Neurological Autoimmunity Associated With Homer-3 Antibody
A Case Series From China
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Abstract
Background and Objective To present 6 new cases with Homer-3 antibodies that expand their clinical spectra and to evaluate the effect of immunotherapy.
Methods Patients with suspected autoimmune cerebellar disorder were tested for rare autoimmune cerebellar ataxia (ACA) antibodies (anti-Tr(DNER)/Zic4/ITPR1/Homer-3/NCDN/PKCγ/PCA-2/AP3B2/mGluR1/ATP1A3 antibodies) using both cell-based and tissue-based assays. Patients with positive serum or CSF results who were diagnosed with ACA were registered and followed up. This study reports and analyzes cases with Homer-3 antibodies.
Results Of the serum and CSF samples of 750 patients tested, 6 were positive for Homer-3 antibodies. All manifested subacute or insidious-onset cerebellar ataxia. Furthermore, 2 patients each exhibited encephalopathy, myeloradiculopathy, REM sleep behavior disorder, and autonomic dysfunction. Brain magnetic resonance images were normal (n = 1) or revealed cerebellar atrophy (n = 1), cerebellum and pons atrophy with the hot cross bun sign (n = 2), and bilateral cerebral abnormalities (n = 2). Definite leukocytosis was identified in the CSF of 2 patients, protein concentration elevation was observed in the CSF of 1 patient, and oligoclonal bands were present in 2 patients. All patients received immunotherapy, including corticosteroid, IV immunoglobulin, plasma exchange, and mycophenolate mofetil, after which the residual disability was still severe (modified Rankin Scale score ≥3 at the last follow-up in 4 patients and final Scale for the Assessment and Rating of Ataxia scores of 12–29), although 4 patients partially improved and 1 patient stabilized. The remaining 1 patient continued to deteriorate after repeated immunotherapy. Two patients relapsed.
Discussion Disorders associated with Homer-3 antibody can mimic multiple system atrophy with cerebellar features in both clinical and radiologic aspects. Accurate identification of autoimmune-mediated cases is critical. Timely, comprehensive immunotherapy is warranted, given the possibility of long-term clinical benefit.
Glossary
- ACA=
- autoimmune cerebellar ataxia;
- RBD=
- REM sleep behavior disorder;
- MSA-C=
- multiple system atrophy with cerebellar features;
- IVIg=
- IV immunoglobulin
Footnotes
Go to Neurology.org/NN for full disclosures. Funding information is provided at the end of the article.
↵* These authors contributed equally to this work.
The Article Processing Charge was funded by the authors.
- Received April 19, 2021.
- Accepted in final form July 6, 2021.
- Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.
This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND), which permits downloading and sharing the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
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