Impaired adipogenesis in obesity, associated with reduced downregulation of preadipocyte pro-inflammatory genes and restricted capacity to store excess fatty acid as triglyceride, may contribute to fat tissue inflammation, ectopic lipid accumulation, lipotoxicity, and insulin resistance, as occurs in aging (Unger, 2002; Xu et al., 2002; Listenberger et al., 2003; DeFronzo, 2004; Tchkonia et al., 2006a; Kim et al., 2007). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.