title: Coenzyme Q deficiency in muscle.
abstract: OBJECTIVE
  Coenzyme Q (CoQ) is a vital component of the mitochondrial respiratory chain. A number of patients with CoQ deficiency presented with different clinical phenotypes, often affecting skeletal muscle, and responded well to CoQ supplementation. We discuss recent advances in this field with special attention to muscle involvement.
  
  
  RESULTS
  The identification of genetic defects causing CoQ deficiency has allowed to distinguish primary forms, due to mutations in biosynthetic genes, from secondary defects caused either by mutations in genes unrelated to CoQ biosynthesis or by nongenetic factors. To date, none of the patients with genetically proven primary deficiency presented with an exclusively (or prominently) myopathic phenotype. Most patients with myopathy were found to harbor other genetic defects (mutations in electron-transferring-flavoprotein dehydrogenase or mitochondrial DNA). The majority of patients with CoQ deficiency still lack a genetic diagnosis. The pathogenesis of CoQ deficiency cannot be attributed solely to the bioenergetic defect, suggesting that other roles of CoQ, including its antioxidant properties or its role in pyrimidine metabolism, may also play crucial roles.
  
  
  CONCLUSIONS
  Early recognition of CoQ deficiency is essential to institute appropriate and timely treatment, thus avoiding irreversible tissue damage.
authors.affiliation: Clinical Genetics Unit, Department of Pediatrics, University of Padova, Italy.
authors.forename: Eva
authors.initials: E
authors.lastname: Trevisson
authors.forename: Salvatore
authors.initials: S
authors.lastname: DiMauro
authors.forename: Placido
authors.initials: P
authors.lastname: Navas
authors.forename: Leonardo
authors.initials: L
authors.lastname: Salviati
mesh_terms: D006801:Humans; D008659:Metabolic Diseases / Q000201:enzymology* / Q000473:pathology; D017240:Mitochondrial Myopathies / Q000201:enzymology / Q000473:pathology; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000473:pathology; D009135:Muscular Diseases / Q000201:enzymology* / Q000473:pathology; D014451:Ubiquinone / Q000172:deficiency* / Q000235:genetics
chemical_list: D014451:Ubiquinone