What is Prion disease?
A '''prion disease''' (also called '''transmissible spongiform encephalopathy''') is a disease which is caused by [[prion]]s. Prions are structurally altered versions of small [[protein]]s that are normally expressed in cells. Unlike [[disease]]s that are caused by gene mutations resulting in the expression of a [[Mutation|mutant]] protein, [[prion]]s are able to replicate and transmit diseases through physical contact with normal proteins. This causes a protein's structure to change from the normal state to the [[prion]] state. Unlike [[bacteria]], [[prion]]s are not considered to be alive because they do not have their own [[metabolism]], they do not possess [[gene]]s and cannot naturally reproduce outside a host cell. Prion diseases are very rare, and no treatment is available for most of them. There is no cure for prion diseases, and they will always result in death. 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]] or balance. This is usually because of a disease or damage in the [[cerebellum]]. * [[Dementia]] or loss of mentality, is a progressive loss of [[cognition|cognitive]] functions. == Prion diseases == Few types of prion diseases are known. The most important ones are: * '''[[Creutzfeldt-Jakob disease]]''' - A person can get the disease by eating beef infected with [[Bovine spongiform encephalopathy|BSE]] (bovine spongiform encephalopathy), having a [[blood tranfusion]] from a person with the disease, injection of Human Growth Hormone extracted from bodies with the disease, or through infected surgical instruments. Patients suffer from ataxia and [[dementia]] and usually die after one year. * '''[[Kuru (disease)|Kuru disease]]''' - This disease is seen in people living in [[New Guinea]] who eat the [[brain]]s of dead people. Patients present with ataxia, dementia and inability in moving