RETN and obesity due to melanocortin 4 receptor deficiency: All known adipokines are markedly dysregulated not only in obesity but also in type 2 diabetes or metabolic syndrome, where adipokines such as resistin, leptin, chemerin, and visfatin-1 implicated in the pathogenesis of inflammation and insulin resistance are overexpressed, and some adipokines with anti-inflammatory properties, such adiponectin and omentin, are decreased [16–21].