Micronucleus-centromere assay and DNA repair gene polymorphism in lymphocytes of industrial radiographers.

The micronucleus-centromere assay using a pan-centromeric probe was used to assess chromosomal damage in lymphocytes of 47 industrial radiographers occupationally exposed to low dose ionizing radiation and 47 controls. The influence of genotype of DNA repair genes (XRCC1(399), XRCC3(241) and XPD(751)) on micronuclei (MN) frequency was also investigated. Centromere negative micronuclei (MNC-) frequency was significantly higher in radiographers than in controls, whereas similar centromere positive micronuclei (MNC+) frequency was observed in both groups. Poisson regression analyses revealed that the MNC- frequency was significantly associated with radiation occupational exposure and with cumulative-radiation doses in radiographers, after adjusting for confounding variables such as age, smoking, alcohol intake and genotypes. Compared to homozygous wild-type subjects, MNC- frequency in radiographers with variant XRCC3 genotype was significantly higher using univariate analysis. There were no differences in MNC- or MNC+ frequencies by genotype in controls. In conclusion, scoring of MNC- is a useful cytogenetic biomonitoring method for radiographers. Polymorphisms in XRCC3 might contribute to the increased genetic damage in individuals occupationally exposed to chronic ionizing radiation.