Coexistence of anti-musk-positive bulbar myasthenia gravis and myotonic dystrophy Type 1: the first case report from Türkiye

Abstract

Muscle-specific tyrosine kinase (MuSK) myasthenia gravis (MG) is an acute-onset subtype of MG that primarily affects the fasciobulbar muscles and begins with progressive velopharyngeal and respiratory symptoms such as early respiratory crises, swallowing, and speaking difficulties. Myotonic dystrophy Type 1 (DM1) is an autosomal dominantly inherited autoimmune neuromuscular disease characterized by distal-dominant muscle weakness, cardiovascular pathologies, and corneal disorders. In this case report, we discussed a 42-year-old female patient with a previous diagnosis of DM1 and diagnosed with MuSK-MG as a result of electroneuromyographic and antibody tests upon the development of bulbar symptoms and thymus hyperplasia. The patient underwent video-assisted thymectomy, and medical treatment was started with a combination of pyridostigmine and methylprednisolone. The coexistence of anti- MuSK positive MG with thymoid hyperplasia and DM 1 has not been reported so far, and it has been predicted that both diseases may trigger each other through neuroinflammatory mechanisms on an autoimmunergic basis.

Keywords

• Autoimmunity
• muscle-specific tyrosine kinase myasthenia gravis
• myotonic dystrophy Type 1
• neuroinflammation
• thymus hyperplasia

Anti-musk pozitif bulbar myastenia gravis ve miyotonik distrofi Tip 1 birlikteliği: Türkiye'den ilk vaka sunumu

Öz

Kas spesifik tirozin kinaz (MuSK) miyastenia gravis (MG), öncelikle fasyobulbar kasları etkileyen ve erken solunum krizleri, yutma ve konuşma güçlükleri gibi ilerleyici velofaringeal ve solunum semptomlarıyla başlayan, MG'nin akut başlangıçlı bir alt tipidir. Miyotonik distrofi Tip 1 (DM1), distal dominant kas zayıflığı, kardiyovasküler patolojiler ve kornea bozuklukları ile karakterize, otozomal dominant geçişli, otoimmün nöromüsküler bir hastalıktır. Bu olgu sunumunda, daha önce DM1 tanısı alan, bulber semptomları ve timus hiperplazisi gelişmesi üzerine elektronöromiyografik ve antikor testleri sonucunda MuSK-MG tanısı alan 42 yaşındaki kadın hastayı tartıştık. Hastaya video yardımlı timektomi uygulandı ve piridostigmin ve metilprednizolon kombinasyonu ile medikal tedaviye başlandı. Anti-MuSK pozitif MG ile timoid hiperplazi ve DM 1'in birlikteliği şu ana kadar bildirilmemiş olup, her iki hastalığın otoimmünerjik temelde nöroinflamatuar mekanizmalar yoluyla birbirini tetikleyebileceği öngörülmektedir.

Anahtar Kelimeler

• Otoimmünite
• kas spesifik tirozin kinaz miyastenia gravis
• miyotonik distrofi Tip 1
• nöroinflamasyon
• timus hiperplazisi

References

1. 1. Poursadeghfard M, Abolhasani Foroughi A, Karamimagham S. Thymolipoma-associated myasthenia gravis with high titer of anti- muskab: a case report. Int J Mol Cell Med 2019;8:90-93. https://doi.org/10.22088/IJMCM.BUMS.8.1.90
2. 2. Lauriola L, Ranelletti F, Maggiano N, et al. Thymus changes in anti-MuSK-positive and -negative myasthenia gravis. Neurology 2005;64:536-538. https://doi.org/10.1212/01.WNL.0000150587.71497.B6
3. 3. Ashizawa T, Sarkar PS. Myotonic dystrophy types 1 and 2. Handb Clin Neurol 2011;101:193-237. https://doi.org/10.1016/B978-0-08-045031-5.00015-3
4. 4. Elahi B, Laughlin RS, Litchy WJ, Milone M, Liewluck T. Neuromuscular transmission defects in myopathies: rare but worth searching for. Muscle Nerve 2019;59:475-478.
5. 5. Rodriguez Cruz PM, Sewry C, Beeson D, et al. Congenital myopathies with secondary neuromuscular transmission defects; a case report and review of the literature. Neuromuscul Disord 2014;24:1103-1110. https://doi.org/10.1016/j.nmd.2014.07.005
6. 6. Burden SJ, Yumoto N, Zhang W. The role of MuSK in synapse formation and neuromuscular disease. Cold Spring Harb Perspect Biol 2013;5:a009167(e1-13). https://doi.org/10.1101/cshperspect.a009167
7. 7. Plomp JJ, Huijbers MG, van der Maarel SM, Verschuuren JJ. Pathogenic IgG4 subclass autoantibodies in MuSK myasthenia gravis. Ann N Y Acad Sci 2012;1275:114-122. https://doi.org/10.1111/j.1749- 6632.2012.06808.x
8. 8. Tieleman AA, denBroeder AA, vande Logt AE, van Engelen BG. Strong association between myotonic dystrophy type 2 and autoimmune diseases. J Neurol Neurosurg Psychiatry 2009;80:1293-1295. https://doi.org/10.1136/jnnp.2008.156562

9. 9. Junghans RP, Ebralidze A, Tiwari B. Does (CUG) Repeatin DMPK mRNA ‘Paint’ chromosome 19 to suppress distant genes to create the Diverse Phenotype of Myotonic Dystrophy?: a new hypothesis of long-range cis autosomal inactivation. Neurogenetics 2001;3:59 67. https://doi.org/10.1007/ s100480000103
10. 10. Mueller CM, Hilbert JE, Martens W, Thornton CA, Moxley RT 3rd, Greene MH. Hypothesis: neoplasms in myotonic dystrophy. Cancer Causes Control 2009;20:2009-2020. https://doi.org/10.1007/s10552-009-9395-y
11. 11. Azotla Vilchis CN, Sanchez Celis D, Agonizantes Juárez LE, et al. Transcriptome Analysis Reveals Altered Inflammatory Pathway in an Inducible Glial Cell Model of Myotonic Dystrophy Type 1. Biomolecules 2021;11:159(e1-22). https://doi.org/10.3390/biom11020159
12. 12. Jeremy D, Rhodes JD, Lott MC, Russell SL, et al. Activation of the innate immune response and interferon signalling in myotonic dystrophy type 1 and type 2 cataracts, Human Molecular Genetics 2012; 21: 852-862. https://doi.org/10.1093/hmg/ddr515
13. 13. Nieuwenhuis S, Widomska J, Blom P, et al. and on behalf of the Optimistic Consortium. Blood transcriptome profiling links immunity to disease severity in myotonic dystrophy Type 1 (DM1). Int J Mol Sci 2022;23:3081(e1-24). https://doi.org/10.3390/ijms23063081
14. 14. Sasson SC, Corbett A, Mc Lachlan AJ, et al. Enhanced serum immunoglobulin g clearance in myotonic dystrophy-associated hypogammaglobulinemia: a case series and review of the literature. J Med Case Rep 2019;13: 338(e1-7). https://doi.org/10.1186/s13256-019-2285-3
15. 15. Takahashi H, Kawaguchi N, Nemoto Y, Hattori T. High- dose intravenous immunoglobulin for the treatment of MuSK antibody-positive seronegative myasthenia gravis. J Neurol Sci 2006;247:239-241. https://doi.org/10.1016/j.jns.2006.05.065