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 mumol/l vs. 9.9 +/- 2.8 mumol/l; P = 0.002). An increase of plasma homocyst(e)ine level by 1 mumol/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. Ophthalmology 2002;109: 1105-1109 (C) 2002 by the American Academy of Ophthalmology.