Morvan syndrome as a paraneoplastic disorder of thymoma with anti-CASPR2 antibodies

Vale, Thiago Cardoso; Pedroso, José Luiz; Dutra, Lívia Almeida; Azevedo, Lyamara Apostólico de; Filho, Lúcio Huebra Pimentel; Prado, Lucila Bizari Fernandes do; Höftberger, Romana; Prado, Gilmar Fernandes do; Barsottini, Orlando Graziani Póvoas

doi:10.1016/s0140-6736(16)31459-3

Cited by 22 publications

(14 citation statements)

References 5 publications

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“…These effects were not yet proven to be IgG4 specific. Caspr2 is expressed in the peripheral and central nervous system, particularly in the juxtaparanodal region of myelinated axons and in hippocampal GABAergic interneurons, and autoantibodies are associated with different clinical syndromes ( 88 , 91 , 250 – 252 ). It is suspected that the antibodies block the interaction between Caspr2 and TAG-1 and affect inhibitory interneuron function, thus leading to hyperexcitability ( 87 ).…”

Section: Definition and Validation Of Igg4 Autoimmune Diseasesmentioning

confidence: 99%

A New Classification System for IgG4 Autoantibodies

2018

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IgG4 autoimmune diseases are characterized by the presence of antigen-specific autoantibodies of the IgG4 subclass and contain well-characterized diseases such as muscle-specific kinase myasthenia gravis, pemphigus, and thrombotic thrombocytopenic purpura. In recent years, several new diseases were identified, and by now 14 antigens targeted by IgG4 autoantibodies have been described. The IgG4 subclass is considered immunologically inert and functionally monovalent due to structural differences compared to other IgG subclasses. IgG4 usually arises after chronic exposure to antigen and competes with other antibody species, thus “blocking” their pathogenic effector mechanisms. Accordingly, in the context of IgG4 autoimmunity, the pathogenicity of IgG4 is associated with blocking of enzymatic activity or protein–protein interactions of the target antigen. Pathogenicity of IgG4 autoantibodies has not yet been systematically analyzed in IgG4 autoimmune diseases. Here, we establish a modified classification system based on Witebsky’s postulates to determine IgG4 pathogenicity in IgG4 autoimmune diseases, review characteristics and pathogenic mechanisms of IgG4 in these disorders, and also investigate the contribution of other antibody entities to pathophysiology by additional mechanisms. As a result, three classes of IgG4 autoimmune diseases emerge: class I where IgG4 pathogenicity is validated by the use of subclass-specific autoantibodies in animal models and/or in vitro models of pathogenicity; class II where IgG4 pathogenicity is highly suspected but lack validation by the use of subclass specific antibodies in in vitro models of pathogenicity or animal models; and class III with insufficient data or a pathogenic mechanism associated with multivalent antigen binding. Five out of the 14 IgG4 antigens were validated as class I, five as class II, and four as class III. Antibodies of other IgG subclasses or immunoglobulin classes were present in several diseases and could contribute additional pathogenic mechanisms.

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Section: Definition and Validation Of Igg4 Autoimmune Diseasesmentioning

confidence: 99%

A New Classification System for IgG4 Autoantibodies

2018

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“…In many cases Morvan syndrome is paraneoplastic, being especially associated with thymoma and small cell lung cancer but it can also occur in the absence of any cancer. It can also be associated with myasthenia gravis (10).…”

Section: Introductionmentioning

confidence: 99%

“…Treatment options include plasma exchange, corticosteroids, intravenous immunoglobulins, immunosuppression with azathioprine / cyclosporine/ cyclophosphamide (3,10).…”

Section: Introductionmentioning

confidence: 99%

A case report of Morvan syndrome, the unique clinical pattern of a rare disease

Epure¹,

Ioghen²,

Roza³

et al. 2020

Ro J Neurol.

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Morvan syndrome is a rare autoimmune disorder mediated by antibodies against voltage-gated potassium channels (VGKC) and characterized by the involvement of both the peripheral and central nervous system. We report a case of Morvan syndrome. The patient presented with peripheral nerve hyperexcitability, dysautonomia and neuropsychiatric symptoms. The diagnosis was based on the unique clinical presentation that was highly suggestive of Morvan syndrome and confirmed by positive VGKC antibodies. In this paper we try to highlight the importance of clinical skills in the diagnosis and decision-making concerning the treatment process.

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“…Morvan's syndrome is an autoimmune disease that affects CNS, PNS and autonomic system [12] . It consists of neuromyotonia (cramps, stiffness, fasciculation) [13] , encephalopathy, insomnia, dysautonomic signs specially hyperhidrosis and cardiovascular instability, and neuropathic pain [4,[13][14][15] . Weight loss, skin lesions or itch, which may result from skin dysautonomia, seizures, fever and SIADH may also be present [12,14] .…”

mentioning

confidence: 99%

“…Most of the patients have both CASPR2 and LGI1 antibodies [4,15] , but CASPR2 antibodies titers are usually higher [14] . Antibodies against Contactin-2, a protein expressed in heart conduction tissue, may also be found, associated with cardiovascular instability [14] .…”

mentioning

confidence: 99%