Embase, Web of Science, and OVID-MEDLINE databases were searched for relevant keywords including: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), alpha-fetoprotein (AFP), ceruloplasmin, nucleotidase (NTP), bilirubin, cirrhosis, alcohol, alcoholic, hepatitis, hepatocellular carcinoma (HCC), hemochromatosis and the resulting incidence of POD. The gene discussed is AFP; the disease is hepatitis A virus infection.