The natural history of chronic hepatitis B.

The natural history of chronic hepatitis B is dependent on the age of acquiring the hepatitis B infection. Those who are infected at adolescence or adulthood (including most of the Caucasians) tend to have stable disease after hepatitis B e antigen seroconversion with normal serum alanine aminotransaminase (ALT) and hepatitis B virus (HBV) DNA levels <10(5) copies/mL (20 000 IU/mL). In contrast, those who are infected at birth or early childhood (including the majority of the world's hepatitis B carriers, i.e. Asians) have a prolonged immune tolerance phase followed by a prolonged immune clearance phase. A proportion of these patients have progressive disease after HBeAg seroconversion with HBV DNA <10(4) copies/mL (<2000 IU/mL) and ALT between 0.5 and 2x upper limit of normal. Core promoter mutations may play a part in the development of cirrhosis-related complications. However, continuing viral replication, even at a relatively low level of <10(4) copies/mL (<2000 IU/mL), is probably the most important factor for the development of complications.