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Carina Törn


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Recognition of glutamic acid decarboxylase (GAD) by autoantibodies from different GAD antibody-positive phenotypes


  • Christiane S Hampe
  • Lisa P Hammerle
  • Lynn Bekris
  • Eva Örtqvist
  • Ingrid Kockum
  • Olov Rolandsson
  • Mona Landin-Olsson
  • Carina Torn
  • Bengt Persson
  • Åke Lernmark

Summary, in English

Autoantibodies against the smaller isoform of glutamic acid decarboxylase (GAD) are markers for Type 1 diabetes. GAD65 autoantibody (GAD65Ab)-positive individuals in the general population are, however, mostly at low risk of developing Type 1 diabetes, suggesting that GAD65Ab phenotypes may be associated with different underlying pathogenic processes. The aim of this study was to test the hypothesis that Type 1 diabetes patients (n = 243; group I), GAD65Ab-positive healthy individuals (n = 28; group II), and healthy first-degree relatives of Type 1 diabetes patients (n = 41; group III) have antibody phenotypes that recognize different GAD65 epitopes. Sera from groups I-III were tested for their binding to GAD65 and GAD67, as well as six different GAD65/67 fusion proteins. Regardless of group, sera reactive to both GAD65 and GAD67 showed broader epitope reactivity than GAD65-specific sera. Furthermore, Type 1 diabetes patients showed a more restricted epitope binding than healthy individuals and first-degree relatives, demonstrating significantly less binding to the N-terminal part of GAD65 and to GAD67. Our analysis demonstrates that the N-terminal part is essential for full antibody binding to GAD65, in particular, to the middle epitope. It is suggested that Type 1 diabetes is associated with restricted GAD65Ab epitope specificity.

Publishing year







Journal of Clinical Endocrinology and Metabolism





Document type

Journal article


Oxford University Press




  • ISSN: 0021-972X