Interleukin-28B (IL-28B) single-nucleotide polymorphisms and interferon plus ribavirin treatment outcome in Italian chronically HCV-infected patients.

To determine the single or combined effect of both rs12979860 and rs8099917 SNPs on HCV treatment response, these variants were genotyped in samples from a cohort of 170 patients infected with different HCV genotypes (HCVGT). The favourable rs12979860 CC genotype was found only in patients with sustained or rapid virological responses (SVR/RVR) and at significantly high proportions in HCVGT1/4 SVR patients. A significant association was also found between the rs8099917 TT genotype and SVR in both HCVGT1/4 and HCVGT2/3 groups of patients. In contrast, we found that there was significantly more of the rs8099917 GG genotype in nonresponders (NR) than in SVR patients which suggests a good association of the minor homozygote GG with the lack of treatment response. The combination of rs12979860/rs8099917 CC/TT favourable genotypes was found only in SVR patients and matched the frequency observed for their rs12979860 CC genotypes alone. By contrast, the inverse unfavourable correlate rs12979860/rs8099917 TT/GG genotype was seen more in NR than in SVR patients as observed for the single GG genotype. This study confirms the impact of both rs12979860 and/or rs8099917 IL-28B SNPs on treatment-induced clearance of HCV-RNA and demonstrates that the rs12979860 CC genotype is stronger than rs8099917 TT genotype in predicting a positive treatment response in HCVGT1/4 patients. The unfavourable rs8099917 GG genotype seems to be more important in predicting the failure of treatment response independently from HCV genotype.