To investigate the mechanisms underlying the development and progression of liver damage in obesity-associated conditions, we analyzed the expression of marker genes involved in lipid metabolism (pparg, ppara and sreb1c), hepatic lipogenesis and fatty acid oxidation (creb3l3), inflammation (il6) and fibrosis (tgfb) (Fig. 4). The gene discussed is IL6; the disease is obesity due to melanocortin 4 receptor deficiency.