[Correlations of single nucleotide polymorphisms of DNA repair gene XRCC1 to risk of colorectal cancer].

X-ray repair cross complementing group 1 (XRCC1) encodes a protein required for DNA base excision repair and single strand break recombination repair. The polymorphisms of XRCC1 affect the function of the protein, therefore, affect the susceptibility of human to cancers. This population-based case-control study was to examine the correlations of the 3 most common single nucleotide polymorphisms (SNPs) of XRCC1 gene, C26304T, G27466A and G28152A, to risk of colorectal cancer. XRCC1 genotypes in 207 colorectal cancer patients and 621 matched healthy controls were analyzed by polymerase chain reaction-restrictive fragment length polymorphism (PCR-RFLP). The adjusted odds ratio (OR) and 95% confidence interval (CI) were calculated using unconditional logistic regression model to evaluate the correlations of the 3 genotypes to risk of colorectal cancer. The haplotype distribution was estimated by EH linkage software 1.2. There was no significant differences in selected characteristics, such as age, sex, body mass index, cigarette-smoking and alcohol-drinking status, between the patients and the controls. The frequencies of mutant 26304T, 27466A, and 28152A alleles were 29.95%, 11.22%, and 28.22%, respectively, in the patients, and 32.87%, 12.34%, and 27.27%, respectively, in the controls; there was also no significant difference between the 2 groups. All the polymorphic genotypes met the Hardy-Weinberg equilibrium. No significant correlation of XRCC1 C26304T, G27466A, and G28152A polymorphisms to risk of colorectal cancer was found. Estimated by EH linkage software 1.2, genetic linkage disequilibrium existed both in the patients and the controls, and CGG, CGA, CAG, and TGG were the 4 most common haplotypes. However, there was no significant difference in haplotype distribution between the 2 groups (95.54% vs. 96.64%, P>0.05). In Han people in southern China, XRCC1 C26304T, G27466A, and G28152A polymorphisms have no correlations to risk of colorectal cancer. However, the genetic linkage disequilibrium exists in these 3 polymorphic sites, and CGG, CGA, CAG, and TGG are the 4 most common haplotypes.