Indication Suspicion of autoimmune encephalitis/autoimmune cerebellar ataxia.
Method Cell-based assay (CBA) with indirect immunofluorescence
Result Reported as positive (with titre) or negative.
Interpretation Metabotropic glutamate receptors are transmembrane proteins in neuronal membranes. Unlike ionotropic receptors, metabotropic glutamate receptors (mGluRs) are not ion channels. Instead, they activate biochemical cascades, leading to the modification of other proteins, as for example ion channels.
Antibodies against mGluR1 (metabotropic glutamate receptor 1) have been described for Morbus Hodgkin together with (paraneoplastic) cerebellar ataxia.
It is recommended to use the test on serum. It has not been reported cases of only CSF positive.
Antibodies against mGlur1 are graded as Lower-risk antibodies with a frequency of 30% of underlying cancer and a positive result yield 0 points PNS score, according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
References
Levite M. Glutamate receptor antibodies in neurological diseases: anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies, anti-NMDA-NR2A/B antibodies, anti-mGluR1 antibodies or anti-mGluR5 antibodies are present in subpopulations of patients with either: epilepsy, encephalitis, cerebellar ataxia, systemic lupus erythematosus (SLE) and neuropsychiatric SLE, Sjogren's syndrome, schizophrenia, mania or stroke. These autoimmune anti-glutamate receptor antibodies can bind neurons in few brain regions, activate glutamate receptors, decrease glutamate receptor's expression, impair glutamate-induced signaling and function, activate blood brain barrier endothelial cells, kill neurons, damage the brain, induce behavioral/psychiatric/cognitive abnormalities and ataxia in animal models, and can be removed or silenced in some patients by immunotherapy. J Neural Transm (Vienna). 2014 Aug;121(8):1029-75. PMID: 25081016.
Jarius S, Wildemann B. 'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII. J Neuroinflammation. 2015 Sep 17;12:166. PMID: 26377085
Graus F, et al. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. Neurol Neuroimmunol Neuroinflamm. 2021 May 18;8(4):e1014. PMID: 34006622
Chandler E, Arvantis N, Morgan B. A Novel Case of Idiopathic MGluR1 Encephalitis in a Pediatric Patient. Child Neurol Open. 2022 Apr 25;9:2329048X221095695. PMID: 35497371
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ENSKILD ANALYS 117
mGlur1-antikroppar (IgG)
Indikation Misstanke om autoimmun encefalit/autoimmun cerebellär ataxi.
Metod Cell-based assay (CBA) med indirekt immunofluorescens
Svar Anges som positiv (med titer) eller negativ.
Tolkning Metabotropiska glutamatreceptorer är transmembranproteiner i neuronala membran. Till skillnad från jonotropa receptorer är metabotropa glutamatreceptorer (mGluRs) inte jonkanaler. I stället aktiverar de biokemiska kaskader, vilket leder till modifieringen av andra proteiner, såsom exempelvis jonkanaler.
Antikroppar mot mGluR1 (metabotropic glutamate receptor 1) har beskrivits vid Morbus Hodgkin i samband med (paraneoplastisk) cerebellär ataxi.
Rekommendationen är att endast testa i serum. Det har inte rapporterats fall som endast har varit positiv i CSF.
Antikropparna riktade mot mGlur1 bedöms vara Lower-risk antibodies med en förekomst på 30% för en underliggande cancer och positivitet ger 0 poäng i PNS score enligt Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
Referenser
Levite M. Glutamate receptor antibodies in neurological diseases: anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies, anti-NMDA-NR2A/B antibodies, anti-mGluR1 antibodies or anti-mGluR5 antibodies are present in subpopulations of patients with either: epilepsy, encephalitis, cerebellar ataxia, systemic lupus erythematosus (SLE) and neuropsychiatric SLE, Sjogren's syndrome, schizophrenia, mania or stroke. These autoimmune anti-glutamate receptor antibodies can bind neurons in few brain regions, activate glutamate receptors, decrease glutamate receptor's expression, impair glutamate-induced signaling and function, activate blood brain barrier endothelial cells, kill neurons, damage the brain, induce behavioral/psychiatric/cognitive abnormalities and ataxia in animal models, and can be removed or silenced in some patients by immunotherapy. J Neural Transm (Vienna). 2014 Aug;121(8):1029-75. PMID: 25081016.
Jarius S, Wildemann B. 'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII. J Neuroinflammation. 2015 Sep 17;12:166. PMID: 26377085
Graus F, et al. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. Neurol Neuroimmunol Neuroinflamm. 2021 May 18;8(4):e1014. PMID: 34006622
Chandler E, Arvantis N, Morgan B. A Novel Case of Idiopathic MGluR1 Encephalitis in a Pediatric Patient. Child Neurol Open. 2022 Apr 25;9:2329048X221095695. PMID: 35497371