title: Association between methylenetetrahydrofolate reductase (MTHFR) C677T/A1298C polymorphisms and essential hypertension: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Many studies have investigated the role of 5,10-methylenetetrahydrofolate reductase gene (MTHFR) C677T/A1298C polymorphisms in essential hypertension (EH), but results are inconclusive. The purpose of this meta-analysis was to clarify the effects of MTHFR C677T/A1298C polymorphisms on the risk of EH.
  
  
  METHODS
  Electronic databases were searched to identify relevant studies published until January 2014. Data were extracted by two independent authors. Odds ratios (ORs) with 95%confidence intervals (CIs) were used to assess the association between MTHFR C677T/A1298C polymorphisms and the risk of EH using random effect models or fixed effect models. Finally,30 studies with 5207 cases and 5383 controls were included for C677T polymorphism and 6 studies with 1009 cases and 994 controls were included for A1298C polymorphism.
  
  
  RESULTS
  Meta-analysis results indicated that MTHFR C677T polymorphism contributed to an increased risk of EH (for T vs. C: OR=1.30, 95%CI=1.18–1.43; for TT+CT vs. CC: OR=1.34, 95%CI=1.24–1.46; for TT vs. CC: OR=1.62, 95%CI=1.32–1.99; for TT vs. CT+CC: OR=1.41, 95%CI=1.26–1.59). However, no significant association was detected between MTHFR A1298C polymorphism and the risk of EH.
  
  
  CONCLUSIONS
  This meta-analysis supports that MTHFR C677T polymorphism plays a role in developing EH. MTHFR A1298C polymorphism may not be associated with an increased risk of EH. Further large and well-designed studies are warranted to confirm these findings.
authors.affiliation: Department of Epidemiology and Health Statistics, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei 230032, Anhui, China.
authors.forename: Yi-Le
authors.initials: YL
authors.lastname: Wu
authors.forename: Cai-Yun
authors.initials: CY
authors.lastname: Hu
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Lu
authors.forename: Feng-Feng
authors.initials: FF
authors.lastname: Gong
authors.forename: Fang
authors.initials: F
authors.lastname: Feng
authors.forename: Zhen-Zhong
authors.initials: ZZ
authors.lastname: Qian
authors.forename: Xiu-Xiu
authors.initials: XX
authors.lastname: Ding
authors.forename: Hui-Yun
authors.initials: HY
authors.lastname: Yang
authors.forename: Ye-Huan
authors.initials: YH
authors.lastname: Sun
mesh_terms: D000075222:Essential Hypertension; D055106:Genome-Wide Association Study; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000235:genetics*; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide
chemical_list: C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2)