ABSTRACT
X-ray repair cross-complementing group 1 [XRCC1] gene is a DNA repair gene and its non-synonymous single nucleotide polymorphisms [SNP] may influence DNA repair capacity which has been considered as a modifying risk factor for cancer development. A case-control study was conducted to investigate impact of three frequently studied polymorphisms [Arg194Trp, Arg280His and Arg399Gln] on developing differentiated thyroid carcinoma [DTC]. Increased risks for DTC were shown in homozygous [odds ratio [OR]: 3.66, 95% confidence interval [CI]: 0.38-35.60] and in dominant trait [OR: 1.22, 95% CI: 1.64-2.32] of Arg194Trp genotype. Also, for Arg280His genotype, an increased risk for DTC was shown in dominant trait [OR: 1.42, 95% confidence interval [CI]: 0.76-2.68], while a mildly reduction of risk for DTC [OR: 0.77, 95% [CI]: 0.50-1.17] was estimated in dominant Gln genotype of Arg399Gln. Considering combinatory effects of Arg194Trp and Arg280His genotypes on DTC, the calculated OR and 95% CI for being heterozygous for one of Arg194Trp or Arg280His genotypes were 1.57 and 0.90-2.74, respectively. Genotyping of codons 194, 280 and 399 in XRCC1 gene may use in risk assessment of DTC