title: Altered gene expression and DNA damage in peripheral blood cells from Friedreich's ataxia patients: cellular model of pathology.
abstract: The neurodegenerative disease Friedreich's ataxia (FRDA) is the most common autosomal-recessively inherited ataxia and is caused by a GAA triplet repeat expansion in the first intron of the frataxin gene. In this disease, transcription of frataxin, a mitochondrial protein involved in iron homeostasis, is impaired, resulting in a significant reduction in mRNA and protein levels. Global gene expression analysis was performed in peripheral blood samples from FRDA patients as compared to controls, which suggested altered expression patterns pertaining to genotoxic stress. We then confirmed the presence of genotoxic DNA damage by using a gene-specific quantitative PCR assay and discovered an increase in both mitochondrial and nuclear DNA damage in the blood of these patients (p<0.0001, respectively). Additionally, frataxin mRNA levels correlated with age of onset of disease and displayed unique sets of gene alterations involved in immune response, oxidative phosphorylation, and protein synthesis. Many of the key pathways observed by transcription profiling were downregulated, and we believe these data suggest that patients with prolonged frataxin deficiency undergo a systemic survival response to chronic genotoxic stress and consequent DNA damage detectable in blood. In conclusion, our results yield insight into the nature and progression of FRDA, as well as possible therapeutic approaches. Furthermore, the identification of potential biomarkers, including the DNA damage found in peripheral blood, may have predictive value in future clinical trials.
authors.affiliation: Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.
authors.forename: Astrid C
authors.initials: AC
authors.lastname: Haugen
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Di Prospero
authors.forename: Joel S
authors.initials: JS
authors.lastname: Parker
authors.forename: Rick D
authors.initials: RD
authors.lastname: Fannin
authors.forename: Jeff
authors.initials: J
authors.lastname: Chou
authors.forename: Joel N
authors.initials: JN
authors.lastname: Meyer
authors.forename: Christopher
authors.initials: C
authors.lastname: Halweg
authors.forename: Jennifer B
authors.initials: JB
authors.lastname: Collins
authors.forename: Alexandra
authors.initials: A
authors.lastname: Durr
authors.forename: Kenneth
authors.initials: K
authors.lastname: Fischbeck
authors.forename: Bennett
authors.initials: B
authors.lastname: Van Houten
mesh_terms: D000293:Adolescent; D000328:Adult; D002478:Cells, Cultured; D002648:Child; D015331:Cohort Studies; D004249:DNA Damage; D005260:Female; D005621:Friedreich Ataxia / Q000235:genetics* / Q000473:pathology*; D015870:Gene Expression; D006801:Humans; D033862:Iron-Binding Proteins / Q000235:genetics; D008297:Male; D008875:Middle Aged; D012313:RNA / Q000097:blood* / Q000235:genetics; D055815:Young Adult; D000096923:Frataxin
chemical_list: D033862:Iron-Binding Proteins; D012313:RNA; D000096923:Frataxin