sentence: Prions are structurally altered versions of small proteins that are normally expressed in cells.
sentences_after: Unlike diseases that are caused by a mutation of the gene resulting in the expression of a mutant protein, prions are able to replicate and transmit diseases through physical contact with the normal proteins resulting in a structural change from the normal to state to the prion state.
concept_name: prion
headings: Prion disease
categories: Infectious diseases Neurology