BACKGROUND: There is increasing evidence to show that TNF-α -308G>A polymorphism may be a risk factor for celiac disease, but the results are inconsistent. OBJECTIVE: Thus, we aimed to perform a meta-analysis involving published studies up to January 2019 to elucidate the association. METHODS: To assess the effect of TNF-α -308G>A polymorphism on celiac disease susceptibility, we searched PubMed, ISI Web of Knowledge, Chinese National Knowledge Infrastructure (CNKI) databases to identify eligible studies, without restriction. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the susceptibility to celiac disease. RESULTS: A total of 11 studies with 1147 cases and 1774 controls were selected for this meta-analysis. The pooled results indicated that TNF-α -308G>A polymorphism was associated with increased risk of celiac disease (A vs G: OR=2.077, 95% CI=1.468-2.939, P=≤0.001; AA vs GG: OR=8.512, 95% CI=3.740-19.373, P=≤0.001; AA+AG vs GG: OR=1.869, 95% CI=1.161-3.008, P=0.010; and AA+AG vs GG: OR=4.773, 95% CI=3.181-7.162, P≤0.001). Subgroup analysis by ethnicity also revealed significant association in Caucasians. In addition, there was a significant association between TNF-α -308G>A polymorphism and celiac disease risk in Italy, Spain and PCR-FRLP group studies. CONCLUSION: Our meta-analysis suggests that the TNF-α -308G>A polymorphism plays an important role in celiac disease susceptibility. However, our results are still needed to strengthen by further studies in different ethnicities and larger sample sizes.
Background: Previous studies have evaluated the impact of MTHFR 677C>T polymorphism on susceptibility to ovarian and cervical cancers in women, but the conclusions are still controversial. To get a more precise evaluation of the association between MTHFR 677C>T polymorphism and risk of ovarian and cervical cancers, we performed a meta-analysis of the association of all eligible studies. Methods: A comprehensive search performed in PubMed, Google Scholar, CNKI, and Web of Science databases to identify the relevant studies up to October 15, 2018. The strength of the association was estimated by odds ratios (OR) with 95% confidence interval (CI). Results: A total of 27 case-control studies including eleven studies with 4990 cases 7730 controls on ovarian cancer and 16 studies with 4990 cases and 7730 controls on cervical cancer were selected. Pooled data revealed that the MTHFR 677C>T polymorphism not significantly associated with an increased risk of ovarian and cervical cancers under all five genetic models. However, stratified analysis by ethnicity showed that the MTHFR 677C>T polymorphism was significantly associated with risk of ovarian cancer in Asians. No publication bias was found in the current meta-analysis. Conclusions: The results of this meta-analysis proposes that the MTHFR 677C>T polymorphism may not play a role in development of ovarian and cervical cancers in overall population. Further well-designed studies are necessary to clarify the precise role of the MTHFR 677C>T polymorphism on ovarian and cervical cancers risk.
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