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

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 micromol/l vs 10.3 +/- 3.4 micromol/l; P =.003). Hyperhomocysteinemia was defined by the 95th percentile of control plasma homocysteine levels as 15.8 micromol/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.

Hyperhomocyst(e)inemia, but not methylenetetrahydrofolate reductase C677T mutation, as a risk factor in branch retinal vein occlusion.

OBJECTIVE: To determine whether hyperhomocyst(e)inemia and methylenetetrahydrofolate reductase (MTHFR) C677T mutation are associated with branch retinal vein occlusion (BRVO). DESIGN: Retrospective, case-control study. PARTICIPANTS: The study cohort consisted of 84 consecutive patients with branch retinal vein occlusion and 84 controls, matched for age and gender. MAIN OUTCOME MEASURES: Fasting plasma homocyst(e)ine, folate, and vitamin B(12) levels, MTHFR C677T genotypes. RESULTS: Mean plasma homocyst(e)ine levels were significantly higher in patients than in controls (11.4 +/- 4.3 micromol/l vs. 9.9 +/- 2.8 micromol/l; P = 0.002). An increase of plasma homocyst(e)ine level by 1 micromol/l was associated with an odds ratio of 1.19 (95% confidence interval 1.06-1.34; P = 0.004). Mean plasma folate levels were significantly lower in patients than in the control group (4.5 +/- 2.1 ng/ml vs. 5.6 +/- 2.1 ng/ml; P = 0.007). The prevalence of the homozygous genotype of the MTHFR C677T mutation did not differ significantly between patients and controls. CONCLUSIONS: Our results suggest that hyperhomocyst(e)inemia, but not homozygosity for the MTHFR C677T mutation, is associated with BRVO. Increased plasma homocyst(e)ine levels in our study are not the result of an increased prevalence of the homozygous genotype of MTHFR C677T mutation.

Hyperhomocyst(e)inemia and MTHFR C677T genotypes in patients with central retinal vein occlusion.

BACKGROUND: Elevated plasma homocyst(e)ine is a major risk factor for venous thrombosis and cardiovascular disease. Homozygosity for the MTHFR C677T mutation and low plasma folate levels increase plasma homocyst(e)ine concentrations. The aim of this retrospective case-control study was to investigate a possible association between hyperhomocyst(e)inemia and central retinal vein occlusion. METHODS: Our study included 78 consecutive patients with central retinal vein occlusion and 78 control subjects, matched for age and sex. High-performance liquid chromatography (HPLC) with fluorescence detection was used to determine fasting plasma homocyst(e)ine concentrations. Plasma folate and vitamin B12 levels were determined by immunological assays. Genotyping for the MTHFR C677T mutation was performed by polymerase chain reaction (PCR). RESULTS: Hyperhomocyst(e)inemia was defined by the 95th percentile of plasma homocyst(e)ine concentrations in the control group (=14.83 micromol/l). Thus 16 patients with central retinal vein occlusion were diagnosed as hyperhomocyst(e)inemic, compared with three control subjects ( P=0.001). The odds ratio of hyperhomocyst(e)inemia for central retinal vein occlusion was 5.29 (95% CI 1.33-21.13). Mean plasma folate levels were significantly lower in patients than in controls (3.94+/-1.94 ng/ml vs. 5.69+/-2.09 ng/ml; P<0.001). Distribution of MTHFR C677T genotypes did not significantly differ between the two groups. CONCLUSIONS: Our study suggests that hyperhomocyst(e)inemia, but not the MTHFR C677T mutation, is associated with central retinal vein occlusion.