Polymorphisms in nucleotide excision repair genes and DNA repair capacity phenotype in sisters discordant for breast cancer.

Interindividual differences in DNA repair capacity (DRC) may play a critical role in breast cancer risk. Previously, we determined that DRC measured via removal of in vitro-induced benzo[a]pyrene diolepoxide-DNA adducts in lymphoblastoid cell lines was lower in cases compared with controls among sisters discordant for breast cancer from the Metropolitan New York Registry of Breast Cancer Families. We have now determined genotypes for seven single nucleotide polymorphisms in five nucleotide excision repair genes, including Xeroderma pigmentosum complementation group A (XPA +62T>C), group C (XPC Lys939Gln and Ala499Val), group D (XPD Asp312Asn and Lys751Gln), and group G (XPG His1104Asp) and ERCC1 (8092 C>A) in a total of 160 sister pairs for whom DRC phenotype data were available. Overall, there were no statistically significant differences in average DRC for most of the genotypes. A final multivariate conditional logistic model, including three single nucleotide polymorphisms (XPA +62T>C, XPC Ala499Val, and XPG His1104Asp) and smoking status, only modestly predicted DRC after adjusting for case-control status and age of blood donation. The overall predictive accuracy was 61% in the model with a sensitivity of 78% and specificity of 39%. These findings suggest that those polymorphisms we have investigated to date in nucleotide excision repair pathway genes explain only a small amount of the variability in DRC.