title: Anti-Tribbles homolog 2 autoantibodies in Japanese patients with narcolepsy.
abstract: OBJECTIVE
  Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness and cataplexy. The association with human leukocyte antigen (HLA)-DQB1*0602 and T-cell receptor alpha locus suggests that autoimmunity plays a role in narcolepsy. A recent study reported an increased prevalence of autoantibodies against Tribbles homolog 2 (TRIB2) in patients with narcolepsy. To replicate this finding, we examined anti-TRIB2 autoantibodies in Japanese patients with narcolepsy.
  
  
  METHODS
  We examined anti-TRIB2 autoantibodies against a full-length [35S]-labeled TRIB2 antigen in Japanese patients with narcolepsy-cataplexy (n = 88), narcolepsy without cataplexy (n = 18), and idiopathic hypersomnia with long sleep time (n = 11). The results were compared to Japanese healthy controls (n = 87). Thirty-seven healthy control subjects were positive for HLA-DRB1*1501-DQB1*0602. We also examined autoantibodies against another Tribbles homolog, TRIB3, as an experimental control.
  
  
  RESULTS
  Autoantibodies against TRIB2 were found in 26.1% of patients with narcolepsy-cataplexy, a significantly higher prevalence than the 2.3% in healthy controls. We found that anti-TRIB3 autoantibodies were rare in patients with narcolepsy and showed no association with anti-TRIB2 indices. No significant correlation was found between anti-TRIB2 positivity and clinical information.
  
  
  CONCLUSIONS
  We confirmed the higher prevalence and specificity of anti-TRIB2 autoantibodies in Japanese patients with narcolepsy-cataplexy. This suggests a subgroup within narcolepsy-cataplexy might be affected by an anti-TRIB2 autoantibody-mediated autoimmune mechanism.
authors.affiliation: Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Toyoda
authors.forename: Susumu
authors.initials: S
authors.lastname: Tanaka
authors.forename: Taku
authors.initials: T
authors.lastname: Miyagawa
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Honda
authors.forename: Katsushi
authors.initials: K
authors.lastname: Tokunaga
authors.forename: Makoto
authors.initials: M
authors.lastname: Honda
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000276:immunology*; D015551:Autoimmunity / Q000276:immunology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology*; D007564:Japan; D008297:Male; D009290:Narcolepsy / Q000276:immunology*; D011869:Radioligand Assay / Q000379:methods
chemical_list: D001323:Autoantibodies; D047908:Intracellular Signaling Peptides and Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C489044:TRIB2 protein, human