Polymorphisms of DNA repair genes OGG1 and XPD and the risk of age-related cataract in Egyptians

PURPOSE To analyze the association of the polymorphisms of xeroderma pigmentosum complementation group D (XPD) and 8-oxoguanine glycosylase-1 (OGG1) genes with the risk of age-related cataract (ARC) in an Egyptian population. METHODS This case-control study included 150 patients with ARC and 50 controls. Genotyping of XPD Asp³¹²Asn was performed by amplification refractory mutation system PCR assay and genotyping of OGG1 Ser³²⁶Cys was carried out by PCR including confronting two-pair primers. RESULTS The Asn/Asn genotype of XPD gene was significantly associated with increased risk of ARC (odds ratio [OR] = 2.74, 95% confidence interval [CI] = 1.01-7.43, p = 0.04) and cortical cataract (OR = 5.06, 95% CI = 1.70-15.05, p = 0.002). The Asn³¹² allele was significantly associated with an increased risk of ARC (OR = 1.75, 95% CI 1.06-2.89, p = 0.03) and cortical cataract (OR = 2.81, 95% CI = 1.56-5.08, p<0.001). The OGG1 Cys/Cys genotype frequency was significantly higher in ARC (OR = 4.13, 95% CI = 0.93-18.21, p = 0.04) and the Cys(³²⁶ allele (OR = 1.85, 95% CI = 1.07-3.20, p = 0.03). Moreover, the Cys/Cys genotype of the OGG1 gene was significantly higher in cortical cataract (OR = 6.00, 95% CI = 1.24-28.99, p = 0.01) and the Cys³²⁶ allele was also significantly associated with cortical cataract (OR = 2.45, 95% CI = 1.30-4.63, p = 0.005). CONCLUSIONS The results suggest that the Asn/Asn genotype and Asn³¹² allele of XPD polymorphism, as well as the Cys/Cys genotype and Cys³²⁶ allele of the OGG1 polymorphism, may be associated with increased risk of the development of ARC, particularly the cortical type, in the Egyptian population.