RETN and obesity due to melanocortin 4 receptor deficiency: Obesity may cause chronic inflammation, as obesity is associated with chronic inflammation in obese subjects [26], and secretion of inflammatory adipokines (such as leptin, interleukin (IL-6), tumor necrosis factor-α, monocyte chemoattractant protein-1, and resistin) are also reported to be secreted by adipocytes [27].