An unusual ryanodine receptor 1 (RYR1) phenotype: Mild, calf-predominant myopathy.

Eugenio Maria Mercuri, Marika Pane, Giorgio Tasca, Maria Benedetta Donati, Manu Jokela, Anna Vihola, Per-Harald Jonson, Sara Lehtinen, Salla Välipakka, Maria Donati, Mridul Johari, Marco Savarese, Sanna Huovinen, Pirjo Isohanni, Johanna Palmio, Päivi Hartikainen, Bjarne Udd

Research output: Contribution to journalArticle


Abstract OBJECTIVE: To identify the genetic defect causing a distal calf myopathy with cores. METHODS: Families with a genetically undetermined calf-predominant myopathy underwent detailed clinical evaluation, including EMG/nerve conduction studies, muscle biopsy, laboratory investigations, and muscle MRI. Next-generation sequencing and targeted Sanger sequencing were used to identify the causative genetic defect in each family. RESULTS: A novel deletion-insertion mutation in ryanodine receptor 1 (RYR1) was found in the proband of the index family and segregated with the disease in 6 affected relatives. Subsequently, we found 2 more families with a similar calf-predominant myopathy segregating with unique RYR1-mutated alleles. All patients showed a very slowly progressive myopathy without episodes of malignant hyperthermia or rhabdomyolysis. Muscle biopsy showed cores or core-like changes in all families. CONCLUSIONS: Our findings expand the spectrum of RYR1-related disorders to include a calf-predominant myopathy with core pathology and autosomal dominant inheritance. Two families had unique and previously unreported RYR1 mutations, while affected persons in the third family carried 2 previously known mutations in the same dominant allele. © 2019 American Academy of Neurology.
Original languageEnglish
Pages (from-to)7146-7249
Number of pages104
Publication statusPublished - 2019


  • ryanodine receptor


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