Clinical significance of glutamic acid decarboxylase antibodies in patients with epilepsy

Epilepsia. 2010 May;51(5):760-7. doi: 10.1111/j.1528-1167.2009.02325.x. Epub 2009 Oct 8.


Purpose: Glutamic acid decarboxylase antibodies (GADAs) have been detected in patients with epilepsy, but the clinical determinants of epilepsy associated with GADA have not been defined.

Methods: We analyzed GADA with a radioimmunoassay in sera of 253 well-characterized patients with epilepsy and 200 control subjects. The positive samples were confirmed by immunohistochemistry and western blotting (WB). Sera were screened for other autoantibodies.

Results: GADA were detected in 15 patients (5.9%) and in three control subjects (1.5%) (p = 0.026). Seven patients (2.8%) had high GADA titers [>or=1,000 relative units (RUs)/ml], six of whom had temporal lobe epilepsy (TLE). All three GADA-positive control subjects had low titers. Two of the five patients with high GADA titers and available cerebrospinal fluid (CSF) samples had intrathecal synthesis (IS) of GADA; one patient had CSF oligoclonal bands. The prevalence of increased levels of GADA tended to be higher in patients with TLE than in patients with extra-TLE [odds ratio (OR) 1.32, 95% confidence interval (CI) 0.39-4.42; p = 0.657]. The patients with high GADA titers had significantly higher number of other autoantibodies compared to the patients with low GADA titers (p = 0.001) and the patients with normal GADA (p < 0.001).

Discussion: High GADA titers were present in a subgroup of patients; close to 90% had TLE. The immunologic profile of these patients suggests that the most probable origin of their epilepsy is autoimmune. A positive IS of GADA may be a marker of an ongoing immune response that could identify those patients in whom a trial with immunosuppressive therapy might be warranted.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Distribution
  • Aged
  • Autoantibodies / blood*
  • Autoantibodies / cerebrospinal fluid
  • Autoantibodies / immunology
  • Autoimmune Diseases / blood
  • Autoimmune Diseases / diagnosis
  • Autoimmune Diseases / immunology*
  • Blotting, Western
  • Epilepsy / blood
  • Epilepsy / cerebrospinal fluid
  • Epilepsy / immunology*
  • Epilepsy, Temporal Lobe / blood
  • Epilepsy, Temporal Lobe / immunology
  • Female
  • Genetic Markers
  • Glutamate Decarboxylase / blood
  • Glutamate Decarboxylase / immunology*
  • Humans
  • Immunohistochemistry
  • Male
  • Middle Aged
  • Polyendocrinopathies, Autoimmune / diagnosis
  • Polyendocrinopathies, Autoimmune / immunology
  • Radioimmunoassay


  • Autoantibodies
  • Genetic Markers
  • Glutamate Decarboxylase