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-T1762 and G-to-A1764 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-T1653 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 T1653 and/or V1753 showed a striking increment from chronic hepatitis patients (18%) to liver cirrhosis and/or hep- atoma patients (82%), whereas that of T1762/A1764 was already high in chronic hepatitis patients (76%). In HBe antigen-negative cases, by contrast, significant difference in the frequency of T1653/V1753 mutants was found between blood donors (22%) and chronic hepatitis patients (67%). Our results suggest that T1653/V(particularly C)1753 mutants are more closely associated than T1762/A1764 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 T1653 and C/A1753 more conveniently. Detecting T1653 and C/A1753 by this method would contribute to the differential diagnosis of HBV-associated liver disease.