Hereditary progressive dystonia with marked diurnal fluctuation/dopa-responsive dystonia (HPD/DRD) shows the considerable heterogeneity of clinical phenotypic expression and a dramatic sustained response to levodopa.
The causative gene for hereditary progressive dystonia with marked diurnal fluctuation/dopa-responsive dystonia (HPD/DRD) was discovered in 1994 to be guanosine triphosphate (GTP) cyclohydrolase I, an enzyme involved in tetrahydrobiopterin biosynthesis.
These results suggest that some novel mutations should exist on one of the alleles in some unknown region of the GCH1 gene, and may decrease the GCH1 mRNA causing the HPD/DRD symptoms.
In juvenile parkinsonism and Parkinson's disease, which have dopamine deficiency in the basal ganglia as HPD/DRD, the GCH gene may be normal, and the molecular mechanism of the dopamine deficiency in the basal ganglia is different from that in HPD/DRD.
We found that mutations of GTP cyclohydrolase I, the rate-limiting enzyme in the biosynthesis of tetrahydrobiopterin, which is the cofactor of dopamine-synthesizing tyrosine hydroxylase, cause dominantly inherited hereditary progressive dystonia with marked diurnal fluctuation (HPD, Segawa's disease) probably owing to the decrease of dopamine in the basal ganglia.
We characterized the GTP cyclohydrolase I (GTP-CH-I) gene in a patient with hereditary progressive dystonia with marked diurnal fluctuation/dopa-responsive dystonia (HPD/DRD).
Kinetics of catecholamine biosynthesis and metabolism have been examined in patients with hereditary progressive dystonia with marked diurnal fluctuation of symptoms (HPD, Segawa's disease).