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GENATLAS PHENOTYPE
last update : 05/05/07
Symbol CHRND
Location 2q33-q34
Name congenital myasthenic syndrome, type II
Corresponding gene CHRND
Main clinical features
  • severe slow-channel (or fast-channel), D
  • postsynaptic form, onset in infancy, with progressive weakness, athrogryposis in any cases, and impaired neuromuscular transmission without over degeneration of the motor endplate
  • Genetic determination not applicable
    Function/system disorder
    Type disease
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    missense     mutation causes delayed opening of the channel, a finding that readily explains the marked congenital weakness in the absence of endplate degeneration
    Remark(s)
  • P250Q mutation caused a decreased amplitude of the miniature endplate potential and current (MEPP and MEPC, respectively) to approximately 26 to 35% of normal
  • mutation impairing co-clustering of the acetylcholine receptor with rapsyn
  • Genotype/Phenotype correlations delta E59K causes dysfunction of fetal as well as the adult AChR and would explain the presence of joint contractures on the basis of reduced fetal movement