Genetic polymorphisms in X-ray repair cross-complementing gene 1 and susceptibility to papillary thyroid carcinoma

Objective To study the association of polymorphisms in the X-ray repair cross-complementing gene 1 (XRCC1) and papillary thyroid carcinoma (PTC). Methods A hospital based, matched case-control study was carried out. The polymorphisms in XRCC1 for 105 pairs of cases with PTC and controls were identified by PCR-RFLP. Results The frequencies of Arg/Arg, Arg/Trp and Trp/Trp genotypes at XRCC1 Arg194Trp site were 47.6 %, 49.5 % and 2.9 % among cases compared to 45.7 %, 48.6 % and 5.7 % among controls. There was no statistically significant difference between the two groups (χ~2=1.07, P=0.59). The frequencies of Arg/Arg, Arg/Gln and Gln/Gln genotypes at XRCC1 Arg399Gln site were 46.7% ,41.9% and 11.4% among cases,while 54.2% ,42.9% and 2.9% among controls respectively. There was statistically significant difference between the two groups (χ~2=6.40, P=0.04). Individuals with Gln/Gln genotype had a 3.65-fold increased risk of developing PTC compared to Arg/Arg genotype (OR=4.65,95% CI: 1.24-17.45 ). The multivariate conditional logistic regression analysis showed that the XRCC1 Arg399Gln polymorphism, negative life events and X-irradiation history were associated with PTC,with odds ratios of 2.71(95% CI: 1.22-6.05),5.34(95% CI:1.40-20.38) and 0.38(95% CI: 0.12-0.72) respectively. However, XRCC1 Arg194Trp polymorphism, drinking tea, fruit and economic levels did not show statistically significant associations with PTC. Conclusion The Gln/ Gln genotype at XRCC1 Arg399Gln site and negative life events significantly increased while X-irradiation history decreased the risk of developing PTC.