CCL13 and obesity due to melanocortin 4 receptor deficiency: The levels of the 4 plasma proteins with the highest importance in the OPLS-DA, namely macrophage inflammatory protein 1-beta (MIP-1β), monocyte chemotactic protein 4 (MCP4), interleukin-1 receptor antagonist protein (IL1RA), and interleukin 6 (IL6) were compared between patients with normal weight (n = 7), overweight (n = 7), and obesity (n = 13) (Fig. 2).