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PN Baird, E Guida, M Cain, DT Chu, BN Mukesh, RH Guymer; Association Studies of the Alleles of the Apolipoprotein (ApoE) Gene and Age Related Macular Degeneration (AMD) . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2833.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:AMD is the leading cause of blindness in our community and its pathogenesis remains unknown. Genetic studies have indicated that there is an association between alleles of the ApoE gene and the risk of end stage AMD. Methods:The ApoE gene has three co-dominant alleles (e2, e3, e4) with the e4 allele being suggested as a protective allele whilst the e2 allele has an association with increased risk of disease in sporadic AMD. In familial cases of AMD however, this association has not been as convincing. We have analysed both sporadic and familial cases of AMD from the Australian population as part of our AMD inheritance study (AMDIS). Information on age, sex, ethnicity and disease status was available for analysis in this study. ApoE genotypes were derived for all individuals using single stranded conformational polymorphism as well as restriction digestion. Results:315 individuals with AMD and 135 ethnically matched controls (free of any ocular abnormality) were collected. 116 of the AMD individuals were sporadic and 199 were familial. Average age of the controls was 70.4 years and of AMD individuals was 80.7 years. Analysis of the three alleles of the ApoE gene indicated that there was a highly statistical significant difference between the controls and AMD groups (c2 = 17.5, p<0.0001). This difference was mainly attributable to either the e3 (c2 = 6.4, p<0.011) or e4 (c2 = 16.2, p<0.0001) alleles of ApoE. In both male and female cases with disease the proportion of individuals with the e4 allele was markedly reduced compared to controls. This finding was most profound in male index cases with familial disease (3%) compared to 26% in controls. Differences in the e2 allele were not as evident but there was an increase in the prevalence of this allele in both male and female familial index cases compared to controls. In sporadic males the e2 allele was present in 9% of AMD cases compared to 4.5% in controls. Conclusion:Our findings indicate that the presence of the e4 allele does appear to be protective for AMD especially in familial cases of disease. In sporadic AMD, the presence of the e2 allele may be associated with an increased risk of disease in males. These findings further support a role for this gene in AMD.
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