Objective: To investigate the range of clinical features to correlate genotypic and phenotypic manifestations in hereditary progressive and/or levodopa-responsive dystonia due to a defect in the guanosine triphosphate-cyclohydrolase (GCH1) gene.
Design and setting: A large family from Texas was studied in an ambulatory setting by clinicians in genetics, neurology, and psychiatry using structured interviews and examinations.
Patients: The family was selected after neurometabolic investigations of a young boy (proband) with foot dystonia and fatigue and his father, who had a long history of anxiety and depression. Results of metabolic studies showed decreased levels of metabolites of biopterin and biogenic amines in cerebrospinal fluid. Subsequently, a novel mutation (37-base pair deletion) in exon 2 of the GCH1 gene was demonstrated in 11 family members. There was no observed female sex bias, but there was a wide variability of motor dysfunctions in family members. Approximately 50% had clinical deafness and a similar number had significant psychiatric dysfunction, including depression and anxiety.
Conclusion: Study of additional families with hereditary progressive and/or levodopa-responsive dystonia using modern molecular methods will be necessary to confirm the neuropsychiatric spectrum of this disorder, in which important clinical features may be unrecognized and thus inappropriately managed.