Background and objective: Mutations in DNA repair system are related to carcinogenesis. This study was to evaluate the correlations of polymorphisms and haplotypes of XPD gene with individual susceptibility to gastric cancer.
Methods: Genomic DNA were extracted from peripheral blood leukocytes of 207 gastric cancer patients and 212 healthy controls. Genotypes at codon 312 and codon 751 polymorphic sites were identified by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) or polymerase chain reaction-restriction fragment length polymorphism (PCR-PFLP), respectively.
Results: At codon 312, the frequency of GA or AA genotype was higher in the gastric cancer patients than in the healthy controls (P<0.01, OR=3.41, 95% CI: 2.06-4.79; P<0.01, OR=3.47, 95% CI: 1.39-8.68). No significant difference was found in the distribution of the polymorphism at codon 751 between the two groups (P>0.05). By the haplotype AA (codon 312A-codon 751A) analysis, the frequency of heterozygote (-/AA) or homozygote (AA/AA) was higher in the patients than in the controls (P<0.01,OR=2.81, 95% CI:1.82-4.34;P=0.02,OR=3.92, 95% CI:1.31-11.70, respectively). Whereas there were no significant differences of the other three haplotypes between the patients and the controls (P>0.05).
Conclusions: The polymorphism of XPD at codon 312 might contribute to the etiology of gastric cancer. The haplotype AA (codon 312A-codon 751A) would be a critical risk factor of the susceptibility to gastric cancer.