Congenital myasthenia: End‐plate acetylcholine receptors and electrophysiology in five cases

Publisher Website
Google Scholar
Abstract
The nature of the defect in congenital myasthenia was investigated in biopsy specimens of intercostal muscle from 5 male patients whose symptoms presented between birth and 2 years of age. Miniature end‐plate potentials were reduced in amplitude in all 5 patients. The number of acetylcholine receptors as determined by α‐bungarotoxin binding was normal in case 1 and reduced in cases 2, 4, and 5. The shape of the endplates as shown by autoradiography and cholinesterase staining was normal in case 1 and elongated in cases 2, 4, and 5. In case 3, α‐bungarotoxin binding was slowly reversible, and there were some muscle fibers with multiple end‐plate regions. The acetylcholine content of the muscle was normal in all 5 cases. None of the patients had serum antibody to human acetylcholine receptor as measured by immunoprecipitation or inhibition of α‐bungarotoxin binding. We conclude that congenital myasthenia is a heterogeneous condition of nonimmune etiology in which both presynaptic and postsynaptic defects can be found.