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GENATLAS PHENOTYPE
last update : 16-01-2018
Symbol MMS
Location 14q11.2
Name myopathy myosin storage
Other name(s) myopathy, hyaline body
Corresponding gene MYH7
Other symbol(s) HBM
Main clinical features
  • sporadic nonprogressive congenital inclusion bodies myopathy with weakness and atrophy of the scapuloperoneal muscles, at muscle biopsy preferential atrophy of type I muscle fibers and subsarcolemmal bodies composed of an acid protein with ATPase activity
  • asymptomatic hyperCKemia, scapulo-peroneal myopathy and proximal and distal myopathy with muscle hypertrophy; muscle MRI identified a unique pattern in the posterior compartment of the thigh, characterized by early involvement of the biceps femoris and semimembranosus, with relative sparing of the semitendinosus (Pegoraro 2007)
  • at biopsy subsarcolemmal, hyaline-like accumulations of myosin in Type I muscle fibres
    • Genetic determination autosomal dominant
    autosomal recessive
    Function/system disorder neuromuscular
    Type disease
    Gene product
    Name myosin, heavy polypeptide 7
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    missense   abnormal protein/loss of function H1904L in the rod region of slow/beta cardiac MYH7, causing disruption of myosin heavy chain assembly or stability of the sarcomeric protein, with an apparent absence of hypertrophic cardiomyopathy usually associated with this mutations
    Remark(s) mutation located in the alpha-helical coiled-coil tail (Armel 2009)
    Genotype/Phenotype correlations due to mutations in exon 37/39)