PARK2 Patient Presenting with Dopa-Responsive Dystonia

We report a 34-year-old female PARK2 patient presenting with dopa-responsive dystonia (DRD). She noticed difficulty in raising her foot while walking at the age of 24. Her lower limb symptoms were identified as dystonia later, and she was started on Menesit, which resulted in improvement of her symptoms. She was diagnosed as DRD and has been on continuous treatment since then. The specific binding ratio (SBR) of ¹²³I FP-CIT SPECT was significantly lower than those of controls of the same age, but ¹²³I-meta-iodobenzylguanidine myocardial scintigraphy showed a normal heart to mediastinum ratio. The Montreal Cognitive Assessment, Japanese version, was normal for her age. DRD is an inherited dystonia that typically begins during childhood and may be caused by mutations of the GCH1 (GTP cyclohydrolase), SPR (sepiapterin reductase), or TH (tyrosine hydroxylase) genes. Our patient was diagnosed as PARK2, known as autosomal-recessive juvenile Parkinson's disease, based on genetic analysis. Although there was no family history of the disease, the decrease in SBR of ¹²³I FP-CIT SPECT enabled us to diagnose PARK2 and to differentiate this from DRD due to other genetic disorders.