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(c)inemia was defined by the 95th percentile of plasma homocyst(e)ine concentrations in the control group (=14.83 mumol/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.