FGF21 and obesity due to melanocortin 4 receptor deficiency: Peroxisome proliferator-activated receptor alpha (PPARα)is a member of the PPAR protein family and functions as a transcriptionfactor that plays a crucial role in regulating lipid metabolism. PPARα influences lipid metabolism by modulatingthe expression of its downstream target genes, which include fibroblastgrowth factor 21 (FGF21), carnitine palmitoyltransferase 1α(CPT1α), and acyl-CoA oxidase 1 (ACOX1). Activation of PPARα has been shown to lead to a reductionin plasma triglyceride levels, a decrease in obesity, and an improvementin hepatic steatosis.