For the development of combined model, we performed multivariate logistic regression analysis of clinical factors in training cohort, including age, sex, hepatitis B, hepatitis C, cirrhosis, serum alanine aminotransferase (ALT) level, serum aspartate aminotransferase (AST) level, serum gamma-glutamyl transferase (GGT) level, and serum alpha-fetoprotein (AFP) level. The gene discussed is AFP; the disease is hepatitis C virus infection.