Inhibitors of DPP-4 (the enzyme that deactivates GLP-1) and GLP-1 analogs that have functions similar to those of GLP-1 have been commercialized for the treatment of diabetes [12,38] and have also recently been used for the treatment of obesity [12,38,39,40]. The gene discussed is DPP4; the disease is obesity due to melanocortin 4 receptor deficiency.