Original Communication - Association of apolipoprotein E (RFLP) polymorphism with myopia

BACKGROUND: Myopia or nearsightedness is a spherical error of refraction, whereby the images are focused in front of retina. Eye, being an organ rich in activated oxygen species, requires a high level of antioxidants to protect the unsaturated fatty acids. Apolipoprotein E (APOE) is one of the proteins that is produced by Muller cells within the retina and is also endowed with antioxidant properties. Genetic polymorphism of APO E is controlled by three common alleles ε3, ε2 and ε4 and rare e1, e4v at the APOE structural gene locus. Different isoforms of APO E differ in their antioxidant properties, and the e4 allele has lesser ability to combat oxidative stress.
AIMS: Myopia being a disease influenced by oxidative stress, the present study was undertaken to find association of myopia with APO E polymorphism.
MATERIALS AND METHODS: A total of 187 myopic cases and 192 controls were genotyped for apolipoprotein E polymorphism.
RESULTS: In both controls and myopic cases, E3/3 genotype was found to be the most frequent one. There was an increase in E3/4 genotype frequency among male probands, high myopia cases and probands with early age at onset, suggesting that the E3/4 genotype might confer risk for myopia development.
CONCLUSION: This association with E3/4 genotype might predispose susceptible individuals to develop high myopia and early onset myopia.

Keywords
Apolipoprotein E polymorphism, genotype, Muller cells, myopia, oxidative stress, retinal degeneration