title: Homocysteine, methylenetetrahydrofolate reductase C677T polymorphism, and risk of retinal vein occlusion: an updated meta-analysis.
abstract: BACKGROUND
  To evaluate the role of plasma total homocysteine (tHcy) and homozygosity for the thermolabile variant of the methylenetetrahydrofolate reductase (MTHFR) C677T genotype in the risk of retinal vein occlusion (RVO).
  
  
  METHODS
  Relevant studies were selected through an extensive search of PubMed, EMBASE, and the Web of Science databases. Summary weighted mean differences (WMDs) or odds ratios (ORs) and 95% confidence intervals (CI) were calculated with a random-effects model.
  
  
  RESULTS
  Forty-two studies with 6445 participants were included in this updated systematic review and meta-analysis. The mean plasma tHcy level in the RVO patients was significantly higher than in the controls (WMD =2.13 μmol/L; 95% CI: 1.29 to 2.98, P < 0.001), but there was evidence of between-study heterogeneity (P < 0.001). No significant association between MTHFR C677T genotype and RVO was found under all genetic models.
  
  
  CONCLUSIONS
  There was some evidence that plasma tHcy is associated with an increased risk of RVO. There was no evidence to suggest an association between homozygosity for the MTHFR C677T genotype and RVO.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.forename: Minwen
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Department of Ophthalmology, Beijing Institute of Ophthalmology, Beijing Ophthalmology and Visual Science Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, 17 Hougou Lane, Chongnei Street, Beijing 100005, China. drpengxy@163.com.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Peng
authors.forename: Huiyu
authors.initials: H
authors.lastname: Sun
mesh_terms: D005260:Female; D005838:Genotype; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide; D012170:Retinal Vein Occlusion / Q000097:blood* / Q000235:genetics*; D012307:Risk Factors
chemical_list: D006710:Homocysteine; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2)