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Diverse phenotype of hypokalaemic periodic paralysis within a family
  1. Albi Jose Chalissery1,
  2. Tudor Munteanu1,
  3. Yvonne Langan2,
  4. Francesca Brett3,
  5. Janice Redmond1
  1. 1Department of Neurology, St James’s Hospital, Dublin, Ireland
  2. 2Department of Neurophysiology, St James Hospital, Dublin, Ireland
  3. 3Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
  1. Correspondence to Dr Albi Jose Chalissery, Department of Neurology Beaumont Hospital, Ireland; albi.chalissery{at}hse.ie

Abstract

Hypokalaemic periodic paralysis typically presents with intermittent mild-to-moderate weakness lasting hours to days. We report a case with an uncommon phenotype of late-onset myopathy without episodic paralytic attacks. Initial work-up including muscle biopsy was inconclusive. A subsequent review of the right deltoid biopsy, long exercise testing and repeated family history was helpful, followed by appropriate genetic testing. We identified a heterozygous pathogenic mutation in calcium ion channel (CACNA1S:c.1583G>A p.Arg528His) causing hypokalaemic periodic paralysis. Myopathy can present without episodic paralysis and the frequency of paralytic episodes does not correlate well with the development and progression of a fixed myopathy. Our report also highlights the intrafamilial phenotypic variation of hypokalaemic periodic paralysis secondary to a CACNA1S gene mutation.

  • hypokalemic periodic paralysis
  • myopathy
  • long exercise testing

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Footnotes

  • Contributors All authors contributed to the work.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed. This paper was reviewed by Jon Walters, Swansea, UK.

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