<prompt> Prions disease all are true except aEURThey are caused by infectious proteinsBiopsy of brain diagnosticNeurodegenrative deseaseMyoclonus found only in 10 cases  <response>: Myoclonus found only in 10 cases Prions are infectious proteins that cause degeneration of the central nervous system They are infectious paicles that lack nucleic acid Prions are composed largely, if not entirely of PrP molecules 