Currently there are no FDA-approved PPARβ/δ drugs, but the recent development of highly specific and selective agonists and antagonists [selective PPARβ/δ modulators (SPPARMs)] such as GW501516, GW0742, GSK0660 and GSK3787 have led to improved approaches to study the PPARβ/δ pathway in disease models including obesity and atherosclerosis [55]. The gene discussed is PPARD; the disease is obesity due to melanocortin 4 receptor deficiency.