Published online May 7, 2016. doi: 10.3748/wjg.v22.i17.4287
Peer-review started: February 17, 2016
First decision: March 7, 2016
Revised: March 10, 2016
Accepted: April 7, 2016
Article in press: April 7, 2016
Published online: May 7, 2016
Despite the availability of an effective vaccine, hepatitis B virus (HBV) infection remains a major health problem, with more than 350 million chronically infected people worldwide and over 1 million annual deaths due to cirrhosis and liver cancer. HBV mutations are primarily generated due both to a lack of proofreading capacity by HBV polymerase and to host immune pressure, which is a very important factor for predicting disease progression and therapeutic outcomes. Several types of HBV precore/core (preC/C) mutations have been described to date. The host immune response against T cells drives mutation in the preC/C region. Specifically, preC/C mutations in the MHC class II restricted region are more common than in other regions and are significantly related to hepatocellular carcinoma. Certain mutations, including preC G1896A, are also significantly related to HBeAg-negative chronic infection. This review article mainly focuses on the HBV preC/C mutations that are related to disease severity and on the HBeAg serostatus of chronically infected patients.
Core tip: The presence of several distinct types of mutations in HBV infections has been shown to contribute to the progression of liver disease in chronically infected patients. Although the relationships between single mutation types in the preC/C region and clinical severity have rarely been studied to date, it was recently reported that some preC/C mutations, particularly in the MHC class II restricted region, are significantly correlated with hepatocellular carcinoma. Several preC/C mutations, including preC G1896A, are also related to HBeAg sero-negative status, which can affect the disease progression of chronic patients. Mutations such as I97F/L or P135Q, which inhibit core nucleocapsid formation, also contribute to disease progression by evading host innate immunity. In addition, the P5H/L/T mutation may lead to hepatocarcinogenesis by inducing the ER stress-ROS axis. In this review, we mainly focus on the clinical implications of the reported preC/C mutations.