Screening for IL28B gene variants identifies predictors of hepatitis C therapy success.

BACKGROUND

Recent research has shown that genetic variation in the IL28B gene predicts both chronicity of HCV infection and sustained virological response (SVR) to antiviral standard therapy. Because HCV affects 170 million people worldwide and is a leading cause of cirrhosis and hepatocellular carcinoma, screening for prognostic factors in routine clinical practice requires rapid and reliable assays.

METHODS

The frequencies of gene polymorphisms IL28B rs8099917, rs12979860 and rs12980275 were investigated in two cohorts of 89 and 187 unrelated HCV-infected Caucasian patients and 195 non-infected participants. This was carried out by means of newly developed sensitive Pyrosequencing™ screening assays.

RESULTS

The minor alleles were more frequent in patients (n=276) than in controls (n=195), with odds ratios (recessive hereditary model) of 2.2-11.6, indicating a moderate to large genotype effect size. The positive predictive values of the minor alleles for chronicity of HCV infection were 68.3%, 64.8% and 65.8% for rs8099917, rs12979860 and rs12980275, respectively. The minor alleles were also more frequent in patients who had a non-SVR (n=49) than in SVR patients (n=40), with odds ratios of 1.1-3.5 showing a small to moderate genotype effect size. The positive predictive values for non-SVR were 56.9%, 79.2% and 74% for rs8099917, rs12979860 and rs12980275, respectively.

CONCLUSIONS

With the screening for IL28B polymorphisms rs12980275, rs8099917 and rs12979860, which are associated with HCV chronicity and with reduced SVR rates, an important prognostic factor of the therapy of chronic hepatitis C can be easily diagnosed.