The Apolipoprotein (ApoE) Gene Is a Risk Factor for Age Related Macular Degeneration (AMD)

Abstract

Abstract: : Purpose: Age related macular degeneration (AMD) is the leading cause of incurable blindness in our society. Both genetic and environmental factors play a role in the causation of this disease. One gene that has been implicated as a risk factor in the aetiology of AMD is the apolipoprotein E (apoE) gene. We wished to examine the association of single nucleotide polymorphisms (SNPs) in this gene with disease. Methods: A large cohort of Anglo-Celtic patients was collected as part of our AMD inheritance study. These consisted of 199 sporadic AMD, 53 familial AMD index cases and 211 controls (no eye disease). Information on age, sex, ethnicity and disease status was available for analysis. Molecular techniques were used to derive the common allelic variants of e2, e3, e4 and for the G/T SNP present at position -219 in the promoter region of apoE. Results: Analysis of the e2, e3, e4 genotypes of apoE indicated a significant association with AMD compared to control individuals with the e2 allele showing an increased risk of disease (OR of 1.36, 95% CI: 0.758 - 2.43) whereas the e4 allele showed a significantly decreased risk of disease (OR of 0.557, 95% CI: 0.354 - 0.876) when adjusted for age and sex. Further analysis indicated that the reduced risk from the e4 allele was more apparent in familial cases (OR of 0.314, 95% CI: 0.132 - 0.745) compared to sporadic cases (OR of 0.655, 95% CI: 0.405 - 1.059). Further SNP detection was undertaken in this gene and revealed the presence of the -219 promoter SNP. Preliminary findings indicated the existence of allelic differences for the G allele at 52% v/s 56% and for the T allele of 48% v/s 44% in cases v/s controls. Conclusions: The apoE gene confers an altered risk of disease in AMD depending on genotype.

Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: ris • genetics