Genotypes of hepatitis C virus in Taiwan and the progression of liver disease.

The existence of four genotypes of hepatitis C virus (HCV)--types 1a, 1b, 2a, and 2b--has been suggested based on variations in nucleotide sequences of the core region. The aim of this study was to investigate the prevalence of HCV genotypes in chronic type C liver disease in Taiwan and correlate distinct genotypes to severity of liver disease. The genotypes of 175 patients with chronic type C liver disease were determined by a polymerase chain reaction with type-specific primers. The prevalence of each genotype in Taiwan was as follows: type 1a, n = 1 (0.6%); 1b, n = 125 (71.4%); 2a, n = 21 (12%); 2b, n = 6 (3.4%); mixed types, n = 18 (10.3%); and unclassified, n = 4 (2.3%). The demographic and clinical features were comparable between patients with different genotypes, except that the mean peak serum transaminase levels of patients with double viruses and type 1b HCV infections were significantly higher than were those of patients with type 2a virus. Moreover, type 1b HCV was more prevalent in patients with liver cirrhosis alone or with hepatocellular carcinoma. In conclusion, type 1b virus is the predominant genotype in chronic hepatitis C in Taiwan, and type 1b virus and mixed infection may trigger more severe liver disease.