title: Correlation of frataxin content in blood and skeletal muscle endorses frataxin as a biomarker in Friedreich ataxia.
abstract: BACKGROUND
  Friedreich ataxia is an autosomal recessive disorder caused by mutations in the frataxin gene, leading to reduced levels of the mitochondrial protein frataxin. Assays to quantitatively measure frataxin in peripheral blood have been established. To determine the validity of frataxin as a biomarker for clinical trials, we assessed frataxin in clinically affected tissue.
  
  
  METHODS
  In 7 patients with Friedreich ataxia, frataxin content was measured in blood and skeletal muscle before and after treatment with recombinant human erythropoietin, applying the electrochemiluminescence immunoassay.
  
  
  RESULTS
  We found frataxin content to be correlated in peripheral blood mononuclear cells and skeletal muscle in drug-naive patients with Friedreich ataxia. The correlation of frataxin content in both compartments remained significant after 8 weeks of treatment. Skeletal-muscle frataxin values correlated with ataxia using the Scale for the Assessment and Rating of Ataxia score.
  
  
  CONCLUSIONS
  Our results endorse frataxin measurements in peripheral blood cells as a valid biomarker in Friedreich ataxia.
authors.affiliation: Department of Neurology, Medical University Innsbruck, Innsbruck, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Nachbauer
authors.forename: Julia
authors.initials: J
authors.lastname: Wanschitz
authors.forename: Hannes
authors.initials: H
authors.lastname: Steinkellner
authors.forename: Andreas
authors.initials: A
authors.lastname: Eigentler
authors.forename: Brigitte
authors.initials: B
authors.lastname: Sturm
authors.forename: Kurt
authors.initials: K
authors.lastname: Hufler
authors.forename: Barbara
authors.initials: B
authors.lastname: Scheiber-Mojdehkar
authors.forename: Werner
authors.initials: W
authors.lastname: Poewe
authors.forename: Markus
authors.initials: M
authors.lastname: Reindl
authors.forename: Sylvia
authors.initials: S
authors.lastname: Boesch
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D004185:Disability Evaluation; D004921:Erythropoietin / Q000627:therapeutic use; D005260:Female; D005621:Friedreich Ataxia / Q000097:blood* / Q000188:drug therapy / Q000473:pathology*; D006801:Humans; D033862:Iron-Binding Proteins / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D013223:Statistics as Topic; D013997:Time Factors; D000096923:Frataxin
chemical_list: D015415:Biomarkers; D004921:Erythropoietin; D033862:Iron-Binding Proteins; D000096923:Frataxin