What is the role of RYR1 in the etiology of congenital fiber-type disproportion (CFTD)?

Updated: Mar 11, 2019
  • Author: Matthew Harmelink, MD; Chief Editor: Amy Kao, MD  more...
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Autosomal recessive mutations in the gene for RYR1 may be a common cause of CFTD, possibly up to 10% of cases. [62] All patients presented at birth with severe weakness and hypotonia with possible ophthalmoplegia except for one who presented at 2 years with difficulty running. The most severe cases developed progressive respiratory failure and died between 1 month and 3 years. Milder cases walked into their teens, although one patient at age 29 could only walk a few steps.

Although none of the patients with CFTD had a family history of malignant hyperthermia, standard precautions are prudent. [62]

Note that there are many other causes of type-1 fiber hypotrophy including other congenital myopathies (nemaline rod myopathy, centronuclear/myotubular myopathy, multiminicore myopathy), muscular dystrophies (eg, Emery-Dreifuss muscular dystrophy, LGMD2A, congenital muscular dystrophy with spine rigidity due to mutations in selenoprotein N), polymyositis, perinatal asphyxia, leukodystrophies, spinal muscular atrophy, arthrogryposis, and Pompe disease.

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