Polymorphisms of TLR9 gene are associated with a decreased risk of H. pylori infection in a Chinese population

Background: A series of evidence suggests that genetic variation in toll-like receptor (TLR) 9 might influence the outcome of Helicobacter pylori (H. pylori) infection and play an important role in gastric carcinogenesis. Methods: We conducted a case-control study to evaluate TLR9 polymorphisms on the risk of H. pylori infection and non-cardia gastric cancer (GC) in a Chinese population. We genotyped a tagging singlenucleotide polymorphism (SNP), rs164640, and a potentially functional SNP, rs187084, by TaqMan technique among 288 patients with non-cardia GC and 281 controls. Unconditional logistic regression (LR) was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for SNPs in association with H. pylori infection and non-cardia GC risk. Results: Our results indicated that among normal controls, the minor allele homozygotes of both SNPs were significantly associated with a decreased risk of H. pylori infection when compared with their major allele homozygotes (for rs164640: OR =0.41, 95% CI, 0.18-0.93; for 187084: OR =0.38, 95% CI, 0.17-0.85). However, neither of the two SNPs demonstrated a significant association with non-cardia GC risk. Conclusions: Our results revealed that TLR9 polymorphisms might have effects on the risk of H. pylori infection, but they do not seem to contribute to the risk of non-cardia GC in our studied population.