INDIVIDUAL TEST 772
AMPA Receptor 1/2 Antibodies (IgG)
Indication Suspicion of paraneoplastic syndromes particularly in autoimmune encephalitis.Method Indirect immunofluorescence (IIF) using transfected cells.
Result The result is reported as positive or negative. A positive result is followed by a titer (serum).
Interpretation Antibodies against AMPA 1/2 receptors can be seen in paraneoplastic syndrome and in classical autoimmune encephalitis, but cases of isolated psychoses have also been described. There are relatively few cases published, of which 90% have been women. Age at diagnosis has been 38-87 years (median 60 years). The antibodies have been associated with tumors (lung, breast and thymoma) in 70% of the cases. Antibodies may occur together with other autoantibodies in around 60% of the cases (antibodies against ANA, GAD-65, cardiolipin, VGCC, SOX1, CV2/CRMP5 and TPO).
The AMPA 1/2 receptors belong to the group of extracellular antigens. Generally, immunotherapy is more often effective in autoantibodies directed against extracellular antigens than in autoantibodies against intracellular antigens. Antibody titers can be used to monitor treatment effectiveness. Screening for cancer diagnosis is recommended.
Antibodies against AMPA 1/2 receptor are graded as Intermediate-risk antibodies with a frequence of >50% of underlying cancer and a positive result yields 2 points PNS score according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
References
- Lancaster, Martinez-Hernandez, Dalmau. Encephalitis and antibodies to synaptic and neuronal cell surface proteins. Neurology. 2011 Jul 12;77(2):179-89. PMID: 21747075.
- Titulaera et al. Screening for tumours in paraneoplastic syndromes: report of an EFNS Task Force. European Journal of Neurology. Epublished 2010. Eur J Neurol. 2011 January; 18(1): 19–23. PMID: 20880069.
- Dalmau J, Geis C, Graus F. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. Physiol Rev. 2017 Apr;97(2):839-887. PMID: 28298428;
- Graus F, et al. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. Neurol Neuroimmunol Neuroinflamm. 2021 May 18;8(4):e1014. PMID: 34006622
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ENSKILD ANALYS 772
AMPA receptor 1/2-antikroppar (IgG)
Indikation Misstanke om paraneoplastiska syndrom och framför allt vid autoimmun encefalit.Metod Indirekt immunofluorescens (IIF) med transfekterade celler.
Svar Resultatet anges som positiv eller negativ. Positivt resultat titreras (serum).
Tolkning Antikroppar mot AMPA 1/2 receptorer kan ses vid paraneoplastiska syndrom och framför allt vid klassisk autoimmun encefalit men fall av isolerade psykoser har också beskrivits. Det finns ett fåtal fall publicerade varav 90% har varit kvinnor. Ålder vid diagnos har varit 38-87 år (median 60 år). Antikropparna har varit associerade med tumörer (lung, bröst och tymom) i 70% av fallen. Antikropparna kan förekomma tillsammans med andra autoantikroppar i runt 60% av fallen (antikroppar mot ANA, GAD-65, kardiolipin, VGCC, SOX1, CV2/CRMP5 och TPO).
AMPA 1/2 receptorer räknas till gruppen extracellulära antigen. Generellt sett är behandling med immunoterapi oftare effektiv vid autoantikroppar riktade mot extracellulära antigen än vid autoantikroppar mot intracellulära antigen. Antikroppstitrar kan användas för att följa behandlingseffektivitet. Uppföljning med cancerdiagnostik rekommenderas.
Antikropparna riktade mot AMPA 1/2 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
- Lancaster, Martinez-Hernandez, Dalmau. Encephalitis and antibodies to synaptic and neuronal cell surface proteins. Neurology. 2011 Jul 12;77(2):179-89. PMID: 21747075.
- Titulaera et al. Screening for tumours in paraneoplastic syndromes: report of an EFNS Task Force. European Journal of Neurology. Epublished 2010. Eur J Neurol. 2011 January; 18(1): 19–23. PMID: 20880069.
- Dalmau J, Geis C, Graus F. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. Physiol Rev. 2017 Apr;97(2):839-887. PMID: 28298428;
- Graus F, et al. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. Neurol Neuroimmunol Neuroinflamm. 2021 May 18;8(4):e1014. PMID: 34006622