Clinical features of hepatitis B virus genotype A in Japanese patients.

BACKGROUND: Hepatitis B virus (HBV) genotype A is predominant in northern Europe and central Africa. In the present study, we examined the clinical features associated with HBV genotype A disease in the Tokyo metropolitan area.

METHODS: We investigated 53 cases of HBV surface antigen (HBsAg)-positive Japanese patients with HBV genotype A. The 53 cases were further classified as to their serum alanine aminotransferase (ALT) status being within the normal range (asymptomatic carriers, n = 17), chronic hepatitis (n = 15), liver cirrhosis (n = 4), and acute hepatitis (n = 17).

RESULTS: Chronic hepatitis patients had significantly higher HBV DNA levels (P = 0.003) and hepatitis B e antigen (HBeAg) positivity rates at the initial visit than did asymptomatic carriers or patients with liver cirrhosis (P = 0.003 and P = 0.054, respectively). The efficacy of treatment (HBeAg seroconversion rate) was 75% in 12 chronic hepatitis patients, which was excellent. A family history of HBsAg positivity was identified in eight (15%) families (five asymptomatic carriers, three with chronic hepatitis). However, none of the mothers in the study was positive for HBV genotype A.

CONCLUSIONS: Maternal transmission of HBV has often been reported in Japan, but our present findings suggest that horizontal infection of HBV genotype A is more prevalent in the Tokyo metropolitan area. Our data indicate that HBV genotype A exhibits a mode of infection different from that of conventional HBV previously seen in Japan.