title: Gene expression in peripheral blood leukocytes in monozygotic twins discordant for chronic fatigue: no evidence of a biomarker.
abstract: BACKGROUND
  Chronic fatiguing illness remains a poorly understood syndrome of unknown pathogenesis. We attempted to identify biomarkers for chronic fatiguing illness using microarrays to query the transcriptome in peripheral blood leukocytes.
  
  
  METHODS
  Cases were 44 individuals who were clinically evaluated and found to meet standard international criteria for chronic fatigue syndrome or idiopathic chronic fatigue, and controls were their monozygotic co-twins who were clinically evaluated and never had even one month of impairing fatigue. Biological sampling conditions were standardized and RNA stabilizing media were used. These methodological features provide rigorous control for bias resulting from case-control mismatched ancestry and experimental error. Individual gene expression profiles were assessed using Affymetrix Human Genome U133 Plus 2.0 arrays.
  
  
  RESULTS
  There were no significant differences in gene expression for any transcript.
  
  
  CONCLUSIONS
  Contrary to our expectations, we were unable to identify a biomarker for chronic fatiguing illness in the transcriptome of peripheral blood leukocytes suggesting that positive findings in prior studies may have resulted from experimental bias.
authors.affiliation: Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
authors.forename: Andrea
authors.initials: A
authors.lastname: Byrnes
authors.forename: Andreas
authors.initials: A
authors.lastname: Jacks
authors.forename: Karin
authors.initials: K
authors.lastname: Dahlman-Wright
authors.forename: Birgitta
authors.initials: B
authors.lastname: Evengard
authors.forename: Fred A
authors.initials: FA
authors.lastname: Wright
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Pedersen
authors.forename: Patrick F
authors.initials: PF
authors.lastname: Sullivan
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism*; D004200:Diseases in Twins / Q000235:genetics*; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D012313:RNA / Q000378:metabolism; D014430:Twins, Monozygotic
chemical_list: D015415:Biomarkers; D012313:RNA