Molecular genetics of human prion diseases in Germany.
ABSTRACT Human prion diseases may be acquired as infectious diseases, they may be inherited in an autosomal dominant fashion or occur sporadically. Mutations and polymorphisms in the sequence of the coding region of the prion protein gene (PRNP) have been established as an important factor in all of these three types of prion diseases. Therefore, a total of 578 patients with suspect prion diseases referred to the German Creutzfeldt-Jakob disease (CJD) surveillance unit over a period of 4.5 years have been examined for mutations and polymorphisms in the coding region of PRNP. We found 40 cases with a missense mutation previously reported as pathogenic. Amongst these, the aspartate to asparagine change at codon 178 (D178N) was the most common mutation. All of these cases carried the D178N mutation in coupling with methionine at codon 129, resulting in the typical fatal familial insomnia (FFI) genotype. Most cases with pathogenic mutations were not found in the group of clinically "probable" cases according to established clinical criteria, supporting the notion that inherited prion diseases often exhibit atypical features. Two novel missense mutations (T188R and P238S) and several silent polymorphisms were found, demonstrating the quality of our screening procedure based on a modified version of the single-stranded conformational polymorphism technique. In "definite" CJD cases with no pathogenic mutation, the patients clinically classified as "probable" were mostly homozygous for methionine at the common polymorphism at codon 129, whereas there was a marked over-representation of patients homozygous for valine amongst those clinically classified as "possible". This large study on suspect cases of human prion diseases in Germany clearly shows that PRNP genetics is essential for a comprehensive analysis of prion diseases.
Article: Prionkrankheiten des Menschen[show abstract] [hide abstract]
ABSTRACT: Prionkrankheiten sind seltene neurodegenerative, übertragbare und letal endende Erkrankungen, die sowohl den Menschen als auch Säugetiere befallen können. Das auslösende Agens ist das Prion. Im Unterschied zu klassischen Infektionserregern haben Prione kein eigenes Genom und bestehen nach heutiger Auffassung aus einer abnormen Form des wirtseigenen Prionproteins. Die Creutzfeldt-Jakob-Krankheit (CJD) ist der Hauptvertreter einer Prionkrankheit beim Menschen. Klinisch kann die Diagnose nur als "wahrscheinlich" oder "möglich" abgegrenzt werden. Für die definitive Diagnose sind Autopsie und neuropathologische Untersuchung unabdingbar. Für die Autopsie und die histologische Gewebeaufarbeitung sind Vorsichtsmaßnahmen notwendig, da das ZNS-Gewebe die höchste Infektiösität aufweist. Für die histologische Diagnose ist die immunhistochemische Darstellung der Prionproteinablagerungen als Goldstandard anzusehen. Darüber hinaus bedarf es zur exakteren Klassifikation humaner Prionkrankheiten zusätzlicher molekularer und genetischer Untersuchungen. Prion diseases are rare neurodegenerative transmissible fatal diseases affecting humans and mammals. The causative agent is a novel pathogen termed the prion. Unlike classical infectious agents such as bacteria or viruses, prions lack an independent genome and consist largely of an abnormal form of the host-encoded prion protein. Creutzfeldt-Jakob disease (CJD) is the main representative of human prion diseases that may be sporadic in most cases, hereditary, or acquired. Clinical examination yields only a suspected diagnosis with formal criteria for probable or possible. Definite diagnosis relies on autopsy and neuropathology findings. This is also true for the new variant CJD (vCJD), a previously unknown prion disease of humans that is connected with the same strain of prions as found in bovine spongiform encephalopathy (BSE). The autopsy and handling of laboratory material for histopathological examination requires specific precautionary measures and decontamination. For definite histopathological diagnosis of a human prion disease, immunohistochemical detection of the prion protein deposits is the gold standard. Furthermore, molecular and genetic investigations are necessary for classification because a close correlation could be established between distinct CJD phenotypes, codon 129 genotypes of the prion protein gene, and the prion protein type. Prion-Creutzfeldt-Jakob-Krankheit-BSE-Autopsie-ImmunhistochemiePrion-Creutzfeldt-Jakob disease-BSE-Autopsy-ImmunhistochemistryDer Pathologe 04/2012; 23(4):241-251. · 0.62 Impact Factor
- Brain 11/2011; 135(Pt 2):e209; author reply e210. · 9.92 Impact Factor
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ABSTRACT: Prion diseases are diagnosed by the detection of their proteinase K-resistant prion protein fragment (PrP(Sc)). Various biochemical protocols use different detergents for the tissue preparation. We found that the resistance of PrP(Sc) against proteinase K may vary strongly with the detergent used. In our study, we investigated the influence of the most commonly used detergents on eight different TSE agents derived from different species and distinct prion disease forms. For a high throughput we used a membrane adsorption assay to detect small amounts of prion aggregates, as well as Western blotting. Tissue lysates were prepared using DOC, SLS, SDS or Triton X-100 in different concentrations and these were digested with various amounts of proteinase K. Detergents are able to enhance or diminish the detectability of PrP(Sc) after proteinase K digestion. Depending on the kind of detergent, its concentration - but also on the host species that developed the TSE and the disease form or prion type - the detectability of PrP(Sc) can be very different. The results obtained here may be helpful during the development or improvement of a PrP(Sc) detection method and they point towards a detergent effect that can be additionally used for decontamination purposes. A plausible explanation for the detergent effects described in this article could be an interaction with the lipids associated with PrP(Sc) that may stabilize the aggregates.Veterinary Microbiology 12/2011; 157(1-2):23-31. · 3.13 Impact Factor