TABLE 1.

Summary of the 3 broad categories of prion diseases and the defining characteristics of each

Category	Prion Disease	Defining characteristics	References
1	Scrapie, sporadic, familial and iatrogenic CJD (sCJD, fCJD, iCJD), BSE, kuru and sporadic and familial fatal insomnia (sFI and fFI)	Vacuolar (spongiform) degeneration of gray matter, accumulation of protease resistant PrPSc in gray matter, little or no PrP amyloid plaque formation.	7
2	Dominantly inherited syndromes (GSS)	Deposition of numerous PrP immunopositive amyloid (abnormal protein) plaques in multiple cortical and subcortical brain regions. PRNP mutation.	7,19
3	Variant CJD (vCJD)	PrPSc amyloid deposition, vacuolation of gray matter, accumulation of protease resistant PrPSc in neuropil (space between neuronal and glial cell bodies comprised of dendrites, axons, synapses microvasculature and glial cell processes).	7,19-22