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Hyperkalemic periodic paralysis

Other Names for this Disease
  • Adynamia episodica hereditaria with or without myotonia
  • Gamstorp disease
  • Gamstorp episodic adynamy
  • HYPP
  • Sodium channel muscle disease
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Hyperkalemic periodic paralysis is a genetic condition that causes episodes of extreme muscle weakness, usually beginning in infancy or early childhood. Most often, these episodes involve a temporary inability to move muscles in the arms and legs. Episodes tend to increase in frequency until about age 25, after which they may occur less frequently. Factors that can trigger attacks include rest after exercise, potassium-rich foods, stress, fatigue, and long periods without food. Muscle strength improves between attacks, although many affected people continue to experience mild stiffness, particularly in muscles of the face and hands. This condition is caused by mutations in the SCN4A gene and is inherited in an autosomal dominant fashion.[1]
Last updated: 9/21/2011


  1. Hyperkalemic periodic paralysis. Genetics Home Reference. April 2007; Accessed 9/21/2011.
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Basic Information

  • Genetics Home Reference (GHR) contains information on Hyperkalemic periodic paralysis. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The National Institute of Neurological Disorders and Stroke (NINDS) collects and disseminates research information related to neurological disorders. Click on the link to view information on this topic.

In Depth Information

  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Hyperkalemic periodic paralysis. Click on the link to view a sample search on this topic.