Low rate of glutamic acid decarboxylase 65 (GAD-65) antibodies in chronic epilepsy. (August 2020)

• Record Type: Journal Article
• Authors: Tizazu, Etsegenet; Ellis, Colin A.; Reichert, Julia; Lancaster, Eric
• Is Part Of: Seizure. Volume 80(2020)
• Page Start: 38
• Page End: 41
• Publication Date: 2020-08
• Subjects: GAD-65 antibodies -- Autoimmune epilepsy -- Temporal lobe epilepsy -- Cell-based assay; Epilepsy -- Periodicals; Epilepsy -- Periodicals; Seizures -- Periodicals; Épilepsie -- Périodiques; Electronic journals; Electronic journals; 616.853
• DOI: 10.1016/j.seizure.2020.05.008
• Languages: English
• ISSNs: 1059-1311

Abstract

Highlights: GAD-65 antibodies in chronic epilepsy are rarer than previously reported. GAD-65 antibodies are associated with drug-resistant temporal lobe epilepsy. Pathogenic role of GAD-65 antibodies in epilepsy merits further investigation. Abstract: Purpose: Autoantibodies against glutamic acid decarboxylase 65 (GAD-65) have been identified in patients with chronic epilepsy. In this study, we ask (1) what is the frequency of GAD-65 antibodies in chronic epilepsy? (2) what is the frequency and type of epilepsy in individuals with GAD-65 antibodies? Methods: For cohort 1, serum samples of patients with epilepsy (without type I diabetes) were obtained from our biobank. Samples were tested for GAD-65 antibodies using a cell-based assay and confirmed by immunohistochemistry. For cohort 2, patients with positive GAD-65 antibodies were identified and their medical records were reviewed for the presence and characteristics of epilepsy. Results: Cohort 1 included 270 patients, of which 53% were women; median age was 47 years; median duration of epilepsy was 16 years. Epilepsy was focal in 87% (temporal lobe in 20%), and drug-resistant in 45%. GAD-65 antibodies were present in two out of 270 cases (0.7%) and zero controls. Cohort 2 consisted of 23 patients with known GAD-65 antibodies, of which ten had epilepsy (43%). Of these, 80% were women with a median age of 40 years and a median duration of epilepsy of 18 years. All ten patients had focal epilepsy, nine had temporal lobe epilepsy, and seven were drug resistant. Conclusions: In patients with chronic epilepsy, the frequency of GAD-65 antibodies detected with our cell-based assay was substantially lower than previously reported with use of other methods. When present, GAD-65 antibodies are associated with drug-resistant temporal lobe epilepsy. GAD-65 positive epilepsy patients merit further investigation.