Role of factor XIII Val34Leu polymorphism in retinal artery occlusion.

BACKGROUND AND PURPOSE Factor XIII (FXIII) Val34Leu, a common polymorphism in the gene for factor XIII, has been associated with a lower risk of stroke, myocardial infarction, and deep vein thrombosis. Ineffective fibrin cross-linking has been suggested to be causative. The aim of the present case-control study was to investigate the role of FXIII Val34Leu polymorphism in patients with retinal artery occlusion. METHODS A total of 108 patients with retinal artery occlusion and 313 age- and sex-matched controls were genotyped for the FXIII Val34Leu polymorphism. Factor XIII Val34Leu genotypes were determined by use of allele-specific polymerase chain reaction. RESULTS Homozygous Leu genotype was found significantly more often in control subjects than in patients with retinal artery occlusion (P=0.018), with an odds ratio of 0.22 (95% confidence interval 0.07 to 0.74). Distribution of the Val/Val and Val/Leu genotypes did not differ significantly between groups. CONCLUSIONS Because prevalence of homozygous Leu genotype was significantly higher in controls, we conclude that the Leu/Leu genotype is associated with a protective effect against retinal artery occlusion.