The aim of this study was to determine the prevalence, types of variants, and clinical significance of mutations in precore, core promoter, and "a" determinant mutations in children with chronic hepatitis B virus infection.

Thirty-one patients with chronic hepatitis B virus infection who visited Seoul National University Children's Hospital in Korea between 2004 and 2005 were enrolled in this study. Serum HBV DNA was amplified by polymerase chain reaction (PCR) and the precore/core promoter and "a" determinant sequences were determined.

Precore mutations were found in 11 of 27 patients (40.7%), and appeared more frequently in the HBeAg-negative group (p<0.05) compared to the HBeAg-positive group. G1896A was detected most frequently (81.8%). BCP mutations were found in 15 of 27 patients (55.6%) and the TA mutation (A1762T/G1764A) was the most common (86.7%). Mutations in the "a" determinant region were detected in 8 of 28 patients (28.6%), and amino acid changes were detected in 6 of 28 patients (21.4%). Of these mutations, substitutions at amino acid position 126 were found most frequently.

In children with chronic hepatitis B virus infection, the most common mutations were G1896A in the precore region and TA mutation(A1762T/G1764A) in the core promoter region. Substitutions at amino acid position 126 was the most common mutation in the "a" determinant. Precore mutants were found to be significantly higher in HBeAg-negative patients. The high prevalence of mutations in the "a" determinant and low frequency of G145R were characteristic features. These mutations were not significantly associated with other clinical features except for high aminotransferase concentration in the core promoter variant group.