INDIVIDUAL TEST 877
GABA B Receptor Antibodies (IgG)
Indication
Suspicion of autoimmune encephalitis and paraneoplastic syndrome
Sample material
Serum
- Minim. volume: 0,5 mL
CSF
- Minim. volume: 0,5 mL
Transport
Within Sweden
- room temperature
International
- cold
Method
Cell-based assay (CBA), Indirect immunofluorescence (IIF)
Reference interval
Serum
- <1:10 negative
CSF
- negative
Result
Results are reported as negative or positive. A positive result is followed by a titer (serum).
Interpretation
Antibodies against GABA B receptors may occur in classical autoimmune encephalitis. There are relatively few cases published, of which 50% have been women, age when diagnosed between 24-75 years (median 62 years). GABA B positivity has been associated with small-cell lung cancer in 50-60% of the cases. Antibodies may occur together with other autoantibodies in around 50% of the cases (antibodies against GAD-65, VGCC, and TPO). Antibody titers can be used to monitor treatment effectiveness. Screening for cancer diagnosis is recommended.
Antibodies against GABA B receptors are graded as Intermediate-risk antibodies with a frequency of >50% of underlying cancer, and a positive result yields a 2 point PNS score, according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
References
- Leypoldt F et al. Ann N Y Acad Sci. 2015. Autoimmune encephalopathies. PMID: 25315420
- Dalmau J et al. Physiol Rev. 2017. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. PMID: 28298428
- Dalmau J et al. Lancet Neurol. 2019. An update on anti-NMDA receptor encephalitis for neurologists and psychiatrists: mechanisms and models. PMID: 31326280
- Graus F et al. Neurol Neuroimmunol Neuroinflamm. 2021. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. PMID: 34006622
- Flanagan EP et al. JAMA Neurol. 2023. Autoimmune Encephalitis Misdiagnosis in Adults. PMID: 36441519
Last updated: 2024-08-13
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ENSKILD ANALYS 877
GABA B receptor-antikroppar (IgG)
Indikation
Misstanke om autoimmun encefalit och paraneoplastiskt syndrom
Provmaterial
Serum
- Minim. volym: 0,5 mL
Likvor
- Minim. volym: 0,5 mL
Transport
Inom Sverige
- rumstemperatur
Internationellt
- kylt
Metod
Cell-based assay (CBA), indirekt immunofluorescens (IIF)
Referensintervall
Serum
- <1:10 negativt
Likvor
- negativt
Resultat
Resultat anges som negativt eller positivt. Positivt resultat titreras (serum).
Tolkning
Antikroppar mot GABA B receptorer kan förekomma vid klassisk autoimmun encefalit. Det finns relativt få fall publicerade varav 50% har varit kvinnor och ålder vid diagnos mellan 24-75 år (median 62 år). Positivitet för GABA B är associerat med småcellig lungcancer i 50-60% av fallen. Antikropparna kan förekomma tillsammans med andra autoantikroppar i runt 50% av fallen (antikroppar mot GAD-65, VGCC, och TPO). Uppföljning med cancerdiagnostik rekommenderas.
Antikroppar riktade mot GABA B receptorer bedöms vara Intermediate-risk antibodies med en förekomst på >50% för en underliggande cancer och positivitet ger 2 poäng i PNS score enligt Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
Referenser
- Leypoldt F et al. Ann N Y Acad Sci. 2015. Autoimmune encephalopathies. PMID: 25315420
- Dalmau J et al. Physiol Rev. 2017. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. PMID: 28298428
- Dalmau J et al. Lancet Neurol. 2019. An update on anti-NMDA receptor encephalitis for neurologists and psychiatrists: mechanisms and models. PMID: 31326280
- Graus F et al. Neurol Neuroimmunol Neuroinflamm. 2021. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. PMID: 34006622
- Flanagan EP et al. JAMA Neurol. 2023. Autoimmune Encephalitis Misdiagnosis in Adults. PMID: 36441519
Senast uppdaterat: 2024-08-13