As mentioned above, the infantile onset patients with PCD principally present hypotonia, Reye-like syndrome and cardiomyopathy. However, the cardiomyopathy may develop solely or with a milder metabolic presentation during childhood or even older age (15). Since skeletal muscle uses fatty acid as a major energy source, muscle weakness can also be observed in PCD patients. Some patients,

who have been asymptomatic for their whole life, may be identified because of their affected children or siblings (16, 17). There is no clear correlation between genotype and either clinical or biochemical phenotype yet reported, suggesting that the wide Inhibitors,research,lifescience,medical phenotypic variability may be related to Inhibitors,research,lifescience,medical epigenetic or exogenous factors which exacerbate carnitine deficiency (18). Common blood tests may reveal increased levels of hepatic enzymes

and CK. As for the diagnosis of PCD, the measurement of free carnitine and all acylcarnitine species is essential and both extremely low levels are indicative of PCD. Secondary carnitine deficiency should be carefully excluded which may show decreased free carnitine level but elevated specific species of acylcarnitine. However, as plasma carnitine Inhibitors,research,lifescience,medical level can occasionally be normal in PCD, carnitine further info transport study in fibroblasts may also be used to confirm the diagnosis. On muscle pathology, markedly increased lipid droplets in both number and size in muscle fibers are seen, especially in type 1 fibers (Fig. 2B). Ultrastructural study often shows that lipid droplets are present Inhibitors,research,lifescience,medical next to mitochondria which are usually enlarged but structurally normal. Moreover, as PCD is caused by the defect of OCTN2, searching for the mutations in SLC22A5 is another way to establish the

diagnosis of PCD. PCD patients are well responsive to carnitine supplementation (100-400 mg/kg per day). Early carnitine therapy has been believed to prevent the occurrence Inhibitors,research,lifescience,medical of cardiomyopathy and other irreversible organ damage (18). In recent years, activation of peroxisome proliferator-activated receptor α (PPARα) has been proved to cause an up-regulation of OCTN2, leading to an increase of intracellular carnitine concentration in animal models (19, AV-951 20). Therefore, PPARα agonists may be potential candidates for treating PCD patients in addition to carnitine supplementation. Multiple acyl-coenzyme A dehydrogenase deficiency (MADD) MADD, also known as glutaric aciduria type II, is caused by the defects in electron transfer flavoprotein (ETF), ETF dehydrogenase (ETFDH) (also called ETFubiquinone oxidoreductase), or an unidentified abnormality in flavin metabolism or transport. In mitochondria, ETF, which is located in the matrix, receives electron from several dehydrogenases involved in fatty acid oxidation. Electrons are then transferred to ETFDH, located in the inner mitochondrial membrane, and subsequently, are passed to ubiquinone in the respiratory chain (Fig. 1).