XRCC1 and XPD genetic polymorphisms and susceptibility to age-related cataract: A meta-analysis

OBJECTIVE This meta-analysis aimed to determine the relationships between XRCC1 Arg399Gln (rs25487 G>A) and XPD Lys751Gln (rs1052559 A>C) polymorphisms and susceptibility to age-related cataract. METHODS Medline (1966-2013), the Cochrane Library Database (Issue 12, 2013), EMBASE (1980-2013), CINAHL (1982-2013), Web of Science (1945-2013) and the Chinese Biomedical Database (CBM; 1982-2013) were searched without language restrictions. Various combinations of the keywords and MeSH terms were used to screen for potentially relevant studies, specifically "genetic polymorphisms" or "SNPs" or "variation" or "single nucleotide polymorphism" or "polymorphism" or "mutation" or "variant"; "X-ray repair cross complementing protein 1" or "Xeroderma Pigmentosum Group D Protein" or "X-ray repair cross complementing protein 1" or "Xeroderma Pigmentosum Group D Protein" or "XPD" or "Xeroderma Pigmentosum Complementation Group D Protein" or "ERCC2" or "XRCC1" or "XRCC1 DNA repair protein"; and "Cataract" or " Membranous Cataract" or " Pseudoaphakia." Meta-analyses were conducted using Stata 12.0 software. Crude odds ratios (ORs) and their corresponding 95% confidence intervals (95% CI) were calculated. RESULTS Six independent case-control studies were included in the meta-analysis. Our results indicated that the association between the genetic polymorphisms of XRCC1 Arg399Gln G>A and XPD Lys751Gln A>C and increased susceptibility to age-related cataracts was statistically significant (XRCC1 Arg399Gln: OR=1.30, 95% CI=1.17-1.44, p<0.001; XPD Lys751Gln: OR=1.25, 95% CI=1.12-1.40, p<0.001, respectively). Ethnicity-stratified analysis indicated that the XRCC1 Arg399Gln G>A polymorphism was correlated with the development and progression of age-related cataract in China, India, and Turkey in the allele model and the dominant model. For the XPD Lys751Gln A>C variant, the association with the pathogenesis of age-related cataract in China and Turkey in the allele model and the dominant model was investigated. CONCLUSIONS The association of XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms with age-related cataract susceptibility observed in our meta-analyses supports the view that XRCC1 and XPD may play important roles in susceptibility to age-related cataract.