title: Narcolepsy without cataplexy: 2 subtypes based on CSF hypocretin-1/orexin-A findings.
abstract: OBJECTIVE
  Cerebrospinal fluid (CSF) hypocretin-1 levels and their relationship with the clinical characteristics of narcolepsy without cataplexy have not been well elucidated. Our aim was to examine whether clinical characteristics vary with CSF hypocretin-1 levels among narcoleptic patients without cataplexy.
  
  
  METHODS
  Clinical features, variables on the multiple sleep latency test, and results of HLA typing were correlated with CSF hypocretin-1 levels.
  
  
  METHODS
  University-based sleep laboratories and a sleep disorders center.
  
  
  METHODS
  Seventeen patients (5 male, 12 female) who fulfilled the diagnostic criteria of narcolepsy without cataplexy according to the International Classification of Sleep Disorders. INERVENTIONS: Patients underwent lumbar puncture for CSF sampling.
  
  
  RESULTS
  Five patients showed a markedly decreased CSF hypocretin-1 level, whereas the remaining 12 patients showed almost normal levels. The mean rapid eye movement (REM) latency was significantly shorter and the age at onset was significantly earlier in the low CSF hypocretin-1 group compared with the normal CSF hypocretin-1 group. HLA-DR2 was positive in all of the patients with low CSF hypocretin-1, whereas only 33.3% of patients with normal CSF hypocretin-1 were DR2 positive.
  
  
  CONCLUSIONS
  Some narcoleptic patients without cataplexy have low CSF hypocretin-1 levels. In patients who have narcolepsy without cataplexy, short mean REM latency, younger age at onset, and HLA-DR2 are associated with CSF hypocretin-1 deficiency. Markedly decreased CSF hypocretin-1 levels could be a significant marker for identifying subgroups of narcolepsy patients without cataplexy.
authors.affiliation: Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, 606-8507 Kyoto, Japan. yoka@kuhp.kyoto-u.ac.jp
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Oka
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanbayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Kuroda
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyamoto
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Akio
authors.initials: A
authors.lastname: Ikeda
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Shimizu
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Hishikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shibasaki
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002385:Cataplexy / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D005838:Genotype; D015802:HLA-DR2 Antigen / Q000235:genetics; D006650:Histocompatibility Testing; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000235:genetics; D009479:Neuropeptides / Q000134:cerebrospinal fluid*; D064446:Orexin Receptors; D000068797:Orexins; D017286:Polysomnography; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000172:deficiency*; D018013:Receptors, Neuropeptide / Q000172:deficiency*; D012895:Sleep, REM / Q000502:physiology; D013223:Statistics as Topic
chemical_list: D015415:Biomarkers; C000596229:HCRT protein, human; D015802:HLA-DR2 Antigen; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide