Common variants of the TLR9 gene influence the clinical course of HBV infection

Hepatitis B virus (HBV) infection leads to the development of liver inflammation, causing morbidity and mortality. Multiple factors influence HBV progression, including genetic factors. Toll-like receptor (TLR)9 plays a key role in innate immunity, and Mutations in the genes encoding this receptor have been associated with liver damage progression. Our study aimed to investigate one-tag single nucleotide polymorphisms (rs 187084) representing the majority of common variations in TLR9 in a population-based study of Chinese patients. A total of 209 Chinese patients with HBV infection (130 with chronic hepatitis and 79 with liver cirrhosis) and 193 healthy individuals were studied. Our results showed that the frequencies of the C/C genotype and C allele were statistically higher in patients with HBV-related liver cirrhosis than in the healthy controls (26.6 vs. 15.5%; OR=1.97, 95% Cl 1.05-3.71, chi(2)=4.483, P=0.034/43.1 vs. 37.8%; OR=1.49, 95% CI 1.02-2.16, chi(2)=4.323, P=0.038). No significant differences in the frequencies of alleles or genotypes were found between patients with chronic hepatitis B and the control subjects. In conclusion, this study is the first to show that small effects within TLR9 contribute towards the development of HBV, supporting the hypothesis that little is currently known regarding the contribution of genetic factors to HBV.