Prion diseases are neurodegenerative diseases that have long incubation periods and progress inexorably once clinical symptoms appear. Five human prion diseases are currently recognized: kuru, Creutzfeldt-Jakob disease (CJD), variant Creutzfeldt-Jakob disease (vCJD also known as new variant CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), and fatal familial insomnia (FFI) [1,2]. Bovine spongiform encephalopathy (BSE), one of a number of prion infections affecting animals, was responsible for bringing these agents to more widespread public attention with its possible link to vCJD [3,4].
These human prion diseases share certain common neuropathologic features including neuronal loss, proliferation of glial cells, absence of an inflammatory response, and the presence of small vacuoles within the neuropil, which produces a spongiform appearance. The current theory is that prion diseases are associated with the accumulation of an abnormal form of a host cell protein, the normal form is designated PrPc, and the abnormal form is designated PrPSc (for Scrapie) .
The clinical manifestations and diagnosis of the prion diseases Kuru, GSS, and FFI will be reviewed here. CJD and variant CJD are discussed separately. (See "Creutzfeldt-Jakob disease" and "Variant Creutzfeldt-Jakob disease".)
The biology of prions and the genetics of prion diseases are discussed separately. (See "Biology and genetics of prions".)
Kuru was the first transmissible neurodegenerative disease to be identified and well studied; it has served as the prototype of human prion diseases [6,7].