Mutation analysis of hepatitis B virus X gene in hepatitis B virus-associated glomerulonephritis

Objective To determine whether mutation of Hepatitis B virus (HBV) X gene is associated with hepatitis B virus-associated glomerulonephritis (HBV-GN). Methods The venous blood was collected from 50 patients with HBV-GN and 60 patients with asymptomatic HBV carriers (control group). Serum HBV DNA was extracted to determine the serum titer of HBV-DNA and then polymerase chain reaction (PCR) was used to detect the HBV X gene mutation. Results (1)There were not statistical significance between age and gender in HBV-GN group and control group (P＞0.05). There were not statistical significance of serum replication level of HBV DNA in HBV-GN with X gene mutation and control group (P＞0.05). Urine protein excretion in HBV-GN group with or without X gene mutation was found with statistical significance (P＜0.05). (2)Nucleotide mutations 84%(42/50)] resulted in amino acid substitution in HBV-GN. Nucleotide mutations changed in trans-function control region of X gene, including position nt1653, nt1726, nt1727, nt1730, nt1753, nt1762 and nt1764. (3)Nucleotide mutations 8%(5/60)] resulted in amino acid substitution in control group. Nucleotide mutations changed in position nt1632 and nt1635, located in non-functional region. Conclusions HBV X gene mutations and the subsequent amino acid substitutions are found in HBV-GN. The urine protein excretion level increases in patients with X mutation, suggesting that these mutations may play an important role in the pathogenesis of HBV-GN.