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Congenital myasthenia: Further evidence of disease heterogeneity
Author(s) -
Lecky B. R. F.,
MorganHughes J. A.,
Murray N. M. F.,
Landon D. N.,
Wray D.,
Prior C.
Publication year - 1986
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.880090307
Subject(s) - acetylcholine receptor , myasthenia gravis , postsynaptic potential , muscle biopsy , acetylcholine , intercostal muscle , atrophy , medicine , anatomy , endocrinology , motor endplate , ultrastructure , bungarotoxin , neuromuscular junction , chemistry , biopsy , receptor , biology , neuroscience , respiratory system
The findings in two cases of congenital myasthenia investigated by intercostal muscle biopsy are presented. The first case, a 16‐year‐old boy, showed reduced miniature endplate potential amplitude and normal 125 l‐α‐bungarotoxin binding to postsynaptic acetylcholine receptors. Muscle biopsy and endplate ultrastructure were normal. Tubocurarine affinity, ion channel properties, and passive membrane properties were normal. Limited data showed reduced effectiveness of applied acetylcholine in opening ion channels. The second case was an 18‐year‐old girl with consanguineous parents. Type 2 muscle fiber atrophy was seen in both limb and intercostal muscle. Intercostal endplates were elongated, although ultrastructure was normal. Negligible postsynaptic α‐bungarotoxin binding suggested an abnormality of the acetylcholine receptor macromolecule.