Chronic viral hepatitis and the human genome

The immunogenetics of chronic viral hepatitis is an immature field, but the molecular tools are becoming available that will allow a more thorough exploration of this area. Inconsistencies in the data presented may be related to inaccurate and/or low resolution HLA typing methods, linkage disequilibrium between genes, ethnic differences in the populations studied, and small sample sizes. In addition, comparison of HBV studies is complicated by differences in immune responses depending on age at acquisition of infection. Genetic associations found in some of these studies support the hypothesis that there is a genetic basis for viral hepatitis outcomes, but a multi-cohort study may be required to overcome the limitations of previous studies. Finding an association between a gene and a viral hepatitis outcome does not imply causality, but instead it opens new avenues to explore and to understand the pathogenesis of these viruses. Thus, such genetic studies can only begin to answer questions about the factors that influence the outcome of an acute viral hepatitis infection. Further studies based on this information include finding a medical basis for the association and embarking on functional studies of the implicated genes. Such studies can provide clues to the pathogenesis of both HBV and HCV and may provide a rationale on which to base future therapeutic strategies.