Definition A dystonia* (OMIM:128230) which typically presents in childhood with ambulatory, postural and motor abnormalities of the lower limbs, showing marked diurnal fluctuation. The symptoms worsen in the evening, with fatigue and exercise, and are alleviated by sleep. There is a favourable response to L-DOPA without side effects.
*Dystonia is defined by the presence of sustained involuntary muscle contractions often leading to abnormal postures.
Molecular pathology Defects of GCH1, which encodes a GTP cyclohydrolase that is the first and rate-limiting enzyme in tetrahydrobiopterin biosynthesis, cause dystonia—DOPA responsive.
Synonyms DOPA-responsive dystonia—autosomal dominant, DRD, dystonia—DOPA-responsive—autosomal dominant, dystonia-Parkinsonism with diurnal fluctuation, dystonia—progressive—with diurnal variation, dystonia type 5, Segawa syndrome—autosomal dominant