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P.N. Baird, A.J. Richardson, L. Robman, P. Dimitrov, G. Tikellis, C. McCarty, R.H. Guymer; Alleles of the Apolipoprotein (ApoE) gene and progression of age related macular degeneration (AMD) . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3729.
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Purpose: Few genes have so far been identified as playing a role in the aetiology of age related macular degeneration (AMD). One gene that has been implicated as a risk factor in AMD is the apolipoprotein E (apoE) gene. We have previously shown that the ε4 allele of the apoE gene shows a protective effect for AMD whilst the ε2 allele appears to be associated with an earlier age of onset of disease (Baird et al, submitted). We wished to investigate whether the alleles of apoE were also associated with progression of AMD. Methods: 254 individuals aged from 51 to 89 years recruited into the Cardiovascular Health and Age Related Maculopathy (CHARM) progression study were available for genotyping for alleles of apoE. Progression of age–related maculopathy was followed over a mean period of 7 years (range 6 to 9 years) and defined as a stepped increase in ARM grading in either eye according to the International Scheme for Grading of ARM/AMD. Information on age, sex, ethnicity and cardiovascular disease status was also available for analysis. The common allelic variants of ε2, ε3 and ε4 of apoE were derived using molecular techniques. Results: Genotyping on 137 age–matched individuals of whom 68 individuals did not progress and 69 individuals who progressed has so far been undertaken. The allele frequencies for the ε2 (8%), ε3 (77%) and ε4 (15%) alleles of apoE in non–progressors were similar to our previous study where ε2 = 9.9%, ε3 = 78.6% and ε4 = 11.5%. Analysis of apoE genotypes indicated a trend for a lower frequency of the ε3 ε4 genotype in individuals who progressed with disease (17%) compared to those who did not progress (26%). Whereas the opposite trend was found in individuals when an ε2 allele was present. ε2 carriers represented 16% of non–progressors and 25% of progressors. Further genotyping to complete the cohort analysis will allow us to better determine the significance of these results. Conclusion: The presence of an ε2 genotype or ε2 allele may result in increased progression of disease.
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