The role of hyperhomocysteinemia and methylenetetrahydrofolate reductase (MTHFR) C677T mutation in patients with retinal artery occlusion

Abstract

PURPOSE: Hyperhomocysteinemia has been established as an important risk factor for cardiovascular diseases. The aim of the present study was to investigate whether hyperhomocysteinemia and/or homozygosity for the methylenetetrahydrofolate reductase (MTHFR) C677T mutation are associated with an increased risk for retinal artery occlusion (RAO).DESIGN: Retrospective case-control study.METHODS: We studied 105 consecutive patients with retinal artery occlusion and 105 age and sex-matched control subjects. Fasting plasma homocysteine levels were determined by high-performance liquid chromatography, while genotypes of the MTHFR C677T mutation were determined by polymerase chain reaction.RESULTS: Mean plasma homocysteine levels were significantly higher in patients with RAO compared with control subjects (12.2 ± 4.8 μmol/l vs 10.3 ± 3.4 μmol/l; P = .003). Hyperhomocysteinemia was defined by the 95th percentile of control plasma homocysteine levels as 15.8 μmol/l. Twenty (19.1%) patients with RAO exceeded this level and were therefore classified as hyperhomocysteinemic compared with 5 (4.8%) control subjects (P = .003). The odds ratio for these patients was calculated at 4.7 (95% confidence interval [CI], 1.5–15.1). Mean plasma folate levels were significantly lower in patients than in the control group (5.6 ± 2.3 ng/ml vs. 6.3 ± 2.5 ng/ml; P = .04). The prevalence of the homozygous genotype of methylenetetrahydrofolate reductase C677T mutation did not significantly differ between patients and controls.CONCLUSIONS: Our results suggest that hyperhomocysteinemia, but not homozygosity, for the MTHFR C677T mutation is associated with RAO.