The association between MTHFR gene polymorphisms and hepatocellular carcinoma risk: a meta-analysis

Identification of hub genes and pathways in hepatitis B virus-associated hepatocellular carcinoma: A comprehensive in silico study

Background and Aim

The hepatitis B virus (HBV) is one of the most common causes of liver cancer in the world. This study aims to provide a better understanding of the mechanisms involved in the development and progression of HBV-associated hepatocellular carcinoma (HCC) by identifying hub genes and the pathways related to their functions.

Methods

GSE83148 and GSE94660 were selected from the Gene Expression Omnibus (GEO) database, differentially expressed genes (DEGs) with an adjusted p-value < 0.05 and a |logFC| ≥1 were identified. Common DEGs of two data sets were identified using the GEO2R tool. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) databases were used to identify pathways. Protein-protein interactions (PPIs) analysis was performed by using the Cytoscap and Gephi. A Gene Expression Profiling Interactive Analysis (GEPIA) analysis was carried out to confirm the target genes.

Results

One hundred and ninety-eight common DEGs and 49 hub genes have been identified through the use of GEO and PPI, respectively. The GO and KEGG pathways analysis showed DEGs were enriched in the G1/S transition of cell cycle mitotic, cell cycle, spindle, and extracellular matrix structural constituent. The expression of four genes (TOP2A, CDK1, CCNA2, and CCNB2) with high scores in module 1 were more in tumor samples and have been identified by GEPIA analysis.

Conclusion

In this study, the hub genes and their related pathways involved in the development of HBV-associated HCC were identified. These genes, as potential diagnostic biomarkers, may provide a potent opportunity to detect HBV-associated HCC at the earliest stages, resulting in a more effective treatment.

Gene variations related to the hepatocellular carcinoma: Results from a field synopsis and Bayesian revaluation

Hepatocellular carcinoma (HCC) is considered as the second cause of cancer-related deaths worldwide. Genetic variations are associated with HCC risk, an issue that has been the subject of several meta-analyses. However, meta-analyses have an important limitation on the likelihood of false positive data. Henceforth, this study aimed to assess the level of noteworthiness in the meta-analyses by means of a Bayesian approach. A systematic search was performed for meta-analyses with associations between gene polymorphisms and HCC. The calculations for the False-Positive Rate Probability (FPRP) and the Bayesian False Discovery Probability (BFDP) were performed to assess the noteworthiness with a statistical power of 1.2 and 1.5 of Odds Ratio at a prior probability of 10^-3 and 10^-5. The quality of studies was evaluated by the Venice criteria. As additional analyses, the gene-gene and protein-protein networks were designed for these genes and products. As results, we found 33 meta-analytic studies on 45 polymorphisms occurring in 35 genes. A total of 1,280 values for FPRP and BFDP were obtained. Seventy-five for FPRP (5.86%) and 95 for BFDP (14.79%) were noteworthy. In conclusion, the polymorphisms in CCND1, CTLA4, EGF, IL6, IL12A, KIF1B, MDM2, MICA, miR-499, MTHFR, PNPLA3, STAT4, TM6SF2, and XPD genes were considered as noteworthy biomarkers for HCC risk.

Biochemical Association of MTHFR C677T Polymorphism with Myocardial Infarction in the Presence of Diabetes Mellitus as a Risk Factor

Myocardial infarction (MI) is a cardiovascular disease that occurs due to the blockage of the coronary artery. Subsequently, cardiac muscles receive a lower oxygen supply, which leads to the death of cardiac muscles. The etiology of MI is linked to various environmental, occupational, and genetic factors. Various studies have been conducted on the polymorphism of genes involved in MI. Previous studies have shown that different variants of the methylene tetrahydrofolate reductase (MTHFR) gene are involved in causing MI by altering the metabolism of folate and homocysteine. However, the genetic polymorphism of MTHFR C677T (rs1801133) and its association with MI in the presence of diabetes mellitus (DM) as a risk factor still needs to be investigated. This study recruited 300 participants who were divided into three groups, i.e., the control, MI, and MI-DM. The blood samples collected from the study participants were subjected to various biochemical tests and their clinical parameters were monitored. MTHFR C677T (rs1801133) genotyping was performed by Tetra ARMS PCR using predetermined primers. The MTHFR C677T (rs1801133) polymorphism was associated with MI in the presence of DM as a risk factor among the participants. The MTHFR C677T (rs1801133) T/T homozygous genotype was found to be significant among MI patients in the presence of DM as a risk factor.

NOTCH3 rs1043996 Polymorphism Is Associated with the Occurrence of Alcoholic Liver Cirrhosis Independently of PNPLA3 and TM6SF2 Polymorphisms

Alcoholic liver cirrhosis (ALC) is the most common indication for liver transplantation (LT) in Croatia and presents a risk factor for the development of hepatocellular carcinoma (HCC). However, genetic susceptibility has not yet been systematically studied. We aimed to investigate the contribution of the risk polymorphisms PNPLA3 rs738409, EGF rs4444903, TM6SF2 rs58542926, MTHFR rs1801133, previously identified in other populations and, additionally, the contribution of Notch-related polymorphisms (NOTCH1 rs3124591, NOTCH3 rs1043996 and rs1044116, NOTCH4 rs422951). The study included 401 patients. The ALC group consisted of 260 LT candidates, 128 of whom had histopathologically confirmed HCC, and 132 of whom were without HCC. The control group included 141 patients without liver disease. Genotyping was performed by PCR using Taqman assays. The patients' susceptibility to ALC was significantly associated with PNPLA3 rs738409, TM6SF2 rs58542926, and NOTCH3 rs1043996 polymorphisms. These polymorphisms remained significantly associated with ALC occurrence in a logistic regression model, even after additional model adjustment for sex and age. Cirrhotic patients with the PNPLA3 GG genotype demonstrated higher activity of ALT aminotransferases than patients with CC or CG genotypes. The susceptibility to the development of HCC in ALC was significantly associated with PNPLA3 rs738409 and EGF rs4444903 polymorphisms, and logistic regression confirmed these polymorphisms as independent predictors.

MTHFR Knockdown Assists Cell Defense against Folate Depletion Induced Chromosome Segregation and Uracil Misincorporation in DNA

Folate depletion causes chromosomal instability by increasing DNA strand breakage, uracil misincorporation, and defective repair. Folate mediated one-carbon metabolism has been suggested to play a key role in the carcinogenesis and progression of hepatocellular carcinoma (HCC) through influencing DNA integrity. Methylenetetrahydrofolate reductase (MTHFR) is the enzyme catalyzing the irreversible conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate that can control folate cofactor distributions and modulate the partitioning of intracellular one-carbon moieties. The association between MTHFR polymorphisms and HCC risk is inconsistent and remains controversial in populational studies. We aimed to establish an in vitro cell model of liver origin to elucidate the interactions between MTHFR function, folate status, and chromosome stability. In the present study, we (1) examined MTHFR expression in HCC patients; (2) established cell models of liver origin with stabilized inhibition of MTHFR using small hairpin RNA delivered by a lentiviral vector, and (3) investigated the impacts of reduced MTHFR and folate status on cell cycle, methyl group homeostasis, nucleotide biosynthesis, and DNA stability, all of which are pathways involved in DNA integrity and repair and are critical in human tumorigenesis. By analyzing the TCGA/GTEx datasets available within GEPIA2, we discovered that HCC cancer patients with higher MTHFR had a worse survival rate. The shRNA of MTHFR (shMTHFR) resulted in decreased MTHFR gene expression, MTHFR protein, and enzymatic activity in human hepatoma cell HepG2. shMTHFR tended to decrease intracellular S-adenosylmethionine (SAM) contents but folate depletion similarly decreased SAM in wildtype (WT), negative control (Neg), and shMTHFR cells, indicating that in cells of liver origin, shMTHFR does not exacerbate the methyl group supply in folate depletion. shMTHFR caused cell accumulations in the G2/M, and cell population in the G2/M was inversely correlated with MTHFR gene level (r = −0.81, p < 0.0001), MTHFR protein expression (r = −0.8; p = 0.01), and MTHFR enzyme activity (r = −0.842; p = 0.005). Folate depletion resulted in G2/M cell cycle arrest in WT and Neg but not in shMTHFR cells, indicating that shMTHFR does not exacerbate folate depletion-induced G2/M cell cycle arrest. In addition, shMTHFR promoted the expression and translocation of nuclei thymidine synthetic enzyme complex SHMT1/DHFR/TYMS and assisted folate-dependent de novo nucleotide biosynthesis under folate restriction. Finally, shMTHFR promoted nuclear MLH1/p53 expression under folate deficiency and further reduced micronuclei formation and DNA uracil misincorporation under folate deficiency. In conclusion, shMTHFR in HepG2 induces cell cycle arrest in G2/M that may promote nucleotide supply and assist cell defense against folate depletion-induced chromosome segregation and uracil misincorporation in the DNA. This study provided insight into the significant impact of MTHFR function on chromosome stability of hepatic tissues. Data from the present study may shed light on the potential regulatory mechanism by which MTHFR modulates the risk for hepatic malignancies.

Association of MTHFR and TYMS gene polymorphisms with the susceptibility to HCC in Egyptian HCV cirrhotic patients

Identification of host genetic factors influencing the risk of developing hepatocellular carcinoma (HCC) in patients with chronic hepatitis C virus (HCV) infection may help to refine patients' selection to benefit from specific preventative measures and/or adapted screening policies. Thus, this study aimed to investigate the association of MTHFR c.677C > T and c.1298A > C in addition to TYMS 3'-UTR 6-bp ins/del polymorphisms with the susceptibility to HCV-related HCC in an Egyptian population. Polymerase chain reaction-restriction fragment length polymorphism was performed to genotype the polymorphisms in 194 HCV-infected patients subdivided into liver cirrhotic (LC, n = 104) and HCC (n = 90) patients as well as 100 healthy subjects. In healthy controls, the MTHFR c.677C > T polymorphism under the homozygous and recessive models (p = 0.005) and the c.1298A > C polymorphism under all the tested genetic models (p-values range from < 0.001 to 0.007) were associated with an increased risk of HCC. In LC patients, the MTHFR c.677C > T polymorphism under the homozygous, dominant, and recessive models (p-values range from 0.001 to 0.007), as well as MTHFR c.1298A > C under the homozygous model only (p = 0.014), increased the susceptibility to HCC. The C/C and T/C haplotypes of MTHFR c.677C > T and MTHFR c.1298A > C polymorphisms were contributed to an increased risk of healthy subjects to develop HCC (p-values range from < 0.001 to 0.015), while only the T/C haplotype was associated with the progression of HCC in LC patients (p = 0.001). In conclusion, MTHFR c.677C > T and c.1298A > C in addition to their haplotypes may contribute to the development of HCV-related HCC in an Egyptian population. These findings may aid in the early diagnosis and management of HCC.

Methylenetetrahydrofolate reductase C677T (Ala>Val, rs1801133 C>T) polymorphism decreases the susceptibility of hepatocellular carcinoma: a meta-analysis involving 12,628 subjects

C677T (Ala>Val, rs1801133 C>T), a non-synonymous variant of methylenetetrahydrofolate reductase (MTHFR) gene, has been found to be associated with an impair enzyme activity of MTHFR. The relationship of MTHFR rs1801133 with hepatocellular carcinoma (HCC) has been extensively investigated. However, the findings were conflicting. Recently, more investigations have been conducted on the relationship of MTHFR rs1801133 with HCC. To obtain a more precise assessment on the effect of this non-synonymous variant to the development of HCC, a pooled-analysis was performed. This meta-analysis consisted of 19 independent case–control studies. By using the odds ratio (OR) combined with 95% confidence interval (CI), the relationship of MTHFR rs1801133 with HCC risk was determined. A total of 19 independent case–control studies were included. Finally, 6,102 HCC cases and 6,526 controls were recruited to examine the relationship of MTHFR rs1801133 with HCC risk. In recessive model (TT vs. CC/CT), the findings reached statistical significance (OR, 0.90; 95%CI, 0.82–0.98; P = 0.016). Subgroup analysis also found an association between MTHFR rs1801133 polymorphism and the decreased risk of HCC in hepatitis/virus related patients (recessive model: OR, 0.85; 95%CI, 0.72–0.99; P = 0.035, and allele model: OR, 0.90; 95%CI, 0.81–0.99; P = 0.028). Subgroup analyses indicated that extreme heterogeneity existed in Asian population, larger sample size investigation, hospital-based study and normal/healthy control subgroups. The shape of Begger’s seemed symmetrical. Egger’s linear regression test also confirmed these evaluations. Sensitivity analyses suggested that our findings were stable. In summary, our results highlight that MTHFR rs1801133 polymorphism decreases HCC susceptibility. The relationship warrants a further assessment.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Association between methylenetetrahydrofolate reductase tagging polymorphisms and susceptibility of hepatocellular carcinoma: a case-control study

Polymorphisms in one-carbon metabolism genes may influence the susceptibility to hepatocellular carcinoma (HCC). In the present study, we studied methylenetetrahydrofolate reductase (MTHFR) tagging polymorphisms in 584 HCC cases and 923 controls. Polymerase chain reaction was harnessed to detect MTHFR genotype. Overall, our results showed that genotype distribution of MTHFR rs4846048 and rs4845882 polymorphisms was not different between HCC patients and controls. MTHFR rs9651118 and rs1801133 loci were protective factors for HCC (rs9651118: CT vs. TT: adjusted odds ratio (OR) = 0.67, 95% confidence interval (CI): 0.49–0.90, P=0.008 and TC/CC vs. TT: adjusted OR = 0.70, 95% CI: 0.53–0.93, P=0.015; rs1801133: GA vs. GG: adjusted OR = 0.72, 95% CI: 0.54–0.97, P=0.031, AA/GA vs. GG: adjusted OR = 0.76, 95% CI: 0.57–0.99, P=0.045). However, MTHFR rs3753584 locus was a candidate for susceptibility to HCC (CT vs. TT: adjusted OR = 1.67, 95% CI: 1.20–2.32, P=0.003 and TC/CC vs. TT: adjusted OR = 1.59, 95% CI: 1.15–2.20, P=0.005). Results of haplotype analysis suggested that MTHFR G_rs1801133T_rs3753584G_rs4845882A_rs4846048T_rs9651118 was associated with the risk of HCC (OR = 1.55, 95% CI: 1.16–2.07, P=0.003). The power of our study also confirmed these associations (the value of power >0.80). In summary, our findings suggested that MTHFR rs3753584, rs9651118 and rs1801133 polymorphisms may affect the risk of HCC in Chinese Han population. In future, our findings should be further validated in additional case–control studies.

The MTHFR polymorphism affect the susceptibility of HCC and the prognosis of HCC liver transplantation

BACKGROUND

Methylenetetrahyfrofolate reductase (MTHFR) is the key enzyme for one carbon and folate metabolism. Previous studies have drawn different conclusions about the relationship between the mutation of MTHFR and hepatocellular carcinoma (HCC) occurrence. MTHFR polymorphisms' influence on liver transplantation for HCC recurrence has yet not been reported. Aim of this study was to clarify the impact of MTHFR polymorphism on hepatocarcinogenesis and the prognosis of liver transplant recipient with HCC.

METHODS

This study enrolled 244 HCC patients and 487 healthy individuals in Chinese Han population to analyze the influence of MTHFR polymorphism on HCC susceptibility first. Furthermore, this research choose another 100 donors' and 104 recipients' specimens to detect the association between polymorphism of MTHFR and post-transplant HCC recurrence.

RESULT

rs1801131 polymorphism A to C was associated with the occurrence of HCC in Chinese Han population (p < 0.05), especially in age exceeding 50 years (p < 0.01). No association was observed with rs1801133 polymorphism and HCC occurrence. The mean tumor-free survival for recipients with donor liver graft rs1801133 C to T variants was shorter than CC type (12.63 ± 3.84 vs 22.43 ± 4.74 months, p < 0.05). Multivariate analysis revealed that Donor rs1801133 and Hangzhou criteria were two independent prognostic factors for tumor-free survival (p < 0.05). Neither donor rs1801131 polymorphism nor recipients' MTHFR polymorphisms was associated with HCC recurrence.

CONCLUSION

This study demonstrated that MTHFR polymorphism was associated with HCC occurrence and post-transplant HCC recurrence. rs1801131 mutation A to C is a valuable molecular biomarker for predicting HCC occurrence in Chinese Han population. Donor MTHFR rs1801133 C to T polymorphism could present as a promising prognostic biomarkers for HCC recurrence in liver transplant recipients.

Association of IL-10-1082A/G Polymorphism with Ischemic Stroke: Evidence from a Case-Control Study to an Updated Meta-Analysis

BACKGROUND AND AIMS

Interleukin-10 (IL-10) plays a vital part in the pathophysiology of vascular inflammation. Several studies have investigated the potential association between the IL-10-1082A/G polymorphism and the risk of ischemic stroke where the inflammatory process is involved, but the conclusions have been inconsistent.

METHODS

Three hundred eighty-six ischemic stroke patients and 386 healthy controls were recruited in the study. Genotyping was conducted by using the polymerase chain reaction-ligation detection reaction method. A meta-analysis was then performed by pooling our data with previous published studies.

RESULTS

In our case-control study, a lack of association was revealed between IL-10-1082A/G and ischemic stroke (p > 0.05). When combined with previous studies, however, a significant relationship between IL-10-1082A/G and ischemic stroke risk was found (G vs. A: OR = 0.73, 95% CI = 0.60-0.88, p < 0.01; GG vs. AA: OR = 0.61, 95% CI = 0.49-0.76, p < 0.01; GG+AG vs. AA: OR = 0.70, 95% CI = 0.54-0.91, p < 0.01; GG vs. AG+AA: OR = 0.68, 95% CI = 0.52-0.89, p < 0.01), as well as in subgroup analyses. Sensitivity analysis and publication bias assessment supported the reliability of the results from the meta-analysis.

CONCLUSIONS

Evidence from a case-control study to an updated meta-analysis suggests that the IL-10-1082A/G polymorphism is associated with ischemic stroke susceptibility.

The MTHFR C677T mutation is not a risk factor recognized for HBV-related HCC in a population with a high prevalence of this genetic marker

BACKGROUND

Polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene can affect disease progression in HBV infection. However, the results from different reports are inconsistent. The aim of this study was to investigate the association between the MTHFR C677T polymorphism and the outcome of HBV infection in a Tianjin Han population.

METHODS

TaqMan SNP genotyping was employed to determine the alleles and genotypes of MTHFR C677T in 2511 subjects from various stages of HBV infection and 549 healthy controls.

RESULTS

Of the 3060 subjects, the genotypic frequencies were CT 48.9%, TT 29.3% and CC 21.8%; the allelic frequencies were T 53.8% and C 46.2%. There was no significant difference in genotypic or allelic distribution among the different disease groups. When either healthy subjects or self-limited subjects were used as controls, the TT genotype and the T allele conferred protective effects against hepatocellular carcinoma (HCC) (HCC vs healthy subjects: OR=0.588, 95% CI=0.413-0.836, P=0.003; OR=0.768, 95% CI=0.645-0.915, P=0.003, respectively. HCC vs self-limited subjects: OR=0.598, 95% CI=0.404-0.886, P=0.010; OR=0.772, 95% CI=0.635-0.940, P=0.010, respectively). After sub-stratification by gender, the prevalence of the TT genotype or T allele was the lowest in the male HCC group (TT 23.5%, T 49.8%). The protective effects of the TT genotype and the T allele were observed in male HCC and cirrhotic subjects (HCC vs self-limited subjects: OR=0.470, 95% CI=0.288-0.766, P=0.002; OR=0.681, 95% CI=0.535-0.866, P=0.002, respectively. Liver cirrhosis vs self-limited subjects: OR=0.624, 95% CI=0.392-0.992, P=0.046; OR=0.791, 95% CI=0.627-0.998, P=0.048, respectively), but not in female. When the subjects were stratified according to the clinical features, no statistically significant difference in the genotypic distribution was observed (P>0.05).

CONCLUSIONS

The TT genotype and T allele of MTHFR C677T may confer a protective effect on disease progression to HCC in HBV-infected individuals, especially among male patients, in a population with a high prevalence of this genetic marker.

Role of CYP2E1 polymorphisms in breast cancer: a systematic review and meta-analysis

BACKGROUND

CYP2E1 polymorphisms have been reported to influence individual's breast cancer susceptibility as a phase I enzyme, but the results of these previous studies remain controversial. We performed a comprehensive meta-analysis to assess their association.

METHODS

A comprehensive search of literature included in various databases (PubMed, Web of Science and Google scholar), published before August 2016, was performed. Odds ratios (ORs) with 95% confidence intervals (CIs) calculated in fixed or random-effects models were used to estimate the strength of the associations between three polymorphisms of CYP2E1 and breast cancer susceptibility. Subgroup analysis, sensitivity analysis and test for publication bias were also performed. A total of 11 separate comparisons involving 4311 cases and 4407 controls were included in the meta-analysis.

RESULTS

Our result showed that there was no significant association between the two common polymorphisms CYP2E1 rs2031920 C>T, CYP2E1*5 Rsa I/Rst I (c1/c2) and BC risk. For CYP2E1*6 Dra I (D/C) polymorphism, a significantly increased BC risk in the overall population was found in genetic model D/C vs. D/D (OR = 1.29, 95% CI = 1.04-1.61, P = 0.023) and C/C + D/C vs. D/D (OR = 1.25, 95% CI = 1.04-1.51, P = 0.019), together with subjects who have at least one C allele (C vs. D: OR = 1.46, 95% CI = 1.20-1.79, P < 0.001). Similar results were also found in subgroup analyses in Caucasians of these three comparison models.

CONCLUSIONS

The present meta-analysis suggests that CYP2E1*6 Dra I (D/C) variation significantly associated with the risk of BC. Individuals with D/C and C/C + D/C genotypes or carried at least one C allele of CYP2E1*6 Dra I (D/C) polymorphism had a significant higher susceptibility to develop BC.

Polymorphisms of folate metabolism genes in patients with cirrhosis and hepatocellular carcinoma

AIM

To evaluated the association of the risk factors and polymorphisms in MTHFR C677T, MTHFR A1298C, MTR A2756G and MTRR A66G genes.

METHODS

Patients with cirrhosis (n = 116), hepatocellular carcinoma (HCC) (n = 71) and controls (n = 356) were included. Polymerase chain reaction followed by enzymatic digestion and allelic discrimination technique real-time PCR techniques were used for analysis. MINITAB-14.0 and SNPstats were utilized for statistical analysis.

RESULTS

Showed that age ≥ 46 years (OR = 10.31; 95%CI: 5.66-18.76; P < 0.001) and smoking (OR = 0.47; 95%CI: 0.28-0.78; P = 0.003) were associated with cirrhosis. Age ≥ 46 years (OR = 16.36; 95%CI: 6.68-40.05; P < 0.001) and alcohol habit (OR = 2.01; 95%CI: 1.03-3.89; P = 0.039) were associated with HCC. MTHFR A1298C in codominant model (OR = 3.37; 95%CI: 1.52-7.50; P = 0.014), recessive model (OR = 3.04; 95%CI: 1.43-6.47; P = 0.0051) and additive model (OR = 1.71; 95%CI: 1.16-2.52; P = 0.0072) was associated with HCC, as well as MTR A2756G in the additive model (OR = 1.68; 95%CI: 1.01-2.77; P = 0.047), and MTRR A66G in the codominant model (OR = 3.26; 95%CI: 1.54-6.87; P < 0.001), dominant model (OR = 2.55; 95%CI: 1.24-5.25; P = 0.007) and overdominant model (OR = 3.05; 95%CI: 1.66-5.62; P < 0.001). MTR A2756G in the additive model (OR = 1.54; 95%CI: 1.02-2.33; P = 0.042) and smokers who presented at least one polymorphic allele for MTRR A66G (OR = 1.71; 95%CI: 0.77-3.82; P = 0.0051) showed increased risk for cirrhosis. There was no association between clinical parameters and polymorphisms.

CONCLUSION

Age ≥ 46 years, alcohol habit and MTR A2756G, MTHFR A1298C and MTRR A66G polymorphisms are associated with an increased risk of HCC development; age ≥ 46 years, tobacco habit and the MTR A2756G polymorphism are associated with cirrhosis.

Three Polymorphisms of Vascular Endothelial Growth Factor (+936C > T, -460C > T, and -2578C > A) and Their Susceptibility to Ovarian Cancer: A Meta-Analysis

OBJECTIVE

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen that plays a vital role in angiogenesis, tumor growth, and metastasis. The associations between 3 polymorphisms of VEGF (+936 C > T, -2578 C > A, and -460 C > T) and ovarian cancer (OC) risk have been extensively investigated, but the currently available results are inconsistent. To obtain a more accurate estimation of the association, a meta-analysis was conducted in this study.

METHODS

PubMed, Cochrane Library, Embase, and Chinese National Knowledge Infrastructure were searched for all relevant studies published before November 30, 2014. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for the VEGF polymorphisms to assess the strength of the association.

RESULTS

With regard to the +936 C > T polymorphism, 5 articles were available for analysis (882 cases and 1155 controls), whereas for -2578 C > A (559 cases and 632 controls) and -460 C > T (350 cases and 409 controls), only 2 articles were eligible for analysis, respectively. A significant association between the VEGF +936 C/T polymorphism and OC was demonstrated in white populations (CT vs CC: OR, 0.638 [95% CI, 0.437-0.932; P = 0.020]; TT + CT vs CC: OR, 0.694 [95% CI, 0.483-0.995; P = 0.047]). No relationship was found between -2578 C > A and -460 C > T and susceptibility to develop OC.

CONCLUSIONS

This meta-analysis provides supportive evidence that the VEGF +936 C/T polymorphism may influence the risk for the development of OC in a protective model among whites.

Association Between IL-4 Polymorphisms and Risk of Liver Disease: An Updated Meta-Analysis

Interleukin-4 (IL-4) polymorphisms have been reported to influence an individual's susceptibility to liver disease as it is a central anti-inflammatory Th2 cytokine; however, these results remain controversial.A comprehensive meta-analysis of the relevant literature was thus performed to better estimate the relationship between IL-4 polymorphisms and liver disease.Systematic searches of various databases (PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure) for studies published before July 5, 2015 were performed. Odds ratios (ORs) with 95% confidence intervals (CIs) calculated in fixed or random-effects models were used to estimate the strength of the association. Subgroup analyses, meta-regression, Galbraith plots, and sensitivity analyses were also performed.A total of 16 case-control studies, of which 15 involved the -590C/T polymorphism and 3 involved the -33T/C polymorphism, were included in the study. With respect to the -590C/T polymorphism, a significantly increased risk of liver diseases was found in the overall population (TT + CT vs CC: OR = 1.25, 95% CI = 1.06-1.49, P = 0.009 and CT vs CC: OR = 1.22, 95% CI = 1.00-1.48, P = 0.048) and the Asian population (TT + CT vs CC: OR = 1.28, 95% CI = 1.04-1.57, P = 0.020). Further subgroup analyses also showed significant associations between the -590C > T polymorphism and the risk of hepatitis C infection and hepatocellular carcinoma. However, no association was found between the -33T/C polymorphism and risk of liver diseases in all comparison models.This meta-analysis suggested that the IL-4 -590C > T polymorphism is associated with an increased risk of hepatitis C infection and hepatocellular carcinoma, especially among the Asian population.

AXIN2 rs2240308 polymorphism contributes to increased cancer risk: evidence based on a meta-analysis

BACKGROUND

Variants in the axis inhibition 2 (AXIN2) gene might alter the protein's structure or function or create a multiprotein destruction complex in the Wnt signaling pathway and thus affect an individual's susceptibility to cancer. The objective of this study is to evaluate broadly the evidence available for the AXIN2 rs2240308 polymorphism and risk of cancer.

METHODS

A comprehensive literature search was undertaken for eligible studies in Embase, PubMed, and Cochrane Library up to Nov 30, 2014. Odds ratios (ORs) and the corresponding 95 % confidence intervals (CIs) were used to measure the strength of the models.

RESULTS

Eight articles (10 case-control studies with 1,502 cases and 1,590 controls) were included in this analysis. Overall, the AXIN2 rs2240308 polymorphism was associated with a significant increase in the risk of cancer (G allele vs. A allele: OR = 1.21, 95 % CI = 1.05-1.40, I (2)  = 39.5 % and P Q  = 0.094 for heterogeneity; GG vs. AA: OR = 1.30, 95 % CI = 1.04-1.63, I (2)  = 35.9 % and P Q  = 0.121 for heterogeneity; GG vs. GA + AA: OR = 1.36, 95 % CI = 1.17-1.58, I (2)  = 19.5 % and P Q  = 0.263 for heterogeneity). Asian populations showed similar results. Stratified analysis by cancer types indicated that the AXIN2 rs2240308 polymorphism increases the risk of lung cancer (G allele vs. A allele: OR = 1.36, 95 % CI = 1.17-1.59; GA vs. AA: OR = 1.43, 95 % CI = 1.01-2.02; GG vs. AA: OR = 1.93, 95 % CI = 1.36-2.75; GG + GA vs. AA: OR = 1.65, 95 % CI = 1.18-2.30; GG vs. GA + AA: OR = 1.45, 95 % CI = 1.18-1.79. All I (2)  < 50 % and P Q  > 0.100 for heterogeneity).

CONCLUSIONS

This study showed that the AXIN2 rs2240308 polymorphism contribute to increasing the risk of cancer, especially lung cancer in Asian populations.

Association between MTHFR A1298C polymorphism and hepatocellular carcinoma risk

BACKGROUND

Hepatocarcinogenesis is a complex process that is influenced by many factors. Several studies have investigated the relationship between MTHFR A1298C polymorphism and hepatocellular carcinoma (HCC) risk, but the results are inconsistent. Therefore, we performed a meta-analysis covering a large sample size to address this controversy.

METHODS

Eligible studies were searched using PubMed, EMBASE, and China National Knowledge Infrastructure (CNKI) databases. A total of 7 studies from 6 publications with 2035 cases and 3096 controls were included. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) was calculated by the fixed or random effects to evaluate the correlation between MTHFR A1298C polymorphism and HCC risk. The Q statistic and I(2) statistic were used to assess the statistical heterogeneity among studies. Publication bias was evaluated by Egger's linear regression test and Begg's funnel plot.

RESULTS

In present study, the results showed that MTHFR A1298C polymorphism was not significantly associated with risk of HCC based on CC + AC vs. AA genetic model (OR=1.01, 95% CI=0.90-1.13). Similarly, in the subgroup analysis by ethnicity, no significant HCC risk was found in Asian population (OR=1.02, 95% CI=0.91-1.14). In the subgroup analysis based on source of control, we found that MTHFR A1298C polymorphism showed no effects on the occurrence of HCC in the population-based (PB) and hospital-based (HB) group (OR=0.97, 95% CI=0.83-1.15; OR=1.04, 95% CI=0.89-1.21).

CONCLUSION

This meta-analysis suggested that MTHFR A1298C polymorphism may not be a risk factor for HCC.

MDM2 SNP309 variation confers the susceptibility to hepatocellular cancer: a meta-analysis based on 4271 subjects

Previous reports have indicated that MDM2 T309G polymorphism might be a risk factor for various cancers. Increasing studies have been conducted on the association of MDM2 T309G polymorphism with hepatocellular carcinoma (HCC) risk. However, the results remain inconclusive. Thus, the present study aimed to address this controversy by meta-analysis. Relevant literature up to Oct 2014 was searched and screened. Necessary information was rigorously extracted for data pooling and analyzing. Separate analyses on ethnicity, source of controls, sample size and P53 polymorphism status were also performed. As a result, eleven case-control studies were selected and the overall data indicated a significant association of MDM2 T309G polymorphism with HCC risk (GG vs. TT: OR=2.31; 95% CI=1.66-3.20; dominant model: OR=1.83; 95% CI=1.36-2.47; recessive model: OR=1.73; 95% CI=1.49-2.00). Similar results could be shown in the subgroups regarding ethnicity, source of controls and sample size. Interestingly, in the subgroup analysis regarding P53 codon 72 polymorphism, increased HCC risk could be observed in the Pro/Pro+Pro/Arg subgroup under a recessive model (OR=1.78; 95% CI=1.29-2.44). In conclusion, the results of the present study suggest that MDM2 T309G polymorphism might be a low-penetrant risk factor for HCC. Homozygous GG alleles might interact with Pro of P53 and thus confer the susceptibility to HCC.

Interleukin-12B+1188A/C polymorphism contributes to increased hepatocellular carcinoma susceptibility: evidence from a meta-analysis

BACKGROUND

Interleukin-12 (IL-12) is a multifunctional cytokine that induces interferon (IFN)-γ secretion and plays an important role in antitumor immunity. The IL-12B +1188A/C polymorphism was found to correlate with a decreased cytokine production and/or activity, which may lead to increased susceptibility to cancers including hepatocellular carcinoma (HCC). Previous epidemiological studies investigating the association between IL-12B +1188A/C polymorphism and HCC risk reported inconsistent results. We performed a meta-analysis to derive a precise estimation of the association.

METHODS

All studies published up to July 2014 on the association between IL-12B +1188A/C polymorphism and HCC risk were identified by searching electronic databases including PubMed, Embase, Cochrane library, and Chinese Biomedical Literature database (CBM). Data were extracted by two independent authors and the odds ratios (ORs) together with corresponding 95% confidence intervals (CIs) were used to assess the association between IL-12B +1188A/C polymorphism and HCC risk.

RESULTS

Five studies with 1864 cases and 2077 controls were included in the meta-analysis. We observed that the IL-12B +1188A/C polymorphism was significantly correlated with increased HCC risk when all studies were pooled into the meta-analysis (CC vs. AA: OR=1.306, 95% CI 1.063-1.606, P=0.011; AC vs. AA: OR=1.193, 95% CI 1.014-1.405, P=0.034; CC+AC vs. AA: OR=1.260, 95% CI 1.098-1.445, P=0.001). In subgroup analyses by ethnicity, source of control, and study quality, significant increased HCC risk was found in Asians, hospital-based studies, and high quality studies.

CONCLUSIONS

The present meta-analysis suggests that the IL-12B+1188A/C polymorphism is a low-penetrant risk factor for HCC development, especially among Asians. Further large and well-designed studies are needed to confirm this association.

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism: epidemiology, metabolism and the associated diseases

The Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is associated with various diseases (vascular, cancers, neurology, diabetes, psoriasis, etc) with the epidemiology of the polymorphism of the C677T that varies dependent on the geography and ethnicity. The 5,10-Methylenetetrahydrofolate reductase (MTHFR) locus is mapped on chromosome 1 at the end of the short arm (1p36.6). This enzyme is important for the folate metabolism which is an integral process for cell metabolism in the DNA, RNA and protein methylation. The mutation of the MTHFR gene which causes the C677T polymorphism is located at exon 4 which results in the conversion of valine to alanine at codon 222, a common polymorphism that reduces the activity of this enzyme. The homozygous mutated subjects have higher homocysteine levels while the heterozygous mutated subjects have mildly raised homocysteine levels compared with the normal, non-mutated controls. Hyperhomocysteinemia is an emerging risk factor for various cardiovascular diseases and with the increasing significance of this polymorphism in view of the morbidity and mortality impact on the patients, further prevention strategies and nutritional recommendations with the supplementation of vitamin B12 and folic acid which reduces plasma homocysteine level would be necessary as part of future health education. This literature review therefore focuses on the recent evidence-based reports on the associations of the MTHFR C677T polymorphism and the various diseases globally.

Single nucleotide polymorphisms of one-carbon metabolism and cancers of the esophagus, stomach, and liver in a Chinese population

One-carbon metabolism (folate metabolism) is considered important in carcinogenesis because of its involvement in DNA synthesis and biological methylation reactions. We investigated the associations of single nucleotide polymorphisms (SNPs) in folate metabolic pathway and the risk of three GI cancers in a population-based case-control study in Taixing City, China, with 218 esophageal cancer cases, 206 stomach cancer cases, 204 liver cancer cases, and 415 healthy population controls. Study participants were interviewed with a standardized questionnaire, and blood samples were collected after the interviews. We genotyped SNPs of the MTHFR, MTR, MTRR, DNMT1, and ALDH2 genes, using PCR-RFLP, SNPlex, or TaqMan assays. To account for multiple comparisons and reduce the chances of false reports, we employed semi-Bayes (SB) shrinkage analysis. After shrinkage and adjusting for potential confounding factors, we found positive associations between MTHFR rs1801133 and stomach cancer (any T versus C/C, SB odds-ratio [SBOR]: 1.79, 95% posterior limits: 1.18, 2.71) and liver cancer (SBOR: 1.51, 95% posterior limits: 0.98, 2.32). There was an inverse association between DNMT1 rs2228612 and esophageal cancer (any G versus A/A, SBOR: 0.60, 95% posterior limits: 0.39, 0.94). In addition, we detected potential heterogeneity across alcohol drinking status for ORs relating MTRR rs1801394 to esophageal (posterior homogeneity P = 0.005) and stomach cancer (posterior homogeneity P = 0.004), and ORs relating MTR rs1805087 to liver cancer (posterior homogeneity P = 0.021). Among non-alcohol drinkers, the variant allele (allele G) of these two SNPs was inversely associated with the risk of these cancers; while a positive association was observed among ever-alcohol drinkers. Our results suggest that genetic polymorphisms related to one-carbon metabolism may be associated with cancers of the esophagus, stomach, and liver. Heterogeneity across alcohol consumption status of the associations between MTR/MTRR polymorphisms and these cancers indicates potential interactions between alcohol drinking and one-carbon metabolic pathway.

Association between MTHFR C677T polymorphism and venous thromboembolism risk in the Chinese population: a meta-analysis of 24 case-controlled studies

The association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and venous thromboembolism (VTE) risk in the Chinese population has been widely reported, but results were inconsistent and underpowered. To elucidate the variable results, a meta-analysis and systematic review were performed from all case-controlled studies relating MTHFR C677T polymorphism by pooling data on them. We estimated the pooled odds ratio with its 95% confidence intervals to assess this possible association. Finally, a total of 24 studies with 2339 cases and 4048 controls were included in the current meta-analysis. Significant association was found with VTE risk for all genetic models. Subgroup analyses by type of VTE further identified the above-mentioned association in deep vein thrombosis/pulmonary embolism and splanchnic vein thrombosis. The findings from our meta-analysis support the associations of MTHFR C677T polymorphism with VTE risk in the Chinese population.

Lack of association between LUM rs3759223 polymorphism and high myopia

PURPOSE

Previous evidence has indicated that the lumican (LUM) gene is a candidate susceptibility gene of high myopia; however, the association between LUM promoter regions rs3759223 polymorphism and high myopia remains controversial and ambiguous. This study performed a meta-analysis to clarify the association between the rs3759223 polymorphism and high myopia risk.

METHODS

Eligible studies were identified by comprehensive search of PubMed, EMBASE, Web of Science, and Chinese Biomedical Literature database. The crude odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were used to estimate the association between the rs3759223 polymorphism and high myopia susceptibility. Meta-regression and subgroup analyses were performed to identify the source of heterogeneity.

RESULTS

Finally, six studies including 1238 cases and 1059 healthy controls were included. Meta-analyses showed no association between rs3759223 polymorphism and high myopia susceptibility in all genetic models (CC vs. TT, OR = 1.089; 95% CI, 0.690 to 1.718; CT vs. TT, OR = 0.865; 95% CI, 0.646 to 1.157; CC + CT vs. TT, OR = 1.202; 95% CI, 0.730 to 1.980; CC vs. CT + TT, OR = 0.914; 95% CI, 0.771 to 1.083) and no significance in subgroup analyses according to the definition of high myopia (based on more myopic than -6.00 diopters vs. not based on more myopic than -6.00 diopters). Publication bias was not evident in this study.

CONCLUSIONS

This meta-analysis has suggested that there is a lack of association of the rs3759223 polymorphism with high myopia risk. However, further large and well-designed studies with the consideration of LUM gene locus interactions and gene-gene and gene-environment interactions are still required to further evaluate high myopia risk.

Meta-analysis of MTHFR C677T and A1298C gene polymorphisms: association with the risk of hepatocellular carcinoma

OBJECTIVE

Several studies have indicated an association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and the risk of hepatocellular carcinoma (HCC). However, the conclusions are inconsistent. Therefore, a meta-analysis was performed.

METHODS

Databases like Pubmed, EMBASE, and EBSCO (up to September 2012) were searched to retrieve case-control trials about MTHFR (C677T or A1298C) polymorphisms and HCC. Literatures were independently screened by two researchers according to the inclusion and exclusion criteria. Data were extracted and analyzed by software STATA 11.0.

RESULTS

Nine studies were included with 10 datasets and 5132 cases. C677T polymorphism was associated with HCC risk in a heterozygous model (TT vs. CT: OR=1.20, 95% CI: 1.02-1.40). For the A1298C polymorphism, a significantly decreased HCC risk was found in the dominant, heterozygous and homozygous models (CC vs. AA+AC: OR=0.52, 95% CI: 0.33-0.80; CC vs. AC: OR=0.50, 95% CI: 0.32-0.79; CC vs. AA: OR=0.52, 95% CI: 0.33-0.81). Subgroup analysis stratified by ethnicity and type of control further indicated decreased HCC risks in Asians (CC vs. AA+AC: OR=0.47, 95% CI: 0.26-0.84; CC vs. AC: OR=0.41, 95% CI: 0.24-0.71; CC vs. AA: OR=0.46, 95% CI: 0.27-0.78), studies with controls of healthy people (CC vs. AA: OR=0.54, 95% CI: 0.31-0.93; CC vs. AC: OR=0.54, 95% CI: 0.31-0.94; CC vs. AA+AC: OR=0.55, 95% CI: 0.32-0.94), and controls of non-HCC patients (CC vs. AC: OR=0.43, 95% CI: 0.19-0.96).

CONCLUSIONS

Homozygous carriers of MTHFR C677T mutation are more susceptible to HCC, but homozygous mutations of MTHFR A1298C may play a protective role for developing HCC.

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.

Association of p53 codon 72 polymorphism with prostate cancer: an update meta-analysis

Many studies have been conducted to explore the association between p53 codon 72 polymorphism and prostate cancer (PCa). However, the results remain inconsistent. Therefore, we performed a large meta-analysis of relevant studies to determine a more precise estimation of this relationship. Systematic searches of the electronic databases PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure (CNKI) up to October 2013 were performed. Fixed or random-effects meta-analytical models were used to calculate the summary odds ratio (OR) and corresponding 95% confidence intervals (CIs). Meta-regression, Galbraith plots, subgroup analysis, and sensitivity analysis were also performed. The study included 17 case-control studies involving 2,371 PCa cases and 2,854 controls. Our results showed that the p53 codon 72 polymorphism was not associated with PCa risk in all genetic models in the overall populations. When limiting the meta-analysis to the studies conforming to Hardy-Weinberg equilibrium, the pooled analyses showed a significant association between p53 codon 72 polymorphism and PCa in a Caucasian population in co-dominant model Pro/Pro vs. Arg/Arg (OR = 1.57, 95% CI = 1.08-2.28, P = 0.017) and recessive model Pro/Pro vs. (Arg/Pro + Arg/Arg) (OR = 1.60, 95% CI = 1.12-2.27, P = 0.009). In subgroup analysis stratified by PCa stages and Gleason grades, a slight but significant association was found when advanced PCa was compared with localized PCa only in recessive model Pro/Pro vs. (Arg/Pro + Arg/Arg) (OR = 1.51, 95% CI = 1.02-2.23, P = 0.039). This meta-analysis suggested that the Pro/Pro genotype of p53 codon 72 polymorphism was associated with increased prostate cancer risk, especially among Caucasians.

CYP2D6*4 allele polymorphism increases the risk of Parkinson's disease: evidence from meta-analysis

Background

Many epidemiological studies have been conducted to explore the association between a single CYP2D6 gene polymorphism and Parkinson’s disease (PD) susceptibility. However, the results remain controversial.

Objectives

To clarify the effects of a single CYP2D6 gene polymorphism on the risk of PD, a meta-analysis of all available studies relating to CYP2D6*4 polymorphism and the risk of PD was conducted.

Methods

A comprehensive literature search of PubMed, EMBASE, and the China National Knowledge Infrastructure (CNKI) up to September 1, 2013 was conducted. Data were extracted by two independent authors and pooled odds ratio (OR) with 95% confidence interval (CI) were calculated. Meta-regression, Galbraith plots, subgroup analysis, sensitivity analysis, and publication bias analysis were also performed.

Results

Twenty-two separate comparisons consisting of 2,629 patients and 3,601 controls were included in our meta-analysis. The pooled analyses showed a significant association between CYP2D6*4G/A polymorphism and PD risk in all of the comparisons (A vs. G allele: OR = 1.28, 95% CI = 1.14–1.43, P = 0.001; AA vs. GG: OR = 1.43, 95% CI = 1.06–1.93, P = 0.018; AG vs. GG: OR = 1.22, 95% CI = 1.06–1.40, P = 0.006; AG+AA vs. GG: OR = 1.26, 95% CI = 1.10–1.44, P = 0.001; AA vs. AG+GG: OR = 1.37, 95% CI = 1.02–1.83, P = 0.036). In subgroup analysis stratified by ethnicity, significant associations were also demonstrated in Caucasians but not in Asians. No significant association was found in subgroup analysis stratified by age of onset or disease form.

Conclusions

We concluded that the CYP2D6*4G/A polymorphism denotes an increased genetic susceptibility to PD in the overall population, especially in Caucasians. Further large and well-designed studies are needed to confirm this association.

Associations of variants in MTHFR and MTRR genes with male infertility in the Jordanian population

Folate pathway is expected to play an important role in spermatogenesis since it is involved in DNA synthesis, repair and methylation. The purpose of this study was to examine the association between male infertility and the MTHFR (C677T and A1298C) and MTRR (A66G) polymorphisms. A group of 300 males was recruited in this study from different Jordanian infertility clinics. Of these, 150 cases of infertile men that included oligozoospermia cases (n=45), severe oligozoospermia (n=71) and azoospermia (n=34) were studied. The other 150 males were age matched fertile controls. Genotyping of MTHFR and MTRR polymorphisms was performed using PCR-RFLP technique. The results showed an association between MTHFR 677TT genotype and male infertility (P<0.05). However, the distribution of MTHFR A1298C and MTRR A66G genotypes were not different between the fertile and infertile groups (P>0.05). In addition, none of the examined polymorphisms was related to any of the semen parameters in the infertile group. In conclusion, this study showed that MTHFR C677T polymorphism is associated with male infertility in Jordanians.

Significant association between MTHFR C677T polymorphism and hepatocellular carcinoma risk: a meta-analysis

Previous studies investigated the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and hepatocellular carcinoma risk, but the impact of MTHFR C677T polymorphism on hepatocellular carcinoma was still unclear, owing to the obvious inconsistence from those studies. This study aimed to quantify the strength of the association between MTHFR C677T polymorphism and hepatocellular carcinoma risk by performing a meta-analysis. We searched the PubMed and Wanfang databases for studies on the association between MTHFR C677T polymorphism and hepatocellular carcinoma risk. We estimated the pooled odds ratios (ORs) with their 95% confidence intervals (95% CIs) to assess the association. Fifteen studies with 8,625 participants were finally included into the meta-analysis. Meta-analyses of total 15 studies suggested that MTHFR C677T polymorphism was significantly associated with an increased risk of hepatocellular carcinoma under two main genetic models (for TT versus CC, OR = 1.19, 95% CI 1.03-1.37, P = 0.016; for TT versus CT/CC, OR = 1.14, 95% CI 1.01-1.28, P = 0.032). Subgroup meta-analyses suggested that MTHFR C677T polymorphism was associated with an increased risk of hepatocellular carcinoma in Asians, but not in Caucasians. Thus, individuals with homozygote genotype TT of MTHFR C677T have obviously increased risk of hepatocellular carcinoma.

Association between MTHFR 677C>T polymorphism and risk of gliomas: evidence from a meta-analysis

Folate metabolism plays an important role in carcinogenesis. Methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism is a genetic alteration in an enzyme involved in folate metabolism, but its effect on risk of gliomas is still uncertain. To shed some light on these contradictory results from previous studies, we performed a meta-analysis of published data investigating the association between MTHFR 677C>T polymorphism and risk of gliomas. PubMed, Embase, and Web of Science databases were searched for eligible case-control studies. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to assess the strength of this association. Ten individual case-control studies from six publications with a total of 1,786 cases and 2,076 controls were included into this meta-analysis. There was no obvious heterogeneity under all comparison models of this meta-analysis. Meta-analysis of those ten studies showed that there was no obvious association between MTHFR 677C>T polymorphism and risk of gliomas under all five genetic models (for T versus C, OR = 1.00, 95 % CI 0.90-1.12, P OR = 0.959; for TT versus CC, OR = 1.02, 95 % CI 0.82-1.27, P OR = 0.870; for CT versus CC, OR = 1.02, 95 % CI 0.89-1.18, P OR = 0.733; for TT+CT versus CC, OR = 1.02, 95 % CI 0.90-1.16, P OR = 0.781; for TT versus CT+CC, OR = 0.99, 95 % CI 0.81-1.21, P OR = 0.902). There was also no obvious association between MTHFR 677C>T polymorphism and risk of gliomas in the sensitivity and subgroup analyses of Caucasians. There was no risk of publication bias in this meta-analysis. The evidence from our meta-analysis supports that there is no association between MTHFR 677C>T polymorphism and risk of gliomas.