Analysis of Reverse Transcriptase Gene Mutations in the Hepatitis B Virus at a University Hospital in Korea

Background: Most mutations in the reverse transcriptase (RT) gene of the hepatitis B virus (HBV) are related to resistance to antiviral agents. Cross-sectional studies on the mutations of this gene are rare. Thus, we analyzed the mutation patterns of RI genes and their biochemical parameters. Methods: From 2009 to 2012, 301 blood specimens from patients with chronic hepatitis B at Daegu Catholic University Medical Center were retrospectively analyzed for the RT gene sequence of HBV, ALT, hepatitis B e antigen (HBeAg), and HBV DNA. The mutation patterns of the RI gene were compared with the biochemical parameters. Results: Of the 301 patients, 100 (33.2%) had no RI gene mutations. The remaining showed the following mutation patterns: rtM204IN (50.2%), rtL180M (39.2%), and rtA181TN (19.6%). Combined mutations were found in 146 cases (48.5%). Of these, the combination of amino acid changes at rt180+rt204 (49.3%) was most frequently detected, followed by rt181+rt236 (11.0%) and rt173+rt180+rt204 (9.6%). In the mutated group, HBV DNA and HBeAg positive rates were significantly higher (P<0.05 for both). Phenotypic analysis showed that lamivudine resistance was most frequently detected (34.6%), followed by adefovir resistance (15.6%). Multidrug resistance was detected in 48 cases (15.9%). The adefovir-resistant group had a higher proportion of cases with HBV loads greater than 2,000 IU/mL. Conclusions: We found correlations between the mutation status of the RI domain and biochemical parameters such as HBV DNA and HBeAg positive rate. The presence of RI gene mutations could therefore be utilized to predict clinical status.