A Study on HBV Precore Mutant in Liver Tissues of Chronic Hepatitis B Patiets

Chung, Hae Chul; Park, Yeong Hong; Chung, Jung Myung

Abstract

BACKGROUND/AIMS: In order to determine the relationship between the HBV precore mutant and the severity of liver disease in Korea, we performed liver biopsies in patients with HBV related chronic liver disease and compared the types of mutations and histologic findings in the same liver tissue simultaneously.
METHODS
HBV DNA in liver tissues was amplified by polymerase chain reaction (PCR). The precore mutants were detected by PCR-SSCP(single strand conformation polymorphism), cloning the amplified PCR products and direct sequencing for them.
RESULTS
1. HBV DNA was detected in liver tissues of 28 cases among 30 patients with PCR. And with SSCP, the most cases were mixed type infections. 2. The HBV precore mutants were found in 12 cases among the total number of 28 cases(42.9%) and all mutations were G to A change at nucleotide 1896, creating a stop codon at codon 28. However, 10 cases among 12 mutants were associated with simultaneous another mutation at different positions or regions;9 cases at core gene region, 2 cases at nucleotide 1856(C to T change at codon 15), one case at core promoter, and one case with double mutations at nucleotide 1837 and 1846 respectively. Also, all HBV precore mutants were combined with wild type HBV sequence. 3. The relationship between HBV precore mutants and HBeAg status revealed that 4 cases from 13 HBeAg positive(30.8%) and 8 from 15 HBeAg negative or Anti-Hbe positive(53.3 %) were mutants. 4. In analysis of the types of mutants and histopathological findings of liver diseases, 6 among 15 chronic active hepatitis(40.0%), all 3 cases with hepatocellular carcinoma(100,0 %), 2 among 4 asymptomatic carriers with minimal histopathologic changes(50.0%) and a case with chronic lobular heaptitis(100.0%) showed precore region mutation.
CONCLUSION
The patterns of HBV precore mutants in Korea could be summarized as followings. Firstly, most of the mutations are composed of G to A change at nucleotide 1896. Secondly, the most of the mutants at nuclmtide 1896 have been associated with simultaneous mutations at core promoter, core gene, and rarely at other positions, and manifested usua'ly mixed type viremic conditions. Thirdly, although precore mutation could be occurred in asymptomatic carrier, this type of mutation might be closely related with chronic or severe liver disease. However, it needs further investigations hereafter.