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Variably Protease-Sensitive Prionopathy (VPSPr)
Variably protease-sensitive prionopathy (VPSPr) is a rare prion disease (identified in 2008).
VPSPr occurs in 2 to 3/100 million people.
VPSPr resembles Gerstmann-Sträussler-Scheinker disease (GSS) in terms of the characteristics of the abnormal prion protein (PrP Sc ). However, unlike in GSS, no mutations in the prion protein gene have been identified.
Clinical manifestations differ from those of CJD, and the PrP Sc is less resistant to digestion by proteases; some variants are more sensitive to proteases than others, hence the name: variably protease-sensitive.
Patients present with psychiatric symptoms, speech deficits (aphasia and/or dysarthria), and cognitive impairment. Ataxia and parkinsonism can develop. Average age at onset is 70 yr, and duration of survival is 24 mo. About 40% of patients have a family history of dementia.
Diagnosis is difficult. MRI, EEG, and tests for 14-3-3 protein and tau are usually not helpful, and no mutations have been observed in the coding region of the PrP gene.
There is only supportive treatment for VPSPr.
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