Published online Mar 27, 2015. doi: 10.4254/wjh.v7.i3.289
Peer-review started: September 20, 2014
First decision: November 14, 2014
Revised: December 4, 2014
Accepted: December 29, 2014
Article in press: December 29, 2014
Published online: March 27, 2015
The Hepatitis B Virus (HBV) has a worldwide distribution and is endemic in many populations. It is constantly evolving and 10 genotypic strains have been identified with varying prevalences in different geographic regions. Numerous stable mutations in the core gene and in the surface gene of the HBV have also been identified in untreated HBV populations. The genotypes and viral variants have been associated with certain clinical features of HBV related liver disease and Hepatocellular carcinoma. For example Genotype C is associated with later hepatitis B e antigen (HBeAg) seroconversion, and more advanced liver disease. Genotype A is associated with a greater risk of progression to chronicity in adult acquired HBV infections. Genotype D is particularly associated with the precore mutation and HBeAg negative chronic hepatitis B (CHB). The genotypes prevalent in parts of West Africa, Central and South America, E, F and H respectively, are less well studied. Viral variants especially the Basal Core Promotor mutation is associated with increased risk of fibrosis and cancer of the liver. Although not currently part of routine clinical care, evaluation of genotype and viral variants may provide useful adjunctive information in predicting risk about liver related morbidity in patients with CHB.
Core tip: Chronic hepatitis B (CHB) is a major global cause of liver related morbidity and mortality. Genotypes of the Hepatitis B virus have distinct geographical distributions and are known to influence a number of clinical features of disease and response to treatment. Certain well recognised viral mutations are also known to influence clinical risk of cirrhosis and hepatocellular carcinoma but in addition may have implications for vaccination programs and screening of blood for donation. This review examines the current state of knowledge about genotype and viral variants of CHB and their utility in the management of this disease.