GFAP Auto-immunity : a French Cohort Study

Glial fibrillary acidic protein (GFAP)-Immunoglobulin G (IgG) have recently been described as a biomarker of a novel inflammatory central nervous system (CNS) disorder, termed autoimmune GFAP astrocytopathy. Thus far, four major clinical series have been published (two from Mayo Clinic USA, one from Italy and one from China). GFAP-IgG detected in serum or in cerebrospinal fluid, by tissue-based assay and confirmed by cell-based assay, are associated with encephalitis or meningoencephalitis of acute or subacute onset, less frequently with myelitis or optic disk edema. The characteristic MRI feature is brain linear perivascular radial gadolinium enhancement in the white matter perpendicular to the ventricle, consistent with the immunohistochemical staining pattern of GFAP in rodent brain sections. Approximately 20% of reported cases are associated with a neoplasm (ovarian teratoma mostly). Coexisting neural autoantibodies are described in some patients, N-methyl-D-aspartate (NMDA)-receptor (R)-IgG mostly, followed by aquaporin 4 (AQP4)-IgG. The disease is usually corticosteroid responsive although relapse can occur. In contrast, Chinese patients display poorer outcomes. Pathophysiology is not well understood but the intracellular antigen location makes GFAP-IgG unlikely pathogenic whereas animal models and neuropathologic data suggest a T-cell immune-mediated disorder. The aim of the investigators is to report the first French cohort of patients GFAP-IgG positive. Investigators retrospectively assessed clinical, immunological and radiological features, treatment response and outcomes.