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Familial paroxysmal nonkinesigenic dyskinesia
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Reviewed September 2008
What is familial paroxysmal nonkinesigenic dyskinesia?
Familial paroxysmal nonkinesigenic dyskinesia is a disorder of the nervous system that causes periods of involuntary movement. Paroxysmal indicates that the abnormal movements come and go over time. Nonkinesigenic means that episodes are not triggered by sudden movement. Dyskinesia broadly refers to involuntary movement of the body.
People with familial paroxysmal nonkinesigenic dyskinesia experience episodes of abnormal movement that develop without a known cause or are brought on by alcohol, caffeine, stress, fatigue, menses, or excitement. Episodes are not induced by exercise or sudden movement and do not occur during sleep. An episode is characterized by irregular, jerking or shaking movements that range from mild to severe. In this disorder, the dyskinesias can include slow, prolonged contraction of muscles (dystonia); small, fast, "dance-like" motions (chorea); writhing movements of the limbs (athetosis); and, rarely, flailing movements of the limbs (ballismus). Dyskinesias also affect muscles in the trunk and face. The type of abnormal movement varies among affected individuals, even among members of the same family. Individuals with familial paroxysmal nonkinesigenic dyskinesia do not lose consciousness during an episode. Most people do not experience any other neurological symptoms between episodes.
Individuals with familial paroxysmal nonkinesigenic dyskinesia usually begin to show signs and symptoms of the disorder during childhood or their early teens. Episodes typically last 1-4 hours, and the frequency of episodes ranges from several per day to one per year. In some affected individuals, episodes occur less often with age.
How common is familial paroxysmal nonkinesigenic dyskinesia?
Familial paroxysmal nonkinesigenic dyskinesia is a very rare disorder. Its prevalence is estimated to be 1 in 5 million people.
What genes are related to familial paroxysmal nonkinesigenic dyskinesia?
Mutations in the PNKD gene cause familial paroxysmal nonkinesigenic dyskinesia. The function of the protein produced from the PNKD gene is unknown; however, it is similar to a protein that helps break down a chemical called methylglyoxal. Methylglyoxal is found in alcoholic beverages, coffee, tea, and cola. Research has demonstrated that this chemical has a toxic effect on nerve cells (neurons). It remains unclear if the PNKD gene is related to the breakdown of methlglyoxal. How mutations in the PNKD gene lead to the signs and symptoms of familial paroxysmal nonkinesigenic dyskinesia is also unknown.
Read more about the PNKD gene.
How do people inherit familial paroxysmal nonkinesigenic dyskinesia?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is typically sufficient to cause the disorder. Almost everyone with a mutation in the PNKD gene will develop familial paroxysmal nonkinesigenic dyskinesia. In all reported cases, an affected person has inherited the mutation from one parent.
Where can I find information about diagnosis or management of familial paroxysmal nonkinesigenic dyskinesia?
These resources address the diagnosis or management of familial paroxysmal nonkinesigenic dyskinesia and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about familial paroxysmal nonkinesigenic dyskinesia?
You may find the following resources about familial paroxysmal nonkinesigenic dyskinesia helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for familial paroxysmal nonkinesigenic dyskinesia?
What if I still have specific questions about familial paroxysmal nonkinesigenic dyskinesia?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding familial paroxysmal nonkinesigenic dyskinesia?
autosomal ; autosomal dominant ; breakdown ; cell ; chorea ; contraction ; dyskinesia ; dystonia ; familial ; gene ; inherited ; involuntary ; menses ; mutation ; nervous system ; neurological ; prevalence ; protein ; stress ; syndrome ; toxic
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (6 links)
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? in the Handbook.