What are Prion Diseases and What Causes Them? (Definition)
Prion diseases or transmissible spongiform encephalopathies (TSEs), comprise several conditions which affect the nervous system in both humans and animals (neurodegenerative disorders). In humans, these conditions impair brain function, causing changes in memory, personality, and behavior.
The causative agents of TSEs are believed to be prions. A prion is a type of protein that can trigger normal proteins in the brain to fold abnormally. The abnormal folding of the prion proteins leads to brain damage and the characteristic signs and symptoms of the disease. Prion diseases are usually rapidly progressive and always fatal. Prion diseases are sometimes spread to humans by infected meat products.
According to the U.S. National Library of Medicine, between 10 and 15 percent of all cases of prion diseases are caused by mutations in the PRNP gene. These forms of prion diseases are classified as familial, as they are passed down in families. Familial prion diseases include:
- Familial Creutzfeldt-Jakob disease (CJD)
- Gerstmann-Sträussler-Scheinker syndrome (GSS)
- Fatal familial insomnia (FFI)
The remaining 85 to 90 percent of cases of prion diseases are either sporadic or acquired. People with sporadic prion disease have no family history of the disease and no identified mutation in the PRNP gene. Sporadic forms of prion disease include:
- Sporadic Creutzfeldt-Jakob disease (sCJD)
- Sporadic fatal insomnia (sFI)
- Variably protease-sensitive prionopathy (VPSPr)
Acquired prion disease results from exposure to PrPSc from an outside source such as eating beef products containing PrPSc from cattle with prion disease. In cows, this form of the disease is known as bovine spongiform encephalopathy (BSE) or, more commonly, “mad cow disease.”
Approximately 350 new cases are reported annually in the United States.
Prion Disease Symptoms
Symptoms of prion diseases include rapidly developing dementia, hallucinations, confusion, difficulty walking and changes in gait, muscle stiffness, difficulty speaking, and fatigue.
For more information regarding Prion diseases, please visit the Centers for Disease Control website.
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