title: [Clinical spectrum associated with aquaporin-4 antibodies (NMO-IgG)].
abstract: BACKGROUND
  The description of a highly sensitive and specific biomarker for neuromyelitis optica (NMO-IgG/aquaporin-4 antibody) extended the clinical spectrum of NMO to limited forms such as optic neuritis (ON) and longitudinally extensive myelitis (LEM).
  
  
  OBJECTIVE
  To asses the sensitivity and specificity of our assay, and to describe the clinical characteristics of the patients who were tested for NMO-IgG.
  
  
  METHODS
  NMO-IgG was analysed by immunohistochemistry and confirmed by assay on HEK cells transfected with aquaporin-4. The clinical information was obtained from forms filled in by the referring neurologists.
  
  
  RESULTS
  A total of 580 samples from 518 patients were analysed from November 2005 to September 2008. Clinical information was available from 358 (68%) patients. All 33 (100%) positive cases were followed up. Twenty-eight of the 43 (65%) patients diagnosed with NMO by the revised criteria of 2006 were positive; the sensitivity was 62.5% when applying the same criteria, but discounting the criterion of NMO-IgG status, or 57% when applying the criteria of 1999. NMO-IgG was detected in 3 (13%) of the recurrent LEM and 2 (4%) of the recurrent ON. NMO-IgG was not detected in the remaining patients (96 with a final diagnosis of multiple sclerosis; 80 with myelitis; 28 with non-recurrent ON; and 33 other diagnosis).
  
  
  CONCLUSIONS
  No false positive cases were found in this large and non-selected study. NMO-IgG positive cases were mostly associated with NMO, and only in a low percentage with recurrent ON or LEM.
authors.affiliation: Servei de Neurologia, Hospital Clínic, Universitat de Barcelona e Institut d'Investigació August Pi i Sunyer (IDIBAPS), Barcelona, España.
authors.forename: Y
authors.initials: Y
authors.lastname: Blanco
authors.forename: K
authors.initials: K
authors.lastname: Hankiewicz
authors.forename: S
authors.initials: S
authors.lastname: Llufriu
authors.forename: L
authors.initials: L
authors.lastname: Sabater
authors.forename: F
authors.initials: F
authors.lastname: Graus
authors.forename: A
authors.initials: A
authors.lastname: Saiz
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D051401:Aquaporin 4 / Q000235:genetics / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D002648:Child; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009471:Neuromyelitis Optica / Q000276:immunology / Q000473:pathology / Q000503:physiopathology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D051401:Aquaporin 4; D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G