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Pathology- Creutzfeldt-Jakob Disease (CJD)
I. Definition & Epidemiology:
I. Definition & Epidemiology:
- Definition: CJD is a rare, fatal spongiform encephalopathy caused by the accumulation of misfolded prion protein (PrP) resistant to normal cellular breakdown. It's the most common human prion disease.
- Epidemiology: Extremely rare, with an annual incidence of approximately 1 per 1,000,000.
- Sporadic CJD: Spontaneous, random misfolding of normal PrP into the abnormal PrP form. The exact mechanism remains unclear.
- Familial CJD: Inherited mutations in the PRNP gene increase the likelihood of PrP misfolding.
- Variant CJD (vCJD): Believed to be transmitted via consumption of beef contaminated with PrPSc from cattle with bovine spongiform encephalopathy (BSE, "mad cow disease").
- Misfolded Protein Propagation: The presence of abnormal PrPSc acts as a template, causing normal PrPC to misfold into the abnormal form.
- Exponential Growth & Cell Death: This process leads to an exponential increase in PrPSc, ultimately causing neuronal cell death and the characteristic brain damage.
- Sporadic CJD: Typically affects middle-aged and elderly individuals. Onset is marked by rapidly progressing neurological symptoms.
- Variant CJD (vCJD): Affects younger individuals (<30 years old). initially presents with psychiatric symptoms, followed by cerebellar ataxia (problems coordination and balance) dementia. < />pan>Key difference from sporadic CJD.
- Sporadic CJD & vCJD: Both show spongiform changes (vacuolation of grey matter), neuronal loss (death of nerve cells), and gliosis (scarring in the brain).
- Variant CJD (vCJD only): The presence of numerous "florid plaques" composed of amyloid forms of PrPSc is a key distinguishing neuropathological feature. These are absent in other CJD forms.
- Currently, no effective treatment exists for CJD. The disease is invariably fatal.
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