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Variably Protease-Sensitive Prionopathy (VPSPr)
Variably protease-sensitive prionopathy (VPSPr) is a very rare prion disease (identified in 2008) that is possibly a variant of CJD.
VPSPr is very rare, occurring in 2 to 3/100 million people. It has similarities to Creutzfeldt-Jakob disease but clinical manifestations differ somewhat and the abnormal prion protein (PrP) is less resistant to digestion by proteases; some variants are more sensitve 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.
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