometric measurements and caries experience data were collected by 2 examiners (κ = 0.80). Genotyping of the selected polymorphisms was carried out by TaqMan real-time PCR using genomic DNA extracted from buccal cells. Allele and genotype frequencies were compared between groups with and without disease. The t test, χ² test, odds ratio, Pearson correlation tests, and logistic regression analysis were used (p ≤ 0.05). The mean white spot lesion score was 1.18 (±2.57) in normal weight children and 2.50 (±3.87) in underweight children (p = 0.05). For MTRR polymorphisms, significant differences were observed for allele and genotype frequency distributions between caries-free and caries-affected children (p = 0.03 and 0.04 for allele and genotype frequencies, respectively) and in the genotype frequencies between normal weight and underweight children (p = 0.04). Our results suggest an association between underweight and ECC; in addition it is suggested that MTRR is a common genetic risk factor for ECC and underweight.

Abstract B08: Meta-analyses of methionine-related polymorphisms and colorectal cancer risk for population health

Abstract Introduction/Purpose: The purpose of this meta-analysis is to determine the associations between the methionine related polymorphisms and the risk of developing colorectal cancer (CRC) for population health. CRC accounts for over 9% of all cancer incidences, is the third most common cancer worldwide, and accounts for the third leading cause of cancer related deaths. Studies have been published to support the important roles of methionine synthase (MTR), and methionine synthase reductase (MTRR) as key enzymes involved in DNA synthesis, repair, and methylation. However, the associations between these methionine-related polymorphisms and the risk of CRC have been inconsistent. Previous meta-analyses on these genes had mixed findings, without clear identification of mutation rates per population groups. Procedure: On-line databases were searched from PubMed (PM) and PM Central databases for meta-analyses by using a combination of key words including methionine synthase or MTR, methionine synthase reductase or MTRR, colorectal or colon or rectal and cancer or carcinoma, and case control studies and meta-analysis. The located papers were cross referenced to find all original studies. For this analysis, 68 studies of human samples published within the last 16 years were located. Following the exclusions of the non-original research and non-case control studies, 34 studies remained. These papers were reviewed and evaluated using the criteria for the quality of studies by two raters. Relative risks (RR) were calculated for increased or decreased risks for CRC. New Data Findings: Preliminary data analysis included 15377 cases and 22445 controls for MTR2756 in 27 studies with 31 race-ethnic groups; and 11594 cases and 16665 controls for MTRR66 in 20 studies with 22 race-ethnic groups. MTRR66 AA subtype was associated with increased CRC risk for Asian-Japanese group (RR = 1.0824, 95% CI = 1.01 – 1.05, p = 0.0165, 1696 cases and 2355 controls in 4 studies); whereas MTRR66 AG subtype was protective against CRC risk for Asian-Japanese group (RR = 0.9236, 0.86 – 0.99, p = 0.0358, 1696 cases and 2355 controls in 4 studies). MTR2756 GG subtype for the Western countries was protective against CRC approaching statistical significance (RR = 0.9107, 0.81-1.02, p = 0.0997, 13485 cases and 19317 controls in 26 study groups). The mutation rates for MTR2756 for all populations were distributed very closely between Western countries and Asian-Japanese groups (overall GG=3.7% for cases and 4% for controls, AG=30.7% for cases and 30.9% for controls, GG+AG=34.4% for cases and 34.9% for controls). The mutation rates for MTRR66 were greater in western countries than Asian-Japanese group (Western countries GG=29% for cases and 28.9% for controls, AG=48.7% for both cases and controls, GG+AG=77.7% for cases and 77.6% for controls; Asian-Japanese GG=8.6% for cases and 9.2% for controls, AG=41.1% for cases and 44.1% for controls, GG+AG=49.7% for cases and 53.3% for controls). Conclusion: Different gene mutation rates across populations may be accredited to the differences in racial origin of the populations, the lifestyle, and the pattern of diet in the respective countries. Further studies are needed to evaluate the associations related to epigenetics pathways and gene-environment interactions for cancer prevention. Citation Format: Carolyn Du, Pamela K. Shiao, Yen-Chun Lin. Meta-analyses of methionine-related polymorphisms and colorectal cancer risk for population health. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B08.

Association between genetic polymorphisms in folate-related enzyme genes and infertile men with non-obstructive azoospermia

Polymorphisms in the genes encoding enzymes in the folate metabolism pathway have been associated with male infertility and chromosome abnormalities. The aim of this study was to analyze the distribution of the methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) polymorphisms in fertile men and infertile men with non-obstructive azoospermia (NOA). A case-control study comprising 85 infertile men with NOA and 246 fertile men as controls was carried out. MTHFR c.677C > T (rs1801133), MTHFR c.1298A > C (rs1801131), MTR c.2756A > G (rs1805087), and MTRR c.66A > G (rs1801394) polymorphisms were determined using the polymerase chain reaction restriction fragment length polymorphism technique. There were significant differences in AC + CC genotype (OR = 1.9, 95% CI = 1.1–3.2) and C allele frequencies (OR = 1.8, 95% CI = 1.2–2.8) of MTHFR c.1298A > C polymorphism between NOA patients and controls after applying the Bonferroni correction. Moreover, the 1298AC genotype, 1298AC + CC genotype, and 1298C allele frequencies were statistically significant in NOA with chromosomal abnormalities and/or a Y chromosome deletion compared to the controls (AC genotype: OR = 3.0; AC + CC genotype: OR = 3.0; C allele: OR = 2.3). Considering the other polymorphisms, no differences were found between cases and controls. Our findings suggest the MTHFR c.1298A > C polymorphism is associated with an increased risk of male infertility, i.e., NOA.

An Association Study Between Gene Polymorphisms of Folic Acid Metabolism Enzymes and Biochemical and Hormonal Parameters in Acromegaly.

Folate metabolism is fundamental to several biological functions and required for cell replication, division, and survival. The mammalian folic acid cycle is highly complex and the enzymes, methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR), have crucial roles in this metabolic pathway. The common polymorphisms of the MTHFR (C677T and A1298C), MTRR (A66G), and MTR (A2756G) enzymes are well documented as folate deficiency-related disorders, but their roles have not been examined in acromegalic patients. The aim of this study was to compare the genotypic distribution of these gene polymorphisms between patients with acromegaly and controls and explore whether these polymorphisms were associated with biochemical and hormonal parameters in acromegaly. We examined 91 acromegaly patients and 112 healthy subjects who were compared in terms of age and gender. Blood specimens of the subjects were collected in tubes containing ethylenediaminetetraacetic acid. Genomic DNA was isolated from peripheral blood leukocytes and genotyping of the MTHFR (C677T and A1298C) gene polymorphisms was assessed by melting temperature analyses after real-time polymerase chain reaction (PCR), whereas MTRR A66G and MTR A2756G gene polymorphism analyses were performed by PCR/restriction fragment length polymorphism from the isolated DNA of the subjects. MTHFR-677TT genotype frequency was significantly higher in the acromegaly group than the control group (p=0.017), and a significant increase was found in fibrinogen (p=0.032) levels in 677TT-carrying acromegaly patients. MTRR-66AA genotype was significantly higher in the control group than the acromegaly group (p=0.004). Total cholesterol (p=0.048) and C-reactive protein (p=0.046) levels decreased significantly in 66AA genotypes. Although MTR-2756AG genotype frequency was not different between the control and acromegaly groups, 2756AG genotype-carrying individuals have higher left carotid intima-media thickness levels within the patient group. Our results suggest that polymorphisms of the genes encoding the folic acid metabolism enzymes affect biochemical parameters in acromegaly and this may result in predispositions to some complications associated with folate metabolism and acromegaly.

Dietary folate and related micronutrients, folate-metabolising genes, and ovarian cancer survival

ObjectiveFolate is essential for DNA synthesis and methylation and is implicated in tumour progression. Few studies have examined its role in ovarian cancer survival. Our objective was to determine relationships between intake of folate, related one-carbon nutrients, single nucleotide polymorphisms (SNPs) in folate-metabolising genes and survival following ovarian cancer diagnosis. MethodsThis analysis included 1270 women with invasive epithelial ovarian cancer diagnosed in 2002–2006. Pre-diagnostic and some post-diagnostic lifestyle, dietary, and sociodemographic information was collected via self-administered questionnaires. DNA samples were genotyped for SNPs in methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR) and methionine synthase reductase (MTRR) genes. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox regression. ResultsMultivariate analyses did not identify associations between higher pre-diagnostic intake of folate, folic acid, vitamins B2, B6, and B12, methionine, betaine or choline and survival overall. In stratified analyses, higher folic acid and folate intake was associated with significantly worse survival among women with mucinous tumours (HRs per 100μg 1.30 and 1.43, respectively) and smokers (HRs per 100μg 1.23 and 1.16 respectively). There was also a suggestion that higher supplemental folic acid use post-diagnosis was associated with worse survival (HR per 100μg 1.03, 95%CI 1.00–1.05). MTHFR SNP rs2066470 was significantly associated with survival (per allele HR 0.81, 95%CI 0.67–0.98). ConclusionsOur data provide little evidence that folate intake affects ovarian cancer survival. However, combined effects with smoking, and findings within the mucinous subtype and for post-diagnosis folic acid, warrant further investigation.

Association between MTR A2756G and MTRR A66G polymorphisms and maternal risk for neural tube defects: A meta-analysis

BackgroundMethionine synthase (MTR) and methionine synthase reductase (MTRR) genes have been considered to be implicated in the development of neural tube defects (NTDs). However, the results are inconsistent. Accordingly, we conducted a meta-analysis to further investigate such an association. MethodsPublished literature from PubMed and Embase databases was retrieved. All studies evaluating the association between MTR A2756G or MTRR A66G polymorphism and maternal risk for NTDs were included. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using the fixed- or random-effects model. ResultsA total of 11 studies (1005 cases and 2098 controls) on MTR A2756G polymorphism and 10 studies (1211 cases and 2003 controls) on MTRR A66G polymorphism were included. Overall, this meta-analysis revealed no significant association between maternal MTR A2756G polymorphism and NTD susceptibility in either genetic model. A significant association between MTRR A66G polymorphism and maternal risk for NTDs was observed for GG vs. AA (OR=1.31, 95% CI 1.03–1.67) among Caucasians. ConclusionThe present meta-analysis indicated that MTRR A66G polymorphism, but not MTR A2756G, is significantly associated with maternal risk for NTDs in Caucasians.

MTHFR, MTR, and MTRR Polymorphisms in Relation to p16INK4A Hypermethylation in Mucosa of Patients with Colorectal Cancer

We recently analyzed the hypermethylation status of the p16INK4a (p16) gene promoter in normal-appearing mucosa obtained from patients with colorectal cancer. Hypermethylation of p16 was associated with reduced survival of these patients. In the present study, germ line polymorphisms in the folate- and methyl-associated genes, methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR) and methionine synthase reductase (MTRR), were analyzed in the same patient cohort to find a possible link between these genetic variants and p16 hypermethylation. Genomic DNA was extracted from blood of patients (n = 181) and controls (n = 300). Genotype analyses were run on an ABI PRISM(®) 7900HT sequence-detection system (Applied Biosystems), using real-time polymerase chain reaction and TaqMan chemistry. The results showed that the genotype distributions of the patient and control groups were similar. No significant differences in cancer-specific or disease-free survival of stage I-III patients according to polymorphic variants were detected, nor were any differences in cancer-specific or disease-free survival detected when patients were subgrouped according to the MTHFR or MTR genotype groups and dichotomized by p16 hypermethylation status in mucosa. However, patients with the MTRR 66 AA/AG genotypes were found to have a significantly worse cancer-specific survival when the mucosa were positive, compared with negative, for p16 hypermethylation (hazard ratio 2.7; 95% confidence interval 1.2-6.4; P = 0.023). In contrast, there was no difference in survival among patients with the MTRR 66 GG genotype stratified by p16 hypermethylation status. These results indicate a relationship between genetic germ-line variants of the MTRR gene and p16 hypermethylation in mucosa, which may affect the clinical outcome of patients with colorectal cancer.

The effects of polymorphisms in methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) on the risk of cervical intraepithelial neoplasia and cervical cancer in Korean women

The purpose of the study was to investigate the association between cervical cancer risk and single-nucleotide polymorphisms (SNPs) in three one-carbon metabolism genes, methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) in Korean women. Twelve SNPs were identified in MTHFR, MTR, and MTRR in the 927 case-control samples, which included 165 cervical intraepithelial neoplasia 1 (CIN1), 167 cervical intraepithelial neoplasia 2 and 3 (CIN2/3), 155 cervical cancer patients, and 440 normal controls. The frequencies of the genotypes and haplotypes were assessed in the controls, CINs, and cervical cancers. Individual carriers of the variant allele C of MTHFR A1298C (rs1801131) had a 0.64-fold [95% confidence interval (CI): 0.42-0.98] decreased risk for CIN2/3 compared with common homozygotes. However, no significant association was found between most other variants and cervical cancer risk. The results also identified an increased CIN1 risk in carriers with at least one copy of haplotype 3 in the MTHFR gene (odds ratio, 1.88; 95% CI: 1.03-3.42). In conclusion, there was no significant association between most SNPs in MTHFR, MTR, or MTRR and the risk of CIN and cervical cancer in Korean women. In addition, there was no significant association of MTHFR haplotypes with risk of CIN2/3 and cervical cancer.

A high frequency of the MTHFR 677C>T polymorphism in Scottish women with epilepsy: Possible role in pathogenesis

The inheritance of most forms of epilepsy is usually considered to be multifactorial, although a number of single gene causes are known. Most previous studies of epilepsy genetics have implicated ion channel genes or ligand receptors. In a previous study of children with adverse effects of prenatal exposure to antiepileptic drugs, we noted an increased frequency of the methylene tetrahydrofolate reductase (MTHFR) 677C>T polymorphism in the mothers. To investigate this further, a new cohort of women with epilepsy has been identified from maternity hospital records and genotyped for polymorphisms in MTHFR, serine hydroxymethyl transferase (SHMT1), methionine synthase (MTR) and methionine synthase reductase (MTRR). Healthy blood donors were genotyped as controls. The frequency of the MTHFR 677TT genotype was significantly higher in women with idiopathic generalised epilepsy than in healthy controls (p=0.012, OR 2.26, 95%CI 1.13-4.51). No association was detected for the other polymorphisms tested. The MTHFR 677C>T polymorphism may be a susceptibility factor for epilepsy, and its higher frequency in women with epilepsy may contribute to the increased risk of malformation in children of women with epilepsy.

Fetal anticonvulsant syndromes and polymorphisms in MTHFR, MTR, and MTRR

The malformations found in fetal anticonvulsant syndromes (FACS) are associated with folic acid deficiency and methylene-tetrahydrofolate reductase (MTHFR) polymorphisms in the general population. To investigate a possible association between FACS and MTHFR genotype, we recruited 200 mothers who had taken anti-epileptic drugs in pregnancy, and delivered at Aberdeen Maternity Hospital over a 26-year period. Clinical findings in the mothers and their 337 children were documented. A clinical algorithm was devised to diagnose FACS objectively. Case-parent triads were genotyped for polymorphisms in MTHFR, serine hydroxymethyl transferase (SHMT1), methionine synthase (MTR), and methionine synthase reductase (MTRR), and analyzed by log-linear regression. No effect of the child's genotype on congenital malformation, neurodevelopmental disorder or FACS was detected using this method. The risk of having a child with congenital malformation or FACS was three to four times higher for mothers who were MTHFR 677TT homozygotes compared with MTHFR 677CC homozygotes. MTR 2756A > G and MTRR 66A > G genotype frequencies in children with FACS and neurodevelopmental disorder were different from those in healthy blood donor controls.

Relation between plasma homocysteine, gene polymorphisms of homocysteine metabolism-related enzymes, and angiographically proven coronary artery disease

Background Hyperhomocyteinemia (HHcy) is a risk factor for coronary artery disease (CAD), and methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) polymorphisms may contribute to plasma total homocysteine (tHcy) variation. We investigated the association of polymorphisms 1298A→C in the MTHFR gene, 2756A→G in the MTR gene, and 66A→G in the MTRR gene with tHcy levels and with CAD in patients undergoing coronary angiography. Methods CAD patients ( n = 151) and control subjects ( n = 79) were compared regarding the prevalence of the polymorphisms, risk factors, and biochemical parameters. Results The mean tHcy concentration was significantly higher in CAD patients than in control subjects ( P < 0.001). HHcy (tHcy ≥ 15 μmol/l) conferred an OR of CAD of 4.1 (95% CI 2.2–7.5, P < 0.001). In both cases and controls, smokers had a higher tHcy level than non-smokers and demonstrated a markedly increased risk for CAD (OR = 2.5, 95% CI 1.7–3.3, P < 0.001). The allele frequencies of the MTHFR 1298A→C, MTR 2756A→G, and MTRR 66A→G mutations were 36.7%, 15.7%, and 36.6%, respectively. The 1298C allele frequency was significantly higher in the CAD group than in controls ( P < 0.05) and showed a significant association with CAD in heterozygote carriers. There was no statistically significant difference between cases and controls in the frequencies of the A2756G alleles/genotypes in the MTR gene and of the A66G alleles/genotypes in the MTRR gene. The contributions to tHcy levels of the three common mutations were statistically significant. The heterozygosity of the MTHFR 1298AC genotype, MTR 2756G allele, and MTRR 66G allele yielded an OR of 3.4, 2.0, and 2.1, respectively, for having HHcy. Conclusion We suggest that HHcy confers a risk for CAD, and smokers with tHcy are at a greatly increased risk. Our finding supports an important role of the MTHFR gene in CAD and provides evidence of polygenic regulation of tHcy.

MTRandMTRRPolymorphisms, Dietary Intake, and Breast Cancer Risk

Methionine, the precursor for the universal methyl donor, S -adenosylmethionine, is produced through the irreversible transfer of a methyl group from 5-methyltetrahydrofolate. This reaction is regulated by two enzymes, methionine synthase ( MTR ) and methionine synthase reductase ( MTRR ). MTR is

Polymorphisms ofMethionine SynthaseandMethionine Synthase Reductaseand Risk of Squamous Cell Carcinoma of the Head and Neck: a Case-Control Analysis

Although tobacco and alcohol use are the major risk factors, folate deficiency has been implicated in the risk of squamous cell carcinoma of the head and neck (SCCHN). We hypothesized that polymorphisms of methionine synthase (MTR) and methionine synthase reductase (MTRR) in the folate metabolic pathway are associated with SCCHN risk. In a hospital-based case-control study of 721 SCCHN cases and 1,234 controls of non-Hispanic Whites, frequency matched by age, sex, and smoking status, we genotyped the MTR A2756G and MTRR G66A polymorphisms. We found that the MTR variant AG and AG/GG genotypes were associated with a significantly increased SCCHN risk [adjusted odd ratio (OR), 1.31; 95% confidence interval (95% CI), 1.07-1.60 for AG and OR, 1.28; 95% CI, 1.05-1.56 for AG/GG] compared with the AA genotype. In contrast, the MTRR variant AA genotype was associated with a significantly decreased SCCHN risk (OR, 0.68; 95% CI, 0.52-0.90) compared with the 66GG genotype. When the two polymorphisms were evaluated together by the number of risk alleles, the SCCHN risk was significantly increased in a dose-dependent manner (P(trend) = 0.002). The risk of SCCHN was 1.47 (95% CI, 1.08-1.99) for one risk allele, 1.67 (95% CI, 1.23-2.27) for two risk alleles, and 1.74 (95% CI, 1.18-2.54) for three or four risk alleles compared with the wild-type (0 risk allele) genotype. In conclusion, our data provide evidence that support the association between the MTR A2756G and MTRR G66A polymorphisms and SCCHN risk and that these two polymorphisms may have a joint effect on risk of SCCHN.

Homocysteine remethylation enzyme polymorphisms and increased risks for neural tube defects

Folic acid supplementation can effectively reduce the risk of neural tube defects (NTDs); however, the mechanism underlying this beneficial effect remains unclear. Recent evidence suggests that certain folate pathway genes, as well as those related to homocysteine metabolism might be contributing to this effect. The purpose of this study is to investigate whether gene polymorphisms of methionine synthase (MTR) and methionine synthase reductase (MTRR) are involved in the risk for NTDs, specifically spina bifida. We detected MTR A2756G and MTRR A66G polymorphisms using PCR-RFLP analysis in a group of NTD infants, their mothers and normal controls. We found that infants with the MTRR mutant genotype had a 2.6-fold higher risk of NTDs when compared to the AA genotype (OR=2.6, 95%CI=1.3–5.3). Mothers with the MTRR mutant genotype also had a 1.9-fold higher risk of having an NTD baby compared to AA genotype (OR=1.9, 95%CI=1.1–3.1). Infants who carry mutant alleles for both MTRR and MTR had exceptionally elevated NTD risks, with odds ratios of 5.1 compared to infants with the wild type genotype at both loci (AA + AA) (OR=5.1, 95%CI=1.7–15.4). A comparable result was observed in the mothers of NTD cases (OR=2.1, 95%CI=1.0–4.7). Our results indicate that MTRR and MTR genes may interact to increase the infants’ NTD risks. These results did not appear to be influenced by maternal periconceptional folic acid intake. However,the sample size of this study was limited, and a larger population study is needed to pursue these initial observations.