IL-17A and IL-17F play an essential role in liver inflammation, fibrogenesis, and the progression of carcinogenesis in various liver diseases, such as hepatitis B and C virus infections (HBV/HCV), non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALD), hepatocellular carcinoma (HCC), and chronic toxic liver injury. The gene discussed is IL17F; the disease is hepatocellular carcinoma.