Patient with homer-3 antibodies and cerebellitis.

Abstract

IMPORTANCE:

Homer proteins are a family of scaffolding proteins of the postsynaptic density. Homer-3 colocalizes and modulates the activity of group I metabotropic glutamate receptors (mGluR1 and mGluR5). Cerebellitis has been reported in association with antibodies to mGluR1. We describe the second patient with cerebellitis and Homer-3 antibodies and report a novel, highly specific immunoblot assay.

OBSERVATIONS:

A 38-year-old man had acute onset of headache, nausea, vomiting, and confusion. He developed a pancerebellar syndrome during the ensuing week. Extensive studies did not reveal any tumor. Cerebrospinal fluid analysis showed a white blood cell count of 60/μL (to convert to ×109 per liter, multiply by 0.001). Brain magnetic resonance imaging findings were normal. For 2 years, the patient was treated with intravenous immunoglobulins and steroids, with partial improvement of the cerebellar ataxia. The patient was negative for onconeural (Hu, Yo, Ri, CV2, Tr, amphiphysin, and Ma2), glutamic acid decarboxylase, and mGluR1 antibodies. Immunohistochemistry on rat brain revealed immunostaining of the cerebellar molecular layer. Homer-3 antibodies were demonstrated by immunoblot of recombinant Homer-3. The clinical features of this patient and a previously described patient with Homer-3 antibodies are similar to those of patients with mGluR1 antibodies.

CONCLUSIONS AND RELEVANCE:

We report the second case of autoimmune cerebellar ataxia associated with Homer-3 antibodies. The presence of Homer-3 autoantibodies should be considered in the differential diagnosis of patients with subacute cerebellar ataxia of unknown cause.

• Authors: Romana Höftberger, Lidia Sabater, Angel Ortega, Josep Dalmau, Francesc Graus
• Journal: JAMA neurology (JAMA Neurol) Vol. 70 Issue 4 Pg. 506-9 (Apr 2013) ISSN: 2168-6157 [Electronic] United States
• PMID: 23400636 (Publication Type: Case Reports, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Autoantibodies
• Carrier Proteins
• Homer Scaffolding Proteins
• Receptors, Metabotropic Glutamate
• metabotropic glutamate receptor type 1

Topics

• Adult
• Autoantibodies (cerebrospinal fluid)
• Carrier Proteins (immunology)
• Cerebellum (pathology)
• Encephalitis (cerebrospinal fluid, complications, pathology)
• Homer Scaffolding Proteins
• Humans
• Magnetic Resonance Imaging
• Male
• Receptors, Metabotropic Glutamate (immunology)