While in patients with chronic HBV infection, lower level of HLA-DP protein expression in individuals bearing AA genotype might favor Th1 responses; therefore, on one hand, repeated liver cell injury mediated by inadequate Th1 responses to HBV infection might increase the risk of HBV-related liver cirrhosis and hepatocellular carcinoma. The gene discussed is HLA-DPA1; the disease is hepatocellular carcinoma.