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H. Bindu, Sr.; Association of GST Polymorphism With Myopia. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5940.
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Myopia or short sightedness is the most common human eye disorder affecting 30% of world population. Genetic and environmental factors are implicated in the onset of myopia. Environmental causes include mechanical factors, oxidative stress, nutritional factors etc. Oxidative stress can arise due to intrinsic or extrinsic factors. The ability to metabolize the exogenous substances is determined by phase 2 enzymes such as Glutathione- s-Transferase .The lack of enzyme activity might result in accumulation of free radicals contributing to oxidative stress. The GST M1, GST T1 are two of the genes of GST family, which exhibit, null genotypes. In the present study 101 cases of myopia comprising of 31 of low myopia and 70 high myopia cases were analyzed for GST polymorphism using multiplex PCR.These results were compared with 176 cases of age and sex matched controls. There was no significant difference in the genotype distribution of GST M1 and GST T1 polymorphism between disease and controls. When the data on myopia was sub grouped with respect to different parameters, interesting results were obtained. Patients with low myopia (16.12%), earlier age at onset (12%) had very high frequency of double null genotype (M0T0) as compared to high myopia(4.28%).Further high myopia patients having M0T0 genotype had very high refractive error (>15D). These results indicate that inefficient detoxification system to combat the accumulation of free radicals might be responsible for the onset of low myopia whereas genetic predisposition is necessary for the onset of high myopia. If high myopia patients happen to have M0T0 genotype, the refractive error would increase to very high levels, which might lead to retinal complications. There was no association of GST polymorphism with sex of the proband, familial incidence and parental consanguinity.
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