Research of DNA repair genes polymorphism XRCC1 and XPD and the risks of thyroid cancer development in persons exposed to ionizing radiation after Chornobyl disaster

Abstract

The objective of this work was to determine and compare the features of DNA repair gene XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms in patients with thyroid cancer (TC), who were exposed to ionizing radiation (IR) as a result of the Chornobyl disaster, and in patients without exposure to ionizing radiation in history. Determination of gene XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms was performed by polymerase chain reaction (PCR) in 102 patients with thyroid cancer: 38 people, who were exposed to ionizing radiation due to Chornobyl disaster (members of the accident, and evacuees and residents from controlled areas contaminated with radionuclides), 64 individuals without exposure to ionizing radiation in history and 41 persons residents of Ukraine without cancer pathology in the control group. For comparison of the data on spontaneous and radiation-associated thyroid cancer and settlement of allele frequencies differences and risk of cancer pathology were used the literature data on control groups of populations of Russia, Belarus and Poland. Comparing to the literature data on XRCC1 Arg399Gln polymorphisms in radiation-exposed individuals without cancer pathology, the risk of thyroid cancer in homozygous minor allele XRCC1 Gln399Gln carriers, who were exposed to ionizing radiation was significantly increased: OR = 4,14, p = 0,001 (CI95 % 1,72-9,93). In homozygous carriers of the minor allele of the gene XPD Lys751Gln, exposed to IR, revealed increased risk of thyroid cancer: OR = 3,30, p = 0,05 (CI 95 % 0,82-14,14), when compared with the control group of Ukrainian population. The carriage of homozygous minor allele Gln399Gln XRCC1 and XPD Gln751Gln of DNA repair genes is a risk factor for thyroid cancer under the influence of ionizing radiation in research group of Ukrainian population.