GABA_A receptor autoimmunity: A multicenter experience.

Area of Science:

• Neuroimmunology
• Neurology
• Clinical Diagnostics

Background:

• Autoimmune encephalitis is a growing area of concern.
• GABA_A receptor (R)-IgG is implicated in certain autoimmune neurological disorders.
• Accurate detection of these antibodies is crucial for diagnosis and treatment.

Purpose of the Study:

• To validate diagnostic methods for GABA_A receptor (R)-IgG.
• To characterize the clinical features of patients with confirmed GABA_AR-IgG.
• To assess the effectiveness of treatments for GABA_AR encephalitis.

Main Methods:

• Indirect immunofluorescence assay (IFA) was used for initial screening of serum and CSF specimens.
• Cell-based assays (CBAs) at two international centers confirmed GABA_AR-IgG positivity.
• Clinical data from seropositive patients were collected and analyzed.

Main Results:

• Eight specimens from 5 patients were confirmed positive for GABA_AR-IgG by CBA.
• Patient IgGs consistently reacted with α1β3 GABA_AR subunits.
• Six patients were identified with GABA_AR-IgG, presenting with encephalitis and refractory seizures.

Conclusions:

• GABA_AR encephalitis, while less common than NMDA-R encephalitis, presents with distinct clinical and radiological features.
• Accurate laboratory diagnosis of GABA_AR-IgG is critical for timely and effective treatment.
• Immunotherapy can lead to good outcomes in patients with GABA_AR encephalitis, especially when initiated early.