Being informed about the genetics of dystonia can be important in the diagnosis and treatment process.
Individuals with dystonia may be concerned that their children are at risk of inheriting the disorder. There are forms of dystonia that are known to be genetic and forms that may or may not have a genetic component—researchers cannot confirm or rule it out at this time. More than 200 genes have been linked to dystonia.
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A genetic counselor can help individuals and families learn about the genetics of dystonia and whether they are eligible for genetic testing. Researchers are actively seeking to better understand the genetics of all dystonias and to identify dystonia-causing genes.
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What forms of dystonia are genetic?
If an individual has a form of dystonia that is known to be genetic then there is a chance that the person may pass the disorder on to his/her biological children. This is especially true if other family members exhibit symptoms or are already diagnosed.
Genetic dystonias that are known to run in families can include early onset dystonias, isolated (primary) cervical dystonia, dopa-responsive dystonias, myoclonus-dystonia, paroxysmal dystonias/dyskinesias, rapid-onset dystonia-parkinsonism, X-linked dystonia-parkinsonism, and others.
However, not everyone who inherits a dystonia-causing gene will develop symptoms. Also, some people develop dystonia due to a genetic mutation without any apparent family history. And to complicate things further, there are families in which many members are diagnosed with dystonia but no specific genetic mutation has yet been identified.
If an individual’s dystonia is secondary to an injury to the brain or nervous system (including exposure to certain medications or stroke), his/her children may not necessarily be at increased risk of developing dystonia. However, researchers do not know at this time whether individuals who develop acquired dystonias have a genetic predisposition that makes them vulnerable to dystonia. It could also be that individuals who do not develop dystonia, despite injuries to the nervous system known to cause symptoms in some cases, have a protective factor that is lacking in those individuals who do develop secondary dystonias. Moreover, dystonia can occur as a symptom of various genetically-caused diseases, in which the inheritance patterns vary.
One of the greatest mysteries that dystonia researchers are working to solve is the fact that not everyone who inherits a dystonia-causing gene will develop symptoms.
Most of the dystonias for which genes have been identified are dominantly inherited, meaning that only one parent needs to have the gene for a child to inherit the disorder. However, most dystonia genes also exhibit reduced penetrance, which means that not every person who inherits the gene will develop symptoms.
Scientists are actively seeking additional dystonia genes. Studying the genetics of dystonia will not only help refine diagnostic and reproductive health applications, but also contributes greatly to our understanding of dystonia and quest for better treatments and a cure.
A detailed discussion of genetic dystonias is available from GeneReviews.
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