Which are the prion diseases?
- Creutz feldt Jakob Disease (CJD) and variants
- Kuru (human) or Scrapie (sheep)
- Fatal familial insomnia
- Gerstmann Straussler Scheinker disease
- Milk transmissible encephalopathy
- Chronic wasting disease in deer and elk
- Bovine spongiform encephalopathy
Etiology
Sporadic:
Infectious protein particle from contaminated food.
Misfolded protein particles that causes other protein particles to misfold.
PrPc is an alpha-helix brain protein with no function. Becomes abnormal by misfolding into beta-pleated sheet isoform PrPsc. This resists protease digestion.
Results in Neurodegeneration.
Familial:
PRNP gene mutation in chromosome 20.
Clinical features
CJD:
- Rapidly progressing dementia (0-6 month) in an old patient.
- Slow progressing dementia in young (Familial CJD).
- Jerking on stimuli or Startle myoclonus (Cerebellar involvement).
- Death within 7 months.
- Subtle behavioral changes.
- Age: Young or Old depending on variant of CJD.
Morphology (Deep grey matter)
- Kuru plaques = extracellular PrPsc deposits.
- Positive with PAS, Congo red.
- STATUS SPONGIOSUS = Collection of vacuoles in Glial and Neuronal tissue (Spongiform change).
