[Creutzfeldt-Jakob disease: the most frequent spongiform encephalopathy in humans]

Creutzfeldt-Jakob disease (CJD) which for many years was interpreted as one of degenerative brain processes is the most frequent spongiform encephalopathy caused by prions--molecules of erroneously conformed protein. In only few percent ill people occurrence of this pathogenic factor occurs as a result of mutation in gene PrP. Because transmissibility of prions was proved it should be supposed that in other cases CJD is a result of "infection" Susceptibility to prions depends in large part on specificity of host proteins. It creates certain individual and species specific barriers. At the present time we witness, fortunately only in single cases, occurrence in people variant CJD caused by prions originated from animals affected by "mad cow disease". Prognosis for human population is dependent on the effectiveness of between species barrier for prions.