Genetic polymorphisms of superoxide dismutases, catalase, and glutathione peroxidase in age-related cataract

PURPOSE: The antioxidant enzymes pathway is considered the most important pathway involved in the repair of reactive oxygen species (ROS)–induced damage. Therefore, we investigate the possible association between polymorphisms of Cu/Zn superoxide dismutase (SOD1), catalase (CAT), and glutathione peroxidase (GPX) genes and age -related cataract development. METHODS: The study included 415 cataract patients (121 patients with cortical, 109 with nuclear, 59 with posterior subcapsular, and 126 with mixed type) and 386 healthy control group of similar age. Genotyping of SOD1–251A/G, CAT–21A/T, and GPX1–198C/T was done by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. Differences in the frequencies were estimated using the χ(2) test and risk was estimated with an unconditional logistic regression after adjusting for age and gender. RESULTS: SOD1 G/G genotype frequency was significantly higher in cataract patients (p=0.012, OR=1.642, 95% CI=1.129–2.389). SOD1 A/A genotypes (p=0.001, OR=0.613, 95% CI=0.461–0.817) seem to have a protective role against cataract, and the G allele (p=0.001, OR=1.479, 95% CI=1.208–1.810) plays a dangeous effect against in the development of cataract. In CAT–21A/T and GPX1–198C/T polymorphisms, there were no significant differences in the variant homozygous frequencies in patients compared to controls (p=0.226, OR=1.358, 95% CI=0.839–2.199; p=0.521, OR=1.205, 95% CI=0.726–2.001, respectively). Stratification by the subtypes revealed that association between SOD polymorphism and cataract was in cortical and mixed type cataract. The genotype frequency of the GG and AA of SOD1–251A/G was significantly different in cortical and mixed type cataract group (p=0.031; OR: 1.805, 95% CI: 1.076–3.026; p=0.002; OR: 2.229, 95% CI: 1.364–3.645; p=0.026; OR: 0.608, 95% CI: 0.396–0.933; p=0.001; OR: 0.474, 95% CI: 0.305–0.734, respectively) compared to healthy controls. CONCLUSIONS: Results suggest that the G/G genotype of the SOD1–251A/G polymorphism may be associated with an increased risk of cataract. However, in CAT–21A/T and GPX1–198C/T polymorphisms, there were no significant differences in the variant homozygous frequencies in patients compared to controls.