Published online May 14, 2014. doi: 10.3748/wjg.v20.i18.5427
Revised: November 20, 2013
Accepted: January 14, 2014
Published online: May 14, 2014
At least 600000 individuals worldwide annually die of hepatitis B virus (HBV)-related diseases, such as chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). Many viral factors, such as viral load, genotype, and specific viral mutations, are known to affect disease progression. HBV reverse transcriptase does not have a proofreading function, therefore, many HBV genotypes, sub-genotypes, mutants, and recombinants emerge. Differences between genotypes in response to antiviral treatment have been determined. To date, 10 HBV genotypes, scattered across different geographical regions, have been identified. For example, genotype A has a tendency for chronicity, whereas viral mutations are frequently encountered in genotype C. Both chronicity and mutation frequency are common in genotype D. LC and progression to HCC are more commonly encountered with genotypes C and D than the other genotypes. Pathogenic differences between HBV genotypes explain disease intensity, progression to LC, and HCC. In conclusion, genotype determination in CHB infection is important in estimating disease progression and planning optimal antiviral treatment.
Core tip: Hepatitis B virus (HBV) infection is the leading cause of chronic liver disease and death worldwide. The clinical course and consequences of HBV infection are affected by several factors such as viral load, mutation, host, environment, and viral genotypes. Different HBV genotypes are associated with different mutations in the HBV precore and core promoter gene regions. HBV genotypes are closely related with optimal treatment strategy for chronic hepatitis B patients and clinical outcomes.