title: Neuromyelitis optica-IgG in idiopathic inflammatory demyelinating disorders amongst Hong Kong Chinese.
abstract: BACKGROUND
  Idiopathic inflammatory demyelinating disorders (IIDD) affect the central nervous system. In classical multiple sclerosis (CMS), brain, optic nerves [optic neuritis (ON)] and spinal cord [acute transverse myelitis (ATM)] are affected. In neuromyelitis optica (NMO), optic nerves and spinal cord are predominantly affected. NMO-IgG, an autoantibody targeting aquaporin-4, is a marker for NMO. We studied the frequency and clinical relevance of NMO-IgG seropositivity in IIDD patients.
  
  
  METHODS
  Neuromyelitis optica-IgG was detected by indirect immunofluorescence using primate cerebellum.
  
  
  RESULTS
  Neuromyelitis optica-IgG was detected in six of 10 NMO patients (60%), six of 10 idiopathic relapsing transverse myelitis (IRTM) patients (60%), two of nine idiopathic relapsing ON patients (22%), one of 11 patients (9%) having single ON attack, one of 30 CMS patients (3%), and none of patients having single ATM attack or controls. Comparing NMO-IgG seropositive (n = 12) with NMO-IgG seronegative (n = 8) patients having NMO or IRTM, NMO-IgG seropositivity was associated with a higher relapse rate in first 2 years, 1.5 and 0.6 attacks/year for seropositive and seronegative groups respectively (P = 0.006), and non-significant trend towards more severe ON and myelitis with poorer clinical outcome.
  
  
  CONCLUSIONS
  Neuromyelitis optica -IgG facilitates diagnosis of NMO spectrum disorders. NMO-IgG seropositivity is associated with higher relapse rate in first 2 years.
authors.affiliation: University Department of Medicine, Research Center for Heart, Brain, Hormone and Healthy Aging, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China. koonho@hkucc.hku.hk
authors.forename: K H
authors.initials: KH
authors.lastname: Chan
authors.forename: D B
authors.initials: DB
authors.lastname: Ramsden
authors.forename: Y L
authors.initials: YL
authors.lastname: Yu
authors.forename: K H H
authors.initials: KH
authors.lastname: Kwok
authors.forename: A C Y
authors.initials: AC
authors.lastname: Chu
authors.forename: P W L
authors.initials: PW
authors.lastname: Ho
authors.forename: J S C
authors.initials: JS
authors.lastname: Kwan
authors.forename: R
authors.initials: R
authors.lastname: Lee
authors.forename: E
authors.initials: E
authors.lastname: Lim
authors.forename: M H W
authors.initials: MH
authors.lastname: Kung
authors.forename: S L
authors.initials: SL
authors.lastname: Ho
mesh_terms: D000328:Adult; D000368:Aged; D051401:Aquaporin 4 / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D020274:Autoimmune Diseases of the Nervous System / Q000276:immunology*; D003711:Demyelinating Diseases / Q000276:immunology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000276:immunology; D009188:Myelitis, Transverse / Q000276:immunology; D009471:Neuromyelitis Optica / Q000276:immunology*; D009902:Optic Neuritis / Q000276:immunology; D012008:Recurrence; D055815:Young Adult
chemical_list: C496030:AQP4 protein, human; D051401:Aquaporin 4; D001323:Autoantibodies; D007074:Immunoglobulin G