Hyperkalemic periodic paralysis

Reviewed April 2007

What is hyperkalemic periodic paralysis?

Hyperkalemic periodic paralysis is a 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 periods without food (fasting). Muscle strength improves between attacks, although many affected people continue to experience mild stiffness (myotonia), particularly in muscles of the face and hands.

Some people with hyperkalemic periodic paralysis have increased levels of potassium in their blood (hyperkalemia) during attacks. In other cases, attacks are associated with normal blood potassium levels (normokalemia). Ingesting potassium can trigger attacks in affected individuals, even if blood potassium levels do not go up.

How common is hyperkalemic periodic paralysis?

Hyperkalemic periodic paralysis affects an estimated 1 in 200,000 people.

What genes are related to hyperkalemic periodic paralysis?

Mutations in the SCN4A gene cause hyperkalemic periodic paralysis.

The SCN4A gene provides instructions for making a protein that plays an essential role in muscles used for movement (skeletal muscles). For the body to move normally, these muscles must tense (contract) and relax in a coordinated way. Muscle contractions are triggered by the flow of certain positively charged atoms (ions), including sodium, into muscle cells. The SCN4A protein forms channels that control the flow of sodium ions into these cells.

Mutations in the SCN4A gene alter the usual structure and function of sodium channels. The altered channels cannot properly regulate the flow of sodium ions into muscle cells, which reduces the ability of skeletal muscles to contract. Because muscle contraction is needed for movement, a disruption in normal ion transport leads to episodes of muscle weakness or paralysis.

Related Gene(s)

Changes in this gene are associated with hyperkalemic periodic paralysis.

SCN4A

How do people inherit hyperkalemic periodic paralysis?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

In most cases, an affected person has one parent with the condition.

Where can I find information about diagnosis or management of hyperkalemic periodic paralysis?

These resources address the diagnosis or management of hyperkalemic periodic paralysis and may include treatment providers.

Gene Review: Hyperkalemic Periodic Paralysis Type 1 (http://www.ncbi.nlm.nih.gov/books/NBK1496/)
Genetic Testing Registry: Familial hyperkalemic periodic paralysis (http://www.ncbi.nlm.nih.gov/gtr/conditions/C0238357)
Genetic Testing Registry: Hyperkalemic Periodic Paralysis Type 1 (http://www.ncbi.nlm.nih.gov/gtr/conditions/CN074266)
MedlinePlus Encyclopedia: Hyperkalemic periodic paralysis (http://www.nlm.nih.gov/medlineplus/ency/article/000316.htm)

You might also find information on the diagnosis or management of hyperkalemic periodic paralysis in Educational resources (http://www.ghr.nlm.nih.gov/condition/hyperkalemic-periodic-paralysis/show/Educational+resources) and Patient support (http://www.ghr.nlm.nih.gov/condition/hyperkalemic-periodic-paralysis/show/Patient+support).

General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).

To locate a healthcare provider, see How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

Where can I find additional information about hyperkalemic periodic paralysis?

You may find the following resources about hyperkalemic periodic paralysis helpful. These materials are written for the general public.

MedlinePlus - Health information
- Encyclopedia: Hyperkalemic periodic paralysis (http://www.nlm.nih.gov/medlineplus/ency/article/000316.htm)
- Health Topic: Muscle Disorders (http://www.nlm.nih.gov/medlineplus/muscledisorders.html)
- Health Topic: Paralysis (http://www.nlm.nih.gov/medlineplus/paralysis.html)
Additional NIH Resources - National Institutes of Health
National Institute of Neurological Disorders and Stroke (http://www.ninds.nih.gov/disorders/periodic_paralysis/periodic_paralysis.htm)
Educational resources - Information pages
- Cleveland Clinic Health Information Center (http://my.clevelandclinic.org/disorders/hyperkalemia/hic_familial_periodic_paralyses.aspx)
- Merck Manual of Medical Information, Second Home Edition (http://www.merckmanuals.com/home/childrens_health_issues/muscular_dystrophies_and_related_disorders/periodic_paralysis.html)
- Neuromuscular Disease Center, Washington University (http://neuromuscular.wustl.edu/mother/activity.html)
- Orphanet (http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=682)
- Swedish Information Center for Rare Diseases (http://www.socialstyrelsen.se/rarediseases/hyperkalemicperiodicparalysisa)
Patient support - For patients and families
- Muscular Dystrophy Association (http://mda.org/disease/inherited-and-endocrine-myopathies)
- Resource list from the University of Kansas Medical Center (http://www.kumc.edu/gec/support/periodic.html)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

Gene Reviews - Clinical summary (http://www.ncbi.nlm.nih.gov/books/NBK1496/)
Genetic Testing Registry - Repository of genetic test information
- Genetic Testing Registry: Familial hyperkalemic periodic paralysis (http://www.ncbi.nlm.nih.gov/gtr/conditions/C0238357)
- Genetic Testing Registry: Hyperkalemic Periodic Paralysis Type 1 (http://www.ncbi.nlm.nih.gov/gtr/conditions/CN074266)
PubMed - Recent literature (http://www.ncbi.nlm.nih.gov/pubmed?term=(hyperkalemic%20periodic%20paralysis%5BTIAB%5D)%20AND%20english%5Bla%5D%20AND%20human%5Bmh%5D%20AND%20%22last%202880%20days%22%5Bdp%5D)
OMIM - Genetic disorder catalog (http://omim.org/entry/170500)

What other names do people use for hyperkalemic periodic paralysis?

Adynamia Episodica Hereditaria
Familial Hyperkalemic Periodic Paralysis
Gamstorp disease
Gamstorp episodic adynamy
HyperKPP
HyperPP
Primary Hyperkalemic Periodic Paralysis

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What if I still have specific questions about hyperkalemic periodic paralysis?

Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).

What glossary definitions help with understanding hyperkalemic periodic paralysis?

autosomal ; autosomal dominant ; cell ; contraction ; familial ; fasting ; gene ; hyperkalemia ; ions ; ion transport ; myotonia ; potassium ; protein ; sodium ; stress

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).

References

Bradley, W G((Walter George)); Neurology in clinical practice; 4th ed.; Philadelphia, PA : Butterworth-Heinemann, c2004. p1852-1853.
Cannon SC. An expanding view for the molecular basis of familial periodic paralysis. Neuromuscul Disord. 2002 Aug;12(6):533-43. Review. (http://www.ncbi.nlm.nih.gov/pubmed/12117476?dopt=Abstract)
Gene Review: Hyperkalemic Periodic Paralysis Type 1 (http://www.ncbi.nlm.nih.gov/books/NBK1496/)
Jurkat-Rott K, Lehmann-Horn F. Paroxysmal muscle weakness: the familial periodic paralyses. J Neurol. 2006 Nov;253(11):1391-8. Epub 2006 Nov 30. Review. (http://www.ncbi.nlm.nih.gov/pubmed/17139526?dopt=Abstract)
Lehmann-Horn F, Jurkat-Rott K, Rüdel R. Periodic paralysis: understanding channelopathies. Curr Neurol Neurosci Rep. 2002 Jan;2(1):61-9. Review. (http://www.ncbi.nlm.nih.gov/pubmed/11898585?dopt=Abstract)
Miller TM, Dias da Silva MR, Miller HA, Kwiecinski H, Mendell JR, Tawil R, McManis P, Griggs RC, Angelini C, Servidei S, Petajan J, Dalakas MC, Ranum LP, Fu YH, Ptácek LJ. Correlating phenotype and genotype in the periodic paralyses. Neurology. 2004 Nov 9;63(9):1647-55. (http://www.ncbi.nlm.nih.gov/pubmed/15534250?dopt=Abstract)
Venance SL, Cannon SC, Fialho D, Fontaine B, Hanna MG, Ptacek LJ, Tristani-Firouzi M, Tawil R, Griggs RC; CINCH investigators. The primary periodic paralyses: diagnosis, pathogenesis and treatment. Brain. 2006 Jan;129(Pt 1):8-17. Epub 2005 Sep 29. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16195244?dopt=Abstract)

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.



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