Additionally, upregulation of FTO/CX3CL1 and suppressor of cytokine signaling 3 (SOCS3) in the hypothalamus impairs leptin- and signal transducer and activator of transcription 3 (STAT3) signaling, resulting in leptin resistance and obesity [234]. Here, SOCS3 is linked to obesity due to melanocortin 4 receptor deficiency.