Homozygosity for HLA group 2 alleles predicts treatment failure with interferon-α and ribavirin in chronic hepatitis C virus genotype 1 infection.

Host genetic factors influence treatment responses to antiviral therapy in chronic hepatitis C virus (HCV) infection. We retrospectively investigated associations between host genetic markers and treatment-induced virologic responses to dual therapy with interferon-α and ribavirin in chronically infected HCV genotype 1 (g1)- and genotype 3 (g3)-infected individuals. A total of 171 patients (89 HCV g1 and 82 HCV g3 infected) were investigated for genetic markers influencing treatment-induced sustained virologic response (SVR). Overall, SVR was observed for 46/89 (52%) HCV g1- and 57/82 (70%) HCV g3-infected patients. Of the 4 interleukin 28B (IL28B) single-nucleotide polymorphisms (SNPs), rs12979860 was the host genetic marker most significantly associated with failure to achieve an SVR in HCV g1-infected individuals [P=3.83×10(-4); odds ratio (OR)=5.61; confidence interval (CI)=2.07-15.18] and gave a positive predictive value for treatment failure of 81.3% for minor homozygotes (TT). Using additive (P=3.54×10(-4)) and dominant models (P=3.83×10(-4)), a dosage effect of the T allele was observed, with the dominance term not significant for this SNP. Logistic regression showed an association between HLA-C1/C1 and rapid virologic response in HCV g1 infections with an OR relative to the heterozygote of 10.0 (95% CI: 1.6-62.5, P=0.014). HLA-C2 homozygosity was a significant predictor of nonresponse to treatment in HCV g1-infected individuals (P=0.023).