Therefore, the reciprocal effects exerted by HIV infection and the CB2 receptor may explain the different association of severe liver necroinflammation and the CB2 variants: CB2 RR in HIV/HCV coinfected patients who show an aggressive disease with a rapid progression to liver cirrhosis and hepatocellular carcinoma and CB2 QQ in HCV-monoinfected patients with an asymptomatic indolent course of the liver disease. The gene discussed is CNR2; the disease is hepatocellular carcinoma.