The characteristic muscle weakness in myasthenia gravis (MG) is caused by antibodies directed against the neuromuscular junction
MG is divided into subgroups on the basis of specific antibodies, other biomarkers, and clinical characteristics, such as age of onset, presence of thymoma, and involvement of ocular muscles
The most common antibodies detected in MG are antibodies against acetylcholine receptors (AChRs), muscle-specific kinase (MuSK) and low-density lipoprotein receptor-related protein 4 (LRP4)
Additional antibodies of interest in MG are directed against agrin, titin, KV1.4, ryanodine receptors, collagen Q, and cortactin
Therapy should be tailored to the individual patient and guided by MG subgroup, and can include symptomatic drug therapy, immunosuppressive drug therapy, thymectomy and/or supportive therapy
The aim of treatment should be normal or near-normal function, which in most patients requires long-term immunosuppressive treatment with a drug combination that is individualized for the patient for optimal effectiveness
Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies that target the neuromuscular junction, leading to muscle weakness and fatigability. Currently available treatments for the disease include symptomatic pharmacological treatment, immunomodulatory drugs, plasma exchange, thymectomy and supportive therapies. Different autoantibody patterns and clinical manifestations characterize different subgroups of the disease: early-onset MG, late-onset MG, thymoma MG, muscle-specific kinase MG, low-density lipoprotein receptor-related protein 4 MG, seronegative MG, and ocular MG. These subtypes differ in terms of clinical characteristics, disease pathogenesis, prognosis and response to therapies. Patients would, therefore, benefit from treatment that is tailored to their disease subgroup, as well as other possible disease biomarkers, such as antibodies against cytoplasmic muscle proteins. Here, we discuss the different MG subtypes, the sensitivity and specificity of the various antibodies involved in MG for distinguishing between these subtypes, and the value of antibody assays in guiding optimal therapy. An understanding of these elements should be useful in determining how to adapt existing therapies to the requirements of each patient.
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N.E.G., G.O.S. and F.R. have received funding from Torbjørg Hauge's Legacy for Neurological Research and from the Norwegian Muscle Disease Association. S.J.T., K.L. and P.Z. have received grants from the Muscular Dystrophy Association of the USA and from the Greek National Strategic Reference Framework (NeuroID ISR-3257).
N.E.G. has received speaker's honoraria from Octapharma, Baxter and Merck Serono. P.Z. is co-inventor in a patent related to myasthenia gravis therapy and diagnosis. S.T. is co-inventor in two patnets related to myasthenia gravis therapy and diagnosis, and is shareholder and scientific advisor of Tzartos Neurodiagnostics. Other authors declare no competing interests.
- Antigenic modulation
Bivalent antibodies can cause crosslinking of receptors and subsequent receptor internalization.
- Epitope pattern
An epitope is a localized region on an antigen capable of eliciting an immune response, and the epitope pattern refers to all epitopes involved in an immune response.
- MG crisis
Severe worsening of myasthenic weakness that requires intubation or noninvasive ventilation to avoid intubation.
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Gilhus, N., Skeie, G., Romi, F. et al. Myasthenia gravis — autoantibody characteristics and their implications for therapy. Nat Rev Neurol 12, 259–268 (2016). https://doi.org/10.1038/nrneurol.2016.44
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