Review and pooled analysis of studies on MTHFR C677T polymorphism and esophageal cancer

Influence of MTHFR polymorphism, alone or in combination with smoking and alcohol consumption, on cancer susceptibility

5,10-methylenetetrahydrofolate reductase (MTHFR) mutations play a significant role in various types of cancers, serving as crucial regulators of folate levels in this process. Several studies have examined the effects of smoking and drinking on MTHFR-related cancers, yielding inconsistent results. Therefore, the objective of this study was to evaluate the magnitude of the effects of gene-smoking or gene-drinking interactions on cancer development. We conducted a comprehensive literature search in PubMed, Web of Science, CNKI, and Wan Fang databases up until May 10th, 2022, to identify relevant articles that met our inclusion criteria. The extracted data from these studies were used to calculate the overall odds ratio (OR) and corresponding 95% confidence interval (95% CI) using either a fixed-effect or random-effect model in Stata version 11.2. Stratified analyses were performed based on ethnicity, control group origin, and cancer classification to assess the risk of cancers associated with gene-smoking or gene-drinking interactions. Sensitivity analyses were conducted to investigate potential sources of heterogeneity, and publication bias was assessed using the Begg's test and Egger's test. Additionally, regression analysis was employed to explore the influence of relevant variables on heterogeneity. To evaluate the statistical correlations, analytical methods such as the false-positive report probability and the Bayesian false discovery probability were applied to assess the reliability of the findings. In our meta-analysis, a total of 47 articles were included, comprising 13,701 cases and 21,995 controls for the C677T polymorphism and 5,149 cases and 8,450 controls for the A1298C polymorphism. The results indicated a significant association between C677T polymorphism and cancer risks when combined with smoking (CT + TT vs CC, OR [95% CI] = 1.225 [1.009-1.487], p = 0.041). Stratified analysis further revealed a significant increase in liver cancer risk for individuals with the C677T when combined with smoking (liver cancer: CT + TT vs CC, OR [95% CI] = 1.564 [1.014-2.413], p = 0.043), particularly among Asian smokers (CT + TT vs CC, OR [95% CI] = 1.292 [1.007-1.658], p = 0.044). Regarding the A1298C polymorphism, an elevated risk of cancer was observed in mixed populations alone (CC + AC vs AA, OR [95% CI] = 1.609 [1.087-2.381], p = 0.018), as well as when combined with smoking (CC + AC vs AA, OR [95% CI] = 1.531 [1.127-2.080], p = 0.006). In non-drinkers, C677T polymorphism was found to be associated with esophageal cancer risk (C677T: CT + TT vs CC, OR [95% CI] = 1.544 [1.011-2.359], p = 0.044) and colon cancer risk (CC + AC vs AA, OR [95% CI] = 1.877 [1.166-3.054], p = 0.010), but there was no clear link between this polymorphism and cancer risk among drinkers. The association between the C677T polymorphism and cancer risk among smokers was found to be significant, suggesting that the combination of tobacco and the C677T polymorphism may enhance the carcinogenic process, particularly in liver cancer. However, no similar relationship was observed for the A1298C polymorphism. Interestingly, significantly increased cancer risk was observed in individuals with C677T genetic variants who were nondrinkers, but not among drinkers. These findings highlight the potential role of the C677T polymorphism in modifying cancer risk in specific contexts, such as smoking and alcohol consumption.

THYLENETETRAHYDROFOLATE REDUCTASE GENE POLYMORPHISMS AND SUSCEPTIBILITY TO ESOPHAGEAL CANCER: A CASE-CONTROL STUDY

BACKGROUND:

The enzyme methylenetetrahydrofolate reductase is engaged in DNA synthesis through folate metabolism. Inhibiting the activity of this enzyme increases the susceptibility to mutations, and damage and aberrant DNA methylation, which alters the gene expression of tumor suppressors and proto-oncogenes, potential risk factors for esophageal cancer.

AIMS:

This study aimed to investigate the association between methylenetetrahydrofolate reductase 677C>T and methylenetetrahydrofolate reductase 1298A>C polymorphisms and susceptibility to esophageal cancer, by assessing the distribution of genotypes and haplotypes between cases and controls, as well as to investigate the association of polymorphisms with clinical and epidemiological characteristics and survival.

METHODS:

A total of 109 esophageal cancer patients who underwent esophagectomy were evaluated, while 102 subjects constitute the control group. Genomic DNA was isolated from the peripheral blood buffy coat followed by amplification by polymerase chain reaction and real-time analysis. Logistic regression was used to assess associations between polymorphisms and the risk of developing esophageal cancer.

RESULTS:

There was no association for methylenetetrahydrofolate reductase 677C>T and methylenetetrahydrofolate reductase 1298A>C polymorphisms and haplotypes, with esophageal cancer susceptibility. Esophageal cancer patients carrying methylenetetrahydrofolate reductase 677TT polymorphism had higher risk of death from the disease. For polymorphic homozygote TT genotype, the risk of death significantly increased compared to wild-type genotype methylenetetrahydrofolate reductase 677CC (reference) cases (p=0.045; RR=2.22, 95%CI 1.02–4.83).

CONCLUSIONS:

There was no association between methylenetetrahydrofolate reductase 677C>T and methylenetetrahydrofolate reductase 1298A>C polymorphisms and esophageal cancer susceptibility risk. Polymorphic homozygote genotype methylenetetrahydrofolate reductase 677TT was associated with higher risk of death after surgical treatment for esophageal cancer.

MTHFR C677T genetic polymorphism in combination with serum vitamin B2, B12 and aberrant DNA methylation of P16 and P53 genes in esophageal squamous cell carcinoma and esophageal precancerous lesions: a case-control study

Background

The study aimed to explore the associations between the interactions of serum vitamin B₂ or B₁₂ levels, aberrant DNA methylation of p16 or p53 and MTHFR C677T polymorphism and the risks of esophageal squamous cell carcinoma (ESCC) and esophageal precancerous lesion (EPL).

Methods

200 ESCC cases, 200 EPL cases and 200 normal controls were matched by age (± 2 years) and gender. Serum vitamin B₂ and B₁₂ levels, MTHFR C677T genetic polymorphisms and the methylation status of genes were assessed. Chi square test, one-way analysis of variance and binary logistic regression were performed.

Results

The lowest quartile of both serum vitamin B₂ and B₁₂ with TT genotype showed significant increased EPL risk (OR = 4.91, 95% CI 1.31-18.35; OR = 6.88, 95% CI 1.10-42.80). The highest quartile of both serum vitamin B₂ and B₁₂ with CC genotype showed significant decreased ESCC risk (OR = 0.16, 95% CI 0.04-0.60; OR = 0.10, 95% CI 0.02-0.46). The ORs of p16 methylation for genotype CT and TT were 1.98 (95% CI 1.01-3.89) and 17.79 (95% CI 2.26-140.22) in EPL, 4.86 (95% CI 2.48-9.50) and 20.40 (95% CI 2.53-164.81) in ESCC, respectively. Similarly, p53 methylation with genotype TT was associated with increased EPL and ESCC risks (OR = 13.28, 95% CI 1.67-105.70; OR = 15.24, 95% CI 1.90-122.62).

Conclusions

The MTHFR C677T genotype and serum vitamin B₂ or B₁₂ levels may interact in ways which associated with the EPL and ESCC risks. The gene-gene interaction suggested that aberrant DNA methyaltion of either p16 or p53 combined with T alleles of MTHFR was associated with increased risks of both EPL and ESCC.

Investigation of methylenetetrahydrofolate reductase tagging polymorphisms with colorectal cancer in Chinese Han population

The aim of this case-control study was to assess the relationship between the tagging polymorphisms in methylenetetrahydrofolate reductase (MTHFR) gene and the susceptibility to colorectal cancer (CRC) in a Chinese Han population. A custom-by-design 48-Plex SNPscan Kit was used to determine the genotypes of MTHFR rs3753584 T>C, rs9651118 T>C, rs1801133 G>A, rs4846048 A>G and rs4845882 G>A polymorphisms in 387 CRC patients and 1,536 non-cancer controls. The results revealed that MTHFR rs1801133 G>A polymorphism was associated with a decreased risk of overall CRC. While MTHFR rs4845882 G>A polymorphism conferred an increased risk to overall CRC. In a stratified analysis by CRC region, we found MTHFR rs3753584 T>C and rs9651118 T>C polymorphisms were associated with the increased risk of colon cancer. In addition, a significantly increased risk of rectum cancer associated with MTHFR rs3753584 T>C polymorphism was overt. However, MTHFR rs1801133 G>A polymorphism conferred a decreased risk to colon cancer. In conclusion, findings of the present study reveal that the tagging polymorphisms in MTHFR gene (rs3753584 T>C, rs9651118 T>C and rs4845882 G>A) are associated with the increased risk of CRC. However, MTHFR rs1801133 G>A polymorphism confers a decreased risk to CRC. Additional studies with larger sample size are needed to confirm these findings.

Alcohol consumption and corresponding factors: A novel perspective on the risk factors of esophageal cancer

Esophageal cancer is the eighth most common type of cancer in the world, and the sixth most common cause of mortality from cancer. Alcohol consumption is the major risk factor for esophageal cancer, due to the worldwide prevalence and high carcinogenicity of the ethanol metabolite. In epidemiological studies, the efficiency of alcohol intake to enhance the risk of esophageal cancer is altered by daily ethanol consumption, type of alcoholic beverages ingested, time since quitting drinking, age of drinking initiation, differences in population and subtypes of esophageal cancer. Corresponding factors, including gene polymorphisms, tobacco smoking, oral microorganisms and folate deficiency, reveal a synergistic effect in concurrent alcohol users that may lead to an increased risk of developing esophageal cancer. Consequently, esophageal cancer prevention involves multiple aspects, including quitting drinking and smoking, maintaining an adequate oral health and ingesting adequate quantities of folate, particularly in genetically high-risk populations.

MTHFR 677C>T polymorphism and the risk of breast cancer: evidence from an original study and pooled data for 28031 cases and 31880 controls

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) acts at an important metabolic point in the regulation of cellular methylation reaction. It assists in the conversion of 5, 10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. The latter aids in remethylation of homocysteine to de novo methionine that is required for DNA synthesis. The objective of this study was to examine the effect of MTHFR 677 C>T polymorphism on the risk of breast cancer in the Indian sub-continent.

METHODS AND RESULTS

We genotyped 677 C>T locus in 1096 individuals that were classified into cases (N=588) and controls (N=508). Genotype data were analyzed using chi-square test. No significant difference was observed in the distribution of genotypes between cases and controls in north Indian (P = 0.932), south Indian (P = 0.865), and pooled data (P = 0.680). To develop a consensus regarding the impact of 677C>T polymorphism on breast cancer risk, we also conducted a meta-analysis on 28031 cases and 31880 controls that were pooled from sixty one studies. The overall summary estimate upon meta-analysis suggested no significant correlation between the 677C>T substitution and breast cancer in the dominant model (Fixed effect model: OR = 0.97, P=0.072, Random effects model: OR = 0.96, P = 0.084) or the recessive model (Fixed effect model: OR = 1.05, P = 0.089; Random effects model: OR= 1.08, P= 0.067).

CONCLUSION

677 C>T substitution does not affect breast cancer risk in the Indo-European and Dravidian populations of India. Analysis on pooled data further ruled out association between the 677 C>T polymorphism and breast cancer. Therefore, 677 C>T substitution does not appear to influence the risk of breast cancer.

MTHFR C677T gene polymorphism and head and neck cancer risk: a meta-analysis based on 23 publications

OBJECTIVE

Conflicting results on the association between MTHFR polymorphism and head and neck cancer (HNC) risk were reported. We therefore performed a meta-analysis to derive a more precise relationship between MTHFR C677T polymorphism and HNC risk.

METHODS

Three online databases of PubMed, Embase, and CNKI were researched on the associations between MTHFR C677T polymorphism and HNC risk. Twenty-three published case-control studies involving 4,955 cases and 8,805 controls were collected. Odds ratios (ORs) with 95% confidence interval (CI) were used to evaluate the relationship between MTHFR C677T polymorphism and HNC risk. Sensitivity analysis, cumulative analyses, and publication bias were conducted to validate the strength of the results.

RESULTS

Overall, no significant association between MTHFR C677T polymorphism and HNC risk was found in this meta-analysis (T versus C: OR = 1.04, 95% CI = 0.92-1.18; TT versus CC: OR = 1.15, 95% CI = 0.90-1.46; CT versus CC: OR = 1.00, 95% CI = 0.85-1.17; CT + TT versus CC: OR = 1.01, 95% CI = 0.87-1.18; TT versus CC + CT: OR = 1.11, 95% CI = 0.98-1.26). In the subgroup analysis by HWE, ethnicity, study design, cancer location, and negative significant associations were detected in almost all genetic models, except for few significant risks that were found in thyroid cancer.

CONCLUSION

This meta-analysis demonstrates that MTHFR C677T polymorphism may not be a risk factor for the developing of HNC.

Methylenetetrahydrofolate reductase C667T polymorphism is associated with increased risk of coronary artery disease in a Chinese population

Coronary artery disease (CAD) is a complex disease resulting from a combination of environmental and genetic factors. We hypothesized that polymorphisms in methylenetetrahydrofolate reductase (MTHFR) rs1801133 C/T, matrix metalloproteinases (MMPs)-2, tumour necrosis factor (TNF)-α, macrophage migration inhibitory factor (MIF) rs755622 G/C and cyclin D1 (CCND1) rs678653 G/C contribute to CAD susceptibility. We examined the association between the five polymorphisms and the risk of CAD in a Chinese population of 435 CAD patients and 480 controls. Genotyping was performed using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF MS). When the MTHFR rs1801133 CC homozygote genotype was used as the reference group, the TT or CT/TT genotypes were associated with a significantly increased risk for CAD. The CT heterozygote genotype was not associated with the risk for CAD. Logistic regression analyses revealed that MMP-2 rs243865 C/T, TNF-α rs1800629 A/G, MIF rs755622 G/C and CCND1 rs678653 G/C polymorphisms were not associated with the risk of CAD. These findings suggest that the MTHFR rs1801133 C/T polymorphism is associated with CAD development. Future larger studies with other ethnic populations are required to confirm current findings.

Genetic variations in MTHFR and esophageal squamous cell carcinoma susceptibility in Chinese Han population

Esophageal cancer is the sixth most common cancer worldwide. Esophageal squamous cell carcinoma (ESCC) is a fatal malignancy associated with low 5-year survival rate. The aim of this study was to assess the association between methylenetetrahydrofolate reductase (MTHFR) tagging single nucleotide polymorphisms (SNPs) rs1801133 C>T, rs3753584 A>G, rs4845882 G>A, rs4846048 A>G and rs9651118 T>C genotypes and ESCC susceptibility in a hospital-based case-control study. We conducted genotyping analyses for these five SNPs with 629 ESCC cases and 686 controls in a Chinese Han population. Ligation detection reaction method was used to identify genotypes of these MTHFR SNPs. Our results demonstrated that MTHFR rs1801133 C>T was associated with the risk of ESCC; however, MTHFR rs4845882 G>A and rs4846048 A>G SNPs were associated with the decreased risk of ESCC, and MTHFR rs3753584 A>G and rs9651118 T>C SNPs were not associated with ESCC risk. Our findings suggests that MTHFR rs1801133 C>T, rs4845882 G>A and rs4846048 A>G SNPs may be genetic modifiers for developing ESCC in Chinese Han population.

Folate intake and the risk of upper gastrointestinal cancers: a systematic review and meta-analysis

BACKGROUND AND AIM

There is conflicting evidence on the association between folate intake and the risk of upper gastrointestinal tract cancers. In order to further elucidate this relationship, we performed a systematic review and quantitative meta-analysis of folate intake and the risk of esophageal, gastric, and pancreatic cancer.

METHODS

Four electronic databases (Medline, PubMed, Embase, and Current Contents Connect) were searched to July 26, 2013, with no language restrictions for observational studies that measured folate intake and the risk of esophageal cancer, gastric cancer, or pancreatic cancer. Pooled odds ratios and 95% confidence intervals were calculated using a random effects model.

RESULTS

The meta-analysis of dietary folate and esophageal cancer risk comprising of nine retrospective studies showed a decreased risk of esophageal cancer (odds ratio [OR] 0.59; 95% confidence interval [95% CI] 0.51-0.69). The meta-analysis of dietary folate and gastric cancer risk comprising of 16 studies showed no association (OR 0.94; 95% CI 0.78-1.14). The meta-analysis of dietary folate and pancreatic cancer risk comprising of eight studies showed a decreased risk of pancreatic cancer (OR 0.66; 95% CI 0.49-0.89).

CONCLUSION

Dietary folate intake is associated with a decreased risk of esophageal and pancreatic cancer, but not gastric cancer. Interpretation of these relationships is complicated by significant heterogeneity between studies when pooled, and by small numbers of studies available to analyze when stratification is performed to reduce heterogeneity.

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.

Impact of methylenetetrahydrofolate reductase C677T polymorphism on the risk of gastric cancer and its interaction with Helicobacter pylori infection

BACKGROUND

Attempts for early detection of gastric cancer have recently focused on host's genetic susceptibility factors and gene-environment interactions. We have, herein, studied the association of MTHFR C677T single nucleotide polymorphism (SNP) and its interaction with Helicobacter pylori infection, smoking, age and gender on the risk of gastric cancer among an Iranian population.

METHODS

Gastric cancer patients (n = 450) and cancer-free controls (n = 780) were studied for serum H. pylori-specific IgG antibodies by ELISA and MTHFR C677T polymorphism (SNP) by PCR-RFLP. Demographic and life style data were collected through patient interviews. Unconditional logistic regression model estimated odds ratio (OR) and the corresponding 95% confidence intervals (CI).

RESULTS

The interactions of MTHFR genotype with H. pylori infection (P = 0.03), age (P = 0.049) and gender (P = 0.007) were statistically significant. Accordingly, MTHFR C677T carriers who were also positive for H. pylori infection exhibited 80% (OR = 1.8, 95% CI = 1.0-2.9) significant excess risk of non-cardia gastric cancer. Furthermore, subjects over the age of 50 or female subjects carrying MTHFR C677T SNP showed 40 (OR = 1.4, 95% CI = 1.0-2.0) and 100 (OR = 2.0, 95% CI = 1.2-3.2) percent increased risk of gastric cancer, respectively.

CONCLUSION

MTHFR C677T SNP seems to increase the risk of gastric cancer and the effect is significantly inflated by interactions with H. pylori infection, age and gender.

The MTHFR C677T polymorphism and prostate cancer risk: new findings from a meta-analysis of 7306 cases and 8062 controls

Methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme involved in folate metabolism; a single nucleotide polymorphism (SNP) C677T has been reported to be linked with altered incidences of several diseases. We here conducted a meta-analysis of 15 published epidemiological studies with a total of 7306 cases and 8062 controls to evaluate its association with prostate cancer risk with overall and subgroup analyses. No statistical relationship was found overall with any genetic model (TT vs. CC: OR = 0.80, 95%CI = [0.62, 1.04], P = 0.094; CT vs. CC: OR = 0.97, 95%CI = [0.84; 1.12], P = 0.667; Dominant: OR = 0.94, 95%CI = [0.82; 1.07], P = 0.343; Recessive: OR = 0.81, 95%CI = [0.64; 1.04], P = 0.104), but after the exclusion of several studies, we could observe the homozygote TT to confer less susceptibility to prostate cancer in carriers; moreover, different effects of the polymorphism on prostate cancer risk was detected from subgroup analysis stratified by participants' residential region: significant reduced prostate cancer risk was found to be associated with the polymorphism from Asian studies (TT vs. CC: OR = 0.47, 95%CI = [0.33; 0.67], P< 0.001; CT vs. CC: OR = 0.73, 95%CI = [0.60; 0.90], P = 0.002; Dominant: OR = 0.67, 95%CI = [0.56; 0.82], P< 0.001; Recessive: OR = 0.55, 95%CI = [0.40; 0.76], P< 0.001) while studies from Europe indicated a slight increased risk under dominant model with marginal significance (OR = 1.14, 95%CI = [0.99; 1.30], P = 0.064). Moreover, the protective effect of the polymorphism against prostate cancer was also shown by studies performed in yellow Asians (TT vs. CC: OR = 0.48, 95%CI = [0.31; 0.75], P = 0.001; CT vs. CC: OR = 0.68, 95%CI = [0.51; 0.90], P = 0.006; Dominant: OR = 0.63, 95%CI = [0.48; 0.82], P < 0.001; Recessive: OR = 0.57, 95%CI = [0.39; 0.84], P = 0.004). We propose that these phenomena should be viewed with the consideration of folate metabolism profile and different gene background as well as living habits of different populations, and more relevant studies should be conducted to confirm our hypothesis and provide a comprehensive and clear picture concerning this topic.

ACMG Practice Guideline: lack of evidence for MTHFR polymorphism testing

MTHFR polymorphism testing is frequently ordered by physicians as part of the clinical evaluation for thrombophilia. It was previously hypothesized that reduced enzyme activity of MTHFR led to mild hyperhomocysteinemia which led to an increased risk for venous thromboembolism, coronary heart disease, and recurrent pregnancy loss. Recent meta-analyses have disproven an association between hyperhomocysteinemia and risk for coronary heart disease and between MTHFR polymorphism status and risk for venous t-hromboembolism. There is growing evidence that MTHFR polymorphism testing has minimal clinical utility and, therefore should not be ordered as a part of a routine evaluation for thrombophilia.

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms and susceptibility for cervical lesions: a meta-analysis

Background

The association between the methylenetetrahydrofolate reductase (MTHFR) C677T/A1298C polymorphisms and the susceptibility to cervical lesions was unclear. This study was designed to investigate their precise association using a large-scale meta-analysis.

Methods

The previous 16 studies were identified by searching PubMed, Embase and CBM databases. The crude odds ratios and their corresponding 95% confidence intervals (CIs) were used to estimate the association between the MTHFR C677T/A1298C polymorphisms and the susceptibility to the cervical lesions. The subgroup analyses were made on the following: pathological history, geographic region, ethnicity, source of controls and source of DNA for genotyping.

Results

Neither of the polymorphisms had a significant association with the susceptibility to the cervical lesions in all genetic models. Similar results were found in the subgroup analyses. No association was found between the MTHFR C677T polymorphism and the cervical lesions in the Asia or the America populations though a significant inverse association was found in the Europe population (additive model: P = 0.006, OR = 0.83, 95% CI = 0.72–0.95; CT vs. CC: P = 0.05, OR = 0.83, 95% CI = 0.69–1.00; TT vs. CC: P = 0.05, OR = 0.73, 95% CI = 0.53–1.00). Interestingly, women with the MTHFR A1298C polymorphisms had a marginally increased susceptibility to invasive cancer (ICC) when compared with no carriers but no statistically significant difference in the dominant model (P = 0.06, OR = 1.21, 95% CI = 0.99–1.49) and AC vs. AA (P = 0.09, OR = 1.21, 95% CI = 0.97–1.51).

Conclusions

The MTHFR C677T and A1298C polymorphisms may not increase the susceptibility to cervical lesions. However, the meta-analysis reveals a negative association between the MTHFR C677T polymorphisms and the cervical lesions, especially in the European populations. The marginal association between the MTHFR A1298C polymorphisms and the susceptibility to cervical cancer requires a further study.

Head and neck carconogenesis: impact of MTHFD1 G1958A polymorphism

OBJECTIVE

To investigate the MTHFD1 G1958A polymorphism involved in the folate metabolism as a risk for head and neck cancer, and to find the association of the polymorphism with the risk factors and clinical and histopathological characteristics.

METHODS

Retrospective study investigating MTHFD1 G1958A polymorphism in 694 subjects (240 patients in the Case Group and 454 in the Control Group) by Restriction Fragment Length Polymorphism (RFLP) Analysis. Multiple logistic regression and chi-square tests were used in the statistical analysis.

RESULTS

Multivariable analysis showed that smoking and age over 42 years were disease predictors (p < 0.05). MTHFD1 1958GA or AA genotypes were associated with smoking (p = 0.04) and alcoholism (p = 0.03) and were more often found in more advanced stage tumors (p = 0.04) and in patients with a shorter survival (p = 0.03).

CONCLUSION

The presence of MTHFD1 G1948A polymorphism associated with smoking and alcoholism raises the head and neck cancer risk.

Association between the MTHFR gene and Alzheimer's disease: a meta-analysis

BACKGROUND

The association between methylenetetrahydrofolate reductase (MTHFR) gene (rs1801133) 677C/T polymorphism and Alzheimer's disease (AD) is controversial. The objective of the study was to investigate the possible association between MTHFR 677C/T polymorphism and AD.

METHOD

We performed a meta-analysis pooling data from all relevant studies including 3,299 cases and 4,363 controls. We applied a random-effects or fixed-effects model to combine odds ratio (OR) and 95% confidence intervals (95% CI).

RESULTS

This meta-analysis demonstrated that the MTHFR T allele or dominant model for T allele (CT + TT) had an increased risk for AD in combined populations (OR, 95% CI: 1.13, 1.05-1.21; 1.18, 1.07-1.31, respectively), and a significant association was found in allele contrast, recessive, and dominant model in Asian populations, but not in Caucasian populations.

CONCLUSION

The MTHFR C677T polymorphism is associated with AD in Asian populations, but not in Caucasians.

MTHFD1 G1958A, BHMT G742A, TC2 C776G and TC2 A67G polymorphisms and head and neck squamous cell carcinoma risk

Alterations in folate metabolism may contribute to the process of carcinogenesis by influencing DNA methylation and genomic stability. Polymorphisms in genes encoding enzymes involved in this pathway may alter enzyme activity and consequently interfere in concentrations of homocysteine and S-adenosylmethionine that are important for DNA synthesis and cellular methylation reactions. The objectives were to investigate MTHFD1 G1958A, BHMT G742A, TC2 C776G and TC2 A67G polymorphisms involved in folate metabolism on head and neck cancer risk and the association between these polymorphisms with risk factors. Polymorphisms were investigated in 762 individuals (272 patients and 490 controls) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Real Time-PCR. Chi-square and Multiple logistic regression were used for the statistical analysis. Multiple logistic regression showed that tobacco and male gender were predictors for the disease (P < 0.05). Hardy-Weinberg equilibrium showed that the genotypic distributions were in equilibrium for both groups in all polymorphisms studied. The BHMT 742GA or AA genotypes associated with tobacco consumption (P = 0.016) increase the risk for head and neck squamous cell carcinoma (HNSCC). The present study suggests that BHMT 742GA polymorphism associated to tobacco modulate HNSCC risk. However, further investigation of gene-gene interactions in folate metabolism and studies in different populations are needed to investigate polymorphisms and HNSCC risk.

Polymorphisms and haplotypes in methylenetetrahydrofolate reductase gene and head and neck squamous cell carcinoma risk

Functional polymorphisms in genes encoding enzymes involved in folate metabolism might modulate head and neck carcinoma risk because folate participates in DNA methylation and synthesis. We therefore conducted a case-control study of 853 individuals (322 head and neck cancer cases and 531 non-cancer controls) to investigate associations among MTHFR C677T and MTHFR A1298C polymorphisms and head and neck squamous cell carcinoma risk. Interactions between these two polymorphisms and risk factors and clinical histopathological parameters were also evaluated. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to genotype the polymorphisms and Chi-square test and multiple logistic regression were used for statistical analyses. The variables age≥49 years, male gender, tobacco habits and alcohol consumption, MTHFR 1298 AC or CC genotypes, combined genotypes with two or more polymorphic alleles and 677T and 1298C polymorphic alleles were associated with increased risk for this disease (P<0.05). Furthermore, we found that 1298 AC or CC genotypes were associated with age≥49 years, tobacco and alcohol habits (P<0.05). Regarding clinical histopathological parameters, the A1298C polymorphism was more frequent in patients with oral cavity as primary site (P<0.05). MTHFR polymorphisms may contribute for increase risk for head and neck carcinoma and the variables age≥49 years, male gender, tobacco and alcohol habits were associated with MTHFR 1298AC or CC genotypes, confirming that individuals with these variables and MTHFR A1298C polymorphism has higher risk for this disease.

Methylenetetrahydrofolate reductase C677T polymorphism and the risk of male infertility: a meta-analysis

Several molecular epidemiological studies have been conducted to examine the association between MTHFR C677T polymorphism and male infertility susceptibility, but the results remain inconsistent. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 10 case-control studies, including 2275 cases and 1958 controls, were selected. Crude odds ratios (ORs) with 95% confidence intervals were used to assess the strength of association in the additive model, dominant model and recessive model. In the overall analysis, no significant association between the polymorphism and risk of male infertility was observed. Stratified analysis showed that significantly strong association between MTHFR C677T polymorphism and male infertility were present only in Asians (OR = 1.79 for TT vs. CC genotype; OR = 1.42 for CT/TT vs. CC genotype; OR = 1.50 for TT vs. CC/CT genotype; OR = 1.36 for T vs. C allele), but not in Caucasians. Additionally, MTHFR 677T was associated with a significant increase in the risk of azoospermia in all genetic models. No significantly increased risks of oligoasthenoteratozoospermia were found in any of the genetic models. In conclusion, this meta-analysis supports that MTHFR C677T polymorphism is capable of causing male infertility susceptibility in Asians, but not in Caucasians.

Diet folate, DNA methylation and genetic polymorphisms of MTHFR C677T in association with the prognosis of esophageal squamous cell carcinoma

Background

Folic acid may affect the development of human cancers. However, few studies have evaluated the consumption of diet folate in the prognosis of patients with esophageal squamous cell carcinoma (ESCC).

Methods

One hundred and twenty five ESCC patients underwent esophagectomy between January 2005 and March 2006 in the Yangzhong People's Hospital were recruited and followed up. The effects of diet folate, aberrant DNA methylation of selected genes and methylenetetrahydrofolate reductase (MTHFR) C677T genetic polymorphisms on the prognosis of ESCC were evaluated by using Cox proportional hazard regression models.

Results

Our analysis showed an inverse association between diet folate intake and the risk of death after esophagectomy. The median survival time was 3.06 years for low or moderate folate consumption and over 4.59 years for high folate consumption. After adjusting for potential confounders, the hazard ratios (95% confidence interval) [HRs (95% CI)] were 0.72 (0.36-1.46) for moderate and 0.39 (0.20-0.78) for high folate intake, respectively (P for trend = 0.007). This preventive effect was more evident in patients carrying MTHFR 677CC genotype. No significant relation was observed between aberrant DNA methylation of P16, MGMT and hMLH1 gene, as well as MTHFR C677T genetic polymorphisms and the prognosis of ESCC.

Conclusions

Our research indicated that diet folate intake may have benefits on the prognosis of ESCC after esophagectomy. From a practical viewpoint, the findings of our study help to establish practical intervention and surveillance strategies for managements of ESCC patients and can finally decrease the disease burden.

Hyperhomocysteinemia, methylenetetrahydrofolate reductase c.677C>T polymorphism and risk of cancer: cross-sectional and prospective studies and meta-analyses of 75,000 cases and 93,000 controls

Global DNA hypomethylation associates with development of cancer. DNA hypomethylation also associates with hyperhomocysteinemia and MTHFR c.677C>T homozygosity, both of which may associate with increased risk of cancer. We tested the putative association of hyperhomocysteinemia with cancer and the association of the MTHFR c.677TC>T variant with hyperhomocysteinemia and with cancer. We performed a cross-sectional study of 5,949 Danish general population adults, a prospective study of 9,235 Danish general population adults with up to 60 years of registry surveillance, and meta-analyses of 231 studies including 74,671 cases and 93,344 controls. Cross-sectionally, plasma homocysteine levels were 12.9 and 11.6 μmol/L in those with and without cancer (p < 0.0001). However, homocysteine levels increased with age and age-adjusted odds ratio for any cancer in those with homocysteine levels >12.4 versus < 9.4 μmol/L did not differ from 1.0. In cancer-free participants, plasma homocysteine levels were 14.7 and 11.7 μmol/L in MTHFR c.677C>T homozygtes and noncarriers (p < 0.0001). Prospectively, hazard ratios for any cancer and for cancer subtypes in MTHFR c.677C>T homozygotes versus noncarriers did not differ from 1.0. However, in meta-analyses odds ratio for MTHFR c.677C>T homozygotes versus noncarriers were 1.07 (95% CI: 1.01-1.12) for any cancer, 1.77 (1.17-2.68) for esophagus cancer, 1.40 (1.19-1.66) for gastric cancer and 0.85 (0.77-0.94) for colorectal cancer. Increased plasma homocysteine levels are not associated with an increased age-adjusted risk of any cancer. However, MTHFR c.677C>T homozygosity with lifelong hyperhomocysteinemia and hence hypomethylation associate with increased risk of esophagus and gastric cancer, and with decreased risk of colorectal cancer.

Evaluation of MTHFR677C>T polymorphism in prediction and prognosis of esophageal squamous cell carcinoma: a case-control study in a northern Indian population

Early diagnosis and better prognosis of esophageal squamous cell carcinoma (ESCC) is still a challenge. Besides environmental risk factors, nutritional deficiencies have an established role in pathogenesis of ESCC. Folate deficiency and functional polymorphisms in folate metabolizing genes such as methylene tetrahydrofolate reductase (MTHFR) 677C>T may have oncogenic role through disruption of normal DNA methylation pattern, synthesis, and impaired DNA repair. MTHFR677C>T or A222V (rs1801133) polymorphism has conflicting role in susceptibility to ESCC among different populations. Thus, we aimed to study the role of MTHFR677C>T polymorphism in susceptibility, survival, and interaction with environmental risk factors in ESCC patients from a northern Indian population. A case control study was performed in 208 ESCC incident cases (including 114 follow-up cases) and 223 healthy controls, and genotyping was done by PCR-RFLP. Our results show no significant association of MTHFR677C>T polymorphism with ESCC, tumor locations, or gender of subjects. However, we found a trend of decreased risk of ESCC due to interaction of MTHFR677CT genotype with smoking and alcohol intake. Kaplan Meier, and Cox regression survival analysis showed no prognostic impact of MTHFR677C>T polymorphism in ESCC patients. In conclusion, MTHFR677C>T polymorphism does not seem to have significant role either in susceptibility or survival of ESCC in a northern Indian population.

An increased risk of differentiated thyroid carcinoma in Iran with the 677C→T homozygous polymorphism in the MTHFR Gene

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) involves in folic acid metabolism which influences DNA methylation. A single nucleotide polymorphism (SNP) called 677C→T in MTHFR gene causes producing a thermolabile enzyme with reducing function and eventually defects DNA methylation. To determine association between germ-line polymorphism in MTHFR gene with differentiated thyroid carcinoma (DTC), this preliminary study was designed.

METHODS

This was a case-control study of 154 DTC patients and 198 cancer free individuals. Genotyping was performed by a multiplex PCR method and the frequencies of the 677C→T SNP in cases and controls were compared. The risk estimation was done by multivariate logistic regression analysis.

RESULTS

Compared to CC genotype, an increased risk of DTC for the 677C→T homozygous genotype was demonstrated (odds ratio [OR]: 2.08, 95% confidence interval [CI]: 0.82-5.25). Also, multivariate analysis demonstrated an increased risk of DTC in recessive fashion (TT vs. CC or CT) (OR: 2.38, 95% CI: 0.97-5.82).

CONCLUSION

The MTHFR 677C→T homozygous variant allele may be associated with increased risk of DTC.

Secondary prevention of esophageal squamous cell carcinoma in areas where smoking, alcohol, and betel quid chewing are prevalent

Esophageal cancer is ranked as the sixth most common cause of cancer death worldwide and has a substantial effect on public health. In contrast to adenocarcinoma arising from Barrett's esophagus in Western countries, the major disease phenotype in the Asia-Pacific region is esophageal squamous cell carcinoma which is attributed to the prevalence of smoking, alcohol, and betel quid chewing. Despite a multidisciplinary approach to treating esophageal cancer, the outcome remains poor. Moreover, field cancerization reveals that esophageal squamous cell carcinoma is closely linked with the development of head and neck cancers that further sub-optimize the treatment of patients. Therefore, preventive strategies are of paramount importance to improve the prognosis of this dismal disease. Since obstacles exist for primary prevention via risk factor elimination, the current rationale for esophageal cancer prevention is to identify high-risk groups at earlier stages of the disease, and encourage them to get a confirmatory diagnosis, prompt treatment, and intensive surveillance for secondary prevention. Novel biomarkers for identifying specific at-risk populations are under extensive investigation. Advances in image-enhanced endoscopy do not just substantially improve our ability to identify small precancerous or cancerous foci, but can also accurately predict their invasiveness. Research input from the basic sciences should be translated into preventive measures in order to decrease the disease burden of esophageal cancer.

Meta-analysis of the methylenetetrahydrofolate reductase C677T polymorphism and susceptibility to Alzheimer's disease

No clear consensus has been reached at the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and Alzheimer's disease (AD) risk. Thus in this meta-analysis, a total of 19 case-control studies was assessed to evaluate the possible association. The data demonstrated that the frequency of T677 allele (T vs. C) was significantly associated with susceptibility to AD in all subjects (OR=1.15, 95% CI=1.06-1.26) and in East Asians (OR=1.22, 95% CI=1.08-1.39). There was statistical difference between AD patients and the controls under recessive genetic mode (CT+TT vs. CC) and homozygote comparison (TT vs. CC) in all subjects and in East Asians as well. Despite a small effect of the polymorphism on late-onset AD (LOAD) risk, MTHFR C677T polymorphism was not a major risk factor for LOAD in East Asians and Caucasians. A subgroup analysis in the subjects without APOE epsilon4 alleles showed T677 allele significantly increased risk of AD in all subjects (OR=1.21, 95% CI: 1.04-1.42) and in East Asians (OR=1.28, 95% CI: 1.06-1.55). However, no association was found in Caucasians. In conclusion, this meta-analysis supports that MTHFR C677T polymorphism is capable of causing AD susceptibility in East Asians, not in Caucasians.

Review of studies on metabolic genes and cancer in populations of African descent

Genetic polymorphisms described for a number of enzymes involved in the metabolism of tobacco carcinogens and alcohol have been linked to increase cancer risk. Racial disparities in cancer between whites and populations of African descent are well documented. In addition to differences in access to health care, both environment and genetic factors and their interaction may contribute to the increased cancer risk in minority populations. We reviewed the literature to identify case-control studies that included subjects of African descent. Meta-analyses investigating the association of genetic polymorphisms in tobacco metabolic genes and cancer were performed. Although several genes and cancers have been studied, only one or two studies per gene for each cancer site have been published, with the exception of breast (CYP1A1 and CYP1B1), lung (GSTM1, CYP1A1, and NQO1), and prostate (CYP3A4 A293G and CYP17). Marginal statistically significant associations were observed for CYP3A4 A293G and CYP17 5'UTR polymorphisms and prostate cancer. Our findings support the need for additional genetic association studies of breast, prostate, and lung cancers that include a larger number of minority participants. Because incidence and mortality rates for these cancers rank highest among populations of African descent, concentrated research in these areas are warranted.

Association between the methylenetetrahydrofolate reductase C677T polymorphism and hepatocellular carcinoma risk: a meta-analysis

Background

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the metabolism of folate. The non-synonymous single nucleotide polymorphism (nsSNP), C677T (Ala>Val, rs1801133), has been verified to impair enzyme activity. The association with cancer susceptibility, including hepatocellular carcinoma (HCC), has also been widely studied. The results, however, were inconsistent. To shed light on the influence of MTHFR C677T polymorphism on HCC, a meta-analysis was conducted.

Methods

The meta-analysis of C677T consisted of 10 studies (1814 cases/2862 controls). The association was measured by using random-effect (RE) or fixed-effect (FE) odds ratio (OR) combined with 95% confidence intervals (CIs) according to the studies' heterogeneity.

Results

Using genetic model analysis, C677T polymorphism was found to increase the risk of HCC in a complete overdominant model, which indicates that heterozygotes CT are at a lesser risk of HCC than either homozygotes CC or TT. Meta-analyses of the 10 studies showed that the TT genotype increased the risk of HCC as compared to the CT genotype: FE OR was 1.20 (95%CI: 1.00-1.45, p for heterogeneity = 0.21). When subgroup analysis was done between the HCC cases and the chronic liver disease (CLD) patients of four studies, meta-analysis showed that individuals with the TT genotype had increased HCC risk compared with those with the CT genotype: FE OR (TT vs. CT) reached 1.81 (1.22-2.71, p for heterogeneity = 0.25). Meanwhile, the C677T polymorphism also increased HCC risk in a recessive model when cases were compared to CLD patients of four studies: RE OR reached 1.85 (95%CI: 1.00-3.42, p for heterogeneity = 0.06). Overall, there was some extent heterogeneity when analyses were performed in various models. There was no publication bias.

Conclusion

MTHFR C677T polymorphism increased the risk of HCC in an overdominant model, and might be a risk factor for HCC occurrence, especially in CLD patients. The association warranted further studies.