The aims of the present study were (a) to assess the relationship between serum leptin levels and the stage of liver disease in a cohort of subjects with CHB and CHC, (b) to evaluate the relationship among leptin, insulin and the stage of hepatic fibrosis and (c) to evaluate the effect of body composition, the leptin system and insulin resistance together with viral factors on SVR in patients with CVH receiving antiviral therapy. The gene discussed is LEP; the disease is liver disorder.