Atypical parkinsonism due to a D202N Gerstmann‐Sträussler‐Scheinker prion protein mutation: First in vivo diagnosed case

Abstract

Parkinsonism with dopa-sensitivity and a correlating DaTSCAN turned out to be due to a D202N mutation which is associated with the Gerstmann-Sträussler-Scheinker (GSS) disease. We report a 51-year old female who presented with left-dominant parkinsonism and a positive DaTSCAN. She was diagnosed with idiopathic Parkinson's syndrome. Dopaminergic medication reduced her symptoms. In addition, punding-like behavior, deficits in organizing daily life and abnormal sleep behavior were reported. Neuropsychological testing, EEG, polysomnography as well as PET imaging with fluorodexyglucose (FDG), [F-18]-desmethoxyfallypride (DMFP), and [C-11]-6-OH-BTA-1 (PIB) were not diagnostic. Cerebral spinal fluid analysis revealed no 14-3-3 protein, but elevated neuron-specific enolase (NSE) and S100-beta and a very low phospho-tau/total-tau ratio. Analysis of the prion gene disclosed the rare D202N mutation. The D202N prion mutation has been associated with GSS pathology and up to now was only reported post mortem. Our patient is the very first case diagnosed in vivo.