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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. 1 Department of Neurology, St James’s Hospital, Dublin, Ireland
  2. 2 Department of Neurophysiology, St James Hospital, Dublin, Ireland
  3. 3 Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
  1. Correspondence to Dr Albi Jose Chalissery, Department of Neurology, Beaumont Hospital, Dublin, Ireland; albi.chalissery{at}


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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  • 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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