Situation of the research area and results by the investigator in this area The above data provided the first evidence for a possible pharmacological effect of PPAR agonists on FAO defects in humans. In the last two years, a pilot clinical trial assessing the potential beneficial effects of bezafibrate on the muscular form of CPT II deficiency has been performed in collaboration between Pitié-Salpêtrière and Necker hospitals (appel d'offre AFM 2004). Six adult patients with CPT II-deficiency received a daily 400 mg dose of bezafibrate during 6 months. Clinical tolerance of the treatment was excellent, and muscular symptoms improved in 5/6 patients with a decrease in myalgia intensity and duration. In vitro analyses were carried out on lymphocytes and skeletal muscle, sampled prior to- and at the end of the study. LCFAO in isolated muscle mitochondria was strongly induced in 6/6 patients, and this effect was shown to result from drug-induced up-regulation of CPT2 mRNA and protein levels (Djouadi et al., 2007). However the major endpoints of this study were mainly biochemical analysis, and we were not able to clearly demonstrate a decrease in the frequency of rhabdomyolysis attacks, neither an improvement of in vivo muscle metabolism.