Role of the MTHFR polymorphisms in cancer risk modification and treatment

Influence of DPYD gene polymorphisms on 5-Fluorouracil toxicities in Thai colorectal cancer patients

DPYD polymorphisms have been widely found to be related to 5-FU-induced toxicities. The aim of this study was to establish significant associations between five single-nucleotide polymorphisms of DPYD and 5-FU hematological toxicities in Thai colorectal cancer patients. The toxicities were analyzed at the first and second cycles of 5-FU administration in 75 patients. Genotyping was performed using TaqMan real-time PCR. The genotype frequencies of DPYD*2A,1905 + 1 G > A and DPYD 1774 C > T were all wild type. The frequencies of genetic testing for DPYD*5, 1627 A > G, DPYD 1896T > C, and DPYD*9A, 85 A > G were 37.30% (AG; 34.60%, GG; 2.70%), 32.00% (TC; 25.30%, CC; 6.70%), and 13.40% (AG; 10.70%, GG; 2.70%), respectively. The results reveal significant findings with neutropenia occurring in 100% (2/2) of the patients with homozygous variant DPYD*9A (GG) from the first cycle of treatment for both Grade 1-4 and Grade 3-4 toxicities (P = 0.003 and P < 0.001 respectively). DPYD *9A was related to Grade 1-4 leukopenia (P = 0.001) and both Grade 1-4 and severe thrombocytopenia (P < 0.001 and P < 0.001) in the first cycle. In the second cycle, DPYD*5 was shown to be closely associated with no Grade 1-4 toxicity (P = 0.02). However, we found that 100% (2/2) of patients carrying the homozygous variant (GG) DPYD*5, presented no significant toxicity, so, DPYD*5 may be a predictive marker of neutropenia in patients treated with 5-FU. These outcomes suggest that there may be an increased risk of developing 5-FU-induced neutropenia in patients carrying the DPYD*9A, which should be considered as part of the standard procedure.

Association study between genetic polymorphisms in MTHFR and stroke susceptibility in Egyptian population: a case-control study

Stroke is a major global disability cause, and genetic variables for multifactorial illnesses like stroke are crucial for precision medicine. The purpose of this study is to see if genetic variants in the MTHFR gene are associated with a higher risk of ischemic stroke among the Egyptian population. A case-control study was conducted at Mansoura University Hospital, involving 100 stroke patients and 150 healthy volunteers as the control group. Peripheral blood genomic DNA was isolated and single-nucleotide polymorphisms were genotyped using ARMS-PCR. The CT and TT genotypes of the C677T gene polymorphism exhibited substantial risks for having stroke disease [(OR 3.856; P ≤ 0.001); (OR 4.026; P ≤ 0.001), respectively]. The T allele was significantly more prevalent among patients compared to controls. (OR 2.517; (P = 0.001)). The over-dominant and dominant models demonstrated a substantial relationship between stroke groups at risk of developing stroke but not the Recessive model. An extensive connection was found between the MTHFR A1298C and stroke danger in three different inheritance models: dominant (CC + CA vs. AA), over-dominant (AA + CC vs AC), and allelic (C allele) (P < 0.001). A highly significant difference in blood pressure, total cholesterol, and triglycerides levels was found between patients and control. While there was no meaningful link discovered between genetic polymorphism with SBP, DBP, TG, LDL, VLDL among stroke group (P > 0.05 for each) except the CC genotype that was significantly associated with lower levels of TC and HDL when compared to CT + TT genotypes. The study evaluates a strong link among MTHFR mutations in genes and the probability to get stroke. The research significantly supports the use of MTHFR ((rs1801133) and (rs1801131) variations in stroke prediction.

Oral Capecitabine Exposures and Use of Uridine Triacetate: A 20-Year Retrospective Analysis

BACKGROUND AND OBJECTIVES

Capecitabine is an oral prodrug of 5-fluorouracil. Toxicity can occur during therapy as well as acutely with overdose and particular genetic susceptibilities. Uridine triacetate is an effective antidote if given within 96 h of exposure. This study seeks to characterize accidental and intentional capecitabine exposures and uridine triacetate use, about which little has been published.

METHODS

A retrospective review of capecitabine exposures from 30 April 2001 to 31 December 2021 reported to a statewide poison control center was performed. All single-substance oral exposures were included.

RESULTS

In total, 81 of 128 reviewed cases were included, with a median age of 63 years. In total, 49 were acute-on-chronic exposures and 32 were acute exposures in capecitabine-naïve patients, 29 of which were accidental. Fifty-six (69%) were managed at home. Of these, none later recontacted the poison control center to report symptoms or were known to have later had healthcare facility evaluations. Of the 25 cases presenting for healthcare facility evaluation, 4 were acutely symptomatic. Thirteen were eligible for uridine triacetate, and six received it; no new or progressive toxicity was reported after. Three developed mild latent toxicity; otherwise, no morbidity or mortality was reported.

CONCLUSIONS

Accidental acute-on-chronic and acute ingestions of capecitabine appear to be well tolerated; most cases were managed at home. Unfortunately, little is known regarding the threshold at which toxicity may present following exposures. The threshold may vary individually given genetic susceptibilities. Management was heterogeneous, likely reflecting inadequate guidelines. Further research is needed to better delineate at-risk populations and treatment strategies.

Genetic variants in African-American and Hispanic patients with breast cancer

Breast cancer is a disease with significant health disparity affecting mortality in minority women. The present study examined the genetic makeup of breast cancers in African-American and Hispanic/Latinx patients to determine specific genetic mutations associated with breast cancer in the minority population from South Los Angeles, United States. Whole-exome sequencing was performed on DNA extracted from breast cancer tumor biopsies collected from 13 African-American and 15 Hispanic women and 8 matched-normal samples for each ethnic category. The results were analyzed using Ensemble Variant Effect Predictor and Mutation Significance. Additionally, a comparative analysis with The Cancer Genome Atlas data was provided. Our data revealed somatic mutations in genes such as SET domain containing (lysine methyltransferase) 8, serine protease 1 and AT-rich interaction domain 1B (ARID1B) and known breast cancer genes, such as BRCA1/2, TP53 and the DNA damage response genes across all ethnicities. Additionally, Hispanic patients had BRCA1 associated RING domain 1B (BARD1) variants, while African-American patients had higher numbers of nonsynonymous variants in the RAD51 paralog B (RAD51B), ARID1B and X-ray repair cross complementing 3 (XRCC3) genes. In addition, our patients exhibited mutational signature enrichment that indicated DNA homologous recombination repair deficiencies. Therefore, African-American and Hispanic breast cancer samples showed considerable overlap in breast cancer genetic mutations. However, there are differences in specific genetic variants in TP53, BRCA1/2, BARD1 or ARID1B, which will require further study of their role in tumorigenesis.

In silico drug screen reveals potential competitive MTHFR inhibitors for clinical repurposing

MTHFR (Methylenetetrahydrofolate reductase) is a pivotal enzyme involved in one-carbon metabolism, which is critical for the proliferation of cancer cells. In line with this, published literature showed that MTHFR knockdown caused impaired growth of multiple types of cancer cells. Moreover, higher MTHFR expression levels were linked to shorter overall survival in hepatocellular carcinoma, adrenocortical carcinoma, and low-grade glioma, bringing the need to design MTHFR inhibitors as a possible treatment option. No competitive inhibitors of MTHFR have been reported as of today. This study aimed to identify potential competitive MTHFR inhibitor candidates using an in silico drug screen. A total of 30470 molecules containing biogenic compounds, FDA-approved drugs, and those in clinical trials were screened against the catalytic pocket of MTHFR in the presence and absence of cofactors. Binding energy and ADMET analysis revealed that Vilanterol (β2-adrenergic agonist), Selexipag (prostacyclin receptor agonist), and Ramipril Diketopiperazine (ACE inhibitor) are potential competitive inhibitors of MTHFR. Molecular dynamics analyses and MM-PBSA calculations with these compounds particularly revealed the amino acids between 285-290 for ligand binding and highlighted Vilanterol as the strongest candidate for MTHFR inhibition. Our results could guide the development of novel MTHFR inhibitor compounds, which could be inspired by the drugs brought into the spotlight here. More importantly, these potential candidates could be quhickly tested as a repurposing strategy in pre-clinical and clinical studies of the cancers mentioned above.Communicated by Ramaswamy H. Sarma.

Interactions Between Obesity and One-Carbon Metabolism Genes in Predicting Prostate Cancer Outcomes Among White and Black Patients

BACKGROUND

One-carbon metabolism genes are linked to several cancers, but the association with prostate cancer (PCa) is less clear. Studies examining the relationship have not accounted for obesity, a risk factor for advanced PCa and altered methylation patterns. We hypothesized that obesity could moderate the association between one-carbon metabolism genes and PCa outcomes.

METHODS

We conducted secondary data analyses of the Study of Clinical Outcomes, Risk and Ethnicity. Obesity was included as a primary exposure and modifier (interacting with genetic polymorphisms) in the analytic models. We used logistic regression to determine associations of common one-carbon metabolism genotypes with odds of high stage (T3/T4) and high grade (Gleason score ≥ 7). We used Cox regression to examine associations of genotypes with biochemical recurrence.

RESULTS

There were 808 patients (632 White and 176 Black.) Among White men, we observed associations of TCN2_R259P with increased odds of high stage (OR = 0.64, 95% CI = 0.41-1.00), but no significant interactions with obesity. Among Black men, the SCL19A1_61bpdel and CBS_68bpINS variants were associated with high grade (OR = 2.61, 95% CI = 1.39-4.89 and OR = 0.29, 95% CI = 0.09-0.91, respectively.) Both the CBS_68bpINS and MTHFR_E429A variants interacted with obesity in Black men, where the highest risk for biochemical failure and odds of high grade, respectively, occurred among obese patients with variants.

CONCLUSIONS

We observed associations of one-carbon metabolism genes with different associations by race. We also observed interactions with obesity related to PCa outcomes in Black men only. Therefore, the involvement of one-carbon metabolism on PCa was dependent upon obesity status for Black men. These novel results could help identify patients that might benefit from effective weight management targeting one-carbon metabolism effects.

Associations of the MTHFR rs1801133 polymorphism with gastric cancer risk in the Chinese Han population

In recent years, increasing evidence has implicated the importance of mutations in the MTHFR gene in the risk of gastric cancer risk. A single nucleotide polymorphism (SNP) in the MTHFR gene (rs1801133) may serve a critical role in gastric cancer. A hospital-based case-controlled study was performed to assess the risk of the rs1801133 polymorphism on gastric cancer. A total of 307 patients with gastric cancer and 560 patients in the control group were recruited. Genomic DNA was extracted from peripheral blood and genotyped for rs1801133 using the ligase detection reaction. The relationship between rs1801133 and gastric cancer risk was evaluated by unconditional logistical regression analysis. The rs1801133-TT genotype was associated with a borderline significantly decreased risk of gastric cancer [(TT vs. CC, adjusted odds ratio (OR)=0.54, 95% confidence intervals (CI)=0.35-0.83; P=0.006; CT vs. CC, adjusted OR=0.59, 95% CI=0.44-0.79, P<0.001; and TT/CT vs. CC, adjusted OR=0.61, 95% CI=0.44-0.83, P=0.001), and further analysis showed the relationship was evident amongst older patients and patients who never drank alcohol. The C>T mutation at rs1801133 of the MTHFR gene was associated with a decreased risk of gastric cancer in older individuals and those who never drink.

Association between methylene tetrahydrofolate reductase polymorphisms and risk of ischemic stroke

Background: The methylene tetrahydrofolate reductase (MTHFR) is a folate-dependent enzyme which catalyzes the conversion of homocysteine to methionine. Two single nucleotide polymorphisms (SNPs) within this gene namely rs1801133 (C677T) and rs1801131 (A1298C) have been associated with elevated risk of ischemic stroke and total serum homocysteine in some populations.Aim: To assess associations between MTHFR SNPs and risk of ischemic stroke in Iranian population.Methods: In the current case-control study, we genotyped rs1801133 and rs1801131 SNPs in 318 Iranian patients with history of ischemic stroke and 400 age- and sex-matched controls using tetra-primer amplification refractory mutation system-polymerase chain reaction method.Results: The rs1801133 was significantly associated with risk of stroke in recessive model (OR (95% CI) = 1.89 (1.12-3.20), p = 0.03). The CT haplotype (rs1801131 and rs1801133, respectively) was significantly over-represented in patients compared with controls (OR (95% CI) = 1.71 (0.25-2.32), p = 0.002).Conclusion: Consequently, our data demonstrate contribution of MTHFR variants in risk of ischemic stroke in Iranian population.

Lack of association between methylenetetrahydrofolate reductase C677T polymorphism, HPV infection and cervical intraepithelial neoplasia in Brazilian women

BACKGROUND

Cervical cancer has high prevalence and mortality rates in worldwide female population. Persistent infection by high-risk Human Papillomavirus (hr-HPV) is the main cause of this cancer. However, many environmental, genetical, and epigenetical cofactors can modulate viral infection and cervical carcinogenesis. Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is a genetic factor that has been associated with many pathologies, including cancer. Nevertheless, studies with cervical cancer presented controversial results, and varied according to ethnicity. Thus, the aim of this study was to determine association between MTHFR C677T polymorphism, Human Papillomavirus (HPV) infection and cervical cancer.

METHODS

A case-control study was performed with 150 histological cervical samples. Case group were divided in Cervical Intraepithelial Neoplasia (CIN) grade I (n = 30), CIN II (n = 30), CIN III (n = 30), and Squamous Cervical Carcinoma (SCC) (n = 30). Control group was composed by 30 samples without lesion, presenting cervicitis. HPV detection was performed by conventional Polymerase Chain Reaction (PCR) with SPF primers set, and by real-time PCR specific for HPV 16 and hr-HPV. MTHFR C677T polymorphism was analyzed by PCR followed by Restriction Fragment Length Polymorphism (RFLP).

RESULTS

Frequency of MTHFR CC genotype was 72.7% (n = 109), CT 23.3% (n = 35) and TT 4.0% (n = 6). Polymorphic T allele frequency was 15.7%. No statistically significant association was observed between MTHFR C677T polymorphism and presence of pre-neoplastic or neoplastic cervical lesions. Similar frequencies of T allele was observed in control (23.3%) and cases (13.3%) groups (p = 0.174). In addition, there was no statistically significant association between MTHFR C677T polymorphism and viral infection, even considering hr-HPV or HPV 16 positivity.

CONCLUSION

MTHFR C677T polymorphism was not associated with cervical cancer and HPV infection.

Frequencies of poor metabolizer alleles of 12 pharmacogenomic actionable genes in Punjabi Sikhs of Indian Origin

Diversity in drug response is attributed to both genetic and non-genetic factors. However, there is paucity of pharmacogenetics information across ethnically and genetically diverse populations of India. Here, we have analyzed 21 SNPs from 12 pharmacogenomics genes in Punjabi Sikhs of Indian origin (N = 1,616), as part of the Sikh Diabetes Study (SDS). We compared the allele frequency of poor metabolism (PM) phenotype among Sikhs across other major global populations from the Exome Aggregation Consortium and 1000 Genomes. The PM phenotype of CYP1A2*1 F for slow metabolism of caffeine and carcinogens was significantly higher in Indians (SDS 42%, GIH [Gujarati] 51%, SAS [Pakistani] 45%) compared to Europeans 29% (pgenotype = 5.3E-05). Similarly, South Asians had a significantly higher frequency of CYP2C9*3 (12% SDS, 13% GIH, 11% SAS) vs. 7% in Europeans (pgenotype = <1.0E-05) and 'T' allele of CYP4F2 (36%) SDS, (43%) GIH, 40% (SAS) vs. (29%) in Europeans (pgenotype = <1.0E-05); both associated with a higher risk of bleeding with warfarin. All South Asians -the Sikhs (0.36), GIH (0.34), and SAS (0.36) had a higher frequency of the NAT2*6 allele (linked with slow acetylation of isoniazid) compared to Europeans (0.29). Additionally, the prevalence of the low activity 'C' allele of MTHFR (rs1801131) was highest in Sikhs compared to all other ethnic groups [SDS (44%), GIH (39%), SAS (42%) and European (32%) (pgenotype = <1.0E-05)]. SNPs in MTHFR affect metabolism of statins, 5-fluorouracil and methotrexate-based cancer drugs. These findings underscore the need for evaluation of other endogamous ethnic groups of India and beyond for establishing a global benchmark for pre-emptive genotyping in drug metabolizing genes before beginning therapeutic intervention.

Interaction between alcohol consumption and methylenetetrahydrofolate reductase polymorphisms in thyroid cancer risk: National Cancer Center cohort in Korea

The effect of alcohol intake on thyroid cancer is unestablished, and its interaction effects with genetic susceptibility are unclear. In this case-control study, the relationship among alcohol intake, the methylenetetrahydrofolate reductase (MTHFR) gene, and thyroid cancer risk has been evaluated. In total, 642 cases and 642 controls of Korean origin were included, and the genetic variants C677T and A1298C of the MTHFR gene were analysed. The interactions between alcohol-consumption behaviour and genetic variants were analysed with a likelihood ratio test, wherein a multiplicative interaction term was added to a logistic regression model. There was an independent association between the C677T polymorphism and thyroid cancer risk but not for drinking history. For C677T C/C homozygotes, individuals with a history of alcohol consumption showed a protective OR (95% CI) of 0.42 (0.15–1.13) when never drinkers were used as the reference. However, this protective association was not observed among individuals with a T+ allele with an OR (95% CI) of 1.27 (0.89–1.82), showing different directions for the association between genotypes with a significant interaction (P_interaction = 0.009). Based on the genetic characteristics of individuals included, an interaction between alcohol intake and MTHFR C677T may modify the risk of thyroid cancer.

The methylenetetrahydrofolate reductase 677T-1298C haplotype is a risk factor for acute lymphoblastic leukemia in children

The etiology of acute lymphoblastic leukemia (ALL) is complex, linked with both environmental exposures and genetic factors. Functional variants of the methylenetetrahydrofolate reductase (MTHFR) gene result in disturbance in folate metabolism and may affect susceptibility to cancer. The study was performed to evaluate whether MTHFR C677T and A1298C polymorphisms, analyzed separately and together, are associated with the development of ALL in a population under 18 years of age of Caucasian ancestry.The study included 117 pediatric patients (59% males, mean age at diagnosis 7.4 ± 5.2 years) with ALL, confirmed by conventional immunophenotyping surface-marker analysis and 404 healthy control subjects (48.5% men, mean age 37.7 ± 11.3 years). The MTHFR C677T and A1298C genotypes were analyzed using allele discrimination tests with Taq-Man fluorescent probes.The MTHFR 677TT genotype was related to a 2-fold increase in risk of ALL (P = .014). The 677T-1298C haplotype was found in ALL patients but not in controls (frequency 0.598%; P <.0001). The observed frequency of carriers of this rare haplotype was 12%, including 677CT/1298CC (1.7%), 677TT/1298AC (6.0%), and 677CT/1298AC (4.3%) genotypes.The MTHFR 677T allele alone or in combination with the MTHFR 1298C allele significantly increases the risk of development of ALL in Polish population under 18 years of age. Further studies of haplotype composition in subjects with the 677CT/1298AC genotype are necessary to assess the risk of childhood ALL.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Supplemental folic acid in pregnancy and maternal cancer risk

BACKGROUND

There is evidence that increased intake of folate protects against the development of several types of cancer. Some studies have, however, raised concern about the safety of folate in relation to cancer risk. Here we examined the risk of maternal cancer after intake of supplemental folic acid in pregnancy.

METHODS

This is a population-based cohort study comprising 429,004 women with data from the Medical Birth Registry of Norway, the Cancer Registry of Norway, and other national registries from 1999 to 2010. Altogether 3781 cancer cases were identified during follow-up (average 7 years). Cox proportional hazards regression models were used to estimate hazard ratios of maternal cancer according to folic acid use prior to and during one or two or more pregnancies as compared to no supplement use.

RESULTS

Folic acid supplementation use had no overall effect on cancer risk in women using folic acid supplementation in one (HR 1.08; 95% CI 1.00-1.18) or two or more pregnancies (HR 1.06; 95% CI 0.91-1.22) (ptrend=0.12). Analyses of 13 cancer types revealed no associations between folic acid and cancer.

CONCLUSION

Folic acid supplementation before and during pregnancy had no overall effect on maternal cancer risk.

IMPACT

Folic acid substitution before and/or during pregnancy does not increase the short-term overall maternal cancer risk.

High concentrations of folate and unmetabolized folic acid in a cohort of pregnant Canadian women and umbilical cord blood

BACKGROUND

Mandatory fortification, prevalent supplement use, and public health guidelines recommending periconceptional supplementation have increased folic acid intakes in North American pregnant women. However, the effects of increased folic acid intakes during pregnancy on maternal and cord blood folate concentrations have not been well established.

OBJECTIVES

In this prospective study, we determined maternal and cord blood concentrations of folate and unmetabolized folic acid (UMFA) in a cohort of pregnant Canadian women and their newborns and examined the effect of maternal intakes of folate and folic acid and fetal genetic variants in folate metabolism on folate status.

DESIGN

Folate and folic acid intakes of 368 Canadian pregnant women were assessed in early (0-16 wk) and late (23-37 wk) pregnancy. Blood concentrations of folate and UMFA were measured with the use of immunoassays and liquid chromatography-mass spectrometry, respectively, in maternal samples in early pregnancy (12-16 wk), at delivery (28-42 wk), and in cord blood. Four fetal genetic variants of the 5,10-methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) genes were assessed for their association with cord blood concentrations of folate and UMFA.

RESULTS

Geometric mean (95% CI) maternal red blood cell (RBC) folate concentrations were 2417 nmol/L (2362, 2472 nmol/L ) and 2793 nmol/L (2721, 2867 nmol/L ) in early pregnancy and at delivery, respectively. The mean (95% CI) cord RBC folate concentration was 2689 nmol/L (2614, 2765 nmol/L). UMFA was detectable in >90% of maternal and cord plasma samples. Although 3 fetal MTHFR and DHFR genetic variants had no effect, the fetal MTHFR 677TT genotype was associated with significantly lower cord serum (P = 0.03) and higher cord RBC (P = 0.02) folate concentrations than those of the wild type.

CONCLUSIONS

Notwithstanding differences in assays, maternal and cord RBC folate and plasma UMFA concentrations were higher than previously reported values. Functional ramifications of high folate and UMFA concentrations in maternal and fetal circulation warrant additional investigation because an excess folate status may affect long-term health outcomes of the offspring. This study was registered at www.clinicaltrials.gov as NCT02244684.

Intake of dietary folate and folic acid in Germany based on different scenarios for food fortification with folic acid

PURPOSE

Besides the adverse health effects of a low folate intake, the risks of high intakes of folic acid have moved into the focus. The aim of this study was to investigate the potential range of folate and folic acid intake of the German population under consideration of different fortification scenarios.

METHODS

Food consumption data of 13,926 participants of the German National Nutrition Survey II (NVS II), collected with two 24-h recalls, were used to calculate the nutrient intake. The nutrient data are based on the German Nutrient Database (BLS), information from a market survey and analyses of multivitamin juices. The scenarios were modelled without, as well as with low and high fortification levels of folic acid.

RESULTS

The median intake of dietary folate equivalents ranged from 191 µg/d (men) and 168 µg/d (women) without fortification to 425 µg/d (men) and 334 µg/d (women) in the highest fortification scenario. Thus, 12.4-68.2% (men) and 5.9-56.1% (women) met the 300 µg/d recommended by the nutrition societies of Germany, Austria and Switzerland. In the highest fortification scenario, 1.9% (men) and 0.8% (women) exceeded the tolerable upper intake level (UL) of 1,000 µg/d folic acid given by the European Food Safety Authority. For supplement users, this proportion was 5.2 and 5.4%.

CONCLUSIONS

Only a high fortification of several foods leads to a marked increase of the proportion of population reaching the recommendation. Simultaneously, with a high fortification a higher proportion exceeds the UL, especially in combination with supplements.

MTHFR C677T polymorphism interaction with heavy alcohol consumption increases head and neck carcinoma risk

MTHFR C677T polymorphism has been indicated to be a risk factor for cancers, but its association with head and neck cancer (HNC) risk remains inconclusive. In the present study, we aimed to get a more precise estimation by performing a quantitative meta-analysis. Published papers up to Jun 2014 was searched and screened. Necessary information was rigorously extracted for data pooling and analyzing, and then, subgroup analyses on ethnicity, source of controls, sample size, tumor type, smoking and drinking status were also carried out. As a result, twenty-three case-control studies including 14298 subjects were included. The overall data failed to reveal a significant association between MTHFR C677T polymorphism and HNC risk (homozygote comparison model: OR = 1.16; 95%CI = 0.93-1.45; dominant model: OR = 1.05; 95%CI = 0.90-1.21; recessive model: OR = 1.14; 95%CI = 0.93-1.38). However, in the subgroup analysis about drinking status, increase risk was shown in the heavy drinking subgroup (TT vs CC: OR = 3.11; 95%CI = 1.52-3.02). In conclusion, the results of the present study suggest that Homozygous TT alleles of MTHFR C677T polymorphism might be a risk factor for HNC among individuals who have a heavy drinking history. Further studies are needed to get a more definitive conclusion.

Superior vena cava syndrome and colon carcinoma: a report of a multifactorial association

Introduction. Superior vena cava (SVC) syndrome results from the obstruction of blood flow through the SVC, having distinct pathophysiological underlying mechanisms. Cancer is associated with an increased risk of thromboembolism that varies according to patient-, tumor-, and treatment-related factors. An individualized clinical approach is important to pursue the accurate diagnosis of the underlying pathology causing thromboembolism in cancer patients. Case Presentation. The authors present a case of a 58-year-old male with an infrequent presentation of an unknown colon carcinoma, who has never had any symptom until he was hospitalized with the diagnosis of superior vena cava syndrome and pulmonary thromboembolism. The patient had an advanced disease by the time of diagnosis and molecular alterations contributing to abnormal hemostasis. He presented venous and arterial thromboembolism and developed disseminated intravascular coagulopathy after surgery, anticoagulant and transfusion therapy, dying 40 days after the hospitalization. Conclusion. The authors discuss thromboembolic disease and tumor metastasis roles in a cancer patient with SVC syndrome. Thromboembolism in a malignancy context is a challenging clinical entity. A multifactorial perspective of the thrombotic disease is warranted to approach thromboembolism risk and stratify patients suitable to receive adequate anticoagulant prophylaxis and targeted therapies, aiming to improve clinical prognosis.

Heterozygote advantage of methylenetetrahydrofolate reductase polymorphisms on clinical outcomes in advanced non-small cell lung cancer (NSCLC) patients treated with platinum-based chemotherapy

Methylenetetrahydrofolate reductase (MTHFR) enzyme is essential for transmethylation reactions including DNA methylation and DNA synthesis and thereby may contribute to cancer prognosis. In our study, a total of 1,004 advanced non-small cell lung cancer (NSCLC) patients receiving first-line, platinum-based chemotherapy regimens were used for genotyping 10 tag single nucleotide polymorphisms (SNPs) of MTHFR. Association was assessed between the SNPs and treatment outcomes. We found that polymorphism of rs1537514 showed the most significant effect: heterozygote associated with better clinical benefit (P = 0.002) and decreased risk of grade 3 or 4 gastrointestinal toxicity (P = 0.027), while the mutant homozygote associated with increased risk of severe gastrointestinal toxicity (P = 0.031) and thrombocytopenia (P = 009). The heterozygotes of exon polymorphisms (rs1801131, rs1801133) also yielded better clinical benefit (P = 0.030 for rs1801131) and decreased risk of severe gastrointestinal toxicity (P = 0.004 for rs1801131) or thrombocytopenia (P = 0.016 for 1801133). However, overall survival (OS) and progression-free survival (PFS) did not differ for the MTHFR polymorphisms, except for heterozygote of rs1537514 showing significant effects with better PFS (P = 0.022). Clinical factors as age, gender, and smoking status had significant effects for the OS (P = 0.003, 0.002, and 0.012, respectively) while performance status and chemotherapy regimens for PFS (P = 0.001 and 3.9 × 10(-6), respectively). The results indicate that a heterozygous advantage may exist in certain MTHFR variants, and the polymorphisms (especially rs1537514) may play a predictive role of treatment efficacy and adverse effects in NSCLC patients treated with platinum-based chemotherapy.

MTHFR gene polymorphism in acute lymphoblastic leukemia among North Indian children: a case-control study and meta-analysis updated from 2011

Studies on the association of methylenetetrahydrofolate reductase (MTHFR) genotype in childhood acute lymphoblastic leukemia (ALL) have yielded conflicting results. The present study examines this association in north Indian children with ALL and includes an updated meta-analysis. MTHFR (677 and 1298) genotype of children with ALL and healthy adult controls were done by the PCR-restriction fragment length polymorphism (PCR-RFLP) method and were compared using various models of inheritance. A total of 150 patients and 300 controls were included. The 677T allele was found protective (odds ratio (OR) 0.21, 95% confidence interval (CI) 0.04-0.94), whereas 1298C allele led to an increase in risk (OR 4.44, 95% CI 2.19-8.99) of childhood ALL. Meta-analysis included 31 and 27 studies examining the association of 677 and 1298 genotypes, respectively. The 677 C -> T polymorphism was protective (OR 0.90, 95% CI 0.82-0.99). Protection was more pronounced in folate-sufficient populations as compared with those not covered by folate fortification guidelines. The 1298A->C polymorphism was associated with a marginal increase in risk (OR 1.19, 95% CI 1.01-1.40).

Associations between methylenetetrahydrofolate reductase polymorphisms and hepatocellular carcinoma risk in Chinese population

Genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) gene are considered to have some influence on both folate metabolism and cancer risk. Previous studies on the associations of MTHFR genetic polymorphisms with hepatocellular carcinoma (HCC) risk in Chinese population reported inconsistent results. We performed this meta-analysis to comprehensively assess the associations. Finally, 12 individual case-control studies were included into the meta-analysis. There were seven studies (6,384 subjects) on the MTHFR C677T polymorphism and five studies (4,502 subjects) on the MTHFR A1298C polymorphism. Overall, MTHFR C677T polymorphism was significantly associated with susceptibility to HCC in Chinese population (T versus C, odds ratio (OR) = 1.09, 95 % confidence interval (95% CI) 1.01-1.17; TT versus CC, OR = 1.17, 95% CI 1.00-1.38; TT/CT versus CC, OR = 1.12, 95% CI 1.00-1.26). MTHFR A1298C polymorphism was conversely associated with HCC risk in Chinese population (CC versus AA, OR = 0.65, 95% CI 0.46-0.91; CC versus AA/AC, OR = 0.64, 95% CI 0.46-0.90). The sensitivity analysis confirmed the reliability and stability of the meta-analysis. Thus, the findings from our meta-analysis support the associations of MTHFR C677T and A1298C polymorphisms with HCC risk in Chinese population.

Reality check: there is no such thing as a miracle food

A recent episode of the Dr. Oz Show suggested endive, red onion, and sea bass as foods that can decrease the risk of ovarian cancer by up to 75%. However, the scientific evidence supporting these recommendations is limited. This commentary discusses some of the concerns related to the promotion of "miracle foods" by the media. Nutritional scientists and epidemiologists should be cognizant of the public health messages that are taken from their individual studies and not sensationalize the findings of a single study.

The polymorphism of methylenetetrahydrofolate reductase C677T but not A1298C contributes to gastric cancer

Increasing epidemiological studies have revealed the important role of methylenetetrahydrofolate reductase (MTHFR) in carcinogenesis. The association of MTHFR A1298C and MTHFR C677T polymorphisms with the risk for gastric cancer remains obscure due to inconsistent findings in independent studies among diverse ethnicities. A meta-analysis based on all available publications on this genetic association was performed. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to estimate the effect of MTHFR variants on gastric carcinogenesis. Totally, 25 eligible case-control studies were included into the meta-analysis according to the inclusion criteria. The MTHFR C677T polymorphism was demonstrated to significantly increase the susceptibility to gastric cancer (OR(T vs. C) = 1.21, 95% CI 1.10-1.34; OR(TT vs. CC )= 1.47, 95% CI 1.22-1.76; OR(TC vs. CC )= 1.20, 95% CI 1.03-1.40; OR(TT + TC vs. CC) = 1.27, 95% CI 1.10-1.47; OR(TT vs. CC + TC )= 1.29, 95% CI 1.15-1.46), whereas no significant correlation was observed when assessing the MTHFR A1298C polymorphism (OR(C vs. A )= 1.00, 95% CI 0.90-1.10; OR(CC vs. AA) = 0.99, 95% CI 0.75-1.31; OR(CA vs. AA )= 1.01, 95% CI 0.89-1.14; OR(CC + CA vs. AA) = 1.00, 95% CI 0.89-1.13; OR(CC vs. AA + CA) = 0.97, 95% CI 0.74-1.27). Subgroup analyses by ethnicity and source of controls further confirmed the findings in overall analysis. The meta-analysis suggests that the polymorphism of MTHFR C677T but not MTHFR A1298C confers a risk effect on the development of gastric cancer among Asians and Caucasians, which provides a new insight into the gastric cancer pathogenesis.

Association between Methylenetetrahydrofolate reductase C677T polymorphism and susceptibility to cervical cancer: a meta-analysis

Background

To assess the association between MTHFR polymorphism and cervical cancer risk, a meta-analysis was performed.

Methods

Based on comprehensive searches of the PubMed, Embase, and Web of Science databases, we identified outcome data from all articles estimating the association between MTHFR polymorphism and cervical cancer risk. The pooled odds ratio (OR) with 95% confidence intervals (CIs) were calculated.

Results

A total of 12 studies with 2,924 cases (331 cervical intraepithelial neoplasia (CIN) I, 742 CIN II/III, 1851 invasive cervical cancer) and 2,581 controls were identified. There was no significant association between MTHFR C677T polymorphism and CIN I risk (T vs. C, OR = 1.10, 95% CI = 0.92–1.31; TT vs. CC, OR = 1.14, 95% CI = 0.78–1.68; TT+CT vs. CC, OR = 1.22, 95% CI = 0.94–1.58; TT vs. CT+CC, OR = 0.99, 95% CI = 0.70–1.40). For the CIN II/III, lack of an association was also found (T vs. C, OR = 1.08, 95% CI = 0.95–1.23; TT vs. CC, OR = 1.15, 95% CI = 0.87–1.52; TT+CT vs. CC, OR = 1.13, 95% CI = 0.94–1.35; TT vs. CT+CC, OR = 1.07, 95% CI = 0.83–1.38). The T allele had significant association to susceptibility of invasive cervical cancer in recessive model (TT vs. CT+CC, OR = 1.23, 95% CI = 1.02–1.49). On subgroup analysis by ethnicity, similarly significant differences in T vs. C, TT vs. CC, and recessive model were found in Asians.

Conclusion

The present meta-analysis suggested that MTHFR C677T polymorphism were to substantially contribute to invasive cervical cancer in recessive model.

Folate and DNA methylation

SIGNIFICANCE

The progressive, dose-dependent, and potentially reversible epigenetic changes observed in cancer present new opportunities in cancer risk modification and prevention using dietary and lifestyle factors. Folate, a water-soluble B vitamin, has been of intense interest because of an inverse association between folate status and the risk of several malignancies (particularly colorectal cancer) and its potential to modulate DNA methylation. Aberrant patterns and dysregulation of DNA methylation are mechanistically related to carcinogenesis.

RECENT ADVANCES

The effects of folate on DNA methylation patterns have recently been investigated in two important life stages: pre- and early postnatal life and aging. Recent studies have demonstrated that folate exposure in the intrauterine environment and early life and during the aging process may have profound effects on DNA methylation with significant functional ramifications, including the risk of cancer.

CRITICAL ISSUES

Evidence from animal, human, and in vitro studies suggest that the epigenetic effects of folate on DNA methylation are highly complex. The effects are gene and site specific and appear to depend on cell type, target organ, stage of transformation, the degree and duration of folate manipulations, interactions with other methyl group donors and dietary factors, and genetic variants in the folate metabolic pathways.

FUTURE DIRECTIONS

The potential for folate to modulate DNA methylation and, thus, modify the risk of cancer in humans is worthy of further investigation. Due to the complex relationship between folate exposure and DNA methylation, more elaborate epidemiological, clinical, and mechanistic studies that determine the clinical, biological, and molecular effects of folate are warranted.

Comprehensive evaluation of one-carbon metabolism pathway gene variants and renal cell cancer risk

Introduction

Folate and one-carbon metabolism are linked to cancer risk through their integral role in DNA synthesis and methylation. Variation in one-carbon metabolism genes, particularly MTHFR, has been associated with risk of a number of cancers in epidemiologic studies, but little is known regarding renal cancer.

Methods

Tag single nucleotide polymorphisms (SNPs) selected to produce high genomic coverage of 13 gene regions of one-carbon metabolism (ALDH1L1, BHMT, CBS, FOLR1, MTHFR, MTR, MTRR, SHMT1, SLC19A1, TYMS) and the closely associated glutathione synthesis pathway (CTH, GGH, GSS) were genotyped for 777 renal cell carcinoma (RCC) cases and 1,035 controls in the Central and Eastern European Renal Cancer case-control study. Associations of individual SNPs (n = 163) with RCC risk were calculated using unconditional logistic regression adjusted for age, sex and study center. Minimum p-value permutation (Min-P) tests were used to identify gene regions associated with risk, and haplotypes were evaluated within these genes.

Results

The strongest associations with RCC risk were observed for SLC19A1 (P_min-P = 0.03) and MTHFR (P_min-P = 0.13). A haplotype consisting of four SNPs in SLC19A1 (rs12483553, rs2838950, rs2838951, and rs17004785) was associated with a 37% increased risk (p = 0.02), and exploratory stratified analysis suggested the association was only significant among those in the lowest tertile of vegetable intake.

Conclusions

To our knowledge, this is the first study to comprehensively examine variation in one-carbon metabolism genes in relation to RCC risk. We identified a novel association with SLC19A1, which is important for transport of folate into cells. Replication in other populations is required to confirm these findings.

The homocysteine controversy

Mild to moderate hyperhomocysteinemia has been identified as a strong predictor of cardiovascular disease, independent from classical atherothrombotic risk factors. In the last decade, a number of large intervention trials using B vitamins have been performed and have shown no benefit of homocysteine-lowering therapy in high-risk patients. In addition, Mendelian randomization studies failed to convincingly demonstrate that a genetic polymorphism commonly associated with higher homocysteine levels (methylenetetrahydrofolate reductase 677 C>T) is a risk factor for cardiovascular disease. Together, these findings have cast doubt on the role of homocysteine in cardiovascular disease pathogenesis, and the homocysteine hypothesis has turned into a homocysteine controversy. In this review, we attempt to find solutions to this controversy. First, we explain that the Mendelian randomization analyses have limitations that preclude final conclusions. Second, several characteristics of intervention trials limit interpretation and generalizability of their results. Finally, the possibility that homocysteine lowering is in itself beneficial but is offset by adverse side effects of B vitamins on atherosclerosis deserves serious attention. As we explain, such side effects may relate to direct adverse effects of the B-vitamin regimen (in particular, the use of high-dose folic acid) or to proinflammatory and proproliferative effects of B vitamins on advanced atherosclerotic lesions.

Pharmacogenetic screening of N-acetyltransferase 2, thiopurine s-methyltransferase, and 5,10-methylene-tetrahydrofolate reductase polymorphisms in Northwestern Mexicans

Specific information about the population pharmacogenetics can be the starting point to study the inheritance of these traits, to design individual drug therapy, and to develop new drugs rationally. Pharmacogenetic studies have been performed in some regions of Mexico, such as Central and Northeast, but this kind of study has not been conducted in the Northwest region so far. Here, we report the distribution of NAT2, TPMT, and MTHFR gene polymorphisms in Baja California, Mexico. We found that our population sample exhibits allele and genotype frequencies that are highly similar to those observed in Caucasian populations, although it should be noted that there are slight similarities with those determined in other populations. As allelic variants of drug-metabolizing enzymes are prevalent in our population, it is important to consider pharmacogenetic testing as part of the standard diagnostic protocols before medication.