title: The Diagnostic Utility of Determining Anti-GM1: GalC Complex Antibodies in Multifocal Motor Neuropathy: A Validation Study.
abstract: BACKGROUND
  Multifocal motor neuropathy (MMN) is associated with IgM antibodies to GM1 ganglioside. The importance of the lipid milieu that might facilitate or inhibit antibody binding to GM1 in immunoassays is well recognised. Existing studies, using a range of different approaches, generally concur that anti-GM1 IgM antibody detection rates are improved by the addition of galactocerebroside (GalC) to the GM1 assay.
  
  
  OBJECTIVE
  The current study sought to formally evaluate the clinical utility of the GM1:GalC complex assay in the diagnosis of MMN.
  
  
  METHODS
  Anti-GM1 and -GM1:GalC antibodies were examined using ELISA and glycoarray (dot blot) in a fully blinded study design, consisting of 100 MMN patients, 100 ALS cases and 100 healthy controls.
  
  
  RESULTS
  The detection of anti-GM1 Abs using glycoarray was 67% sensitive and 85% specific. The addition of GalC to GM1, (1:1 weight to weight ratio), increased the sensitivity to 81% , whilst dropping specificity to 80% . Increasing the GalC content to a 1:5 ratio (or higher) further decreased specificity, and in doing so limited the usefulness of the GM1:GalC assay to the level of GM1 alone. The addition of GalC to the ELISA method also significantly increased sensitivity compared with GM1 alone, albeit with a significant decrease in specificity.
  
  
  CONCLUSIONS
  This study indicates that the GM1:GalC assay is an advantageous assay adaptation for detecting anti-GM1 antibodies in MMN, using either glycoarray or ELISA, and warrants introduction into clinical diagnostic practice.
authors.affiliation: Neuroimmunology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Francesc
authors.initials: F
authors.lastname: Galban-Horcajo
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology, University Medical Center Utrecht, Utrecht,The Netherlands.
authors.forename: Lotte
authors.initials: L
authors.lastname: Vlam
authors.affiliation: Neuroimmunology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Emilien
authors.initials: E
authors.lastname: Delmont
authors.affiliation: Neuroimmunology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Susan K
authors.initials: SK
authors.lastname: Halstead
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology, University Medical Center Utrecht, Utrecht,The Netherlands.
authors.forename: Leonard
authors.initials: L
authors.lastname: van den Berg
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology, University Medical Center Utrecht, Utrecht,The Netherlands.
authors.forename: W-Ludo
authors.initials: WL
authors.lastname: van der Pol
authors.affiliation: Neuroimmunology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Hugh J
authors.initials: HJ
authors.lastname: Willison
keywords: ALS; Autoimmune neuropathy; GM1; MMN; autoantibody; galactocerebroside; ganglioside; glycolipid; validation study