Clinical Evaluation of a Novel DAB Chromogenic Tissue-Based Assay for Detecting Anti-GABABR Antibodies
This multicenter, blinded, cross-sectional study aims to evaluate the clinical performance of a novel DAB chromogenic tissue-based assay (TBA) for detecting anti-GABAB receptor (anti-GABABR) antibodies. A total of 300 participants will be enrolled across four groups: (a) 50 patients with anti-GABABR antibody-positive encephalitis; (b) 100 patients with suspected autoimmune encephalitis and negative anti-neuronal antibody cell-based assay (CBA); (c) 50 patients with non-autoimmune disease (Alzheimer's disease); and (d) 100 patients with anti-NMDAR antibody-positive encephalitis. Residual serum and cerebrospinal fluid samples will be tested using the optimized DAB-TBA. Discordant results between CBA and DAB-TBA will be adjudicated by an independent panel using confirmatory methods (immunoblot, repeat CBA, and clinical follow-up), and inter-reader agreement will be reported. The sensitivity, specificity, and ROC curve of the assay will be evaluated against the reference standard.
Residual serum or CSF volume insufficient for DAB-TBA and confirmatory testing. [+4]