Apolipoprotein E Genotypes in Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma

Purpose: Pseudoexfoliation (PEX) syndrome, an age-related, systemic, elastic microfibrillopathy, is characterized by fibrillar-granular deposits in the anterior segment of the eye. Although not representing a true amyloidosis, PEX syndrome shares some features with amyloid disorders, such as Alzheimer disease. It has been shown that amyloid-associated proteins also occur in association with PEX fibrils. Apolipoprotein E (Apo-E) is directly involved in these amyloid deposition and fibrils formation. The epsilon 4 allele of APOE gene was shown to be associated both with an increased risk for coronary heart disease and late-onset Alzheimer disease. In this study, we therefore investigated whether APOE alleles are associated with PEX syndrome and/or PEX glaucoma (PEXG) in 2 large cohorts of German and Italian origin. Methods: The 3 common APOE alleles epsilon 2, epsilon 3, and epsilon 4 were genotyped in 661 unrelated patients (459 PEXG and 202 PEX patients) and 342 healthy individuals of German origin and furthermore in 209 unrelated patients (133 PEXG and 76 PEX patients) and 190 healthy individuals of Italian origin using TaqMan assays for allelic discrimination. A genetic association study was then performed. Results: The epsilon 3 allele was found to be the most common in both populations (80% to 83%), whereas the epsilon 2 allele was the rarest (6% to 9%). No significant differences in allele and genotype frequencies between both groups were observed in either population. Conclusion: Our data show that APOE genotypes are not associated with PEX and PEXG in either Germans or Italians.