Case Report: Semantic Variant of Primary Progressive Aphasia Associated With Anti-Glial Fibrillary Acid Protein Autoantibodies

Abstract

BackgroundFrontotemporal lobar degeneration is a heterogeneous disorder entailing a semantic variant of primary progressive aphasia (svPPA). A subtype of frontotemporal dementia associated with glutamate receptor subunit 3 (GluA3) antibody of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) was recently identified. Here, we describe the novelty of a svPPA associated with anti-glial fibrillary acid protein (GFAP) antibodies.MethodsTo diagnose this 68-year-old woman we conducted a clinical examination, neuropsychological testing, CSF analysis, MRI and 18F-fluorodeoxyglucose (18F-FDG) Positron Emission Tomography (PET)/computed tomography (CT) imaging.ResultsThe clinical phenotype corresponds to a svPPA based on impaired confrontation naming and single-word comprehension. In addition, we observed spared speech production, impaired object knowledge, and surface dyslexia - further supporting the diagnosis of svPPA. Additional characteristic imaging features such as anterior temporal hypometabolism in 18F-FDG PET/CT confirmed patient’s svPPA diagnosis. CSF analysis revealed signs of axonal degeneration, as both tau and phosphorylated tau proteins exceeded normal levels. Her serum showed anti-GFAP autoantibodies.ConclusionWe diagnosed a svPPA in this patient and report an association between serum anti-GFAP antibodies and svPPA never reported in the literature so far, thereby expanding the clinical spectrum of svPPA and anti-GFAP-antibody related disease. Further research is needed to elucidate the underlying immunopathology of this disease entity to ultimately improve treatment.

Semantic Variant of Primary Progressive Aphasia With Glycine Receptor α1 Autoantibodies

“…As a subtype of frontotemporal dementia (FTD), svPPA is characterized by semantic language impairment and by predominant left anterior temporal atrophy on brain MRI . It has been previously reported that glial fibrillary acid protein autoantibodies were detected in a patient with svPPA . The verbal and cognitive functions of the patient in the present study improved after immunotherapy, whereas the previous patient did not respond.…”

“…1 It has been previously reported that glial fibrillary acid protein autoantibodies were detected in a patient with svPPA. 2 The verbal and cognitive functions of the patient in the present study improved after immunotherapy, whereas the previous patient did not respond. SQSTM1 variants were identified in patients with FTD.…”