{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T12:53:42Z","timestamp":1791204822132,"version":"4.1.0"},"reference-count":45,"publisher":"Wiley","issue":"S1","license":[{"start":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:00:00Z","timestamp":1782777600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:00:00Z","timestamp":1782777600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Muscle and Nerve"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Introduction\/Aims<\/jats:title>\n                    <jats:p>Muscle\u2010specific kinase myasthenia gravis (MuSK\u2010MG) is an autoimmune neuromuscular disorder predominantly mediated by IgG4 autoantibodies disrupting MuSK signaling. The contribution of other isotypes remains incompletely defined. We characterized the serological profile of a Greek cohort of MuSK\u2010MG patients.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Baseline (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u2009140) and longitudinal (available\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200999) samples from 140 patients, positive for anti\u2010MuSK by radioimmunoprecipitation (RIPA) were analyzed using a live cell\u2010based assay (L\u2010CBA) to detect total IgG, IgG1\u20134 subclasses, IgM, and IgA. Also, disease and healthy controls (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u2009102) were included. Selected samples were additionally analyzed by flow cytometry. Clinical data were available for specific patients.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Our analysis revealed 15 distinct immunoglobulin combinations and provided insights into the presence of IgA isotype. IgG4 was the most common subclass in 120\/140 of patients, followed by IgG1 in 79\/140, IgG3 in 59\/140, and IgG2 in 42\/140 patients, while IgM positivity was detected in selected patients. Anti\u2010MuSK IgA(1) immunoreactivity was detected in 54\/140 patients, frequently co\u2010occurring with IgG, and in four patients at baseline with only\u2010IgA positivity. IgA was detected both near disease onset and at later stages, and persisted over time in rituximab\u2010treated patients. Controls tested largely negative for IgA, although low\u2010intensity signals were observed in six samples and were considered non\u2010specific. L\u2010CBA detected anti\u2010MuSK IgA more frequently than flow cytometry.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>Our findings expand the serology of MuSK\u2010MG beyond IgG subclasses, identifying IgA as an additional component of the anti\u2010MuSK response. These results enhance further investigation into the clinical significance, pathogenic potential, and treatment\u2010associated fluctuations of anti\u2010MuSK IgA antibodies.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mus.70284","type":"journal-article","created":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T19:37:45Z","timestamp":1782848265000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["<scp>IgG<\/scp>\n                    Subclass (\n                    <scp>IgG1<\/scp>\n                    \u20104) and\n                    <scp>IgA<\/scp>\n                    Autoantibody Profiles Against Muscle\u2010Specific Kinase in a Greek Cohort"],"prefix":"10.1002","volume":"74","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-2065-7769","authenticated-orcid":false,"given":"Sofia\u2010Nats\u03bfuko","family":"Gkotzamani","sequence":"first","affiliation":[{"name":"Tzartos NeuroDiagnostics  Athens Greece"},{"name":"Second Department of Neurology, \u201cAttikon\u201d University Hospital, School of Medicine National &amp; Kapodistrian University of Athens  Athens Greece"},{"name":"Department of Immunology Hellenic Pasteur Institute  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6985-0906","authenticated-orcid":false,"given":"Maria","family":"Pechlivanidou","sequence":"additional","affiliation":[{"name":"Tzartos NeuroDiagnostics  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-5009-2835","authenticated-orcid":false,"given":"Francisca","family":"Faber","sequence":"additional","affiliation":[{"name":"Division of Neuropathology and Neurochemistry, Department of Neurology Medical University of Vienna  Vienna Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7941-1413","authenticated-orcid":false,"given":"Cansu","family":"Elmas","sequence":"additional","affiliation":[{"name":"Division of Neuropathology and Neurochemistry, Department of Neurology Medical University of Vienna  Vienna Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4652-3582","authenticated-orcid":false,"given":"Vasiliki","family":"Zouvelou","sequence":"additional","affiliation":[{"name":"First Department of Neurology \u201cEginition\u201d Hospital, School of Medicine National and Kapodistrian University of Athens  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9237-4963","authenticated-orcid":false,"given":"Elisabeth","family":"Chroni","sequence":"additional","affiliation":[{"name":"Department of Neurology, School of Medicine University of Patras  Rio\u2010Patra Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8925-3327","authenticated-orcid":false,"given":"Dimitrios","family":"Tzanetakos","sequence":"additional","affiliation":[{"name":"Second Department of Neurology, \u201cAttikon\u201d University Hospital, School of Medicine National &amp; Kapodistrian University of Athens  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria","family":"Kourouvani","sequence":"additional","affiliation":[{"name":"Tzartos NeuroDiagnostics  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-8589-2574","authenticated-orcid":false,"given":"Marlene","family":"Wolfsgruber","sequence":"additional","affiliation":[{"name":"Division of Neuropathology and Neurochemistry, Department of Neurology Medical University of Vienna  Vienna Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0774-5772","authenticated-orcid":false,"given":"Ioannis","family":"Zaganas","sequence":"additional","affiliation":[{"name":"School of Medicine University of Crete  Crete Greece"},{"name":"Neurology Department Heraklion University General Hospital  Crete Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dimitra","family":"Kolovou","sequence":"additional","affiliation":[{"name":"First Department of Neurology \u201cEginition\u201d Hospital, School of Medicine National and Kapodistrian University of Athens  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Rentzos","sequence":"additional","affiliation":[{"name":"First Department of Neurology \u201cEginition\u201d Hospital, School of Medicine National and Kapodistrian University of Athens  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6292-858X","authenticated-orcid":false,"given":"Ariadne","family":"Daponte","sequence":"additional","affiliation":[{"name":"First Department of Neurology \u201cEginition\u201d Hospital, School of Medicine National and Kapodistrian University of Athens  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria","family":"Chondrogiorgi","sequence":"additional","affiliation":[{"name":"Neurology Clinic, Faculty of Medicine, Health Sciences School University of Ioannina  Ioannina Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5217-1317","authenticated-orcid":false,"given":"Spyridon","family":"Konitsiotis","sequence":"additional","affiliation":[{"name":"Neurology Clinic, Faculty of Medicine, Health Sciences School University of Ioannina  Ioannina Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Georgios","family":"Nicolaou","sequence":"additional","affiliation":[{"name":"Neurology Clinic 417 NIMTS Military Hospital  Athens Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stavroula","family":"Salakou","sequence":"additional","affiliation":[{"name":"Second Department of Neurology, \u201cAttikon\u201d University Hospital, School of Medicine National &amp; 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