Moreover, since obesity have been shown to markedly alter the expression pattern of GH/IGF-I axis (as well as SST/CORT and ghrelin systems) in other tissues [56,59], we hypothesized that a similar deregulation may also occur in mammary gland, which could therefore influence the (patho)physiology of the mammary gland. The gene discussed is IGF1; the disease is obesity due to melanocortin 4 receptor deficiency.