Homocysteine, B Vitamins, Methylenetetrahydrofolate Reductase Gene, and Risk of Primary Open-Angle Glaucoma : A Meta-analysis

BackgroundTo evaluate the association between plasma total homocysteine (tHcy) levels, serum folic acid, vitamin B12 and vitamin B6 levels, methylenetetrahydrofolate reductase (MTHFR) C677T genotype and risk of primary open-angle glaucoma (POAG).Clinical RelevanceThere are conflicting reports on the association of Hcy, folic acid, vitamin B12, vitamin B6, MTHFR, and risk of POAG. We conducted this meta-analysis to derive a more precise estimation of the association.MethodsPertinent articles were identified through a systematic search of the EMBASE and Medline databases. Results were pooled using meta-analytic methods. The main outcome measure included tHcy, folic acid, vitamin B12 and vitamin B6 levels, and MTHFR C677T genotype.ResultsTwelve studies were eligible for Hcy, 6 studies for folic acid, 6 studies for vitamin B12, 3 studies for vitamin B6, and 10 studies for MTHFR. The combined results showed that plasma tHcy levels in POAG were 2.05 μmol/L (95% confidence interval [CI], 0.63–3.47) higher than in controls. There was no difference between serum folic acid, vitamin B6, and vitamin B12 levels in POAG and controls. The weighted mean difference with 95% CI were 0.34 μmol/L (−0.37 to 1.05), 2.75 μmol/L (−3.68 to 9.18), and 0.97 μmol/L (−30.45 to 32.40), respectively. The MTHFR 677TT genotype was not associated with the risk of POAG (odds ratio, 1.10; 95% CI, 0.83–1.47).ConclusionsWe found that POAG is associated with elevated plasma tHcy levels, but not serum folic acid, vitamin B12, vitamin B6 levels, or MTHFR C677T genotype.Financial Disclosure(s)The authors have no proprietary or commercial interest in any of the materials discussed in this article.