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Neurological rarities
Brody disease: when myotonia is not myotonia
  1. Luís Braz1,2,
  2. Ricardo Soares-dos-Reis1,2,3,4,
  3. Mafalda Seabra1,2,
  4. Fernando Silveira1,5,
  5. Joana Guimarães1,2,6
  1. 1 Neurology Department, Centro Hospitalar Universitário de São João, Porto, Portugal
  2. 2 Department of Clinical Neurosciences and Mental Health, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
  3. 3 Department of Biomedicine, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
  4. 4 i3S, Institute for Research and Innovation in Health, Porto, Portugal
  5. 5 Neurophysiology Unit, Neurology Department, Centro Hospitalar Universitário de São João, Porto, Portugal
  6. 6 Centre for Drug Discovery and Innovative Medicines (MedInUP), Universidade do Porto, Porto, Portugal
  1. Correspondence to Dr Luís Braz, Neurology Department, Centro Hospitalar Universitário de São João, Porto, Portugal; luispereirabraz{at}gmail.com

Abstract

A 56-year-old man presented with painless impairment of muscle relaxation on vigorous contraction (eg, eyelid closure, hand grip, running). There were no episodes of paralysis, symptom progression, weakness or extramuscular symptoms. Five of his fifteen siblings had similar complaints. His serum creatine kinase was normal. Electromyography showed electrical silence on muscle relaxation, without myotonic discharges. DMPK, ClCN1 and SCN4A genetic testing was normal, but he had a homozygous pathogenic variant of ATP2A1 (c.1315G>A; pGlu439Lys). Brody disease is a rare autosomal recessive myopathy due to ATP2A1 mutations that reduce sarcoplasmic reticulum calcium-ATPase1 activity, hence delaying muscle relaxation.

  • brody disease
  • pseudomyotonia
  • ATP2A1
  • muscle disease

https://doi.org/10.1136/practneurol-2019-002224

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    Footnotes

    • LB and RS-d-R are joint first authors.

    • Contributors LB, RS-d-R and MS drafted the initial manuscript. LB and RS-d-R produced a revised version of the manuscript. LB filmed the patient. All authors were involved in clinical care of the patient, contributed to and revised the final version of the manuscript.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Patient consent for publication Obtained.

    • Provenance and peer review Not commissioned. Externally peer reviewed by Jon Walters, Swansea, UK.

    • Data sharing statement No additional data are available.

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