DOPA-Responsive Dystonia (GCH1)
DOPA-Responsive Dystonia (DRD) (OMIM 128230) is a childhood-onset dystonia that responds well to low doses of levodopa. Average age of onset is about 6 years. Dystonia of the foot and Parkinson like symptoms result in abnormal gait. Patients occasionally present with arm dystonia, hand tremor, or slowness of movements. Symptoms can increase in severity later in the day and/or following exertion. Localized symptoms often progress to a more generalized dystonia. Misdiagnosis as either cerebral palsy or early onset Parkinson disease is not uncommon.
Since DRD has a similar phenotype to other progressive neurodegenerative disorders and severe metabolic disorders, genetic testing and early diagnosis is critical for initiation of synthetic dopamine therapy treatment. (Furukawa,Y., GeneReviews. 2002; ncbi.nlm.nih.gov/books/NBK1508 (Grotzsch et al., Neurology. 2002; 58(12): 1839-1842).
Synthetic Dopamine Therapy
Increased life expectancy and prolonged survival was evident in DRD patients treated with synthetic dopamine at an early stage (Rajput, A., Parkinsonism and Related Disorders. 2001; 8(2): 95-100). This non-toxic drug has been proven to restore full physical functionality immediately including running, walking, speaking and writing (Dystonia Medical Research Foundation. 2010; dystonia-foundation.org). Studies of patients treated with synthetic dopamine have shown a stable, nearly complete, symptomatic response to the drug; and treated patients have avoided typical long-term treatment complications that are prevalent with DRD (Nygaard et al., Annals of Neurology. 1992; 32(5): 601-608). Although discontinuation of synthetic dopamine can yield immediate return of dystonia, continual therapy of synthetic dopamine has proven to be the most effective treatment alternative for DRD patients, often restoring patients to full, normal function (Nygaard and Nutt, JAMA Neurology. 2001; 58(6): 905-910).
For more information on GCH1 testing, please see our full Test Description.
This article is a summary of information that has been reported in the biomedical research literature. It is not medical advice for patients. All disease treatments should be under the direction of a qualified healthcare provider.