PPARA and obesity due to melanocortin 4 receptor deficiency: An extensive research effort into PPARs, much of it published since 2001, has been set off by evidence that highly prevalent chronic diseases such as diabetes, obesity, atherosclerosis, and cancer may involve PPAR activity and may be affected by PPAR agonists such as thiazolidinediones and fibrates (Kersten et al. 2000).