PARK2 Patient Presenting with Dopa-Responsive Dystonia

Area of Science:

• Neurology
• Genetics
• Medical Imaging

Background:

• Dopa-responsive dystonia (DRD) is typically inherited and presents in childhood, often linked to GCH1, SPR, or TH gene mutations.
• PARK2, or autosomal-recessive juvenile Parkinson's disease, is a distinct genetic disorder.
• Accurate genetic diagnosis is crucial for differentiating between various causes of DRD.

Observation:

• A 34-year-old female presented with a 10-year history of lower limb dystonia, initially responsive to medication and diagnosed as DRD.
• ¹²³I FP-CIT SPECT showed a significantly reduced specific binding ratio (SBR) compared to age-matched controls.
• ¹²³I-meta-iodobenzylguanidine myocardial scintigraphy was normal, and cognitive assessment was unremarkable.

Findings:

• Genetic analysis confirmed the patient had PARK2 mutations, despite no family history.
• Reduced SBR on ¹²³I FP-CIT SPECT was a key indicator for diagnosing PARK2.
• This imaging finding aided in distinguishing PARK2 from other genetic forms of DRD.

Implications:

• This case highlights that PARK2 can present with symptoms mimicking DRD.
• ¹²³I FP-CIT SPECT is a valuable tool for diagnosing PARK2 in patients with suspected DRD.
• Genetic testing combined with specific imaging biomarkers improves diagnostic accuracy for movement disorders.