<prompt> True about prion protein diseases is all, except -Myoclonus is seen in 10 of the patientsCaused by infectious proteinBrain biopsy is diagnosticCommonly manifests as dementia  <response>: Most patients 90 with Cruetzfeldt-Jacob Disease CJD exhibit myoclonus that appears at various times throughout the illness.Unlike other involuntary movements, myoclonus persists during sleep. Startle myoclonus elicited by loud sounds or bright lights is frequent 