Genetics

A pressing question for many people with dystonia is: Will I pass dystonia onto my children and grandchildren? The answer to this question depends greatly on the form of dystonia and what is currently known about the genetics of that form. There are genetic forms of dystonia that we know can be inherited, forms that are not inherited, and forms that may or may not be inherited—scientists simply don’t have all the answers yet, but are actively working to find out. 

Scientists are actively seeking additional dystonia genes. Studying the genetics of dystonia will not only help refine diagnostic and reproductive technology applications, but it also contributes greatly to our understanding of dystonia and quest for better treatments and a cure.

What Forms of Dystonia are Heritable? 

If you have a form of dystonia that is known to be genetic—especially if other people in your family have symptoms—then there is a chance that you may pass the disorder on to your children. At present researchers have recognized multiple forms of dystonia that can be inherited genetically and have identified at least 13 genes or chromosomal locations responsible for the various forms.

The forms of dystonia for which genes or gene markers have been identified include early onset generalized dystonia, dopa-responsive dystonia, paroxysmal dystonias, x-linked dystonia-parkinsonism, myoclonic dystonia, and rapid-onset dystonia-parkinsonism. However, as we will discuss below, not everyone who inherits a “dystonia gene” will develop symptoms, and some people develop dystonia that is believed to be genetic without any family history.

Scientists are actively seeking additional dystonia genes. Studying the genetics of dystonia will not only help refine diagnostic and reproductive technology applications, but it also contributes greatly to our understanding of dystonia and quest for better treatments and a cure. For more information on genes are proteins linked with dystonia, click here. 

Inheritance Patterns

One of the greatest mysteries that dystonia researchers are working to solve is the fact that not everyone who inherits a dystonia gene mutation will develop symptoms.

Most of the dystonias for which gene mutations have been identified are dominantly inherited, meaning that only one parent needs to have the mutation for a child to inherit the disorder. However, most dystonia mutations also exhibit reduced penetrance, which means that not every person who inherits the gene will develop symptoms.

Forms of Dystonia that are (likely) not Inherited

 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 are in all likelihood not at increased risk of inheriting a known dystonia-causing mutation.  However, researchers do not know at this time whether individuals who develop secondary 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.

How can I Prevent Passing on my Dystonia?

A genetic counselor can help individuals and families learn more about the genetics of dystonia and whether they are eligible for genetic testing. 

In addition, a major development in genetics and reproductive technology that has increasing applications to the dystonia community is a process called preimplantation genetic diagnosis (PGD). PGD is a method of in vitro fertilization in which couples can dramatically reduce the possibility of a child inheriting a potentially disease-causing genetic mutation. Several of a woman’s eggs are fertilized outside her body and those conceptions that test negative for the disease mutation are re-implanted into her uterus.

PGD is feasible for forms of dystonia that are associated with a single gene mutation such as DYT1 dystonia. You can find out more about PGD from the Canadian Association of Genetic Counsellors here.