Genetic susceptibility in chronic viral hepatitis.

Infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) may result in a number of different clinical outcomes. There is strong evidence in HBV infection that host genetic factors play a major role in determining the outcome of infection. A number of approaches may be used to determine the specific genetic factors involved but the principal method which has been used to date is the disease association study. Disease association studies have a number of drawbacks but trials with well-constructed designs and large numbers of cases have recently produced compelling and reproducible results. In particular alleles in the MHC class II loci and interleukin 10 promoter have been demonstrated to influence the outcome of these infections.