Investigations into the possible association of XRCC1 Arg399Gln, Arg280His, and Arg194Trp polymorphisms with thyroid cancer revealed that hetero- and homozygous XRCC1 Arg399Gln polymorphism coincided with a decreased risk of DTC in the Caucasian population and mixed population (19–22). The gene discussed is XRCC1; the disease is thyroid cancer.