Ectopic fat accumulation can exert lipotoxic effects leading to cellular dysfunction (e.g. impaired cardiac function(17)) and is responsible for metabolic complications of obesity, like insulin resistance, impaired insulin secretion and impaired glucose uptake in various tissues (e.g. Jacob et al.(8) and Thamer et al.(18)). This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.