Prion disease

A prion disease (also called transmissible spongiform encephalopathy) is a disease which is caused by prions. Prions are structurally altered versions of small proteins that are normally expressed in cells. Unlike diseases that are caused by a mutation of the gene resulting in the expression of a mutant protein, prions are able to replicate and transmit diseases through physical contact with the normal proteins resulting in a structural change from the normal state to the prion state.

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Scrapie prions

Unlike bacteria, prions are not considered to be alive because they do not have their own metabolism, they do not possess genes and cannot naturally reproduce outside a host cell. Prion diseases are very rare, and no treatment is available for most of them.

Almost all of the known prion diseases are neurologic diseases. There are two common signs which are seen in typical prion diseases:

• Ataxia or disequilibrium, is when a patient cannot stand or walk well because he cannot maintain his equilibrium. This is usually because of a disease in the cerebellum.
• Dementia or loss of mentality, is a progressive loss of cognitive functions.

Related pages

• Prion
• Encephalopathy
• List of prion diseases