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Trouble at the junction: When myopathy and myasthenia overlap
Author(s) -
Nicolau Stefan,
Kao Justin C.,
Liewluck Teerin
Publication year - 2019
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.26676
Subject(s) - myopathy , myasthenia gravis , physical medicine and rehabilitation , neuromuscular junction , medicine , neuroscience , psychology , pathology
Abstract Although myopathies and neuromuscular junction disorders are typically distinct, their coexistence has been reported in several inherited and acquired conditions. Affected individuals have variable clinical phenotypes but typically display both a decrement on repetitive nerve stimulation and myopathic findings on muscle biopsy. Inherited causes include myopathies related to mutations in BIN1 , DES , DNM2 , GMPPB , MTM1 , or PLEC and congenital myasthenic syndromes due to mutations in ALG2 , ALG14 , COL13A1 , DOK7 , DPAGT1 , or GFPT1 . Additionally, a decrement due to muscle fiber inexcitability is observed in certain myotonic disorders. The identification of a defect of neuromuscular transmission in an inherited myopathy may assist in establishing a molecular diagnosis and in selecting patients who would benefit from pharmacological correction of this defect. Acquired cases meanwhile stem from the co‐occurrence of myasthenia gravis or Lambert‐Eaton myasthenic syndrome with an immune‐mediated myopathy, which may be due to paraneoplastic disorders or exposure to immune checkpoint inhibitors.