A multiple regression analysis, in which the dependent variable was serum leptin levels and independent variables were gender, age, BMI, liver fibrosis and steatosis, transaminase levels, insulin, HOMA-IR and categorized individuals according to their conditions (patients and controls), was performed showing that leptin concentration was jointly significantly correlated with gender, BMI and stage of fibrosis at the baseline liver biopsy in patients with CHB (R2 = 0.6, p = 0.004) and in CHC patients (R2 = 0.72, p = 0.004) . The gene discussed is LEP; the disease is cryohydrocytosis.