Indeed, previous studies have showed that DPP4 was a novel adipokine (45) released from immune cells, adipose cells, and bone marrow cells, which correspondingly indicated that sDPP4 concentrations and activity were linked to obesity, metabolic syndrome, T2D, and inflammatory diseases (10, 46, 47). The gene discussed is DPP4; the disease is obesity due to melanocortin 4 receptor deficiency.