SOCS3 and obesity due to melanocortin 4 receptor deficiency: It is known that SOCS3 is able to block LepRb signalling and, since hyperleptinaemia is characterised by high hypothalamic SOCS3 levels, it was hypothesised that the upregulation of SOCS3 in leptin-responsive cells is, therefore, a potential mechanism for leptin resistance, a characteristic feature of human obesity [75].