Cytogenetic monitoring of hospital staff exposed to ionizing radiation: optimize protocol considering DNA repair genes variability

Purpose: Chronic occupational exposure to ionizing radiation (IR) induces a wide spectrum of DNA damages. The aim of this study was to assess the frequencies of micronucleus (MN), sister chromatid exchanges (SCE) and to evaluate their association with XRCC1 399 Arg/Gln and XRCC3 241 Thr/Met polymorphisms in Hospital staff occupationally exposed to IR. Materials and methods: A questionnaire followed by a cytogenetic analysis was concluded for each subject in our study. The exposed subjects were classified into two groups based on duration of employment (Group I < 15 years; Group II >= 15years). The genotypes of all individuals (subjects and controls) were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: DNA damage frequencies were significantly greater in IR workers compared with controls (p <. 05). However, no association arised between XRCC1 399 Arg/Gln and XRCC3 241 Thr/Met polymorphisms, on one hand, and the severity of DNA damages in the studied cohort of Tunisian population, on the other hand. Conclusion: Our data provide evidence for an obvious genotoxic effect associated with IR exposure and reinforce the high sensitivity of cytogenetic assays for biomonitoring of occupationally exposed populations. These results indicate that workers exposed to IR should have periodic monitoring, along their exposure. The variants, rs25487 and rs861539, of XRCC1 and XRCC3 genes have obvious functional effects. Paradoxically, these variants are not associated with the severity of damages, according to used assays, in the studied cohort of Tunisian population, unlike other studies.