Adult Diagnosis of Type 1 Fiber Predominance Myopathy Caused by Novel Mutations in the RYR1 Gene

Leema Reddy Peddareddygari, Kinsi Oberoi, Leroy R. Sharer, Raji P. Grewal

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We describe a 57-year-old patient with mild diffuse weakness that was incidentally detected when he was evaluated for restless leg syndrome. An electromyography confirmed the presence of a myopathy without suggestion of inflammatory myopathy. A muscle biopsy demonstrated type 1 fiber predominance with minimal inflammatory features suggesting a genetic myopathy. Exome sequencing revealed c.10648C > T variant (p.R3550W), and a novel variant, c.10749-10753delGGAGG (E3584Rfs3), in the ryanodine receptor 1 (RYR1) gene transmitted through his asymptomatic father indicating these mutations are in trans. Prompted by these results, a 47-year-old sister presented for evaluation. Her examination showed mild proximal muscle weakness, and an electromyography confirmed a noninflammatory myopathy. Her genotype was identical to her affected brother confirming that in these siblings, the RYR1 mutations, transmitted in an autosomal recessive pattern, are the cause of their myopathy. The adult age at diagnosis of these affected siblings likely reflects the mild and minimally progressive nature of the myopathy.

Original languageEnglish (US)
Pages (from-to)214-216
Number of pages3
JournalJournal of clinical neuromuscular disease
Issue number4
StatePublished - Jun 1 2019

All Science Journal Classification (ASJC) codes

  • Neurology
  • Clinical Neurology


  • RYR1 mutations
  • minimally progressive myopathy
  • muscle weakness
  • type 1 fiber predominance


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