Association of Single Nucleotide Polymorphisms in XRCC1 (194) and XPD (751) with Age-related cataract.

Purpose: Age-related cataract (ARC) is a multifactorial disease and different risk factors, including genetic and environmental, are responsible for the development of its various types. The aim of this study was to find out a correlation, if any, between ARC and the single nucleotide polymorphisms (SNPs) in DNA repair genes XRCC1 (X-ray repair cross-complementary-1) [Arg194Trp (rs1799782)] and XPD (xerodermapigmentosa complementation group D) [Lys751Gln (rs13,181].

Method: The genotype at these two SNPs was analyzed in 260 subjects (125 control and 135 patients) from Southern Punjab population (Pakistan) by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. Genotype at both analyzed codons was correlated either individually or in various combinations with the studied epidemiological factors known to be associated with ARC.

Results: Our results indicated that both SNPs Arg194Trp in XRCC1 (P = 0.967) and Lys751Gln in XPD (P = 0.995) were not associated with ARC whether they were analyzed individually or in combined form (P > 0.05). Analysis of epidemiological factors revealed that age (P < 0.001), cast of subjects (P = 0.001), diabetes (P < 0.001), hypertension (P = 0.001), smoking habit (P = 0.01), drug abuse (P < 0.05), steroid use (P = 0.001) and body weight (P < 0.001) can influence the incidence of ARC in enrolled subjects. After applying Binary logistic regression it was found that the weight (P < 0.01), family history (P = 0.05), drug abuse (P = 0.05), smoking (P < 0.05) and steroid use (P < 0.05) has a significant association with the phenotype of the subjects. All epidemiological factors were also studied in association with various genotypic combinations of both SNPS, diabetes was the only factor that had a significant association (P < 0.001) association with ARC. Hypertension (P = 0.01), body weight (P < 0.05) and cast (P < 0.001) were found associated with ARC when epidemiological factors were individually correlated with ARC. Result of the two proportion test indicated that gender had no influence on the incidence of disease.

Conclusion: It is concluded that studied SNPs in XRCC1 and XPD have no association with the incidence of age related cataract in the analyzed group of subjects.