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last update : 12-01-2016
Symbol CMS1A
Location 2q31.1
Name congenital myasthenic syndrome, type I A
Other name(s) myasthenic syndrome, congenital slow-channel
Corresponding gene CHRNA1
Other symbol(s) SCCMS, CMS IIa
Main clinical features
  • severe slow-channel
  • postsynaptic form, with selective involvement of cervical, scapular, and finger extensor muscles and ophthalmoparesis from infancy or early childhood, with a decremental compound muscle action potential (CMAP) response to stimulus, prolonged endplate potentials, and prolonged miniature endplate potentials (MEPP) and endplate currents (MEPC); at muscle biopsy, predominance of type I fibers, atrophic type 2 fibers, and abnormal endplate configuration
  • Genetic determination autosomal dominant
    Related entries including CMS1B (OMIM: 608930)
    Function/system disorder neuromuscular
    Type disease
    Gene product
    Name cholinergic receptor, nicotinic, alpha polypeptide (CHRNA1)
    Gene mutationChromosome rearrangementEffectComments
    missense   other alphaF256L resulting in fast channel kinetics
    various types