Dopa-responsive dystonia (DRD) is a rare but highly treatable form of genetic dystonia. It often responds very well to regular doses of Levodopa (a synthetic form of the brain chemical, dopamine).
In many patients onset is characterised by an abnormal, 'stiff-legged' manner of walking, with upward bending of the sole of the foot, or turning of the foot outward at the ankle and a tendency to walk on the toe.
DRD may also extend to involve muscles of the arms and trunk. In addition DRD is typically characterised by signs on Parkinsonism that may be relatively subtle. Signs may include slowness of movement, stiffness and resistance to movement (rigidity), balance difficulties and postural instability.
Many patients experience improvements with sleep and are relatively free of symptoms in the morning, developing increasingly severe symptoms as the day progresses. Accordingly the condition has sometimes been referred to as 'progressive hereditary dystonia'. It is a common characteristic that symptoms will fluctuate and worsen as the day progresses.
DRD usually presents itself in childhood between ages of 6 and 16 and is 2-4 times more likely to affect girls than boys. As with generalised dystonia, DRD has reduced penetrance - only about 30 - 40% of people carrying the gene will actually go on to develop the condition.
What causes DRD?
The most common form of DRD is often refered to as DYT5 dystonia. DYT5 is a dominantly inherited condition caused by mutations in a specific gene. A dominantly inherited disorder means that only one parent needs to have the DYT5 gene mutation in order for the child to inherit the disorder. Individuals with DYT5 DRD often have a parent who also has the mutation, with or without symptoms. The DYT5 mutation has variable penetrance, meaning that not everyone who inherits the gene will develop symptoms. Children of a parent with DYT5 mutation have a 50% chance of inheriting the mutation. At this time there is no way to predict whether a person with the mutation will go on to develop dystonia.
The gene abnormality in DRD causes a problem with the brain's production of the chemical dopamine, and this is what causes the dystonia and other movement disorders.
How may DRD be treated?
Symptoms can usually be treated effectively with levodopa (Sinemet). In many cases, full physical functionality is restored. Even those whose symptoms have been untreated for up to 50 years respond to levadopa and a stable responce after years of continuous treatment is typical. Side effects of the medication may include light-headednes, nausea, constipation and in some cases fatigue.
How do I live with DRD?
As this form of dystonia may be genetic, some people find it helpful to speak to a genetic counsellor regarding the genetic issues and what this may mean for you and your family.
If you have any questions or would like to discuss Dopa-responsive dystonia please contact our Helpline on 0845 458 6322, 020 7793 3658 or firstname.lastname@example.org
Last reviewed 2013
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