Clinical and virological characteristics of untreated patients with chronic hepatitis C who develop serum alanine aminotransferase flare-up.

Among patients with chronic hepatitis C virus (HCV) infection, serum alanine aminotransferase (ALT) rarely increases above 500 IU/L. We examined the clinical and virological features of untreated patients with serum ALT > or = 500 IU/L. One thousand seven hundred and sixty adult patients with chronic HCV infection were followed-up. Among these patients, 22 developed ALT flare-up (M:F=13:9, median age, 50.5 years). We evaluated liver function tests, genotype, and viral titer in these patients and 44 randomly selected age- and sex-matched control without ALT flare-up. In four patients with ALT flare-up, we examined changes in viral loads and sequential changes in amino acid sequences of the core region, hypervariable region 1 (HVR1), and interferon sensitivity determining region (ISDR) before and after ALT flare-up. Multivariate analysis identified genotype 2 as the only significant determinant of ALT flare-up. ALT flare-up occurred in three of four patients without increase in viral load. Several alterations in amino acids were noted in HVR1 before and within 6 months of ALT flare-up. One or two alterations in the core region and many alterations in HVR1 were noted after ALT flare-up in some patients. Genotype 2 is an important factor for ALT flare-up. However, we could not directly relate ALT flare-up to these alterations in amino acids of the core region, HVR1, and ISDR.