GFAP Auto-immunity : a French Cohort Study

Study Overview
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Brief Summary
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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.

Official Title
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GFAP Auto-immunity : a French Cohort Study

Conditions
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Autoimmune GFAP Astrocytopathy

Intervention / Treatment
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* Other: Description and analysis


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Positive GFAP-Ab in serum and/or CSF tested by immunohistochemistry on mouse brain slices and confirmed by cell-based assay (CBA) of HEK293 cells expressing GFAP. Diagnosis and follow-up in France No age limit : from 0 to unlimited age Exclusion Criteria: Patients GFAP-IgG negative in serum and CSF Absence of complete clinicopathological data Foreign follow-up
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patients GFAP-IgG positive in serum and/or CSF<br>Patients developing clinical autoimmune encephalitis or meningoencephalomyelitis with anti-GFAP antibodies, managed by the National Reference Center for Paraneoplastic Syndromes and Autoimmune Encephalitis or the National Reference Center for Centre de référence for Neuro-inflammatory diseases of the brain and the spinal cord at the Neurological Hospital of Bron. | Other: Description and analysis<br>* Retrospective, non-interventional study, using clinical, biological, radiological and therapeutic data collected during the initial diagnosis and follow-up.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Report retrospectively clinical data of patients GFAP-IgG positive. | Describe prodromes (yes or no), neurologic signs and clinical course (acute/subacute - yes or no - or progressive onset - yes or no), if admitted in intensive care units (yes or no), retrospectively provided by the treating physicians using a structured questionnaire.or progressive onset), if admitted in intensive care units, neoplastic and dysimmune associated diseases and T cell dysregulation condition . | 13 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Describe GFAP-antibody test results. | positivity of GFAP α -IgG in cerebrospinal fluid, in serum and isoform type at diagnostic and follow up. positivity of GFAP α -IgG in cerebrospinal fluid, in serum and isoform type at diagnostic and follow up. | 13 months | 
| demographic data of patients GFAP-IgG positive : age at onset | age at onset (years) retrospectively provided by the treating physicians using a structured questionnaire | 13 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Acidic Protein IgG, astrocytopathy, meningoencephalomyelitis, perivascular-radial parenchymal enhancement, autoimmune, paraneoplasic