The role of apolipoprotein E gene polymorphisms in primary open-angle glaucoma

Objective: To test the hypothesis that genetic polymorphisms of the apolipoprotein E (APOE) gene are associated with primary open-angle glaucoma (POAG), based on the association between neurodegenerative diseases and the APOE genotype. Methods: Genomic DNA was examined from an unrelated cohort of 137 POAG patients and 75 control subjects from the ophthalmology department of the Royal Victoria Infirmary. The APOE allele frequency (epsilon2, epsilon3, and epsilon4 alleles) was studied by polymerase chain reaction amplification of the related locus (19q13.2), enzymatic digestion of the products, gel electrophoresis, and imaging under UV illumination. For statistical analysis, we used a logistic regression model that included intraocular pressure as a continuous variable to study the possible correlation between POAG and APOE allele frequency. Results: Logistic regression analysis showed no statistically significant association between the frequency of the APOE allele and POAG for the population studied, irrespective of the IOP (epsilon2 odds ratio, 0.82; 95% confidence interval, 0.12-5.79 [P = .84]; epsilon3 odds ratio, 0.39; 95% confidence interval, 0.10-1.49 [P = .17]; and epsilon4 odds ratio, 3.84; 95% confidence interval, 0.80-18.49 [P = .09]). Conclusion: In our cohort, the APOE genotype does not constitute a risk factor for developing POAG, even in patients with normal-tension glaucoma. Clinical Relevance: Apolipoprotein E polymorphisms do not appear to be contributory to POAG.