association of arg194trp, arg280his and arg399gln polymorphisms in x-ray repair cross-complementing group 1 gene and risk of differentiated thyroid carcinoma in iran

background: 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. methods: a case-control study was conducted to investigate impact of three frequently studied polymorphisms (arg194trp, arg280his and arg399gln) on developing differentiated thyroid carcinoma (dtc). results: 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. conclusion: genotyping of codons 194, 280 and 399 in xrcc1 gene may use in risk assessment of dtc.