RETN and obesity due to melanocortin 4 receptor deficiency: Eight studies [6, 16, 17, 19, 23–26] reported similar levels of cytokine (resistin, adiponectin, leptin, IL-6, IL-8, IL-10, IL1β, TNF-α, CRP, and PAI-1) among CP patients with and without obesity, while 5 studies [6, 16, 20, 25, 26] showed significantly higher levels of cytokine (IL-8, IL-1β, TNF-α, progranulin, MCP-4, and lipocalin) in obese CP patients as compared to nonobese CP subjects.