Clinical implications of mutations C-to-T1653 and T-to-C/A/G1753 of hepatitis B virus genotype C genome in chronic liver disease

Among many mutational "hot spots" on hepatitis B virus (HBV) genome, A-to-T-1762 and G-to-A(1764) within the core promoter have been underscored in view of disease association as well as viral expression/replication. Although to a lesser extent, C-to-T-1653 and T-to-V(C/A/G)(1753) were also noteworthy in our previous study. To assess the clinical significance of these mutations, we determined the nucleotide sequence of an HBV DNA fragment covering these sites in HBsAg-positive blood donors (n=160) and patients with chronic hepatitis (n=66), liver cirrhosis (n=45), and hepatocellular carcinoma (n=58), most of whom were infected with genotype C HBV (subtype adr). In cases where HBe antigen was positive, the frequency of T-1653 and/or V-1753 showed a striking increment from chronic hepatitis patients (18%) to liver cirrhosis and/or hepatoma patients (82%), whereas that of T-1762/A(1764) was already high in chronic hepatitis patients (76%). In HBe antigen-negative cases, by contrast, significant difference in the frequency of T-1653/V-1753 mutants was found between blood donors (22%) and chronic hepatitis patients (67%). Our results suggest that T-1653/V(particularly C)(1753) mutants are more closely associated than T-1762/A(1764) with the progression of liver disease from chronic hepatitis to cirrhosis in HBe antigen-positive patients. A system of site-directed mutagenesis PCR RFLP was constructed to diagnose T-1653 and C/A(1753) more conveniently. Detecting T-1653 and C/A(1753) by this method would contribute to the differential diagnosis of HBV-associated liver disease.