Genetic Testing for Hepatitis C Virus Genotype 2 or 3 Infection

Polymorphisms in the IL28B gene have been shown to play an important role in how patients infected with hepatitis C virus (HCV) genotype 1 develop chronic infection and respond to treatment (JW Gastroenterol Oct 16 2009). Now, researchers have evaluated the potential role of IL28B polymorphisms in patients infected with HCV genotype 2 or 3.

The study was a secondary analysis of a randomized trial in which 283 white patients with HCV genotype 2 or 3 received 12 or 24 weeks of peginterferon alfa-2b (1.0 µg/kg weekly) plus ribavirin (1000–1200 mg daily), depending on whether they had achieved rapid virologic response (RVR; undetectable viral load at 4 weeks; JW Gastroenterol Jul 26 2005). For the present analysis, 268 patients had available clinical, laboratory, and genetic data (IL28B genotyping of the rs12979860 single nucleotide polymorphism).

Of the 268 patients, 37% had IL28B genotype CC, 48% had genotype CT, and 15% had genotype TT. Sustained virologic response (SVR) was achieved by more genotype CC patients (82%) than genotype CT (75%) or TT (58%) patients (P=0.0046). However, this difference was evident only among patients who had not initially achieved RVR (87% SVR for CC vs. 67% for CT and 29% for TT; P=0.0002). In a multivariate analysis, IL28B genotype was a significant, independent predictor of SVR.