Overlapping Autoimmune Syndromes in Patients With Glial Fibrillary Acidic Protein Antibodies

Background: Glial fibrillary acidic protein (GFAP) astrocytopathy, an autoimmune central nervous system disorder with a specific GFAP-IgG, often coexists with other antibodies. Objective: The aim of this article was to study overlapping syndromes in autoimmune GFAP astrocytopathy. Methods: Antibody was detected by indirect immunofluorescence assay. Patient data were analyzed retrospectively. Results: Thirty patients with positive GFAP-IgG were included, of whom 10 were defined as overlapping syndrome. Four patients with positive aquaporin-4 (AQP4)-IgG, two with N-methyl-d-aspartate receptor-IgG, three with unknown neuronal antibodies, and one with double AQP4 and myelin oligodendrocyte glycoprotein-IgG were identified. GFAP-IgG and other specific antibodies occurred simultaneously at the initial attack in eight patients. The main symptoms included fever, headache, ataxia, psychosis, hypersomnia, dyskinesia, dementia, seizure, myelitis, and optical symptoms. Brain magnetic resonance imaging in four patients revealed characteristic radial enhancing patterns in the white matter. Cortical abnormalities were found in four patients. Other brain abnormalities occurred in the hypothalamus, midbrain, pons, medulla, cerebellum, and meninges. Six patients exhibited lesions in the spinal cord. In a subgroup study, patients with overlapping syndrome were younger at onset than those with non-overlapping syndrome. Conclusion: Overlapping antibodies are common in GFAP astrocytopathy.