Lymphocyte DNA adducts and polymorphism in the DNA repair enzyme XPD

The effect of genetic polymorphism of DNA repair enzyme on the DNA adduct l evels was evaluated in this study. We explored the relationship between pol ymorphism in the nucleotide excision repair enzyme XPD and DNA adduct level s in lymphocytes. Lymphocyte DNA adducts were measured by a P-32-postlabell ing method from 42 subjects. XPD ex23 genotypes were identified by the PCR- RFLP method. Subjects with the XPD ex23 heterozygous genotype (AC) showed s ignificantly lower DNA adduct levels (0.63-0.19 per 10(8) nucleotides, n = 6) than those (0.92-0.38, n = 36) with major homozygous genotypes (AA). Thi s result suggests that the genotype of the repair enzyme may be one of the important determinants for DNA adduct levels.