Congenital myasthenic syndromes: II. Syndrome attributed to abnormal interaction of acetylcholine with its receptor

Osvaldo Uchitel, Andrew G. Engel, Timothy J. Walls, Alexandre Nagel, M. Zouhair Atassi, Vera Bril

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59 Scopus citations


A 21‐year‐old woman had myasthenic symptoms since birth that responded poorly to anticholinesterase therapy. Tests for acetylcholine receptor (AChR) antibodies were negative. An intercostal muscle specimen was obtained to investigate the character of the neuromuscular transmission defect. There were no immune deposits at the endplates. The quantal content of the endplate potential was normal. Miniature endplate potentials and currents were very small, but the number of AChR per endplate was normal. On electron microscopy, the synaptic vesicles were of normal size, the junctional folds were intact, and the density and distribution of AChR on the folds was normal. The kinetic properties of AChR were studied by analysis of acetylcholine (ACh)‐induced current noise. The mean single channel conductance was normal. The noise power spectrum was abnormal, containing two components of different time course. This could result from an abnormal interaction of ACh with AChR, or from two populations of AChR at the endplate. The second possibility is unlikely because if two populations of AChR were present at the endplate, then both would have to have low conductance to explain the small miniature endplate current, but the average conductance of the channels that did open was normal. © 1993 John Wiley & Sons, Inc.

Original languageEnglish (US)
Pages (from-to)1293-1301
Number of pages9
JournalMuscle & Nerve
Issue number12
StatePublished - Dec 1993


  • acetylcholine receptor
  • congenital myasthenic syndrome
  • neuromuscular junction
  • noise analysis

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)


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