Hemophilic siblings with chronic hepatitis C: Familial aggregation of spontaneous and treatment-related viral clearance

Genetic variants at the IFNL3 locus and their association with hepatitis C virus infections reveal novel insights into host-virus interactions

Human genetic variation plays a critical role in both spontaneous clearance of and response to interferon (IFN)-based therapies against hepatitis C virus (HCV) as shown by the success of recent genome-wide association studies (GWAS). Several GWAS and later validation studies have shown that single nucleotide polymorphisms (SNPs) at the IFNL3 (formerly IL28B) locus on chromosome 19 are involved in eliminating HCV in human patients. No doubt that this information is helping clinicians worldwide in making better clinical decisions in anti-HCV therapy, but the biological mechanisms involving the SNPs leading to differential responses to therapy and spontaneous clearance of HCV remain elusive. Recent reports including the discovery of a novel IFN (IFN-λ4) gene at the IFNL3 locus and in vitro functional studies implicating 2 SNPs as causal variants lead to novel conclusions and perhaps to new directions in research. An attempt is made in this review to summarize the major findings of the GWAS, the efforts involved in the discovery of causal SNPs; and to explain the biological basis for spontaneous clearance and response to treatment in HCV infections.

Interferon lambda 3 rs12979860 polymorphism in patients with haemophilia and HCV infection: a predictor of spontaneous viral clearance and sustained virological response

Chronic hepatitis C is the main cause of morbidity and mortality in adult haemophilic patients who received non-virally inactivated plasma-derived clotting factor concentrates. Overall, spontaneous viral clearance rate is 10-25% and the only approach that can halt disease progression is hepatitis C virus (HCV) eradication by means of antiviral therapy. In non-haemophilic patients a single nucleotide polymorphism located upstream the gene of interferon lambda 3 (IFNλ3) has been associated with both spontaneous viral clearance and sustained virological response after antiviral treatment. The aim of this study was to assess whether the rs12979860 polymorphism was a predictor of spontaneous viral clearance and of sustained virological response after antiviral therapy in a large cohort of haemophilic patients with HCV infection. The rs12979860 polymorphism, defined as CC genotype or T allele, was tested in a cohort of 342 haemophilic patients and evaluated as predictor of spontaneous clearance or response to antiviral therapy. By multivariate regression analysis the IFNλ3 CC genotype was an independent predictor of spontaneous viral clearance (odds ratio: 3.7, 95% confidence interval: 2.0-6.8). Sustained virological response rates were doubled in patients with the CC genotype than in those with the T allele (78% vs 44%; p<0.001), especially in patients with HCV type 1 (67% vs 32%; p<0.001) and higher sustained response rates were observed in patients with the CC genotype who did not achieve rapid virological response (61% vs 30% in T allele patients; p=0.006).

Genetic polymorphism of IL28B in hepatitis C-infected haemophilia patients in Israel

Single-nucleotide polymorphisms (SNPs) near the IL28B gene were identified as major predictors of treatment response (sustained virologic response--SVR) and spontaneous clearance of HCV. Haemophilia patients have the highest prevalence of HCV, and are a unique target for genetic studies. The Israeli population is ethnically heterogeneous; therefore, genetic variability is anticipated. To determine the IL28B haplotypes in HCV-infected haemophilia patients and association with SVR and spontaneous viral clearance. IL28B polymorphism at SNPs rs12979860 and rs8099917 was determined in sera obtained from 130 HCV-infected haemophilia patients. The frequency of the various haplotypes was analysed according to treatment response, spontaneous HCV clearance, viral load and degree of fibrosis. The CC haplotype at SNP rs12979860 was found in 31% of patients, whereas the TT genotype at SNP rs8099917 was detected in 57% of cases. SVR was achieved in 70% of patients carrying the CC haplotype (P = 0.0196 vs. CT/TT), and 50% of the TT genotype at SNP rs8099917 (P = 0.0227 vs. TG/GG). Thirty-five percent of patients carrying the CC haplotype and 26% with the TT genotype at SNP rs8099917 showed spontaneous clearance of HCV infection (P = 0.00262 vs. CT/TT; and P = 0.00371 vs. TG/GG respectively). The C-allele frequency was exceptionally high (71%) in immigrants from the Asian republics of Russia. In HCV-infected haemophilia patients, SVR was more commonly achieved among patients who had the CC (rs12979860) or TT (rs8099917) genotype. Likewise, patients who possess harbour the CC or TT genotypes were more likely to clear HCV infection spontaneously. A unique distribution of the CC genotype was observed in some ethnic groups.

The natural history of hepatitis C virus infection acquired during childhood

BACKGROUND

The outcome of patients with hepatitis C virus (HCV) infection acquired during childhood in the absence of antiviral therapy is not clear.

AIMS

The purpose of this study was to review the outcome of untreated HCV acquired in childhood. Only population-based studies were included, as referred cases would be predicted to have more severe disease.

METHODS

A systematic review of the literature was completed up to October 2010 to identify studies where a population was screened for HCV infection that was presumably acquired during childhood. Demographical and clinical data were collected on infected patients who had not been treated with an antiviral. Primary outcome was development of a severe adverse outcome (cirrhosis, hepatoma, need for a liver transplant or liver-related death).

RESULTS

There were 25 studies reporting a total of 733 infected patients. Liver biopsy results were provided for 180 patients (25%), revealing cirrhosis in eight (1.0% of the total and 4.0% of those who had a biopsy). None of the other patients developed a severe adverse outcome. As a result of the small number of patients with a severe adverse outcome, risk factors for HCV progression could not be identified.

CONCLUSION

Although HCV can lead to liver transplantation and death during childhood, the vast majority of patients with disease acquired during childhood have slowly progressive disease. There is no clear indication for antiviral therapy in the majority of children with HCV infection.

Effects of a sustained virologic response on outcomes of patients with chronic hepatitis C

For patients with chronic hepatitis C virus infection, the goal of antiviral therapy is to achieve a sustained virologic response (SVR). We review the durability of the SVR and its effects on liver-related mortality, hepatic decompensation, and the development of hepatocellular carcinoma. We performed a systematic review of the effects of the SVR on liver-related hepatic outcomes and found the SVR to be durable (range, 98.4%-100%). An SVR reduced liver-related mortality among patients with chronic hepatitis C (3.3- to 25-fold), the incidence of hepatocellular carcinoma (1.7- to 4.2-fold), and hepatic decompensation (2.7- to 17.4-fold). An SVR can lead to regression of fibrosis and cirrhosis, and has been associated with a reduced rate of hepatic decompensation, a reduced risk for hepatocellular carcinoma, and reduced liver-related mortality.

Molecular and contextual markers of hepatitis C virus and drug abuse

The spread of hepatitis C virus (HCV) infection involves a complex interplay of social risks, and molecular factors of both virus and host. Injection drug abuse is the most powerful risk factor for HCV infection, followed by sexual transmission and additional non-injection drug abuse factors such as co-infection with other viruses and barriers to treatment. It is clearly important to understand the wider context in which the factors related to HCV infection occur. This understanding is required for a comprehensive approach leading to the successful prevention, diagnosis, and treatment of HCV. An additional consideration is that current treatments and advanced molecular methods are generally unavailable to socially disadvantaged patients. Thus, the recognition of behavioral/social, viral, and host factors as components of an integrated approach to HCV is important to help this vulnerable group. Equally important, this approach is key to the development of personalized patient treatment - a significant goal in global healthcare. In this review, we discuss recent findings concerning the impact of drug abuse, epidemiology, social behavior, virology, immunopathology, and genetics on HCV infection and the course of disease.