MTR Polymorphisms Research Articles

The effects of genetic polymorphism on toxicity and pharmacokinetics of methotrexate in Egyptian adult patients with leukaemia or lymphoma

Polymorphisms in genes coding folate-metabolising enzymes might alter the pharmacokinetics and sensitivity for methotrexate “MTX”. The aim of the study aimed to investigate the influence of MTHFR C677T, DHFR19 Ins/del, GGH −401 C > T, and MTR A2756G polymorphisms on MTX toxicity and pharmacokinetics in Egyptian patients with Acute lymphoblastic leukaemia (ALL) or Non-Hodgkin lymphoma (NHL). Fifty adult Egyptian patients with ALL and NHL, treated with high dose MTX, were prospectively enrolled in the study. Clinical and biochemical data was collected objectively from medical records after each cycle of MTX. Plasma concentrations of MTX were measured after 72 h of initiation of infusion. Genotyping was done with a PCR-ARMS and PCR-RFLP assays. The MTHFR C677T T variants significantly increased the risk of leukopoenia, whereas the genotype MTHFR 677 C > T TT significantly associated with lymphocytopenia, thrombocytopenia, and anaemia. The genotype GGH-401 TT was significantly correlated with anaemia. Plasma MTX level was significantly higher in patients with MTR A2756G G variants. MTHFR polymorphism played the main role in MTX toxicities. The pharmacokinetics of MTX was affected by MTR polymorphism. GGH mutation was mainly concerned with anaemia. Pharmacogenetic testing are recommended to optimise MTX therapy.

Association of Methionine Synthase rs1805087 Polymorphism With Arsenic-Related Skin Pigmentary Changes: A Population-Based Case-Control Study

Objective: Chronic arsenic exposure causes skin lesions including skin cancers, pigmentary changes, and keratosis. Genetic polymorphism in arsenic metabolism may increase susceptibility to the development of arsenic-related skin lesions. This study was performed to determine whether arsenic metabolism-related gene variants are associated with arsenic-related pigmentary changes. Methods: This case–control study involved 189 patients with arsenic-related pigmentary changes and 103 controls. Thirty-eight polymorphisms in 10 genes determined by mass spectrometry assay served as candidate drivers of arsenic-induced pigmentary changes. Urine and plasma arsenic levels were determined by inductively coupled plasma mass spectrometry. Hair arsenic concentrations were measured by nondispersive atomic fluorescence spectrometry. Arsenic metabolites in urine were determined using high-performance liquid chromatography with inductively coupled plasma mass spectrometry. Serum folate was measured using a folate radio assay kit. Analysis of variance, nonparametric test, or the chi-square test was selected according to the data distribution. Spearman correlation analysis was used to determine the correlation between two parameters. Logistic regression was used to estimate the effect of single-nucleotide polymorphisms. Results: The arsenic concentrations in urine, plasma, and hair and the urine arsenic species were not significantly different between patients and controls. Logistic regression revealed that among the polymorphisms, the methionine synthase (MTR) rs1805087 polymorphism showed a protective effect against arsenic-related pigmentary changes. In the codominant model, the adjusted odds ratio for age, sex, and ethnicity was 0.41 (95% confidence interval [CI], 0.21–0.80; P = 0.008) for the AG genotype and 0.11 (95% CI, 0.02–0.60; P = 0.012) for the GG genotype. Conclusion: MTR polymorphism showed a protective effect against arsenic-related pigmentary changes in the logistic regression model. The effect of MTR rs1805087 might be independent of arsenic metabolism and one-carbon metabolism. More studies are needed to clarify the biological function of MTR rs1805087 and its relationship with the etiology of arsenic-related pigmentary changes.

Association of MTR and MTRR genes and oral health-related quality of life in children with dental caries.

This study aimed to assess whether genetic polymorphisms in MTR and MTRR are potential biomarkers of oral health-related quality of life (OHRQoL) in children with caries. A cross-sectional study was designed wherein pairs of parents/caregivers and children (aged two-five years) were selected. Clinical examination was used to detect dental caries, which were classified as low-severity and high-severity caries. The Early Childhood Oral Health Impact Scale (ECOHIS) questionnaire was used to assess OHRQoL. Genomic DNA extracted from the saliva was used to analyze two missense genetic polymorphisms: MTR (rs1805087) and MTRR (rs1801394). Mann-Whitney non-parametric test was used to analyze candidate genes with OHRQoL scale and domain, with a significance level of p≤0.05. MTR (rs1805087) was found associated (p = 0.05) with children's OHRQoL subscale scores in the dominant model (GG + AG). Genetic polymorphisms in MTR may increase the risk of poor OHRQoL in children with caries. Further studies are needed to investigate genetics, molecular factors, and OHRQoL.

Evidence of Association between MTRR and TNF-α Gene Polymorphisms and Oral Health-Related Quality of Life in Children with Anterior Open Bite.

To assess the impact of AOB on OHRQoL in children and to evaluate whether MTR (rs1805087), MTRR (rs1801394), TGFβ1 (rs1800469) and TNF-α (rs1799964, rs1799724 and rs1800629) genes are potential biomarkers for OHRQoL in children with AOB. A cross-sectional study was performed with 173 children aged between 2-6 years. The Brazilian version of Early Childhood Oral Health Impact Scale (ECOHIS) was applied. Genetic polymorphisms were analyzed using real-time PCR. Mann-Whitney U-test and Chi-square were used. The overall mean ECOHIS scores were 5.49 (SD= 5.72) and 3.45 (SD = 4.49) (p < 0.01) in the AOB and control groups, respectively. Children with the CC genotype of TNF-α (rs1799724) had a significantly higher psychological QoL level. The MTRR AA genotype group showed a lower QoL level in the child subscale (p = 0.006), function (p = 0.017), and psychological (p = 0.006) domains. There was no significant difference between OHRQoL and the genetic polymorphisms in MTR and TGFβ1. Genetic polymorphisms in TNF-α and MTRR are associated with the impact on the OHRQoL in children with AOB.

Association between folate metabolism polymorphisms and breast cancer: a case-control study.

We investigated the association between methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), methionine synthetase (MTR A2756G), and methionine synthase reductase (MTRR A66G) polymorphisms involved in folate pathway and breast cancer risk, and the interaction between these polymorphisms and tobacco and alcohol consumption. Furthermore, we evaluated the association between these polymorphisms and clinicopathological variables. This case-control study included 606 Brazilian women, comprising 128 patients with breast cancer and 478 controls. MTHFR and MTR polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and MTRR polymorphisms using real-time PCR. Age ≥50 years (odds ratio [OR]: 2.65; 95% confidence interval [CI]: 1.65-4.26; p<0.001) and alcohol consumption (OR: 1.76; 95% CI: 1.0-2.85; p=0.021) were associated with an increased risk of breast cancer. For MTHFR A1298C, we observed a reduced risk of developing breast cancer in the codominant model (genotype CC-OR: 0.22; 95% CI: 0.06-0.74; p=0.014), recessive model (OR: 0.22; 95% CI: 0.07-0.76 p=0.004), and log-additive model (OR: 0.70; 95% CI: 0.49-0.98; p=0.035). Women aged ≥50 years and those who are alcohol consumers had increased susceptibility to breast cancer, and MTHFR A1298C modulated the risk for this disease. This is the first study to evaluate the association between polymorphisms in folate metabolism and breast cancer in the northwest region of São Paulo State, Brazil.

MTR-G is a high-risk allele for lower-extremity arteriosclerotic occlusion

Objective This study investigated the relationship between the MTRA2576G polymorphism of the key enzyme in homocysteine metabolism and deep vein thrombosis (DVT), chronic venous insufficiency (CVI) and arteriosclerotic occlusion (ASO) of the lower extremities. Methods Genomic DNA was extracted from the peripheral blood of patients with lower-extremity vascular diseases, including 125 cases of DVT, 125 cases of CVI and 125 cases of ASO. DNA samples extracted from 197 healthy individuals were used as control samples. PCR-RFLP was used to investigate the polymorphisms of MTR in these subjects. Results The frequency of the G allele in MTR was 6.8%, 6.1% and 12.8% for the DVT group, CVI group and ASO group, respectively (p = 0.003). The frequency of the GG allele was 13.6%, 12.2% and 22.4% for the DVT group, CVI group and ASO group, respectively (p = 0.014). Only the allele frequency of GG in the ASO group was higher than that in the control group, and the disease risk was also 1.3 times higher than that in the control group (OR = 1.299, 95% CI = 1.025 ∼ 2.575). Conclusion Patients with the G allele in MTR have a high risk for ASO, and the GG allele is a risk gene for ASO.

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

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. 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. 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. 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 < 132.7mmHg (AOR 1.842, 95% CI 1.039-3.266, P = 0.037) and fasting blood glucose level < 106.3mg/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 < 216.3mg/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. Results of this study suggest that MTRR and TSER polymorphisms might be potential genetic markers for the risk of MetS development in Korean population.

Genetic polymorphisms in MTR are associated with non-syndromic congenital heart disease from a family-based case-control study in the Chinese population

Genetic polymorphisms of folate pathway genes have been reported to be associated with congenital heart diseases (CHDs); however, the results remain conflicting. We conducted a family-based case-control study, which included160 CHD case-parent triads and 208 control-parent triads to explore the association of 18 genetic variants of seven folate metabolism-related genes with the risk of CHDs. The MTR C allele of rs1770449 (OR = 1.961, 95%CI: 1.379–2.788) and the MTR A allele of rs1050993 (OR = 1.994, 95%CI: 1.401–2.839) in infants were associated with an increased risk of CHDs. Over-transmission of SNPs rs1770449 and rs1050993 and haplotype CAA (rs1770449-rs1805087-rs1050993) in MTR were detected in total CHDs. The above mentioned associations of MTR with CHDs were also observed in septal defects and conotruncal heart defects subgroups. Without maternal periconceptional folate intake, the risk of CHDs among women carrying the rs1770449 “CT or CC” genotype or the rs1050993 “AG or AA” genotype in MTR was 3.262(95%CI: 1.656–6.429) or 3.263(95%CI: 1.656–6.429) times greater than the aOR in women carrying wild genotype, respectively. Our study suggests that MTR polymorphisms (rs1770449 and rs1050993) may be associated with the risk of CHDs and modify the relation between maternal folate intake and CHDs.

WITHDRAWN: Association of homocysteine-metabolizing enzyme gene polymorphisms and lipid profiles: an investigation of a geneenvironment interaction

// Shanqun Jiang 1, 2, * , Scott A. Venners 3, * , Yi-Hsiang Hsu 4, 5 , Justin Weinstock 6 , Suwen Wu 1 , Yanfeng Zou 7 , Faming Pan 7 and Xiping Xu 2, 8 1 School of Life Sciences, Anhui University, Hefei, China 2 Institute of Biomedicine, Anhui Medical University, Hefei, China 3 Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada 4 Institute for Aging Research, HSL and Harvard Medical School, Boston, MA, USA 5 Molecular and Integrative Physiological Sciences Program, Harvard School of Public Health, Boston, MA, USA 6 Department of Statistics, University of Virginia, Charlottesville, VA, USA 7 Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, China 8 Division of Epidemiology and Biostatistics, University of Illinois at Chicago School of Public Health, Chicago, IL, USA * These authors contributed equally to this work Correspondence to: Shanqun Jiang, email: shanqunjiang2014@163.com Keywords: MTHFR; MTR; polymorphism; lipid; interaction Received: September 11, 2017&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Accepted: November 16, 2017&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Published: January 04, 2018 ABSTRACT This cross-sectional study investigated the gene-environment interactions between the MTHFR and MTR polymorphisms and gender with regard to lipid profiles in a general Chinese population. We recruited 2,124 individuals from Anhui Province, China. The MTHFR (C677T and A1298C) and MTR (A2756G) polymorphisms were genotyped, and serum lipid levels, including TC, TG, LDL-C, and HDL-C, were determined. Our results showed that male MTR AG + GG genotype carriers had significantly lower serum TC (adjusted &beta; &plusmn; [SE]:-0.25 &plusmn; 0.10 mmol/L; P = 0.0159), LDL-C (adjusted &beta; &plusmn; [SE]:-0.24 &plusmn; 0.09 mmol/L; P = 0.0049), and HDL-C (adjusted &beta; &plusmn; [SE]:-0.09 &plusmn; 0.03 mmol/L; P = 0.0055) levels than the AA carriers. Male MTHFR677TT genotype carriers had significantly higher serum TC (adjusted &beta;&plusmn;[SE]: 0.28 &plusmn; 0.13 mmol/L; P = 0.0287) and LDL-C (adjusted &beta; &plusmn; [SE]: 0.26 &plusmn; 0.13 mmol/L; P = 0.0485) levels than CC + CT carriers. In subsequent analyses, there was a significant interaction between the MTR AG+GG genotypes and gender in association with TC, LDL-C and TG levels ( P = 0.0378, 0.0054 and 0.0183 for interaction, respectively).The interaction term for the MTHFR 677TT genotype and gender was also significant for TC and LDL-C levels ( P = 0.0147 and 0.0243 for interaction, respectively). Further haplotype analysis showed that there also were significant interactions between gender and hap2 (MTHFR 677C/1298A) on TC ( P = 0.009) and LDL-C ( P = 0.013). We suggest that the negative effects of the MTR and MTHFR genotypes on serum lipids are based on certain gene-environment interactions in the Chinese general population.

Methionine synthase 2756AA polymorphism is associated with the risk of cognitive impairment in patients with late-life depression.

Apolipoprotein E epsilon-4 (APOE ε4) allele, methylenetetrahydrofolate reductase (MTHFR C677T), and methionine synthase (MTR A2756G) were tested their associations with cognitive impairment in people with late-life depression (LLD). People with LLD were assessed by mini-mental state examination and were examined the distribution of APOE ε4 allele, MTHFR, and MTR polymorphisms. Odds ratio of MTR 2756 AA to MTR 2756 AG and GG genotypes for the risk of cognitive impairment was 5.80 (95% confidence interval = 1.18-28.50; P = 0.03). People with LLD carrying MTR2756 AA genotype have higher risk of cognitive impairment than those carrying G allele.

Analysis of methionine synthase (rs1805087) gene polymorphism in autism patients in Northern Iran.

Autism is characterized by impairment in reciprocal communication and speech, repetitive behaviors, and social communication. The genetic and environmental factors play roles in the pathogenesis of autism. It was recently shown that the genes involved in the folate/homocysteine pathway may be risk factors for autistic children. One of the genes that may be the risk factor for autism is Methionine synthase (MTR). MTR is responsible for the regeneration of methionine from homocysteine. The aim of this study was to analyze the association of MTR A2756G gene polymorphism (rs1805087) and the risk of autism in a population in northern Iran. The prevalence of MTR A2756G polymorphism was determined in 108 children with autism and 130 controls in northern Iran. Genotypes and allele frequencies were determined in patients and controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The prevalence of genotype frequencies of AA, AG and GG in autistic children were 57.41%, 22.22% and 20.37%, respectively, while in controls were 61.54%, 32.31% and 6.15%, respectively. There was significant difference between the MTR polymorphism distribution in control and patient groups. The prevalence of allele frequencies of A and G in autistic children were 0.69 and 0.31, respectively and in controls were 0.78 and 0.22, respectively (P=0.03). The MTR G allele conferred a 1.6-fold increased risk to autism relative to the A allele (95% CI=1.06-2.41, P=0.02). The present study suggests that the G allele of MTR A2756G polymorphism is associated with an increased risk of autism.

Association of MTHFR and RFC1 gene polymorphism with hyperhomocysteinemia and its modulation by vitamin B12 and folic acid in an Indian population

Unlike most Western populations, MTHFR 677T is a rare allele and a risk factor for a variety of disorders in India. What kind of nutritional (environmental) and/or genetic factors could contribute to the genetic risk is not known. To assess the incidence of hyperhomocysteinemia and its correlation with the polymorphism in homocysteine (Hcy)-pathway genes and associated cofactors in the native populations of eastern India. Healthy population from four eastern states of India. Genotyping of SNPs, HPLC and chemiluminescence-based assay for homocysteine, vitamin B12 and folic acid. Approximately 30% of the population has hyperhomocysteinemia (>15 μmol/lit; hypHcy) with varying frequencies in the four states from where samples were collected (n=1426). Polymorphisms of MTR and CBS do not affect hypHcy. 677T and 1298C alleles of MTHFR and G80 RFC-1 show association with hypHcy. In contrast, RFC-1 80AA is protective even in presence of 677T MTHFR. Addition of each mutant allele has an additive effect on Hcy level. Vitamin B12 (cofactor in methionine synthesis) clearly modulates the genotypic effect on Hcy level. Although frequency of individuals with low folic acid is ≈11, 49% of the population is vitamin B12 deficient (<220 pg/lit) and has a significant negative correlation with Hcy. Individuals with optimum vitamin B12 and folic acid generally have low Hcy, even in risk genotypes. One of the plausible reasons for susceptibility of individuals with MTHFR C677T in the studied population to various disorders is the high frequency of hyperhomocysteinemia and vitamin B12 deficiency in the 'healthy population'. Apparently, supplementation of vitamin B(12) to this health-impoverished community may help lessen the risk of several multifactorial disorders.

The search for risk factors that contribute to the etiology of non-syndromic cleft lip with or without cleft palate (CL/P) in the Polish population

Abstract Non-syndromic cleft lip with or without cleft palate (CL/P) has severe long-lasting adverse effects on both physical and psychological development. Although recent years have brought significant improvement in clinical treatment, our understanding of the etiology of this congenital anomaly is lagging. Many genes, genetic pathways, harmful exposures, as well as nutrient deficiencies have been implicated in abnormal palatogenesis. Extrapolating data regarding risk factors for CL/P from different populations is not always straightforward. This review gives an overview of knowledge about both environmental and genetic risk factors in the etiology of CL/P in the Polish population, which was originally presented in research papers by the author and collaborating investigators. The findings suggest a possible association between maternal consumption of α-tocopherol, retinol, zinc, citrulline, and dietary compounds contributing to methyl-group homeostasis and CL/P risk. Polymorphisms in BHMT1 and BHMT2 were significantly associated with decreased CL/P risk in the Polish population. Other interesting findings include associations of CL/P risk with polymorphisms in MTR, PCYT1A, ASS1, SLC 25A13, GSTM1, GSTT1, SUMO1 genes, and 8q24.21 loci. Reviewed research papers indicate interesting pathways and new candidate genes for further investigation, and partly confirm earlier findings according risk factors for orofacial clefts.

Genetic and lifestyle variables associated with homocysteine concentrations and the distribution of folate derivatives in healthy premenopausal women

Low folate and high homocysteine (Hcy) concentrations are associated with pregnancy-related pathologies such as spina bifida. Polymorphisms in folate/Hcy metabolic enzymes may contribute to this potentially pathogenic biochemical phenotype. The study comprised 26 Caucasian and 23 African-American premenopausal women. Subjects gave fasting blood samples for biochemical phenotyping and genotyping. Total Hcy (tHcy) and both plasma and red blood cell (RBC) folate derivatives (i.e. tetrahydrofolate [THF], 5-methylTHF [5-MTHF], and 5,10-methenylTHF [5,10-MTHF]) were measured using stable isotope dilution liquid chromatography, multiple reaction monitoring, and mass spectrometry. Eleven polymorphisms from nine folate/Hcy pathway genes were genotyped. Tests of association between genetic, lifestyle, and biochemical variables were applied. In African American women, tHcy concentrations were associated (p < 0.05) with total RBC folate, RBC 5-MTHF, B(12), and polymorphisms in methionine synthase (MTR) and thymidylate synthase (TYMS). In Caucasian women, tHcy concentrations were not associated with total folate levels, but were associated (p < 0.05) with RBC THF, ratios of RBC 5-MTHF:THF, and polymorphisms in 5,10-methylenetetrahydrofolate reductase (MTHFR) and MTR. In African Americans, folate derivative levels were associated with smoking, B(12), and polymorphisms in MTR, TYMS, methionine synthase reductase (MTRR), and reduced folate carrier1 (RFC1). In Caucasians, folate derivative levels were associated with vitamin use, B(12), and polymorphisms in MTHFR, TYMS, and RFC1. Polymorphisms in the folate/Hcy pathway are associated with tHcy and folate derivative levels. In African American and Caucasian women, different factors are associated with folate/Hcy phenotypes and may contribute to race-specific differences in the risks of a range of pregnancy-related pathologies.

DNA Promoter Methylation in Breast Tumors: No Association with Genetic Polymorphisms in MTHFR and MTR

Aberrant promoter methylation is recognized as an important feature of breast carcinogenesis. We hypothesized that genetic variation of genes for methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MTR), two critical enzymes in the one-carbon metabolism, may alter DNA methylation levels and thus influence DNA methylation in breast cancer. We evaluated case-control association of MTHFR C677T, A1298C, and MTR A2756G polymorphisms for cases strata-defined by promoter methylation status for each of three genes, E-cadherin, p16, and RAR-beta2 in breast cancer; in addition, we evaluated case-case comparisons of the likelihood of promoter methylation in relation to genotypes using a population-based case-control study conducted in Western New York State. Methylation was evaluated with real-time methylation-specific PCRs for 803 paraffin-embedded breast tumor tissues from women with primary, incident breast cancer. We applied unordered polytomous regression and unconditional logistic regression to derive adjusted odds ratios and 95% confidence intervals. We did not find any association of MTHFR and MTR polymorphisms with breast cancer risk stratified by methylation status nor between polymorphisms and likelihood of promoter methylation of any of the genes. There was no evidence of difference within strata defined by menopausal status, estrogen receptor status, folate intake, and lifetime alcohol consumption. Overall, we found no evidence that these common polymorphisms of the MTHFR and MTR genes are associated with promoter methylation of E-cadherin, p16, and RAR-beta2 genes in breast cancer.

Risk of colorectal cancer associated with the C677T polymorphism in 5,10-methylenetetrahydrofolate reductase in Portuguese patients depends on the intake of methyl-donor nutrients

Background:Polymorphisms located in genes involved in the metabolism of folate and some methyl-related nutrients are implicated in colorectal cancer (CRC). Objective:We evaluated the association of 3 genetic polymorphisms [C677T MTHFR (methylene tetrahydrofolate reductase), A2756G MTR (methionine synthase), and C1420T SHMT (serine hydroxymethyltransferase)] with the intake of methyl-donor nutrients in CRC risk. Design:Patients with CRC (n = 196) and healthy controls (n = 200) matched for age and sex were evaluated for intake of methyl-donor nutrients and the 3 polymorphisms. Results:Except for folate intake, which was significantly lower in patients (P = 0.02), no differences were observed in the dietary intake of other methyl-donor nutrients between groups. High intake of folate (>406.7 μg/d) was associated with a significantly lower risk of CRC (odds ratio: 0.67; 95% CI: 0.45, 0.99). The A2756G MTR polymorphism was not associated with the risk of developing CRC. In contrast, homozygosity for the C677T MTHFR variant (TT) presented a 3.0-fold increased risk of CRC (95% CI: 1.3, 6.7). Similarly, homozygosity for the C1420T SHMT polymorphism also had a 2.6-fold increased risk (95% CI: 1.1, 5.9) of developing CRC. When interactions between variables were studied, low intake of all methyl-donor nutrients was associated with an increased risk of CRC in homozygous participants for the C677T MTHFR polymorphism, but a statistically significant interaction was only observed for folate (odds ratio: 14.0; 95% CI: 1.8, 108.5). No significant associations were seen for MTR or SHMT polymorphisms. Conclusion:These results show an association between the C677T MTHFR variant and different folate intakes on risk of CRC.

The methionine synthase polymorphism c.2756A&gt;G (D919G) influences diastolic blood pressure

The functional polymorphism methionine synthase (MTR) c.2756A>G (D919G) has been reported to modify the risk of vascular disease and to promote disease-free longevity. In 714 individuals from 187 families, blood pressure was measured, antihypertensive medication recorded and MTR genotype determined. A significant association of the MTR polymorphism with diastolic blood pressure was found which might explain the beneficial effects of its G-allele on vascular disease and disease-free longevity and could be a basis for novel antihypertensive strategies.

Genetic Polymorphisms in Folate Metabolism and the Risk of Stomach Cancer

Folate deficiency has been implicated in the etiology of stomach cancer through abnormal DNA methylation and disrupted DNA synthesis and repair. Enzyme-coding genes involved in folate metabolism are often polymorphic. In a population-based study of 305 cases and 427 controls in Warsaw, Poland, we evaluated the risk of stomach cancer in relation to polymorphisms in folate-metabolizing genes, including MTHFR (Ex5+79C>T and Ex8-62A>C), MTR (Ex26-20A>G), and MTRR (Ex2-64A>G, Ex5+123C>T, Ex15+572C>T, Ex15-405A>T, Ex9-85C>T, Ex15-526G>A, and Ex14+14C>T). Polymorphisms in the MTHFR gene were not associated with stomach cancer risk. No notable effect was found for polymorphisms in MTR or MTRR either, although MTR Ex26-20 A>G and MTRR Ex5+123C>T polymorphisms were associated with a borderline increased risk of stomach cancer (MTR Ex26-20A>G, AG/GG versus AA: odds ratio, 1.35; 95% confidence interval, 0.96-1.90; MTRR Ex5+123C>T, CT/TT versus CC: odds ratio, 1.30; 95% confidence interval, 0.93-1.82). We did not find significant interactions between polymorphisms in MTHFR, MTR, and MTRR genes and dietary folate and alcohol consumption. Our study did not identify strong genetic determinants in the folate metabolism pathway for stomach cancer risk.

Polymorphisms of methionine synthase and methionine synthase reductase and risk of lung cancer: a case–control analysis

Although tobacco is the major lung cancer risk factor, folate deficiency has also been implicated as a risk. Methionine synthase (MS; gene symbol, MTR) and methionine synthase reductase (MSR; gene symbol, MTRR) play important roles in the folate metabolism pathway. It was hypothesized that polymorphisms of MTR and MTRR are associated with lung cancer risk and interact with dietary intake of folate-related nutrients in lung cancer etiology. In a hospital-based, case-control study of 1,035 lung cancer cases and 1,148 controls of non-Hispanic whites, frequency matched by age, sex, ethnicity and smoking status, the MTR 2756A>G and MTRR 66A>G polymorphisms were genotyped. It was found that the MTRRG allele was associated with a significantly increased lung cancer risk [adjusted odd ratio (OR)=1.34, 95% confidence interval (CI)=1.06-1.70 for the AG genotype and OR=1.39, 95% CI=1.08-1.78 for the GG genotype compared to the AA genotype]. Further analysis suggested some evidence of gene-diet interactions between the MTRR 66A>G polymorphism and dietary intake of total folate and vitamin B12. When the two polymorphisms were evaluated together by the number of the variant alleles (i.e. the MTR2756G and MTRR66A), lung cancer risk was significantly increased in a dose-dependent manner (Ptrend=0.045). The risk of lung cancer was 1.29 (0.98-1.69) for one variant allele, and 1.36 (1.04-1.77) for two or more variant alleles compared to the wild-type (0 variant allele) genotype. In conclusion, our data provide evidence supporting the association between the MTR 2756A>G and MTRR 66A>G polymorphisms and lung cancer risk, which may be modulated by dietary nutrient intake.

Methylenetetrahydrofolate reductase gene (MTHFR) polymorphisms and reduced risk of malignant lymphoma

Folate and methionine are important nutrients in the "one-carbon" metabolism that is closely associated with DNA synthesis and DNA methylation. Genetic variation in these pathways may change susceptibility to cancer development. We have previously reported associations between lymphoma risk and germline polymorphisms in genes of methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) and methionine synthase (MTR A2756G), finding the genotype other than the MTHFR 677CC/1298AA to confer a half-risk compared to the MTHFR 677CC/1298AA and a 3-fold higher risk with the MTR GG genotype than the AA/AG genotypes. To confirm the association and explore the histological difference, we extended the previous case series. A case-control study was conducted in Japan with a total of 372 lymphoma cases and 500 noncancer controls examined for genotypes. The relative risks were estimated by unconditional logistic regression analysis. In overall analyses, the age-sex adjusted odds ratio (OR) for the subjects harboring MTHFR 677T or 1298C alleles relative to 677CC/1298AA genotype was 0.58 (95% confidence interval: 0.41-0.83, P = 0.002). The MTR GG genotype showed an OR of 1.75 (0.87-3.52, P = 0.114). These findings were validated in separate analyses of the 273 new incident cases. Subgroup analyses according to histological subtype [diffuse large B-cell lymphoma (DLB), follicular lymphoma (FL), low-grade lymphoma of mucosa associated lymphoid tissue (MALT), and others] illustrated similar associations with certain exceptions for FL and MALT. Our data showed an association between the MTHFR polymorphisms and malignant lymphoma risk for all histological subtypes, although the extent of contribution of these polymorphisms may differ somewhat with histological subtype. Lack of association with MTR polymorphism was also confirmed.