INDIVIDUAL TEST 958

Lrp4 (lipoprotein receptor-related protein-4) antibodies

IndicationSuspected Myasthenia gravis.MethodIndirect immunofluerescens (IIF) using cells transfected with LRP4.ResponseThe result is given as negative or positive. Follow up samples can be requested to be titrated. InterpretationLipoprotein receptor-related protein-4 (LRP4) is a member of a family of membrane proteins with key roles in neuronal and synaptic development. LRP4 and muscle-specific kinase (MuSK) forms together with acetylcholine receptor (AChR) clusters in the neuromuscular Junktion (NMJ) and in these clusters depolarization occurs in response to nerve stimulation. Antibodies against LRP4 have been identified in Myasthenia Gravis patients who are sero-negative for both AChR and MuSK antibodies. The frequency of LRP4 antibodies was 18.7% in a large international study (635 patients), but with a large variation between different populations (7 to 32.7%). The variation could not be linked to any geographic distribution. LRP4 antibody-positive patients respond to similar treatment strategy as AChR-antibody-positive patients, in contrast to MuSK antibody-positive patients. There are also double-positive MG patients who are positive for antibodies against AChR/LRP4 or double positive against MuSK/LRP4. Double-positive patients generally have more severe symptoms.

ReferencesZouvelou V, Zisimopoulou P Rentzos M, Karandreas N, Evangelakou P Stamboulis E, Tzartos SJ Double seronegative myasthenia gravis with anti-LRP 4 antibodies. Neuromuscul Disord. 2013 Jul, 23 (7):568-70. PMID: 23768983

Zisimopoulou P. et al. A Comprehensive Analysis of the epidemiology and clinical characteristics of the anti-LRP4 in myasthenia gravis, Journal of Autoimmunity (2013), http://dx.doi.org/10.1016/j.jaut.2013.12.004 . PMID: 24373505

Berrih-Aknin S Frenkian-Cuvelier M, Eymard B. Diagnostic and Clinical Classification of autoimmune myasthenia gravis. J Autoimmun. 2014 Feb-Mar; 48-49:143-8. PMID: 24530233

Pevzner A, Schoser B, Peters K, Cosma NC, Karakatsani A, Schalke B, Melms A, Kröger S. Anti-LRP4 autoantibodies in AChR-and MuSK-antibody-negative myasthenia gravis. J Neurol. 2012 Mar; 259(3):427-35. PMID: 21814823

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Neurology

ENSKILD ANALYS 958

Lrp4 (lipoprotein receptor-related protein-4)-antikroppar

IndikationMisstanke om Myastenia gravis.MetodImmunoflourescensce på transfekterade celler.SvarResultatet anges som negativt eller positivt. Vid uppföljning av patient kan man begära att provet ska titreras.TolkningLipoprotein receptorrelaterat protein-4 (LRP4) är en medlem av en familj av membranproteiner med centrala roller i neuronal och synaptisk  utveckling. LRP4 och muskelspecifikt kinas (MuSK) formar tillsammans med acetylkolinreceptorer (AChR) clusters i neuromuskulär junktion (NMJ)  och i dessa clusters sker depolarisering som svar på nervstimulering.  Antikroppar mot LRP4 har identifierats hos Myastenia Gravis patienter som är seronegativa för både AChR- och MuSK-antikroppar. Frekvensen av LRP4-antikroppar var 18,7%  i en stor internationell studie (635 patienter), men med en stor variation mellan olika populationer (7 till 32.7%). Variationen kunde inte kopplas till något geografiskt mönster. LRP4-antikroppspositiva patienter svarar på liknande behandlingsstrategi som  AChR-antikroppspositiva patienter i motsatts till MuSK-antikroppspositiva patienter. Det finns även dubbelpositiva MG patienter med som är positiva för antikroppar mot AChR/LRP4 samt dubbelpositiva mot MuSK/LRP4. Dubbelpositiva patienter har generellt allvarligare symptom.

ReferenserR. Pirskanen-Matell, G. Matell, B. Kalb, S. Bjelak. (2000). Myasthenia gravis – en autoimmun neuromuskulär sjukdom. Läkartidningen 45:4594-8.

Zouvelou V, Zisimopoulou P, Rentzos M, Karandreas N, Evangelakou P, Stamboulis E, Tzartos SJ Double seronegative myasthenia gravis with anti-LRP 4 antibodies. Neuromuscul Disord. 2013 Jul;23(7):568-70.  PMID: 23768983

Zisimopoulou P, et al., A comprehensive analysis of the epidemiology and clinical characteristics of anti-LRP4 in myasthenia gravis, Journal of Autoimmunity (2013), http://dx.doi.org/10.1016/j.jaut.2013.12.004 . PMID: 24373505

Berrih-Aknin S, Frenkian-Cuvelier M, Eymard B. Diagnostic and clinical classification of autoimmune myasthenia gravis. J Autoimmun. 2014 Feb-Mar;48-49:143-8.  PMID: 24530233

Pevzner A, Schoser B, Peters K, Cosma NC, Karakatsani A, Schalke B, Melms A, Kröger S. Anti-LRP4 autoantibodies in AChR- and MuSK-antibody-negative myasthenia gravis. J Neurol. 2012 Mar;259(3):427-35. PMID: 21814823

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