Homocysteine, B Vitamins, Methylenetetrahydrofolate Reductase Gene, and Risk of Primary Open-Angle Glaucoma

To evaluate the association between plasma total homocysteine (tHcy) levels, serum folic acid, vitamin B(12) and vitamin B(6) levels, methylenetetrahydrofolate reductase (MTHFR) C677T genotype and risk of primary open-angle glaucoma (POAG).There are conflicting reports on the association of Hcy, folic acid, vitamin B(12), vitamin B(6), MTHFR, and risk of POAG. We conducted this meta-analysis to derive a more precise estimation of the association.Pertinent 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 B(12) and vitamin B(6) levels, and MTHFR C677T genotype.Twelve studies were eligible for Hcy, 6 studies for folic acid, 6 studies for vitamin B(12), 3 studies for vitamin B(6), 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 B(6), and vitamin B(12) 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).We found that POAG is associated with elevated plasma tHcy levels, but not serum folic acid, vitamin B(12), vitamin B(6) levels, or MTHFR C677T genotype.The authors have no proprietary or commercial interest in any of the materials discussed in this article.