To define the gene expression profile changes during the progression to NASH, we used hepatic samples from young (16-week-old) and old (48-week-old) mice from three obesity models: hyperphagic ob/ob and db/db mice with disruption of leptin signalling and wt C57BL/6J mice fed a HFD. The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.