Helicobacter pylori infection causes the defect of mismatch repair (MMR) in eucaryotes, and microsatellite instability (MSI) in gastric epithelial cells, which increases the spontaneous mutation of relative genes, and finally results in the susceptibility to tumors in human bodies. DNA MMR can prevent the excessive proliferation of mutant cells and development of tumors by correcting mismatched bases, which occur in the process of duplication and recombination, and inducing apoptosis of the cells in which DNA had been seriously impaired. The majority of the mutation in mismatch repair gene is the gene mutation in which substitution exceeds the absence or insertion of the single basic group. In MMR, hMLH1 and hMSH2 gene are the main controlling genes. Current research showed that H pylori infection might lead to functional defect of MMR, which had played an important role in the development of gastric carcinomas. In this article, we reviewed the correlations between H pylori infection and DNA mismatch repair system.

• Mismatch repair
• Microsatellite instability
• Helicobacter pylori
• Mutation
• Tumor

AIM: To assess the relationship between XPD single nucleotide polymorphism (SNP) and susceptibility to gastric cancer in Han Chinese from northeast region via a hospital-based, case-control study.

METHODS: Polymerase chain reaction-restriction fragment length polymorphism analysis was used to determine the Asp312Asn and Lys751Gln polymorphisms of XPD gene in 238 patients with gastric cancer and 200 healthy controls. The adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariate logistic regression.

RESULTS: The polymorphism of Lys751Gln was not significantly different between gastric cancer patients and normal controls. The frequency of Asp/Asn and Asn/Asn genotypes in gastric cancer was significantly increased as compared with that in the controls (P = 0.041). Individuals carrying at least one 312Asn variant allele (Asp/Asn and Asn/Asn genotypes) tended to have an increased risk (1.901 times) for gastric cancer as compared with those with the Asp/Asp genotype (OR = 1.901, 95%CI: 1.119-3.229).

CONCLUSION: The Asp312Asn polymorphisms in XPD gene are risky factors of gastric cancer in Han Chinese from northeast region.

• Gastric cancer
• XPD gene
• Single nucleotide polymorphism
• Northeast region