Indication Suspicion of paraneoplastic neuropathy, Lambert-Eaton myasthenic syndrome and cerebellar dysfunction.
Method Radioimmunoprecipitation (RIA).
Result The result is reported as a ratio for VGCC N-type antibodies and as pmol / L for P/Q type antibodies.
Interpretation Calcium channel antibodies occur in paraneoplastic neuropathy in e.g. small cell lung cancer, but even without this association. Causes include Lambert-Eaton myasthenic syndrome and cerebellar dysfunction. It is primarily the VGCC P/Q type antibodies that are of clinical significance while the importance of VGCC N-type antibodies is less known.
Generally, treatment with immunotherapy is more effective against auto-antibodies directed to extracellular antigens than with auto-antibodies against intracellular antigens.
Antibodies against VGCC P/Q are graded as Intermediate-risk antibodies with an frequency of 50% (LEMS ; nearly 90% for rapidly progressive cerebellar syndrome) of underlying cancer and a positive result yield 2 points PNS score, according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
References
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
Alexopoulos H, Dalakas MC. The immunobiology of autoimmune encephalitides. J Autoimmun. 2019 Nov;104:102339. PMID: 31611142.
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 845
VGCC-antikroppar
Indikation Misstanke om paraneoplastisk neuropati, Lambert-Eatons myastena syndrom och cerebellär dysfunktion.
Metod Radioimmunoprecipitation (RIA).
Svar Resultat för N-typ ges som kvot och resultat för P/Q typ ges som pmol/L.
Tolkning Antikroppar mot spänningsberoende kalciumkanaler (Voltage gated calcium channels, VGCC) förekommer vid paraneoplastisk neuropati vid t.ex småcellig lungcancer, men även utan denna association. Ger upphov till bland annat Lambert-Eatons myastena syndrom och cerebellär dysfunktion. Det är främst VGCC P/Q typ av antikroppar som är kopplade till sjukdom. Signifikansen av N-typ antikroppar är mindre känd.
Generellt sett är behandling med immunoterapi oftare effektfull vid auto-antikroppar riktade mot extracellulära antigen än vid auto-antikroppar mot intracellulära antigen.
Antikropparna riktade mot VGCC P/Q bedöms vara Intermediate-risk antibodies med en förekomst på 50% (vid LEMs; nästan 90% vid snabb progressiv cerebellär syndrom) för en underliggande cancer och positivitet ger 2 poäng i PNS score enligt Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
Referenser
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
Alexopoulos H, Dalakas MC. The immunobiology of autoimmune encephalitides. J Autoimmun. 2019 Nov;104:102339. PMID: 31611142.
Graus F, et al. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. Neurol Neuroimmunol Neuroinflamm. 2021 May 18;8(4):e1014. PMID: 34006622