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GENATLAS PHENOTYPE
last update : 04-12-2013
Symbol MCB
Location 7q34
Name myotonia, congenita, generalized of Becker
Other name(s) Becker disease
Corresponding gene CLCN1
Other symbol(s) GMAR
Main clinical features
  • nondystrophic skeletal muscle disorder characterized by muscle stiffness and an inability of the muscle to relax after voluntary contraction with symptom onset in the legs, and later progression to the arms, neck, and facial muscles
  • MRI is frequently abnormal in non-dystrophic myotonia providing evidence of fatty infiltration and/or oedema (PMID: 23810313))
    • Genetic determination autosomal recessive
    Function/system disorder neuromuscular
    Type disease
    Gene product
    Name chloride channel, skeletal muscle (CLCN1)
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    abnormal splicing   truncated protein G-to-T mutation on the donor splice site of intron 17, leading to the skipping of exon 17
    abnormal splicing   truncated protein 696+1G>A
    Remark(s)
  • mutation enhances the degradation of human CLCN1 chloride channels (PMID: 23424641))