Dopa-responsive dystonia and early-onset Parkinson's disease in a patient with GTP cyclohydrolase I deficiency?

We describe a patient with a combination of dystonic and parkinsonian signs. Paraclinical studies revealed a mutation in the GTP cyclohydrolase I gene (GCH1) and a decrease in [123I]-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodophenyl) nortropane (123I-FP-CIT) binding ratios indicative of Parkinson's disease. We conclude that the patient probably suffers from a variant of dopa-responsive dystonia (DRD) or two separate movement disorders, normally considered to be differential diagnoses, DRD and early-onset Parkinson's disease with resulting difficulties concerning treatment and prognosis.