PT  - JOURNAL ARTICLE
AU  - Mange Liu
AU  - Haitao Ren
AU  - Siyuan Fan
AU  - Weihe Zhang
AU  - Yao Xu
AU  - Weili Zhao
AU  - Hongzhi Guan
AU  - and the Encephalitis Collaborative Group
TI  - Neurological Autoimmunity Associated With Homer-3 Antibody
AID  - 10.1212/NXI.0000000000001077
DP  - 2021 Nov 01
TA  - Neurology - Neuroimmunology Neuroinflammation
PG  - e1077
VI  - 8
IP  - 6
4099  - http://nn.neurology.org/content/8/6/e1077.short
4100  - http://nn.neurology.org/content/8/6/e1077.full
SO  - Neurol Neuroimmunol Neuroinflamm2021 Nov 01; 8
AB  - 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.ACA=autoimmune cerebellar ataxia; RBD=REM sleep behavior disorder; MSA-C=multiple system atrophy with cerebellar features; IVIg=IV immunoglobulin