Delayed Changes in the Frequency of Unstable Chromosomal Aberrations and the CNA-Genetic Landscape of Blood Leukocytes in People Exposed to Long-Term Occupational Irradiation

Abstract—The results of a study of delayed changes in the frequency of unstable chromosomal aberrations and the CNA- and LOH-genetic landscape of blood leukocytes in healthy employees at the main facilities of the Siberian Group of Chemical Enterprises exposed to external irradiation are presented. In 2014, 11 persons with de novo induced mosaic deletions and amplifications associated with dicentric and/or ring chromosomes (markers for individual radiosensitivity) were detected. Three years later, the frequency levels of chromosomal aberrations were compared. In 2017 the frequency of aberrant cells had increased by 1.7 times compared to 2014, the frequency of the chromosomal type aberrations had doubled, the frequency of pair fragments had a more than fourfold increase, and the frequency of dicentrics had almost doubled. The mosaic deletion in employee no. 1490 (3q12.3–13.11) identified in 2014 persisted until 2017. Mosaic amplifications identified in 2014 were preserved in five out of six employees (nos. 178, 203, 450, 1620, and 1792). Moreover, we identified that the CNstate in employee no. 450 had increased 1.5 times by 2017. The mosaic amplification of the short arm of the third chromosome in employee no. 278 had been eliminated by 2017. Other changes in the CNA and LOH-genetic landscape were not detected. Thus, these data indicate the formation of self-sustained bone marrow clones, whose descendants produce a population of aberrant cells in the blood of irradiated individuals. Further research into the preservation of chromosomal aberrations and CNA is needed, as well as studies aimed at detecting the clones of aberrant cells in the bone marrow.