TPO and Autoimmunity: It is notable that some of the AMPA and GABAB-R antibody-positive patients had GAD antibodies.23,24 In addition to the presence of GAD antibody in patients with GABA-R antibodies, these patients often have other autoantibodies [e.g., thyroid peroxidase (TPO), ANA, GAD65], reflecting a tendency to autoimmunity.25