Effects of ionizing radiation (IR) is a verified factor in thyroid carcinogenesis. In recent years, several common low-penetrance genes that cause susceptibility to cancer were identified. The special place among those genes belongs to DNA reparation genes, which included XPD gene. The carrier of polymorphic alleles of this gene increases the risk of breast cancer, gastric cancer, lung cancer, prostate cancer.
The aim of this work is to establish the relationship of polymorphism Lys751Gln of DNA repair gene XPD with the risk of thyroid cancer in patients with exposure to IR. The genotyping of polymorphism Lys751Gln of gene XPD was carried out in 102 patients with thyroid cancer. For comparison of the data on spontaneous and radiation-associated thyroid cancer and settlement of allele frequencies differences and risk of cancer pathology we used literature data on control groups of Polish and Russian populations. Among patients with thyroid cancer with IR history distribution of genotypes did meet Hardy–Weinberg equation. Among patients with thyroid cancer without IR in history distribution of genotypes probably did not meet Hardy–Weinberg equation. It should be noted, that the values obtained c2=3.91 on the verge of critical c2=3.84, so the discrepancy found may be random. The basic factor of disparity of genotypes distribution to Hardy–Weinberg equation can be a greater amount of heterozygotes at proportionally less amount of homozygotes of both types in the study group. There was found no association of polymorphisms Lys751Gl of the gene XPD with the risk of spontaneous and radiation-associated thyroid cancer in patients of the studied groups. The obtained results for the distribution of genotypes frequencies of XPD gene in patients with thyroid cancer are consistent with the compared literature data on the distribution of genotypes frequency of XPD gene in Slavic populations.