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GENATLAS PHENOTYPE
last update : 18-04-2017
Symbol MTM1
Location Xq28
Name myopathy, myotubular 1
Other name(s) myopathy, centronuclear
Corresponding gene MTM1
Other symbol(s) CNM, MTMX, XMM
Main clinical features
  • congenital muscle disorder characterized by severe hypotonia and respiratory insufficiency, leading to death at a mean age of 4-5 months
  • muscle histology consists of small rounded muscle cells with centrally located nuclei surrounded by a halo without contractile elements with disorganization of the tubulo-reticular network (T-tubules were found concentrated around the abnormally located central nuclei, or in irregular densities in the centers of several fibers)
    • . including milder forms
    Genetic determination sex linked
    Function/system disorder neuromuscular
    Type disease
    Gene product
    Name myotubularin (MTM1)
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    various types   truncated protein severe form
    missense     milder form
    Remark(s)
  • possibility of germinal mosaicism
    • Genotype/Phenotype correlations
  • truncating mutations cause the severe and early lethal phenotype
  • some missense mutations are associated with milder forms and prolonged survival (up to 54 years)
  • loss of AKT1-dependent growth/survival cues due to impaired myotubularin function may be a critical factor underlying the severe skeletal muscle atrophy characteristic of muscle fibers in patients with X-linked myotubular myopathy (PMID: 21478156))
  • unbalanced regulation of the ubiquitin proteasome pathway and the autophagy machinery is a primary cause of the MTM1 pathogenesis (PMID: 23695157))