Furthermore, since clinical data reported that rheumatoid arthritis patients treated with PPAR agonists for type 2 diabetes or dyslipidemia are paradoxically suffering from osteoarthritis [46], the proof of concept that PPAR agonists have therapeutical relevance may benefit from an epidemiological study of joint lesions in patients with advanced osteoarthritis treated for long periods of time with PPAR α > γ (pioglitazone) or PPAR α (fibrate, Wy14643) agonists. The gene discussed is PPARA; the disease is metabolic syndrome.