The evaluation of several parameters at multiple time points up to 24 weeks without the use of chemicals such as carbon-tetrachloride and avoiding the nutritional deficiency associated with a methionine/choline-deficient diet39, that does not reflect the conditions of human NASH patients, allowed us to demonstrate the sequential biochemical and pathological changes in the presence or absence of CYP2E1. The gene discussed is CYP2E1; the disease is metabolic dysfunction-associated steatohepatitis.