Purpose: Study the apoptotic death of peripheral blood lymphocytes in long-term period in persons exposed to chronic radiation exposure, and analysis of association of the polymorphic regions rs4645878, rs2279115, rs28362491, rs664677, rs1042522, rs1801270, rs2279744 of the BAX, BCL2, NFkB, ATM, TP53, CDKN1A, MDM2 genes with apoptotic lymphocytes frequency in residents of the coastal villages of the Techa River. Material and methods: The study of apoptosis and genotyping was conducted in 390 persons exposed to chronic radiation exposure as a result of Mayak PA radioactive waste releases into the Techa–Iset–Tobol river system. The early stage of apoptosis was assessed on a flow cytometer by the presence of phosphatidylserine on the surface of the cell membranes using the Annexin V Apoptosis Detection Kit I and the late stage of apoptosis using the TUNEL method. Real-time PCR genotyping was performed of allelic variations of rs4645878, rs2279115, rs28362491, rs664677, rs1042522, rs1801270, rs2279744 of BAX, BCL2, NFkB, ATM, TP53, CDKN1A, MDM2 genes in a group of irradiated individuals. Results: The number of cells at the early stage of apoptosis is statistically significantly increased in individuals whose irradiation began during the period of intrauterine development and continued in the postnatal period compared to individuals exposed only in the postnatal period. At the same time, the number of lymphocytes at the stage of DNA fragmentation in the group irradiated in utero is lower than in the group irradiated postnatally and non-irradiated individuals. Also, a weak negative correlation between intrauterine doses of RBM irradiation and the doses of thymus and peripheral lymphoid organs with the number of cells in the late stage of apoptosis in individuals irradiated in utero. The influence of allelic variation rs4645878 of the BAX gene was established on the number of lymphocytes at the early stage of apoptosis in residents of coastal villages of the Techa River. A statistically significant decrease in the number of cells at an early stage of apoptosis is observed in C/C genotype carriers according to the allelic variation rs4645878 of the BAX gene compared with carriers of the T/T and T/C genotypes. Conclusion: Residents of coastal villages of the Techa River exposed to radiation during the period of prenatal development, there are differences in the frequency of apoptotic death of peripheral blood lymphocytes compared with non-irradiated persons and persons who were irradiated in the postnatal period. SNPs of apoptosis-regulating genes can modify the response of blood lymphocytes to radiation in a wide range of doses RBM.

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