Lymphocyte DNA adducts and polymorphism in the DNA repair enzyme XPD

The effect of genetic polymorphism of DNA repair enzyme on the DNA adduct levels was evaluated in this study. We explored the relationship between polymorphism in the nucleotide excision repair enzyme XPD and DNA adduct levels in lymphocytes. Lymphocyte DNA adducts were measured by a ³²P-postlabelling method from 42 subjects. XPD ex23 genotypes were identified by the PCR-RFLP method. Subjects with the XPD ex23 heterozygous genotype (AC) showed significantly lower DNA adduct levels (0.63±0.19 per 10⁸ nucleotides, n=6) than those (0.92±0.38, n=36) with major homozygous genotypes (AA). This result suggests that the genotype of the repair enzyme may be one of the important determinants for DNA adduct levels.