Ancestral origins and worldwide distribution of the PRNP 200K mutation causing familial Creutzfeldt-Jakob disease

Genetic Creutzfeldt-Jakob disease in Turkish Jews-demographic and clinical features

BACKGROUND

The largest cluster of genetic Creutzfeldt- Jakob Disease (CJD) exists in Libyan Jews carrying the E200K mutation in the PRNP gene. However, there is another cluster of genetic CJD with E200K mutation in families of Turkish-Jewish origin.

AIMS

In this retrospective study, we aim to describe the demographic and clinical features of this population of patients.

MATERIAL AND METHODS

The Israeli National CJD database was searched for demographic, clinical, imaging, and laboratory data of genetic CJD patients of Libyan and Turkish ancestry with the E200K mutation. The data of Libyan and Turkish patients were compared with notice similar or different demographic or clinical courses.

RESULTS

Four hundred and twenty-three patients with CJD of Libyan (L) ancestry and 27 patients with CJD of Turkish (T) ancestry were identified. There were no significant differences in demographic and clinical data between the two populations (age of onset: T = 62 ± 8.8, L = 60 ± 9.7; age of death: T = 63 ± 8.6, L = 61 ± 9.7; and disease duration: T = 7.8 ± 8.4 months, L = 9.6 ± 13.6 months). Rapidly progressive dementia was the most common presentation in both groups, followed by pure cerebellar onset. The levels of tau protein in CSF did not differ between groups (T = 1290 ± 397.6 pg/ml, L = 1276 ± 594.2 pg/ml). MRI and EEG showed classical CJD features in most patients in both groups.

DISCUSSION

The E200K mutation is the most common mutation among gCJD patients and was reported in different ethnical populations, suggesting several independent haplotypes of the mutation. The Turkish-Jew cluster, first described in this study, shares similar demographic and clinical features with the bigger cluster of Libyan-Jews CJD patients.

CONCLUSION

E200K gCJD patients of Turkish ancestry share similar demographic and clinical features to patients of Libyan descent, suggesting a common origin of both populations.

Genetic Creutzfeldt-Jakob disease in Sardinia: a case series linked to the PRNP R208H mutation due to a single founder effect

In genetic prion diseases (gPrD), five genetic variants (E200K, V210I, V180I, P102L, and D178N) are responsible for about 85% of cases. The R208H is one of the several additional rare mutations and to date, only 16 cases carrying this mutation have been reported worldwide. To describe the phenotypic features of 5 affected patients belonging to apparently unrelated Sardinian (Italian) families with R208H gPrD, and provide evidence for a possible founder effect are the aims of this study. The R208H PRNP mutation has a much higher relative frequency in Sardinia than elsewhere in Italy (72% vs. 4.4% of gCJD cases). Our cohort shared similar phenotypic features to the previously described patients with R208H-129M haplotype with most patients showing the classical Creutzfeldt-Jakob disease (CJD) phenotype. The analysis of 10 controls and 5 patients by NGS sequencing identified 4 haplotypes, 3 associated with the wild type variant, and one (H1) shared by all patients carrying the 208His variant. This is the first report of a regional cluster for R208H mutation in gPrD and the first report of the presence of a common ancestor for this Sardinian R208H cluster, confirming the probable consequences of genetic isolation process even for rare diseases.

Age at onset in genetic prion disease and the design of preventive clinical trials

OBJECTIVE

To determine whether preventive trials in genetic prion disease could be designed to follow presymptomatic mutation carriers to onset of disease.

METHODS

We assembled age at onset or death data from 1,094 individuals with high penetrance mutations in the prion protein gene (PRNP) in order to generate survival and hazard curves and test for genetic modifiers of age at onset. We used formulae and simulations to estimate statistical power for clinical trials.

RESULTS

Genetic prion disease age at onset varies over several decades for the most common mutations and neither sex, parent's age at onset, nor PRNP codon 129 genotype provided additional explanatory power to stratify trials. Randomized preventive trials would require hundreds or thousands of at-risk individuals in order to be statistically powered for an endpoint of clinical onset, posing prohibitive cost and delay and likely exceeding the number of individuals available for such trials.

CONCLUSION

The characterization of biomarkers suitable to serve as surrogate endpoints will be essential for the prevention of genetic prion disease. Parameters such as longer trial duration, increased enrollment, and the use of historical controls in a postmarketing study could provide opportunities for subsequent determination of clinical benefit.

Genetic PrP Prion Diseases

Genetic prion diseases (gPrDs) caused by mutations in the prion protein gene (PRNP) have been classified as genetic Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker disease, or fatal familial insomnia. Mutations in PRNP can be missense, nonsense, and/or octapeptide repeat insertions or, possibly, deletions. These mutations can produce diverse clinical features. They may also show varying ancillary testing results and neuropathological findings. Although the majority of gPrDs have a rapid progression with a short survival time of a few months, many also present as ataxic or parkinsonian disorders, which have a slower decline over a few to several years. A few very rare mutations manifest as neuropsychiatric disorders, with systemic symptoms that include gastrointestinal disorders and neuropathy; these forms can progress over years to decades. In this review, we classify gPrDs as rapid, slow, or mixed types based on their typical rate of progression and duration, and we review the broad spectrum of phenotypes manifested by these diseases.

Genetic PrP Prion Diseases

Genetic prion diseases (gPrDs) caused by mutations in the prion protein gene (PRNP) have been classified as genetic Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker disease, or fatal familial insomnia. Mutations in PRNP can be missense, nonsense, and/or octapeptide repeat insertions or, possibly, deletions. These mutations can produce diverse clinical features. They may also show varying ancillary testing results and neuropathological findings. Although the majority of gPrDs have a rapid progression with a short survival time of a few months, many also present as ataxic or parkinsonian disorders, which have a slower decline over a few to several years. A few very rare mutations manifest as neuropsychiatric disorders, with systemic symptoms that include gastrointestinal disorders and neuropathy; these forms can progress over years to decades. In this review, we classify gPrDs as rapid, slow, or mixed types based on their typical rate of progression and duration, and we review the broad spectrum of phenotypes manifested by these diseases.

Public health: surveillance, infection prevention, and control

Human prion diseases, though relatively rare, remain an ongoing public health problem. They are fatal diseases, with unconventional host responses and no early diagnostic tests or robust treatments. Public health measures were put in place to protect the food chain in the United Kingdom from the late 1980s, with similar measures following elsewhere. However, human prion diseases are transmissible through other routes, including through blood transfusion and surgery. As a result, the public health threat remains for all forms of human prion diseases and makes continued surveillance and infection prevention and control imperative.

Genetic Creutzfeldt-Jakob disease

Genetic Creutzfeldt-Jakob disease (CJD) is associated with mutations in the human PrP gene (PRNP) on chromosome 20p12-pter. Pathogenic mutations have been identified in 10-15% of all CJD patients, who often have a family history of autosomal-dominant pattern of inheritance and variable penetrance. However, the use of genetic tests implemented by surveillance networks all over the world increasingly identifies unexpectedly PRNP mutations in persons apparently presenting with a sporadic form of CJD. A high phenotypic variability was reported in genetic prion diseases, which partly overlap with the features of sporadic CJD. Here we review recent advances on the epidemiologic, clinical, and neuropathologic features of cases that phenotypically resemble CJD linked to point and insert mutations of the PRNP gene. Multidisciplinary studies are still required to understand the phenotypic spectrum, penetrance, and significance of PRNP mutations.

Genetic prion disease: Experience of a rapidly progressive dementia center in the United States and a review of the literature

Although prion diseases are generally thought to present as rapidly progressive dementias with survival of only a few months, the phenotypic spectrum for genetic prion diseases (gPrDs) is much broader. The majority have a rapid decline with short survival, but many patients with gPrDs present as slowly progressive ataxic or parkinsonian disorders with progression over a few to several years. A few very rare mutations even present as neuropsychiatric disorders, sometimes with systemic symptoms such as gastrointestinal disorders and neuropathy, progressing over years to decades. gPrDs are caused by mutations in the prion protein gene (PRNP), and have been historically classified based on their clinicopathological features as genetic Jakob-Creutzfeldt disease (gJCD), Gerstmann-Sträussler-Scheinker (GSS), or Fatal Familial Insomnia (FFI). Mutations in PRNP can be missense, nonsense, and octapeptide repeat insertions or a deletion, and present with diverse clinical features, sensitivities of ancillary testing, and neuropathological findings. We present the UCSF gPrD cohort, including 129 symptomatic patients referred to and/or seen at UCSF between 2001 and 2016, and compare the clinical features of the gPrDs from 22 mutations identified in our cohort with data from the literature, as well as perform a literature review on most other mutations not represented in our cohort. E200K is the most common mutation worldwide, is associated with gJCD, and was the most common in the UCSF cohort. Among the GSS-associated mutations, P102L is the most commonly reported and was also the most common at UCSF. We also had several octapeptide repeat insertions (OPRI), a rare nonsense mutation (Q160X), and three novel mutations (K194E, E200G, and A224V) in our UCSF cohort. © 2016 Wiley Periodicals, Inc.

Deep Learning Representation from Electroencephalography of Early-Stage Creutzfeldt-Jakob Disease and Features for Differentiation from Rapidly Progressive Dementia

A novel technique of quantitative EEG for differentiating patients with early-stage Creutzfeldt–Jakob disease (CJD) from other forms of rapidly progressive dementia (RPD) is proposed. The discrimination is based on the extraction of suitable features from the time-frequency representation of the EEG signals through continuous wavelet transform (CWT). An average measure of complexity of the EEG signal obtained by permutation entropy (PE) is also included. The dimensionality of the feature space is reduced through a multilayer processing system based on the recently emerged deep learning (DL) concept. The DL processor includes a stacked auto-encoder, trained by unsupervised learning techniques, and a classifier whose parameters are determined in a supervised way by associating the known category labels to the reduced vector of high-level features generated by the previous processing blocks. The supervised learning step is carried out by using either support vector machines (SVM) or multilayer neural networks (MLP-NN). A subset of EEG from patients suffering from Alzheimer’s Disease (AD) and healthy controls (HC) is considered for differentiating CJD patients. When fine-tuning the parameters of the global processing system by a supervised learning procedure, the proposed system is able to achieve an average accuracy of 89%, an average sensitivity of 92%, and an average specificity of 89% in differentiating CJD from RPD. Similar results are obtained for CJD versus AD and CJD versus HC.

Quantifying prion disease penetrance using large population control cohorts

More than 100,000 genetic variants are reported to cause Mendelian disease in humans, but the penetrance-the probability that a carrier of the purported disease-causing genotype will indeed develop the disease-is generally unknown. We assess the impact of variants in the prion protein gene (PRNP) on the risk of prion disease by analyzing 16,025 prion disease cases, 60,706 population control exomes, and 531,575 individuals genotyped by 23andMe Inc. We show that missense variants in PRNP previously reported to be pathogenic are at least 30 times more common in the population than expected on the basis of genetic prion disease prevalence. Although some of this excess can be attributed to benign variants falsely assigned as pathogenic, other variants have genuine effects on disease susceptibility but confer lifetime risks ranging from <0.1 to ~100%. We also show that truncating variants in PRNP have position-dependent effects, with true loss-of-function alleles found in healthy older individuals, a finding that supports the safety of therapeutic suppression of prion protein expression.

A Comparison of Classical and H-Type Bovine Spongiform Encephalopathy Associated with E211K Prion Protein Polymorphism in Wild-Type and EK211 Cattle Following Intracranial Inoculation

In 2006, a case of H-type bovine spongiform encephalopathy (BSE-H) was diagnosed in a cow that was associated with a heritable polymorphism in the bovine prion protein gene (PRNP) resulting in a lysine for glutamate amino acid substitution at codon 211 (called E211K) of the prion protein. Although the prevalence of this polymorphism is low, cattle carrying the K211 allele may be predisposed to rapid onset of BSE-H when exposed or to the potential development of a genetic BSE. This study was conducted to better understand the relationship between the K211 polymorphism and its effect on BSE phenotype. BSE-H from the US 2006 case was inoculated intracranially (IC) in one PRNP wild-type (EE211) calf and one EK211 calf. In addition, one wild-type calf and one EK211 calf were inoculated IC with brain homogenate from a US 2003 classical BSE case. All cattle developed clinical disease. The survival time of the E211K BSE-H inoculated EK211 calf (10 months) was shorter than the wild-type calf (18 months). This genotype effect was not observed in classical BSE inoculated cattle (both 26 months). Significant changes in retinal function were observed in H-type BSE challenged cattle only. Cattle challenged with the same inoculum showed similar severity and neuroanatomical distribution of vacuolation and disease-associated prion protein deposition in the brain, though differences in neuropathology were observed between E211K BSE-H and classical BSE inoculated animals. Western blot results for brain tissue from challenged animals were consistent with the inoculum strains. This study demonstrates that the phenotype of E211K BSE-H remains stable when transmitted to cattle without the K211 polymorphism, and exhibits a number of features that differ from classical BSE in both wild-type and heterozygous EK211 animals.

A Case of Familial Creutzfeldt-Jakob Disease Presenting with Dry Cough

Background:

Clinical diagnosis of Creutzfeldt-Jakob disease (CJD) is based on the classical triad of rapidly progressive dementia, myoclonus and abnormal EEG. The 200k mutation within the gene encoding PrP, located on the short arm of chromosome 20, accounts for more than 70% of families with CJD worldwide.

Case Report:

Herein, we report a patient who developed persistent dry cough and classical signs of CJD, including severe cognitive decline, cerebellar signs, and myoclonic jerks, leading to death a few weeks after disease onset. Mutation screening showed that he had the 200k point mutation in the PRNP gene. His mother had died twenty years earlier with neuropathologically confirmed CJD. She had presented a rapidly progressive ataxia with myoclonus, dementia, visual hallucinations, and the same persistent dry cough.

Conclusions:

The clinical presentation of this familial CJD case with persistent dry cough is quite unusual. Therefore, a neurological etiology should be sought when confronted with an unexplained persistent cough.

Genetic CJD with a novel E200G mutation in the prion protein gene and comparison with E200K mutation cases

A novel point mutation resulting in a glutamate-to-glycine substitution in PRNP at codon 200, E200G with codon 129 MV polymorphism (cis valine) and type 2 PrP^Sc was identified in a patient with a prolonged disease course leading to pathology-proven Jakob-Creutzfeldt disease. Despite the same codon as the most common genetic form of human PRNP mutation, E200K, this novel mutation (E200G) presented with a different clinical and pathological phenotype, including prolonged duration, large vacuoles, no vacuolation in the hippocampus, severe neuronal loss in the thalamus, mild cerebellar involvement, and abundant punctate linear and curvilinear deposition of PrP^Sc in synaptic boutons and axonal terminals along the dendrites.

Small-molecule theranostic probes: a promising future in neurodegenerative diseases

Prion diseases are fatal neurodegenerative illnesses, which include Creutzfeldt-Jakob disease in humans and scrapie, chronic wasting disease, and bovine spongiform encephalopathy in animals. They are caused by unconventional infectious agents consisting primarily of misfolded, aggregated, β -sheet-rich isoforms, denoted prions, of the physiological cellular prion protein (PrP(C)). Many lines of evidence suggest that prions (PrP(Sc)) act both as a template for this conversion and as a neurotoxic agent causing neuronal dysfunction and cell death. As such, PrP(Sc) may be considered as both a neuropathological hallmark of the disease and a therapeutic target. Several diagnostic imaging probes have been developed to monitor cerebral amyloid lesions in patients with neurodegenerative disorders (such as Alzheimer's disease, Parkinson's disease, and prion disease). Examples of these probes are Congo red, thioflavin T, and their derivatives. We synthesized a series of styryl derivatives, denoted theranostics, and studied their therapeutic and/or diagnostic potentials. Here we review the salient traits of these small molecules that are able to detect and modulate aggregated forms of several proteins involved in protein misfolding diseases. We then highlight the importance of further studies for their practical implications in therapy and diagnostics.

Gerstmann-Sträussler-Scheinker syndrome with variable phenotype in a new kindred with PRNP-P102L mutation

Gerstmann-Sträussler-Scheinker syndrome (GSS) is a dominantly inherited disorder belonging to the group of transmissible human spongiform encephalopathies or prion diseases. Several families affected by GSS with patients carrying mutations in the prion protein gene have been described worldwide. We report clinical, genealogical, neuropathology and molecular study results from two members of the first Argentine kindred affected by GSS. Both family members presented a frontotemporal-like syndrome, one with and the other without ataxia, with different lesions on neuropathology. A Pro to Leu point mutation at codon 102 (P102L) of the prion protein gene was detected in one of the subjects studied. The pathogenic basis of phenotypic variability observed in this family remains unclear, but resembles that observed in other P102L GSS patients from the same family.

PrP(ST), a soluble, protease resistant and truncated PrP form features in the pathogenesis of a genetic prion disease

While the conversion of PrP(C) into PrP(Sc) in the transmissible form of prion disease requires a preexisting PrP(Sc) seed, in genetic prion disease accumulation of disease related PrP could be associated with biochemical and metabolic modifications resulting from the designated PrP mutation. To investigate this possibility, we looked into the time related changes of PrP proteins in the brains of TgMHu2ME199K/wt mice, a line modeling for heterozygous genetic prion disease linked to the E200K PrP mutation. We found that while oligomeric entities of mutant E199KPrP exist at all ages, aggregates of wt PrP in the same brains presented only in advanced disease, indicating a late onset conversion process. We also show that most PK resistant PrP in TgMHu2ME199K mice is soluble and truncated (PrP(ST)), a pathogenic form never before associated with prion disease. We next looked into brain samples from E200K patients and found that both PK resistant PrPs, PrP(ST) as in TgMHu2ME199K mice, and "classical" PrP(Sc) as in infectious prion diseases, coincide in the patient's post mortem brains. We hypothesize that aberrant metabolism of mutant PrPs may result in the formation of previously unknown forms of the prion protein and that these may be central for the fatal outcome of the genetic prion condition.

Snord 3A: a molecular marker and modulator of prion disease progression

Since preventive treatments for prion disease require early identification of subjects at risk, we searched for surrogate peripheral markers characterizing the asymptomatic phases of such conditions. To this effect, we subjected blood mRNA from E200K PrP CJD patients and corresponding family members to global arrays and found that the expression of Snord3A, a non-coding RNA transcript, was elevated several times in CJD patients as compared to controls, while asymptomatic carriers presented intermediate Snord3A levels. In the brains of TgMHu2ME199K mice, a mouse model mimicking for E200K CJD, Snord 3A levels were elevated in an age and disease severity dependent manner, as was the case for brains of these mice in which disease was exacerbated by copper administration. Snord3A expression was also elevated in scrapie infected mice, but not in PrP^0/0 mice, indicating that while the expression levels of this transcript may reflect diverse prion etiologies, they are not related to the loss of PrP^C’s function. Elevation of Snord3A was consistent with the activation of ATF6, representing one of the arms of the unfolded protein response system. Indeed, SnoRNAs were associated with reduced resistance to oxidative stress, and with ER stress in general, factors playing a significant role in this and other neurodegenerative conditions. We hypothesize that in addition to its function as a disease marker, Snord3A may play an important role in the mechanism of prion disease manifestation and progression.

Hereditary form of prion disease in Poland

BACKGROUND AND PURPOSE

The aim of the study was to perform molecular analysis in a group of patients affected with prion disease. Diagnosis was based on results of clinical and/or histopathological examination of the brain. This is the largest investigation of this type performed so far in Poland.

MATERIAL AND METHODS

Analysed material contained 36 cases of prion disease, including 35 cases of Creutzfeldt-Jakob disease and one case of Gerstmann-Sträussler-Scheinker disease, as well as two familial cases initially suspected of Huntington disease and Alzheimer disease. The control group consisted of 87 subjects. The most frequent known mutations in the PRNP gene were looked for, namely those in codons 102, 117, 178, 200, 217 and OPRI; the polymorphism Met/Val in codon 129 was also analysed. The methods applied were PCR-RFLP and DNA sequencing.

RESULTS

The following mutations were found: E200K in 5 families, P102L in one family (previously identified), D178N in one family and 6OPRI in one family. Overall, mutations were detected in 17 persons (including 8 preclinical ones) from 8 pedigrees. Highly significant difference of codon 129 Met/Val heterozygosity frequencies was found between the affected subjects and the controls. Frequency of the familial form of prion disease in the material analysed was 14%.

CONCLUSIONS

Screening for mutations in the PRNP gene should be performed in all diagnosed cases of prion disease and in cases of familial occurrence of early onset dementia of unknown aetiology. Families with identified mutations should be offered genetic counselling and informed of risks of blood and organs' donation.

Creutzfeldt-Jakob disease surveillance in Argentina, 1997-2008

BACKGROUND

Epidemiological data on Creutzfeldt-Jakob disease (CJD) from Latin America are limited. We present a comprehensive epidemiological survey on CJD patients in Argentina based on systematic surveillance between 1997 and 2008.

METHODS

A CJD Surveillance Referral Center (SRC) was established in Argentina in 1997; previously a Neuropathology Referral Center was used from 1983 to 1996. All suspected cases referred to the SRC were classified using established criteria on the basis of information derived from the following: clinical data form, EEG, MRI (both for central review), cerebrospinal fluid (CSF) for protein 14-3-3 Western blot (WB), autopsy or biopsy material for neuropathology, prion protein (PrP) immunohistochemistry and PrP WB, as well as blood for DNA studies (when brain tissue was not available).

RESULTS

Of the 517 patients referred to the SRC between 1997 and 2008, 211 (40.8%) had CJD or other transmissible spongiform encephalopathies (TSEs) (definite or probable). Possible cases totaled 14.5%, while cases with no WHO criteria accounted for 16.4%. Non-CJD cases excluded by biopsy/autopsy or during follow-up corresponded to 28.2% of the 517 referrals. Main differential diagnoses included neurodegenerative diseases such as Alzheimer's disease, frontotemporal dementia, vascular, metabolic or viral encephalopathy, and Hashimoto's disease. Five percent of referred patients ultimately recovered. Eighty-three percent of TSE cases were sporadic CJD; 17% were genetic, mainly E200K (15.6%); the remaining 1.4% included an octarepeat insertion and two Gerstmann-Sträussler-Scheinker cases (P102L). Seventy-four of 100 definite cases had frozen tissue available for molecular subtyping (PrP(Sc)/codon 129). CSF protein 14-3-3 WB sensitivity was 72.3% and specificity was 92.1%. Clinical diagnostic criteria for probable CJD when compared to definite diagnosis by neuropathology showed 71.3% sensitivity, 86.2% specificity, 94.4% positive predictive value and 48% negative predictive value. Country incidence increased over time and reached 0.85 cases per million in 2008, with the highest rate detected in the city of Buenos Aires (1.8). Districts with 6% of the total population have never reported suspected cases.

CONCLUSION

In spite of an increase in incidence observed over time, the difference between Buenos Aires city, where the incidence is comparable to that of smaller European countries with higher population density, and the incidence observed in the rest of the country suggests underreporting in nonmetropolitan areas, probably due to a lack of access to specialized medical facilities. CSF WB sensitivity results for protein 14-3-3 were probably linked to the fact that testing was not routinely repeated during the course of the disease, when earlier test results had been negative. The spectrum of molecular CJD subtypes observed did not differ from other countries in Europe. No iatrogenic or variant CJD cases were identified. The sensitivity and negative predictive value of clinical diagnostic criteria for probable CJD (which includes EEG and/or CSF protein 14-3-3 levels) may have been resulted from confirmed cases not meeting probable criteria before autopsy, due to a lack of ancillary tests such as EEG and/or CSF 14-3-3 WB, or because negative tests were not repeated during follow-up.

Fatal prion disease in a mouse model of genetic E200K Creutzfeldt-Jakob disease

Genetic prion diseases are late onset fatal neurodegenerative disorders linked to pathogenic mutations in the prion protein-encoding gene, PRNP. The most prevalent of these is the substitution of Glutamate for Lysine at codon 200 (E200K), causing genetic Creutzfeldt-Jakob disease (gCJD) in several clusters, including Jews of Libyan origin. Investigating the pathogenesis of genetic CJD, as well as developing prophylactic treatments for young asymptomatic carriers of this and other PrP mutations, may well depend upon the availability of appropriate animal models in which long term treatments can be evaluated for efficacy and toxicity. Here we present the first effective mouse model for E200KCJD, which expresses chimeric mouse/human (TgMHu2M) E199KPrP on both a null and a wt PrP background, as is the case for heterozygous patients and carriers. Mice from both lines suffered from distinct neurological symptoms as early as 5–6 month of age and deteriorated to death several months thereafter. Histopathological examination of the brain and spinal cord revealed early gliosis and age-related intraneuronal deposition of disease-associated PrP similarly to human E200K gCJD. Concomitantly we detected aggregated, proteinase K resistant, truncated and oxidized PrP forms on immunoblots. Inoculation of brain extracts from TgMHu2ME199K mice readily induced, the first time for any mutant prion transgenic model, a distinct fatal prion disease in wt mice. We believe that these mice may serve as an ideal platform for the investigation of the pathogenesis of genetic prion disease and thus for the monitoring of anti-prion treatments.

Inherited prion diseases, such as genetic CJD, are dominant disorders linked to mutations in the gene encoding the prion protein, PrP. Since therapeutic intervention in all types of human prion diseases has failed, we propose that therapeutic efforts should be directed mostly to the development of preventive treatments for subjects incubating prion diseases, as is the case for asymptomatic carriers of pathogenic PrP mutations. These subjects will develop disease symptoms at some point in their adult life; therefore they should be treated before clinical deterioration. Candidate treatments will need to be tested for efficacy and safety first in animal models that mimic most properties of genetic CJD. In this work, we describe a new transgenic mouse model for E200K genetic CJD, presenting progressive neurodegenerative disease and age related prion disease pathology and biochemistry, as is the case in the human disease. Brain extracts from these mice also transmitted prion disease to wt mice, as shown before for parallel human samples. We propose that these animals will play a significant role in the development of novel anti-prion prophylactic treatments.

Genetic Creutzfeldt-Jakob disease associated with the E200K mutation: characterization of a complex proteinopathy

The E200K mutation is the most frequent prion protein gene (PRNP) mutation detected worldwide that is associated with Creutzfeldt-Jakob disease (CJD) and thought to have overlapping features with sporadic CJD, yet detailed neuropathological studies have not been reported. In addition to the prion protein, deposition of tau, α-synuclein, and amyloid-β has been reported in human prion disease. To describe the salient and concomitant neuropathological alterations, we performed a systematic clinical, neuropathological, and biochemical study of 39 individuals carrying the E200K PRNP mutation originating from different European countries. The most frequent clinical symptoms were dementia and ataxia followed by myoclonus and various combinations of further symptoms, including vertical gaze palsy and polyneuropathy. Neuropathological examination revealed relatively uniform anatomical pattern of tissue lesioning, predominating in the basal ganglia and thalamus, and also substantia nigra, while the deposition of disease-associated PrP was more influenced by the codon 129 constellation, including different or mixed types of PrP(res) detected by immunoblotting. Unique and prominent intraneuronal PrP deposition involving brainstem nuclei was also noted. Systematic examination of protein depositions revealed parenchymal amyloid-β in 53.8%, amyloid angiopathy (Aβ) in 23.1%, phospho-tau immunoreactive neuritic profiles in 92.3%, neurofibrillary degeneration in 38.4%, new types of tau pathology in 33.3%, and Lewy-type α-synuclein pathology in 15.4%. TDP-43 and FUS immunoreactive protein deposits were not observed. This is the first demonstration of intensified and combined neurodegeneration in a genetic prion disease due to a single point mutation, which might become an important model to decipher the molecular interplay between neurodegeneration-associated proteins.

Molecular, biochemical and genetic characteristics of BSE in Canada

The epidemiology and possibly the etiology of bovine spongiform encephalopathy (BSE) have recently been recognized to be heterogeneous. In particular, three types [classical (C) and two atypical (H, L)] have been identified, largely on the basis of characteristics of the proteinase K (PK)-resistant core of the misfolded prion protein associated with the disease (PrP^res). The present study was conducted to characterize the 17 Canadian BSE cases which occurred prior to November 2009 based on the molecular and biochemical properties of their PrP^res, including immunoreactivity, molecular weight, glycoform profile and relative PK sensitivity. Two cases exhibited molecular weight and glycoform profiles similar to those of previously reported atypical cases, one corresponding to H-type BSE (case 6) and the other to L-type BSE (case 11). All other cases were classified as C-type. PK digestion under mild and stringent conditions revealed a reduced protease resistance in both of these cases compared to the C-type cases. With Western immunoblotting, N-terminal-specific antibodies bound to PrP^res from case 6 but not to that from case 11 or C-type cases. C-terminal-specific antibodies revealed a shift in the glycoform profile and detected a fourth protein fragment in case 6, indicative of two PrP^res subpopulations in H-type BSE. No mutations suggesting a genetic etiology were found in any of the 17 animals by sequencing the full PrP-coding sequence in exon 3 of the PRNP gene. Thus, each of the three known BSE types have been confirmed in Canadian cattle and show molecular characteristics highly similar to those of classical and atypical BSE cases described from Europe, Japan and the USA. The occurrence of atypical cases of BSE in countries such as Canada with low BSE prevalence and transmission risk argues for the occurrence of sporadic forms of BSE worldwide.

The first Chinese case of Creutzfeldt-Jakob disease with mutation of E200K in PRNP

OBJECTIVE

To investigate epidemiological, clinical and genetic features of the first Chinese case of Creutzfeldt-Jakob disease (CJD ) with mutation of E200K in PRNP.

METHODS

The general epidemiological and clinical data were collected; CSF 14-3-3 protein was analyzed by Western blot; The PRNP was amplified by PCR and analyzed.

RESULTS

A missense mutation in codon 200 (E200K) of the PRNP was identified in this patient; CSF 14-3-3 protein was positive; sleep disturbance was the initial sign and the other symptoms gradually appeared, including memory loss, dizziness and ataxia.

CONCLUSION

The CJD patient who was first reported in China has a missense mutation in codon 200 (E200K) of the PRNP, and the codon 129 is a methionine homozygous genotype.

Codistribution of amyloid beta plaques and spongiform degeneration in familial Creutzfeldt-Jakob disease with the E200K-129M haplotype

BACKGROUND

Dominantly inherited Creutzfeldt-Jakob disease (CJD) represents 5% to 15% of all CJD cases. The E200K mutation in the prion protein (PrP) gene (PRNP) is the most frequent cause of familial CJD. Coexistent amyloid beta (Abeta) plaques have been reported in some transmissible spongiform encephalopathies but to date have not been reported in familial CJD with the E200K mutation.

OBJECTIVE

To characterize a family with CJD in which Abeta plaques codistribute with spongiform degeneration.

DESIGN

Clinicopathologic and molecular study of a family with CJD with the E200K-129M haplotype.

SETTING

Alzheimer disease research center.

PARTICIPANTS

Two generations of a family.

MAIN OUTCOME MEASURES

Clinical, biochemical, and neuropathologic observations in 2 generations of a family.

RESULTS

In this kindred, 3 autopsied cases showed pathologic changes typical for the E200K-129M haplotype, including spongiform degeneration, gliosis, neuronal loss, and PrP deposition. Moreover, 2 of these cases (ages 57 and 63 years) showed numerous Abeta plaques codistributed with spongiform degeneration. APOE genotyping in 2 cases revealed that Abeta plaques were present in the APOE epsilon4 carrier but not in the APOE epsilon4 noncarrier. Two additional cases exhibited incomplete penetrance, as they had no clinical evidence of CJD at death after age 80 years but had affected siblings and children.

CONCLUSIONS

To our knowledge, this is the first description of Abeta plaques in familial CJD with the E200K mutation. The codistribution of plaques and CJD-associated changes suggests that PrP plays a central role in Abeta formation and that Abeta pathology and prion disease likely in fluence each other. The kindred described herein provides support that PrP(E200K) may result in increased Abeta deposition.

Creutzfeldt-Jakob disease with E200K PRNP mutation: a case report and revision of the literature

Creutzfeldt-Jakob disease (CJD) is typically characterized by rapidly progressive dementia and myoclonus, and it is caused by a conformational change of the prion protein. The heritable forms are associated with mutation in the gene encoding the prion protein (PRNP). We report a 63-year-old Italian woman harboring the E200K PRNP mutation. Electroencephalogram, cerebrospinal fluid analysis, PRNP gene sequencing, histopathologic examination, immunohistochemical studies, and Western blotting analysis confirmed the diagnosis of CJD. Pyramidal involvement was the first sign and the prominent clinical feature. Later on, she developed also myoclonus, ataxia, spastic tetraplegia, and at last dementia with akinetic mutism. Usually, signs of degeneration of the pyramidal tracts occur in a small number of patients as the disease advances. Our report supports the variability of the clinical expression of the E200K genetic CJD. Further studies are needed to understand the molecular basis underlying the phenotypic variability among patients carrying this mutation.

Prevalence of the prion protein gene E211K variant in U.S. cattle

BACKGROUND

In 2006, an atypical U.S. case of bovine spongiform encephalopathy (BSE) was discovered in Alabama and later reported to be polymorphic for glutamate (E) and lysine (K) codons at position 211 in the bovine prion protein gene (Prnp) coding sequence. A bovine E211K mutation is important because it is analogous to the most common pathogenic mutation in humans (E200K) which causes hereditary Creutzfeldt - Jakob disease, an autosomal dominant form of prion disease. The present report describes a high-throughput matrix-associated laser desorption/ionization-time-of-flight mass spectrometry assay for scoring the Prnp E211K variant and its use to determine an upper limit for the K211 allele frequency in U.S. cattle.

RESULTS

The K211 allele was not detected in 6062 cattle, including those from five commercial beef processing plants (3892 carcasses) and 2170 registered cattle from 42 breeds. Multiple nearby polymorphisms in Prnp coding sequence of 1456 diverse purebred cattle (42 breeds) did not interfere with scoring E211 or K211 alleles. Based on these results, the upper bounds for prevalence of the E211K variant was estimated to be extremely low, less than 1 in 2000 cattle (Bayesian analysis based on 95% quantile of the posterior distribution with a uniform prior).

CONCLUSION

No groups or breeds of U.S. cattle are presently known to harbor the Prnp K211 allele. Because a carrier was not detected, the number of additional atypical BSE cases with K211 will also be vanishingly low.

Spatial clusters of Creutzfeldt-Jakob disease mortality in Japan between 1995 and 2004

BACKGROUND

There is suggested to be a geographical difference in Creutzfeldt-Jakob disease (CJD) mortality in Japan. We performed a study to detect localized clusters and hot-spot areas of deaths from CJD in Japan during the 10-year period from 1995 to 2004.

METHODS

The diagnosis of CJD was taken from the death certificate (coded as A81.0 in the ICD-10). A total number of 1,168 CJD deaths (500 males and 668 females) were used for analysis using empirical Bayes estimates of standardized mortality ratios and the flexible spatial scan statistic to detect clusters. To detect the most likely cluster, p values were obtained using Monte Carlo hypothesis testing (with p < 0.05 as statistical significance).

RESULTS

The most likely cluster of CJD mortality was located in the northwest region from the base of Mt. Fuji, stretching over the two neighboring prefectures of Yamanashi and Shizuoka (relative risk = 2.28, p = 0.021). Some other clusters were detected but were not significant.

CONCLUSIONS

The present study supports the evidence of geographical clustering of deaths from CJD at a specific location in Japan.

Molecular evidence of founder effects of fatal familial insomnia through SNP haplotypes around the D178N mutation

This work presents a detailed investigation of the genomic region surrounding the PRNP gene in a sample of patients diagnosed with fatal familial insomnia (FFI) from several European countries, notably Spain. The main focus of the study was to explore the origins of the chromosomes carrying the D178N mutation by designing a single-nucleotide polymorphism (SNP) haplotype around the PRNP gene. Haplotypes were constructed by genotyping six SNPs (rs2756271, rs13040327, rs6037932, rs13045348, rs6116474, and rs6116475) in 25 FFI patients from all over Spain. To augment the geographical scope of our study, 13 further FFI cases from Germany (9) and Italy (4) were also examined. Genotyping of SNPs in conjunction with the analysis of genealogical data for a group of FFI patients revealed the existence of two distinct haplotypes potentially associated with the D178N mutation. Of them, GCATTA-M proved to be the common haplotype of Spanish patients, whereas ACATTA-M was typical of the German cases. It is interesting to note that both haplotypes were identified in the Italian samples: GCATTA-M in a family from the Tuscany region and ACATTA-M in a family from the Veneto region. Our findings suggest the occurrence of two independent D178N-129M mutational events in Europe, preserved and transmitted from one generation to the next until nowadays. Likewise, results based on the analysis of SNP data indicate that previous hypotheses postulating that the D178N mutation had independent origins for each family and that its global distribution was determined by recurrent mutational events must be regarded with caution.

Creutzfeldt-Jakob disease associated with a missense mutation at codon 200 of the prion protein gene in Brazil

Genetic Creutzfeldt-Jakob disease (gCJD) represents less than 15% of CJD cases, and its clinical picture may be either indistinguishable from that of sporadic CJD (sCJD) or be atypical, usually with younger onset and longer duration. We report a case of 59-year old Brazilian man who presented rapidly progressive cognitive decline and cerebellar ataxia. EEG revealed periodic activity. A brother and a cousin of the patient had CJD. A point mutation at codon 200 (E200K) of the prion protein gene (PRNP) was found and death occurred 11 months after onset of symptoms. Autopsy was not performed. The clinical presentation of gCJD associated with E200K, which is the most frequent PRNP mutation, is quite similar to sCDJ. This is the first report of E200K mutation in Brazil, and it is possible that a more systematic search for its occurrence may show it to be relatively frequent in Brazil.

Retrospective sequence analysis of the human PRNP gene from the formaldehyde-fixed paraffin-embedded tissues: report of two cases of Creutzfeldt-Jakob disease

The definitive diagnosis of the CJD (Creutzfeldt-Jakob disease; very rare neurodegenerative disorder) can be established only on the basis of post-mortem examination of the central nervous system tissue. Formaldehyde-fixed paraffin-embedded (FFPE) tissue samples may thus constitute the only material available for molecular pathology analyses. We performed post-mortem analysis of the coding region of the prion-protein gene (PRNP)-sequence variations in two definite CJD cases suggestive of genetic form. Only FFPE tissues were available for molecular analyses. The PRNP gene open reading frame was amplified from the genomic DNA (FFPE isolated) in four overlapping, two round semi-nested PCR products that were directly sequenced. We found known pathogenic sequence variation g.532 G>A (Asp178Asn) in patient 1 but we did not find any pathogenic sequence variation in patient 2 despite her origin from the Slovak Orava region. Based on these results, we were able to discriminate between genetic and sporadic form of CJD in patient 1 and 2, respectively. The established method was found to be efficient for the sequence-variation analysis of the entire PRNP gene coding region using the genomic DNA isolated from the FFPE tissues; it can be employed in other retrospective molecular studies.

An overview of transmissible spongiform encephalopathies

Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative disorders of humans and animals associated with an accumulation of abnormal isoforms of prion protein (PrP) in nerve cells. The pathogenesis of TSEs involves conformational conversions of normal cellular PrP (PrPc) to abnormal isoforms of PrP (PrPSc). While the protein-only hypothesis has been widely accepted as a causal mechanism of prion diseases, evidence from more recent research suggests a possible involvement of other cellular component(s) or as yet undefined infectious agent(s) in PrP pathogenesis. Although the underlying mechanisms of PrP strain variation and the determinants of interspecies transmissibility have not been fully elucidated, biochemical and molecular findings indicate that bovine spongiform encephalopathy in cattle and new-variant Creutzfeldt–Jakob disease in humans are caused by indistinguishable etiological agent(s). Cumulative evidence suggests that there may be risks of humans acquiring TSEs via a variety of exposures to infected material. The development of highly precise ligands is warranted to detect and differentiate strains, allelic variants and infectious isoforms of these PrPs. This article describes the general features of TSEs and PrP, the current understanding of their pathogenesis, recent advances in prion disease diagnostics, and PrP inactivation.

The expanding universe of prion diseases

Prions cause fatal and transmissible neurodegenerative disease. These etiological infectious agents are formed in greater part from a misfolded cell-surface protein called PrP(C). Several mammalian species are affected by the diseases, and in the case of "mad cow disease" (BSE) the agent has a tropism for humans, with negative consequences for agribusiness and public health. Unfortunately, the known universe of prion diseases is expanding. At least four novel prion diseases--including human diseases variant Creutzfeldt-Jakob disease (vCJD) and sporadic fatal insomnia (sFI), bovine amyloidotic spongiform encephalopathy (BASE), and Nor98 of sheep--have been identified in the last ten years, and chronic wasting disease (CWD) of North American deer (Odocoileus Specis) and Rocky Mountain elk (Cervus elaphus nelsoni) is undergoing a dramatic spread across North America. While amplification (BSE) and dissemination (CWD, commercial sourcing of cervids from the wild and movement of farmed elk) can be attributed to human activity, the origins of emergent prion diseases cannot always be laid at the door of humankind. Instead, the continued appearance of new outbreaks in the form of "sporadic" disease may be an inevitable outcome in a situation where the replicating pathogen is host-encoded.

Prion disease genetics

Prion diseases have stimulated intense scientific scrutiny since it was proposed that the infectious agent was devoid of nucleic acid. Despite this finding, genetics has played a key role in understanding the pathobiology and clinical aspects of prion disease through the effects of a series of polymorphisms and mutations in the prion protein gene (PRNP). The advent of variant Creutzfeldt-Jakob disease has confirmed one of the most powerful human genetic susceptibility factors, as all tested patients have an identical genotype at polymorphic codon 129 of PRNP. This review will also consider the accrued reports of inherited prion disease and attempt a genotype-phenotype correlation. The prospects for detection of novel genetic susceptibility factors using mouse models and human genetic association studies will be explored.

Ancestral origins of the prion protein gene D178N mutation in the Basque Country

Fatal familial insomnia (FFI) and familial Creutzfeldt-Jakob disease (fCJD) are familial prion diseases with autosomal dominant inheritance of the D178N mutation. FFI has been reported in at least 27 pedigrees around the world. Twelve apparently unrelated FFI and fCJD pedigrees with the characteristic D178N mutation have been reported in the Prion Diseases Registry of the Basque Country since 1993. The high incidence of familial prion diseases in this region may reflect a unique ancestral origin of the chromosome carrying this mutation. In order to investigate this putative founder effect, we developed "happy typing", a new approach to the happy mapping method, which consists of the physical isolation of large haploid genomic DNA fragments and their analysis by the Polymerase Chain Reaction in order to perform haplotypic analysis instead of pedigree analysis. Six novel microsatellite markers, located in a 150-kb genomic segment flanking the PRNP gene were characterized for typing haploid DNA fragments of 285 kb in size. A common haplotype was found in patients from the Basque region, strongly suggesting a founder effect. We propose that "happy typing" constitutes an efficient method for determining disease-associated haplotypes, since the analysis of a single affected individual per pedigree should provide sufficient evidence.

Numerous polymorphic microsatellites in the human prion gene complex (including PRNP, PRND and PRNT)

Microsatellite sites were analysed with DNA screening software by using about 148 kilobases (kb) of the human genomic DNA sequence GenBank accession number (acc. no.) which includes the genes PRNP, PRND and PRNT. Regarding microsatellites (MS) with at least four repeats and base replacements within the repetitive motifs<10%, 127 sites were found. Sixteen of the sites were analysed and nine of them proved to be polymorphic with up to nine alleles per site. Frequencies<0.95 of the predominant allele were observed for all polymorphic sites, and frequencies<0.4 for four sites. Some allelic DNA sequences were not only different in microsatellite repeats but also in flanking regions. Distances between microsatellite sites were in average of 1.2 kb and allow the identification of a number of further informative markers in the prion protein gene complex. The large number of polymorphic sites within a narrow chromosomal interval can be applied to study the origin of alleles as well as the association to the incidence of diseases.

Distinctive cerebellar immunoreactivity for the prion protein in familial (E200K) Creutzfeldt-Jakob disease

We have compared the immunomorphological spectrum of the deposition of the disease-associated prion protein (PrP(Sc)) in the cerebral and cerebellar cortex of 32 Creutzfeldt-Jakob disease (CJD) patients with the PrP gene (PRNP) E200K mutation to 45 sporadic CJD and 14 other genetic prion disease cases. PrP deposits correlate with the genotype at the methionine/valine (MV) polymorphic codon 129. While the diffuse/synaptic and patchy/perivacuolar PrP deposits and PrP plaques have a similar distribution and correlation with the genotype at codon 129 as in sporadic CJD, an additional peculiar PrP immunostaining pattern occurs in the cerebellum in 81% E200K mutation brains including 93% of M129M, 71% of M129V, but not in the single V129V case. It is localized to the molecular layer and consists of coarse granular PrP deposits arranged in a stripe-like manner predominantly perpendicular to the surface, closely resembling the parasagittal arborization of climbing fibers. Our results suggest that (1) the type of PrP deposits in the cerebellum may suggest genetic disease and the need for genetic testing; and (2) the peculiar stripes of PrP deposits might reflect selective vulnerability of cerebellar structures.

Sporadic and familial CJD: classification and characterisation

Prion diseases are unique transmissible neurodegenerative diseases that have diverse phenotypes and can be familial, sporadic, or acquired by infection. Recent findings indicate that the PrP genotype and the PrP(Sc) type have a major influence on the disease phenotype in both sporadic and familial human prion diseases. This review attempts to classify and characterise sporadic and familial Creutzfeldt-Jakob disease (CJD) as a function of these two disease determinants. Based on the genotype at codon 129 on both PRNP alleles, the size of protease resistant PrP(Sc) fragments and disease phenotype, we divide sporadic CJD into six subtypes: sCJDMM1/sCJDMV1, sCJDVV2, sCJDMV2, sCJDMM2, sCJDVV1, and sporadic fatal insomnia (sFI). Familial CJD is classified into many haplotypes based on the PRNP mutation and codon 129 (and other polymorphic codons) on the mutant allele. The clinical and pathological features are summarised for each sporadic CJD subtype and familial CJD haplotype.

Spontaneous mutations in the prion protein gene causing transmissible spongiform encephalopathy

We analyzed the prion protein gene (PRNP) region in patients with transmissible spongiform encephalopathy associated with the PRNP D178N mutation. The results suggest that the D178N chromosomes had independent origins in each affected pedigree or apparently sporadic case. A de novo spontaneous PRNP mutation was observed. We provide evidence that hereditary and apparently sporadic transmissible spongiform encephalopathy cases associated with the D178N mutation result from multiple recurrent mutational events.