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MM2-Thalamic Creutzfeldt-Jakob Disease: Neuropathological, Biochemical and Transmission Studies Identify a Distinctive Prion Strain
Brain Pathology
Abstract
In Creutzfeldt–Jakob disease (CJD), molecular typing based on the size of the protease resistant core of the disease-associated prion protein (PrPSc) and the M/V polymorphism at codon 129 of the PRNP gene correlates with the clinico-pathologic subtypes. Approximately 95% of the sporadic 129MM CJD patients are characterized by cerebral deposition of type 1 PrPSc and correspond to the classic clinical CJD phenotype. The rare 129MM CJD patients with type 2 PrPSc are further subdivided in a cortical and a thalamic form also indicated as sporadic fatal insomnia.
We observed two young patients with MM2-thalamic CJD. Main neuropathological features were diffuse, synaptic PrP immunoreactivity in the cerebral cortex and severe neuronal loss and gliosis in the thalamus and olivary nucleus. Western blot analysis showed the presence of type 2A PrPSc. Challenge of transgenic mice expressing 129MM human PrP showed that MM2-thalamic sporadic CJD (sCJD) was able to transmit the disease, at variance with MM2-cortical sCJD. The affected mice showed deposition of type 2A PrPSc, a scenario that is unprecedented in this mouse line. These data indicate that MM2-thalamic sCJD is caused by a prion strain distinct from the other sCJD subtypes including the MM2-cortical form.
... *Ratio between diglycosylated and unglycosylated PrP Sc fragment; ° Lacks diglycosylated PrP Sc . Data summarized in the Table are taken from the following studies: disease frequency [32,60,69], disease duration [32,60,69,70], T50 [68], PK-resistance ED50, glycosylation and aggregation ratios [67], attackrate and incubation time [71][72][73][74][75][76][77][78]. NA, not available; ND, not defined. ...
... Neuropathological findings and PrP Sc properties in the affected mice showed striking similarities between FFI and MM2T inocula, which is consistent with a common strain (M2T) [146] (Figure 3). Data from subsequent transmissions in murine lines either overexpressing human PrP, such as Tg(MHu2M,M165V,E167Q), Tg(MHu2M), and Tg(HuPrP,M129) [129], or expressing normal PrP levels (HuMM) [74] further corroborated the conclusion. ...
... Among the sCJD subtypes, the MM2C (strain M2C) is the only one that did not successfully transmit to knock-in mice expressing human PrP at physiological levels [71,73,74]. However, the disease propagated successfully in transgenic and knock-in murine lines overexpressing human PrP with 129M by 2 to 6 fold [78,129,130,147], although with a remarkably longer incubation time than M1 prions [17,78,129,130]. ...
Prion diseases are a unique group of rare neurodegenerative disorders characterized by tissue deposition of heterogeneous aggregates of abnormally folded protease-resistant prion protein (PrPSc), a broad spectrum of disease phenotypes and a variable efficiency of disease propagation in vivo. The dominant clinicopathological phenotypes of human prion disease include Creutzfeldt–Jakob disease, fatal insomnia, variably protease-sensitive prionopathy, and Gerstmann–Sträussler–Scheinker disease. Prion disease propagation into susceptible hosts led to the isolation and characterization of prion strains, initially operatively defined as “isolates” causing diseases with distinctive characteristics, such as the incubation period, the pattern of PrPSc distribution, and the regional severity of neuropathological changes after injection into syngeneic hosts. More recently, the structural basis of prion strains has been linked to amyloid polymorphs (i.e., variant amyloid protein conformations) and the concept extended to all protein amyloids showing polymorphic structures and some evidence of in vivo or in vitro propagation by seeding. Despite the significant advances, however, the link between amyloid structure and disease is not understood in many instances. Here we reviewed the most significant contributions of human prion disease studies to current knowledge of the molecular basis of phenotypic variability and the prion strain phenomenon and underlined the unsolved issues from the human disease perspective.
... The characterization of human strains by transmission studies (see also the dedicated section in this review) demonstrated an excess of biological variability with respect to PrP Sc types 1 and 2 dichotomy (ie, five CJD strains vs. two protein types) (17,76,104,124), which, according to the protein-only hypothesis, would indicate that types 1 and 2 are structurally heterogeneous PrP Sc species. Evidence from recent studies supports this contention. ...
... The results of the studies conducted to date with sCJD prions indicate that five of the sCJD subtypes defined by the current classification behave as different prion strains (17,68,76,79,82,104,110,124,174,175) (Figure 6). As the only exception, prions associated with VV2 and MV2K shared transmission properties despite the different phenotypic features in the natural host, suggesting a host genotype effect related to PRNP codon 129. ...
... Specifically, sCJD MM1 and MV1 isolates showed identical transmission properties (M1 strain), which significantly differed from those of sCJD VV2 or MV2K (V2 strain) (17,124). Furthermore, sCJD MM2C, MM2T and VV1 isolates generated distinctive transmission properties, suggesting they are caused by specific strains too (17,68,80,82,91,104,114,174,175). ...
Prion diseases are progressive neurodegenerative disorders affecting humans and other mammalian species. The term prion, originally put forward to propose the concept that a protein could be infectious, refers to PrPSc, a misfolded isoform of the cellular prion protein (PrPC) that represents the pathogenetic hallmark of these disorders. The discovery that other proteins characterized by misfolding and seeded aggregation can spread from cell to cell, similarly to PrPSc, has increased interest in prion diseases. Among neurodegenerative disorders, however, prion diseases distinguish themselves for the broader phenotypic spectrum, the fastest disease progression and the existence of infectious forms that can be transmitted through the exposure to diseased tissues via ingestion, injection or transplantation. The main clinicopathological phenotypes of human prion disease include Creutzfeldt‐Jakob disease, by far the most common, fatal insomnia, variably protease‐sensitive prionopathy, and Gerstmann‐Sträussler‐Scheinker syndrome. However, clinicopathological manifestations extend even beyond those predicted by this classification. Because of their transmissibility, the phenotypic diversity of prion disease can also be propagated into syngeneic hosts as prion strains with distinct characteristics, such as incubation period, pattern of PrPSc distribution and regional severity of histopathological changes in the brain. Increasing evidence indicates that different PrPSc conformers, forming distinct ordered aggregates, encipher the phenotypic variants related to prion strains. In this review, we summarize the most recent advances concerning the histo‐molecular pathology of human prion disease focusing on the spectrum of the disease including the effect of co‐pathologies, the characterization of prion strains by experimental transmission and their correlation with the physicochemical properties of PrPSc aggregates.
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... 6,7 Transmission studies using susceptible transgenic mice have consistently demonstrated that the same prion strain is associated with both sFI and FFI. 8,9 In contrast to what has been the rule for the most common neurodegenerative disorders, sFI is rarer than its genetic counterpart. 10 Whereas the recognized patients with FFI are numerous and belong to >50 families worldwide, only about 30 cases of CJD MM2T and a few cases with mixed MM2T and MM2C features (MM2T+C) have been recorded to date. ...
... 10 Whereas the recognized patients with FFI are numerous and belong to >50 families worldwide, only about 30 cases of CJD MM2T and a few cases with mixed MM2T and MM2C features (MM2T+C) have been recorded to date. 6,8,9,[11][12][13][14][15][16][17][18][19][20][21][22][23] Moreover, whereas the first description of FFI dates back to 1986 and its recognition as a genetic prion disease to 1992, the characterization of sFI as a distinct sporadic prion disease subtype was only achieved in 1999. 6,8 It is noteworthy, however, that a few cases previously reported under the terms thalamic dementia, thalamic degeneration, or thalamic form of CJD, either sporadic or familial, likely belonged to the same disease entity. ...
... 41 Patients 1, 5, and 6 were briefly described in previous studies. 9, 16 We conducted the study according to the revised Declaration of Helsinki and Good Clinical Practice guidelines. The protocol for this study received prior approval by the Institute of Neurological Sciences of Bologna Institutional Review Board. ...
Objective
Comprehensively describe the phenotypic spectrum of sporadic Fatal Insomnia (sFI) to facilitate diagnosis and management of this rare and peculiar prion disorder.
Methods
A survey among major prion disease reference Centres in Europe identified 13 patients diagnosed with sFI in the past 20 years. We undertook a detailed analysis of clinical and histopathological features, and the results of diagnostic investigations.
Results
Mean age at onset was 43 years and mean disease duration 30 months. Early clinical findings included psychiatric, sleep and oculomotor disturbances, followed by cognitive decline and postural instability. In all tested patients, video‐polysomnography demonstrated a severe reduction of total sleep time and/or a disorganized sleep. CSF levels of proteins 14‐3‐3 and t‐tau were unrevealing, the concentration of neurofilament light protein (NfL) was more consistently increased, and the real‐time quaking‐induced conversion assay (RT‐QuIC) revealed a positive prion seeding activity in 60% of cases. EEG and MRI showed non‐specific findings, whereas FDG‐PET demonstrated a profound bilateral thalamic hypometabolism in 71% of cases. Molecular analyses revealed PrPSc type 2 and methionine homozygosity at PRNP codon 129 in all cases.
Interpretation
sFI is a disease of young or middle‐aged adults, which is difficult to reconcile with the hypothesis of a spontaneous etiology related to stochastic, age‐related, PrP misfolding. The combination of psychiatric and/or sleep‐related symptoms with oculomotor abnormalities represent early peculiar clinical feature of sFI to be valued in the differential diagnosis. Video‐polysomnography, FDG‐PET, and especially CSF prion RT‐QuIC and NfL constitute the most promising supportive diagnostic tests in vivo.
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... This outcome is predictable since the specific FFI mutation D178N is likely to impose more constraints on the initial spontaneous conversion to a prion-like conformation of the mutated PrP compared to the presumably idiopathic conversion and subsequent selection process of wildtype PrP (Collinge and Clarke, 2007;Collinge, 2010;Li et al., 2010;Imberdis and Harris, 2016). Although the phenotypic similarities to FFI outweigh the features shared with any of the sCJD subtypes, also after experimental transmission (Mastrianni et al., 1999;Krasnianski et al., 2014), sFI is often referred to as the thalamic form of sCJDMM2 (Moda et al., 2012;Parchi and Saverioni, 2012;Hayashi et al., 2015;Iwasaki, 2017). ...
... Similar to FFI, many patients experience psychomotor hyperactivity and autonomic dysfunction (Sikorska and Liberski, 2012). Despite its name, insomnia has not been a prominent symptom in many cases of sFI unless it is specifically investigated with the patient and family members (Moda et al., 2012). Symptoms observed in atypical parkinsonian syndromes, such as oculomotor symptoms, dyskinesia, and parkinsonism, are often present in sFI at presentation (Parchi et al., 1999b;Cracco et al., 2017). ...
... In 18 of the 23 typical sFI cases in which it was tested, PrP TSE presence was demonstrated by immunohistochemistry. Positive PrP immunostaining is favored by the presence of spongiform degeneration. In locations free of spongiform degeneration, PrP immunostaining may be inconspicuous, limited to a few foci often in subpial cortical regions forming a punctate or synaptic pattern with occasional presence of small polymorphic aggregates similar to those observed in FFI (Fig. 15.4A) (Moda et al., 2012;Blase et al., 2014). In the presence of spongiform degeneration, the immunostaining pattern mimics that of sCJDMM2 and exhibits perivacuolar deposition and aggregate formation, as well as plaque-like pattern in the cerebellum (Fig. 15.6B) (Parchi et al., 1999a;Blase et al., 2014). ...
Fatal familial insomnia (FFI) and sporadic fatal insomnia (sFI), or thalamic form of sporadic Creutzfeldt-Jakob disease MM2 (sCJDMM2T), are prion diseases originally named and characterized in 1992 and 1999, respectively. FFI is genetically determined and linked to a D178N mutation coupled with the M129 genotype in the prion protein gene (PRNP) at chromosome 20. sFI is a phenocopy of FFI and likely its sporadic form. Both diseases are primarily characterized by progressive sleep impairment, disturbances of autonomic nervous system, and motor signs associated with severe loss of nerve cells in medial thalamic nuclei. Both diseases harbor an abnormal disease-associated prion protein isoform, resistant to proteases with relative mass of 19 kDa identified as resPrPTSE type 2. To date at least 70 kindreds affected by FFI with 198 members and 18 unrelated carriers along with 25 typical cases of sFI have been published. The D178N-129M mutation is thought to cause FFI by destabilizing the mutated prion protein and facilitating its conversion to PrPTSE. The thalamus is the brain region first affected. A similar mechanism triggered spontaneously may underlie sFI.
... Sporadic fatal insomnia (sFI) is defined as a rapidly progressive neurodegenerative disease with a clinical phenotype very similar to the fatal familial insomnia characterized by neurological and cognitive deterioration along with severe sleep impairment [45], transient diplopia [46] and cerebellar dysfunction [47], followed by dysautonomia, coma and death [45]. These patients are rare codon 129 methionine homozygotes with PrP Sc type 2 and predominant thalamic involvement [48]. Microscopically, slight spongiform degeneration but severe neuronal loss with gliosis is present in thalamus and inferior olives, although immunohistochemical detection of PrP mostly shows focal or no positivity [48]. ...
... These patients are rare codon 129 methionine homozygotes with PrP Sc type 2 and predominant thalamic involvement [48]. Microscopically, slight spongiform degeneration but severe neuronal loss with gliosis is present in thalamus and inferior olives, although immunohistochemical detection of PrP mostly shows focal or no positivity [48]. The distribution of the PrP Sc -immunoreactive structures is similar in familial and sporadic form [49][50][51]. ...
Human prion disorders (transmissible spongiform encephalopathies, TSEs) are unique, progressive, and fatal neurodegenerative diseases caused by aggregation of misfolded prion protein in neuronal tissue. Due to the potential transmission, human TSEs are under active surveillance in a majority of countries; in the Czech Republic data are centralized at the National surveillance center (NRL) which has a clinical and a neuropathological subdivision. The aim of our article is to review current knowledge about human TSEs and summarize the experience of active surveillance of human prion diseases in the Czech Republic during the last 20 years. Possible or probable TSEs undergo a mandatory autopsy using a standardized protocol. From 2001 to 2020, 305 cases of sporadic and genetic TSEs including 8 rare cases of Gerstmann–Sträussler–Scheinker syndrome (GSS) were confirmed. Additionally, in the Czech Republic, brain samples from all corneal donors have been tested by the NRL immunology laboratory to increase the safety of corneal transplants since January 2007. All tested 6590 corneal donor brain tissue samples were negative for prion protein deposits. Moreover, the routine use of diagnostic criteria including biomarkers are robust enough, and not even the COVID-19 pandemic has negatively impacted TSEs surveillance in the Czech Republic.
... Patients sharing clinical and histopathologic features with FFI, without any PRNP mutation or any positive familial history, have been ascribed to the clinical definition of Sporadic Fatal Insomnia (sFI) [22,76], often referred to as the thalamic form of sCJDMM2 [77][78][79]. ...
... The sFI clinical and histopathologic phenotype appears to be more variable than that of the FFI variant linked to the 129 homozygous genotype [9,24]. Consequently, although many symptoms of sFI overlap with those observed in FFI, insomnia has not been a prominent symptom in many cases of sFI (only 29% of patients at onset) [80], unless specifically investigated [77]. This is true also for autonomic symptoms, reported only in half of the cases and in one-third of the recently reviewed European patients [76]. ...
Fatal familial insomnia (FFI) is a hereditary prion disease linked to a missense mutation at codon 178 of the prion-protein gene (PRNP) located on chromosome 20, determining severe and selective atrophy of mediodorsal and anteroventral thalamic nuclei. FFI is characterized by physiological sleep loss, polygraphically appearing as a slow wave sleep loss, autonomic and motor hyperactivation with peculiar episodes of oneiric stupor. Dysfunction of the autonomic system is a great burden for FFI patients consisting of sympathetic overactivation, dysregulation of its physiological responses, and disruption of circadian rhythms. Cardiovascular and thermoregulatory systems are the most frequently affected, confirming the increased sympathetic drive with preserved parasympathetic responses. Sleep loss, autonomic, and motor hyperactivation define agrypnia excitata (AE), which is not exclusive to FFI, but described also in Morvan syndrome (MS) and delirium tremens (DT). These three conditions (FFI, MS and DT) present different pathophysiological mechanisms but share the same thalamolimbic impairment of which AE is one of the possible clinical presentations. FFI, and consequently AE, is a model for the investigation of the essential role of the thalamus in the organization of body homeostasis, integrating both sleep and autonomic function control.
... A number of variants of CJD have been defined based upon focal neurologic findings reflecting predominant involvement of individual brain regions. Examples of these include forms with mainly visual (Heidenhain variant) [5], cerebellar (Oppenheimer-Brownell variant) [6], and thalamic features [7]. ...
... Similar to symptomatic palatal myoclonus, these movements did not terminate during sleep [17]. In one thalamic subtype of sporadic CJD, severe neuronal loss and gliosis in the olives, not accompanied by spongiosis, has been described [7]. Furthermore, pathological and immunohistochemical analysis has confirmed that the abnormal prion protein is prominently deposited in the inferior olivary nuclei even when there is no associated significant neuronal loss or spongiform changes [18]. ...
A 38-year-old male presented with a three-week history of bilateral lower extremity choreiform movements. History included sleep abnormalities, rushed and unintelligible speech, with delusions two to six months prior to presentation. He also developed mild dysphagia, staring spells, and anterograde amnesia. On examination, he had pressured speech, asynchronous cycling movements of the bilateral lower extremities persisting during sleep, occasional ballistic movements of the upper extremities, and ataxia. Magnetic resonance imaging (MRI) of the brain showed high cortical signal change in bilateral parieto-occipital cortices with evidence of medullary olive hypertrophy bilaterally. Electroencephalography showed generalized slowing without periodic spikes. Cerebrospinal fluid was positive for protein 14-3-3 and real-time quaking-induced conversion. Genetic testing was positive for autosomal dominant prion protein gene (PRNP) genetic mutation. The patient passed away three months after discharge.
This case provides previously undescribed imaging and movement abnormalities in a patient with familial Creutzfeldt-Jakob disease (CJD), and suggests that CJD should not be removed from the differential in patients with these atypical findings.
... Patients sharing clinical and histopathologic features with FFI, without any PRNP mutation or any positive familial history, have been ascribed to the clinical definition of Sporadic Fatal Insomnia (sFI) (Abu-Rumeileh et al., 2018;Montagna et al., 2003), often referred to as the thalamic form of sCJDMM2 (Hayashi et al., 2015;Iwasaki et al., 2017;Moda et al., 2012). ...
... The sFI clinical and histopathologic phenotype appears to be more variable than that of the FFI variant linked to the 129 homozygous genotype (Cracco et al., 2018;Montagna, 2005). Consequently, although many symptoms of sFI overlap with those observed in FFI, insomnia has not been a prominent symptom in many cases of sFI (only 29% of patients at onset) (Puoti et al., 2012), unless specifically investigated (Moda et al., 2012). This is true also for autonomic symptoms, reported only in half of the illustrated cases (Table 2) and in one third of the recently reviewed European patients (Abu-Rumeileh et al., 2018). ...
Fatal Familial Insomnia (FFI) is a hereditary prion disease caused by a mutation at codon 178 of the prion-protein gene leading to a D178N substitution in the protein determining severe and selective atrophy of mediodorsal and anteroventral thalamic nuclei. FFI is characterized by physiological sleep loss, which polygraphically appears to be a slow wave sleep loss, autonomic and motor hyperactivation with peculiar episodes of oneiric stupor.
Alteration of autonomic functions is a great burden for FFI patients consisting in sympathetic overactivation, dysregulation of its physiological responses and disruption of circadian rhythms. The cardiovascular system is the most frequently and severely affected confirming the increased sympathetic drive with preserved parasympathetic responses.
Sleep loss, autonomic and motor hyperactivation define Agrypnia Excitata (AE), which is not exclusive to FFI, but it has been canonically described also in Morvan Syndrome and Delirium Tremens. These three conditions present different pathophysiological mechanisms but share the same thalamo-limbic impairment of which AE is one of the possible clinical presentations.
FFI, and consequently also AE, is a model for the investigation of the essential role of the thalamus in the organization of body homeostasis, integrating both sleep and autonomic function control.
... MM2 sCJD has been further subdivided into MM2-cortical (MM2C) and MM2-thalamic (MM2T) based on where the predominant neuropathological changes are found within the brain. Patients with MM2T (also known as sporadic fatal insomnia) tend to present at a young age with a variety of neurological symptoms, including mental disturbances and progressive insomnia 64 . Thus, MM2T may represent the spontaneous equivalent of FFI. ...
... Heterogeneity in PrP Sc staining patterns within sCJD subtypes is also possible. For example, in a recent publication on MM2T sCJD, one case showed scant PrP Sc immunoreactivity in both the cortex and thalamus, while the other case showed a synaptic PrP Sc pattern with no detectable deposits in the thalamus 64 . A plausible explanation for this heterogeneity would be the existence of distinct prion strains resulting in a variety of histochemical PrP Sc staining patterns. ...
The presence of protein aggregates in the brain is a hallmark of neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). Considerable evidence has revealed that the pathological protein aggregates in many neurodegenerative diseases are able to self-propagate, which may enable pathology to spread from cell-to-cell within the brain. This property is reminiscent of what occurs in prion diseases such as Creutzfeldt-Jakob disease. A widely recognized feature of prion disorders is the existence of distinct strains of prions, which are thought to represent unique protein aggregate structures. A number of recent studies have pointed to the existence of strains of protein aggregates in other, more common neurodegenerative illnesses such as AD, PD, and related disorders. In this review, we outline the pathobiology of prion strains and discuss how the concept of protein aggregate strains may help to explain the heterogeneity inherent to many human neurodegenerative disorders.
... Thus, PK treatment removed all significant differences between the two gradient profiles although minor differences remained in the glycoform ratios ( Fig. 4B and Supplementary Fig. S5). In contrast, when PK digestion was carried out on the whole totPrP Sc preparations before SE (rather than on the individual SE fractions), two distinct although overlapping aggregate populations were observed that involved fractions of lower density (fractions [8][9][10][11][12][13][14][15][16][17][18] in sFI than in sCJDMM2 (12)(13)(14)(15)(16)(17)(18)(19)(20)(21) (Supplementary Fig. S6). ...
... Thus, PK treatment removed all significant differences between the two gradient profiles although minor differences remained in the glycoform ratios ( Fig. 4B and Supplementary Fig. S5). In contrast, when PK digestion was carried out on the whole totPrP Sc preparations before SE (rather than on the individual SE fractions), two distinct although overlapping aggregate populations were observed that involved fractions of lower density (fractions [8][9][10][11][12][13][14][15][16][17][18] in sFI than in sCJDMM2 (12)(13)(14)(15)(16)(17)(18)(19)(20)(21) (Supplementary Fig. S6). ...
In most human sporadic prion diseases the phenotype is consistently associated with specific pairings of the genotype at codon 129 of the prion protein gene and conformational properties of the scrapie PrP (PrPSc) grossly identified types 1 and 2. This association suggests that the 129 genotype favours the selection of a distinct strain that in turn determines the phenotype. However, this mechanism cannot play a role in the phenotype determination of sporadic fatal insomnia (sFI) and a subtype of sporadic Creutzfeldt-Jakob disease (sCJD) identified as sCJDMM2, which share 129 MM genotype and PrPSc type 2 but are associated with quite distinct phenotypes. Our detailed comparative study of the PrPSc conformers has revealed major differences between the two diseases, which preferentially involve the PrPSc component that is sensitive to digestion with proteases (senPrPSc) and to a lesser extent the resistant component (resPrPSc). We conclude that these variations are consistent with two distinct strains in sFI and sCJDMM2, and that the rarer sFI is the result of a variant strain selection pathway that might be favoured by a different brain site of initial PrPSc formation in the two diseases.
... Previous studies have suggested that thalamic involvement is a diagnostic feature of variant CJD (vCJD) (Zeidler et al., 2000), and thalamic involvement has also been occasionally reported in the MM2 thalamic form of sCJD (Hirose et al., 2006;Moda et al., 2012). In addition, one case of VV2 type sCJD also reported changes in the thalamus (Fukushima et al., 2004). ...
Background
Pathogenic prion protein may start to deposit in some brain regions and cause functional alterations in the asymptomatic stages in Creutzfeldt–Jakob disease patients. However, the disease trajectory of Creutzfeldt–Jakob disease in the asymptomatic stage and when and where the degenerative process begins are still not clear.
Methods
At baseline, we enrolled five asymptomatic mutation carriers, six affected genetic Creutzfeldt–Jakob diseasepatients, and 23 healthy controls from whom ¹⁸ F fluorodeoxyglucose‐positron emission tomography, clinical, and neuropsychological measures were acquired. Only five asymptomatic mutation carriers had completed longitudinal follow‐up. We set three‐time points to identify the changing trajectory in asymptomatic carriers group including baseline, 2‐year and 4‐year follow‐up.
Results
At baseline, the cerebral glucose metabolic rate, measured as the standardized uptake value rate ratio, clinical and neuropsychological scales in all 5 asymptomatic cases were normal. In the 4‐years follow‐up, hypometabolic brain regions in asymptomatic genetic Creutzfeldt–Jakob disease group were found in the insula, frontal, parietal, and temporal lobes (false discovery rate corrected p<0.01). The standardized uptake value rate ratio changing trajectories of all asymptomatic cases were within the range between the healthy controls and affected patients. Notably, the metabolism values of one asymptomatic individual whose baseline age was older than the expected age of onset showed a rapid decline and approached the mean value of genetic Creutzfeldt–Jakob disease condition at the last follow‐up.
Conclusion
Our study illustrates that neurodegenerative process associated with genetic Creutzfeldt–Jakob disease may involve the insula, frontal, temporal, and parietal lobes before clinical presentation of the disease, and the decline will accelerate when close to the expected age of onset. Although there are no effective means to cure this fatal disease, the time interval before clinical disease onset may aid important trials or therapies intended to slow or halt the disease process.
... Previous studies have suggested that thalamic involvement is a diagnostic feature of variant CJD (vCJD) (Zeidler et al., 2000), and thalamic involvement has also been occasionally reported in the MM2 thalamic form of sCJD (Hirose et al., 2006;Moda et al., 2012). In addition, one case of VV2 type sCJD also reported changes in the thalamus (Fukushima et al., 2004). ...
Background
Insomnia and thalamic involvement are hallmarks of fatal familial insomnia; however, it was occasionally reported that genetic E200K Creutzfeldt‐Jakob disease (CJD) patients had also manifested thalamic‐insomnia phenotype. The study aimed to explore the clinical and neuroimage characteristics of genetic E200K CJD by comprehensive neuroimage analysis.
Methods
Six genetic CJD patients carried Glu to Lys change at codon 200 (E200K) mutations on prion protein gene (PRNP), thirteen sporadic CJD (sCJD), and twenty‐two age‐ and sex‐matched normal controls were enrolled in the study. All participants completed hybrid positron emission tomography/ magnetic resonance imaging (PET/MRI) examinations. The high signal was visually inspected on diffusion weighted imaging (DWI) sequence. ¹⁸ F‐fluorodeoxyglucose positron emission tomography (18F‐FDG‐PET) and structural images were quantitively analyzed by statistically parameter mapping (SPM). Clinical and image characteristics are compared between genetic E200K CJD patients and sporadic CJD patients.
Results
There was no group difference in age (49.0±7.1 versus 55.0±4.9 versus 52.7±7.3, p = 0.193) and gender (3/3 versus 4/9 versus 11/11, p = 0.513) between genetic E200K CJD, sCJD, and normal controls. Insomnia was the main complaint in the genetic E200K CJD patients’ group (4/2 versus 1/12, p = 0.007). Hyperintensity, hypometabolism but not predominant atrophy of the thalamus was found by visual inspection in genetic E200K CJD patients. A decreased trend was found on gray matter volume (uncorrected p<0.0001) and metabolism (FWE corrected) of the thalamus in genetic E200K patients.
Conclusion
The clinical and image characteristics of genetic E200K CJD mimic fatal familial insomnia, manifested as a thalamic‐insomnia phenotype, indicating some specific underlying pathological changes might exist in E200K mutations. PET measurement is a sensitive approach to help identify the functional changes of the thalamus in prion disease.
... MM2-type sCJD is the less frequent sCJD type with atypical phenotypes, which consists of two subtypes designated as MM2cortical (MM2C) and MM2-thalamic (MM2T) based on distinctive pathologic a l features 2, 3 . The MM2T-type sCJD is also known as sporadic fatal insomnia (sFI) because it shares strong clinical and neuropathological parallels with fatal familia l insomnia (FFI), a hereditary prion disease linked to a D178N mutation coupled with methionine substitution at codon 129 in the PRNP [4][5][6] . Both diseases primar ily characterized by progressive sleep-related symptoms, neuropsychiatric symptoms, and disturbances in the autonomic nervous system due to severe neuronal loss and atrophy in thalamic nuclei and the inferior olivary nucleus and harbor resPrPTSE type 2, an abnormal protease-resistant disease-associated prion protein isoform with a relative mass of 19 kDa 7 . ...
Objective:
To elucidate the clinical profile of sporadic fatal insomnia (sFI), assess the similarities and differences between sFI and fatal familial insomnia (FFI), and evaluate the influence of ethnicity on the phenotype of sFI patients.
Methods:
The data of sFI and FFI patients was retrieved from our case series and through literature review. The clinical and diagnostic features of sFI and FFI were compared, as were the phenotypes of Asian and Caucasian sFI patients.
Results:
We identified 44 sFI and 157 FFI cases. The prevalence of sleep-related, neuropsychiatric and autonomic symptoms among the sFI patients were 65.9%, 100.0% and 43.2% respectively. Compared to FFI, sFI exhibited longer disease duration and a higher proportion of neuropsychiatric symptoms, while FFI was characterized by a higher incidence of sleep-related and autonomic symptoms in the early stages of the disease or throughout its course. In addition, a higher proportion of the sFI patients showed hyperintensity on MRI and PSWCs on EEG compared to the FFI patients, especially those presenting with pathological changes associated with MM2-cortical type sCJD. The Asian sFI patients had a higher proportion of males and positivity for CSF 14-3-3 protein, and fewer sleep-related symptoms compared to Caucasian sFI patients. The age of onset and duration of sFI differed between ethnic groups, but failed to reach statistical significance.
Conclusions:
Despite its similarities to FFI, sFI is characterized by longer disease duration, higher proportion of neuropsychiatric symptoms and hyperintensity on MRI, along with differences in the clinical characteristics based on ethnicity.
... Even in CJD, type 1 and type 2 PrP Sc are biochemically characterized [75]. sCJD can develop using six genotype/PrP Sc combinations (MM1, MM2, MV1, MV2, VV1, and VV2) and result in five major strains of sCJD: MM1/MV1, MV2/VV2, MM2 cortical (MM2c), MM2 thalamic (MM2t), and VV1 [76][77][78][79]. These variations probably influence their individual resistance. ...
Prions, which cause transmissible spongiform encephalopathies (TSEs), are a notorious group of infectious agents with possibly the highest resistance to complete inactivation. Although various gas plasma instruments have been developed, studies on prion inactivation using gas plasma instruments are limited. Among them, the hydrogen peroxide gas plasma instrument, STERRAD® (Advanced Sterilization Products; ASP, Johnson & Johnson, Irvine, CA, USA), is recommended for prion inactivation of heat-sensitive medical devices. However, STERRAD® is not a plasma sterilizer but a hydrogen peroxide gas sterilizer. In STERRAD®, plasma generated by radio frequency (RF) discharge removes excess hydrogen peroxide gas and does not contribute to sterilization. This is also supported by evidence that the instrument was not affected by the presence or absence of RF gas plasma. However, recent studies have shown that other gas plasma instruments derived from air, nitrogen, oxygen, Ar, and a mixture of gases using corona, dielectric barrier, microwave, and pulse discharges can inactivate scrapie prions. As inactivation studies on prions other than scrapie are limited, further accumulation of evidence on the effectiveness of gas plasma using human-derived prion samples is warranted for practical purposes.
... Clinicamente os pacientes apresentam deterioração neurológica e cognitiva, com comprometimento grave do sono, diplopia transitória e disfunção cerebelar, seguida de disautonomia, coma e morte. Para distinguir de sua forma familiar observa-se a ausência de histórico familiar e mutação no códon 178 (D178N) (Mehta et al., 2008;Moda et al., 2012). ...
As doenças priônicas (DPr) humanos são um grupo de doenças neurodegenerativas progressivas, incuráveis e fatais causadas por um agente infeccioso proteico (PrP), capaz de propagar a doença alterando a estrutura conformacional de proteínas, as quais sofrem agregação e depósito no tecido neuronal. Devido ao potencial neurodegenerativo desta doença, bem como a um aumento global de casos, o objetivo do nosso artigo é revisar o conhecimento atual sobre DPr humanas e analisar a situação epidemiológica dessas doenças, no Brasil nos últimos 17 anos. Sabemos, que existem diferentes tipos de DPr com diferenças relacionadas a sua forma de transmissão/manifestação, neuropatologia e manifestações clínicas e que os príons consistem em PrPSc a forma patológica agregada da proteína priônica celular PrPc. Apesar dos mecanismos envolvidos na neurodegeneração não estarem totalmente descritos, sabemos que envolvem múltiplos processos operando simultânea e sinergicamente no cérebro, incluindo degeneração espongiforme, alterações sinápticas, inflamação cerebral, morte neuronal e acúmulo de agregados proteicos. No Brasil, as DPr tornaram-se doenças de notificação compulsória ao Sistema de Informação de Agravos de Notificação (SINAN) a partir de 2005, sendo confirmados até 2020 mais de 400 casos de DPr, com aumento significativo de casos a partir do ano de 2012, principalmente nos estados de São Paulo, Minas Gerais e Paraná, provavelmente pela maior capacidade de diagnóstico destes estados. Dessa forma, uma compreensão mais abrangente destas doenças e sua epidemiologia pode ajudar no diagnóstico precoce e desenvolvimento de terapias muito necessárias para estas doenças devastadoras.
... Previous studies have suggested that thalamic involvement is a diagnostic feature of variant CJD (vCJD) (Zeidler et al., 2000), and thalamic involvement has also been occasionally reported in the MM2 thalamic form of sCJD (Hirose et al., 2006;Moda et al., 2012). In addition, one case of VV2 type sCJD also reported changes in the thalamus (Fukushima et al., 2004). ...
Background:
Insomnia and thalamic involvement were frequently reported in patients with genetic Creutzfeldt-Jakob disease (gCJD) with E200K mutations, suggesting E200K might have discrepancy with typical sporadic CJD (sCJD). The study aimed to explore the clinical and neuroimage characteristics of genetic E200K CJD patients by comprehensive neuroimage analysis.
Methods:
Six patients with gCJD carried E200K mutation on Prion Protein (PRNP) gene, 13 patients with sporadic CJD, and 22 age- and sex-matched normal controls were enrolled in the study. All participants completed a hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) examination. Signal intensity on diffusion-weighted imaging (DWI) and metabolism on PET were visually rating analyzed, statistical parameter mapping analysis was performed on PET and 3D-T1 images. Clinical and imaging characteristics were compared between the E200K, sCJD, and control groups.
Results:
There was no group difference in age or gender among the E200K, sCJD, and control groups. Insomnia was a primary complaint in patients with E200K gCJD (4/2 versus 1/12, p = 0.007). Hyperintensity on DWI and hypometabolism on PET of the thalamus were observed during visual rating analysis of images in patients with E200K gCJD. Gray matter atrophy (uncorrected p < 0.001) and hypometabolism (uncorrected p < 0.001) of the thalamus were more pronounced in patients with E200K gCJD.
Conclusion:
The clinical and imaging characteristics of patients with gCJD with PRNP E200K mutations manifested as a thalamic-insomnia phenotype. PET is a sensitive approach to help identify the functional changes in the thalamus in prion disease.
... Therefore, this case can be used to expand our understanding of the characteristics of the sCJDMM2T/sFI, sCJDMM2C, and sCJDMM1 subtypes ( sCJDMM2T/sFI sFI (the thalamic form of CJD) is the most rare type of sporadic prion disease. 9 The symptoms of sFI overlap with those of FFI. 6 However, insomnia is not evident in most sFI cases, unless the patients and family members are surveyed for sleep disorders 10 (Table 1). Neuroimaging findings of sFI are similar to FFI, while most sFI cases do not exhibit typical MRI features of sCJD, 11 with DWI showing hyperintensity in approximately 8% cases. ...
Qingqing Sun, Pingping Shen, Jiayi Tang, Hongmei Meng, Jiachun Feng, Zan Wang, Li Cui Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, People’s Republic of ChinaCorrespondence: Zan Wang; Li Cui Email wangzan@jlu.edu.cn; wangzanprof@163.com; lcui@jlu.edu.cnAbstract: Creutzfeldt–Jakob disease (CJD) subtypes are difficult to identify due to the heterogeneity of the clinical phenotype, and early accurate identification of sporadic CJD (sCJD) subtypes aids prognosis prediction. Currently, the diagnosis of sCJD subtypes is mainly based on brain tissue biopsy or autopsy. In this report, we present a case of confirmed sCJD initially presenting as insomnia. We described detailed information including clinical, electroencephalographic, polysomnographic, positron emission tomography-computed tomographic and other neuroimaging findings, cerebrospinal fluid biomarkers, skin tissue biopsy and whole blood PRNP gene sequencing in this patient. An extensive literature search was performed in order to better understand the diagnosis of various sCJD subtypes, particularly the thalamic form, sCJDMM2 (also known as sporadic fatal insomnia). Our study highlights sporadic fatal insomnia as a differential diagnosis of sCJD.Keywords: sporadic Creutzfeldt–Jakob disease, sporadic fatal insomnia, sCJDMM, polysomnography, PET
... Given that prions are not known to contain nucleic acids, these properties must be encoded in the higherorder aggregate structure. Indeed, prions exist in distinct conformational variants, known as strains, whose properties can be serially transmitted and reproduced in animal models of disease and also in human infection [6,8,9]. Furthermore, human sporadic prion disease strains can also be reproduced by the in vitro prion amplification technique protein misfolding cyclic amplification (PMCA), where prions are propagated in the presence of brain homogenate [10]. ...
Despite being caused by a single protein, prion diseases are strikingly heterogenous. Individual prion variants, known as strains, possess distinct biochemical properties, form aggregates with characteristic morphologies and preferentially seed certain brain regions, causing markedly different disease phenotypes. Strain diversity is determined by protein structure, post-translational modifications and the presence of extracellular matrix components, with single amino acid substitutions or altered protein glycosylation exerting dramatic effects. Here, we review recent advances in the study of prion strains and discuss how a deeper knowledge of the molecular origins of strain heterogeneity is providing a foundation for the development of anti-prion therapeutics.
... Our data resemble those recently described in a transmission study employing the same Tg129M mouse line as in our study [12]. These findings confirm the incompetence of human PrP C -129M to reproduce -VV2 T2 [12,24] as opposed to the faithful transmission of -MM2 to Tg129M mice [30,34]. ...
Current classifications of sporadic Creutzfeldt–Jakob disease (sCJD) identify five subtypes associated with different disease phenotypes. Most of these histopathological phenotypes (histotypes) co-distribute with distinct pairings of methionine (M)/valine (V) genotypes at codon 129 of the prion protein (PrP) gene and the type (1 or 2) of the disease-associated PrP (PrP D ). Types 1 and 2 are defined by the molecular mass (~ 21 kDa and ~ 19 kDa, respectively) of the unglycosylated isoform of the proteinase K-resistant PrP D (resPrP D ). We recently reported that the sCJDVV1 subtype (129VV homozygosity paired with PrP D type 1, T1) shows an electrophoretic profile where the resPrP D unglycosylated isoform is characterized by either one of two single bands of ~ 20 kDa (T1 ²⁰ ) and ~ 21 kDa (T1 ²¹ ), or a doublet of ~ 21–20 kDa (T1 ²¹⁻²⁰ ). We also showed that T1 ²⁰ and T1 ²¹ in sCJDVV have different conformational features but are associated with indistinguishable histotypes. The presence of three distinct molecular profiles of T1 is unique and raises the issue as to whether T1 ²⁰ and T1 ²¹ represent distinct prion strains. To answer this question, brain homogenates from sCJDVV cases harboring each of the three resPrP D profiles, were inoculated to transgenic (Tg) mice expressing the human PrP-129M or PrP-129V genotypes. We found that T1 ²⁰ and T1 ²¹ were faithfully replicated in Tg129V mice. Electrophoretic profile and incubation period of mice challenged with T1 ²¹⁻²⁰ resembled those of mice inoculated with T1 ²¹ and T1 ²⁰ , respectively. As in sCJDVV1, Tg129V mice challenged with T1 ²¹ and T1 ²⁰ generated virtually undistinguishable histotypes. In Tg129M mice, T1 ²¹ was not replicated while T1 ²⁰ and T1 ²¹⁻²⁰ generated a ~ 21–20 kDa doublet after lengthier incubation periods. On second passage, Tg129M mice incubation periods and regional PrP accumulation significantly differed in T1 ²⁰ and T1 ²¹⁻²⁰ challenged mice. Combined, these data indicate that T1 ²¹ and T1 ²⁰ resPrP D represent distinct human prion strains associated with partially overlapping histotypes.
... Clinical features are: a longer disease duration (average 24 months); insomnia and autonomic dysfunction accompanied by classical CJD symptoms and significantly disrupted sleep architecture on EEG. Pathology is maximal in the thalamus; the characteristic findings are severe gliosis and neuronal loss 193 ; again these neuropathology findings are similar to what is seen in patients with FFI. PrP Sc is present but to a lesser extent than that seen in the more usual MM2 ...
Future therapeutic trials in human prion disease will require the use of biomarkers of disease activity such as MRI in order to assess efficacy of treatment. Whilst the development of biomarkers is of importance it is also necessary to be able to understand and interpret what imaging findings characterise at post-mortem and furthermore how they correlate with clinical symptoms. In this thesis I investigate whether both conventional and quantitative imaging parameters can act as biomarkers to predict disease progression in symptomatic patients. I also assess what conventional MRI findings represent on a microstructural level and how imaging findings correlate with clinical symptoms of prion disease such as sleep disturbance. This work is detailed in four projects, the first of which I investigate if abnormalities found on conventional MRI brain scans, PRNP genotype and prion strain can act as predictors of disease progression in patients with the sporadic form of prion disease. I was unable to show that conventional MR brain imaging helps to predict disease progression in this patient group, but I was able to show that codon 129 remains the main predictor of disease progression and strain subtype has an additional effect. In the second project I test the hypothesis that MTR, a quantitative imaging parameter can predict disease progression in symptomatic patients. I found that both on cross-sectional and longitudinal analysis there were significant differences in symptomatic patients and that there was a strong correlation with the MRC Scale score, clinical outcome measure, and MTR value in patients with symptomatic disease which could be used as a clinical biomarker in combination to predict response to therapeutics in future clinical trials. In the third project I focus on investigating the prevalence of sleep disturbance and its association with other features of disease and imaging findings. I found that sleep disturbance was highly prevalent in all forms of prion disease. I also found that there was a significant association found between thalamic signal change seen on MRI scan and sleep symptomatology. In order to capture more data on the diversity of sleep symptoms in this population I constructed the Prion Disease Sleep Questionnaire a bedside screening tool that can be used to both record and monitor the incidence and severity of sleep disturbance. In the final project I assess if specific histopathological findings on post-mortem correlate with cortical imaging abnormalities seen on DWI in patients diagnosed with sporadic CJD. I found that there were significant difference between patients with and without cortical ribboning present on their MRI brain scans those with DWI signal change had more frontal cortex spongiosis than those that didn’t. There was also a modest correlation identified between the 3 histopathological parameters: PrPSc, deposition, gliosis and spongiosis.
... Two major types of PrP Sc in human prion diseases have been biochemically characterized, type 1 and type 2 PrP Sc in CJD [35], which may vary in resistance. Sporadic CJD can develop with six genotype/PrP Sc combinations (MM1, MM2, MV1, MV2, VV1, and VV2), resulting in five major strains of sporadic CJD, namely, MM1/MV1, MV2/VV2, MM2 cortical (MM2c), MM2 thalamic (MM2t), and VV1 [36][37][38][39]. Nonetheless, VHP has been shown to be equally effective in vitro against five different strains of prions from human, cattle, hamster, and mouse [40]. ...
To date, there have been no studies on the sterilization of prions by non-concentrated and concentrated vaporized hydrogen peroxide (VHP) applied by the same instrument. Here, the effect of the two types of VHP applied using an ES-700 sterilizer on prions was investigated. Brain homogenate from scrapie (Chandler) prion-infected mice was spotted on a cover glass and subjected to ES-700 treatment in soft (non-concentrated VHP from 59% hydrogen peroxide) or standard (concentrated VHP from 80% hydrogen peroxide) mode. Proteinase K-resistant prion protein (PrPres), an indicator of the abnormal isoform of prion protein (PrP Sc), was reduced by ES-700 treatment under several conditions: SFT1/4 (soft mode, quarter cycle), SFT1/2 (soft mode, half cycle), SFT1 (soft mode, full cycle), and STD1/2 (standard mode, half cycle). PrPres was detected after the first and second rounds of protein misfolding cyclic amplification (PMCA) of untreated samples, but was undetectable in SFT1/4, SFT1/2, SFT1, and STD1/2 treated samples. In a mouse bioassay, SFT1/2 and STD1/2 treatment of prions significantly prolonged survival time, suggesting that prion infectivity is reduced after ES-700 treatment. In summary, both non-concentrated and concentrated VHP inactivate prions and may be useful for the low-temperature sterilization of prion-contaminated medical devices.
... Second, MM2 was associated with two quite distinct phenotypes: one with sCJD-like features including severe spongiform degeneration (SD) of the cerebral cortex, named sCJDMM2 (or MM2C for cortical), and the other, very rare, characterized by insomnia and severe thalamic atrophy that is commonly referred to as sporadic fatal insomnia (sFI or MM2T for thalamic) [8]. Specific variations of PrP D as well as distinct transmission characteristics indicate that MM2 and sFI are associated with distinct prion strains [3,9,19,26]. ...
Abstract One of remarkable features of sporadic Creutzfeldt-Jakob disease (sCJD) is the great phenotypic variability. Understanding the molecular basis of this variability has important implications for the development of therapeutic approaches. It is well established that, in many cases, phenotypic heterogeneity of sCJD is under control of two determinants: the genotype at the methionine (M)/valine (V) polymorphic codon 129 of the human prion protein gene and the type, 1 or 2, of the pathogenic and disease-related form of the prion protein, PrPD. However, this scenario fails to explain the existence of distinct heterozygous sCJDMV2 subtypes, where heterogeneity occurs without any variation of the 129 allotype and PrPD type. One of these subtypes, denoted sCJDMV2C, associated with PrPD type 2, is characterized by widespread spongiform degeneration of the cerebral cortex (C). The second variant, denoted sCJDMV2K, features prominent deposition of PrPD amyloid forming kuru type (K) plaques. Here we used a mass spectrometry based approach to test the hypothesis that phenotypic variability within the sCJDMV2 subtype is at least partly determined by the abundance of 129 M and 129 V polymorphic forms of proteinase K-resistant PrPD (resPrPD). Consistent with this hypothesis, our data demonstrated a strong correlation of the MV2C and MV2K phenotypes with the relative populations of protease-resistant forms of the pathogenic prion proteins, resPrPD-129 M and resPrPD-129 V, where resPrPD-129 M dominated in the sCJDMV2C variant and resPrPD-129 V in the sCJDMV2K variant. This finding suggests an important, previously unrecognized mechanism for phenotypic determination in human prion diseases.
... MM2C was later shown to be transmissible to mice that overexpress human PrP (17). An additional prion strain was identified on the basis of the transmission of one MM2 thalamic case in Met 129 human PrP mice (28). Considering the relative variability in terms of prion strain content that we observed within the MM/MV1 and VV/MV2 isolates assessed here, it is difficult to reconcile that strain typing by bioassay of a single isolate could provide a reliable reflection of the diversity of prions associated with a particular sCJD clinicopathological phenotype. ...
sCJD occurrence is currently assumed to result from spontaneous and stochastic formation of a misfolded PrP nucleus in the brains of affected patients. This original nucleus then recruits and converts nascent PrP C into PrP Sc , leading to the propagation of prions in the patient’s brain. Our study demonstrates the coexistence of two prion strains in the brains of a majority of the 23 sCJD patients investigated. The relative proportion of these sCJD strains varied both between patients and between brain areas in a single patient. These findings strongly support the view that the replication of an sCJD prion strain in the brain of a patient can result in the propagation of different prion strain subpopulations. Beyond its conceptual importance for our understanding of prion strain properties and evolution, the sCJD strain mixture phenomenon and its frequency among patients have important implications for the development of therapeutic strategies for prion diseases.
... The pure molecular sCJD subtypes were found to correspond to 5 different PrP Sc strains: M1, M2C, M2T, V1, and V2, which, when coupled with a host's genotype, are consid-ered to explain the heterogenous clinical and neuropathological presentation of CJDs (15,(18)(19)(20)(21). ...
The purpose of this study was to perform an updated reclassification of all definite prion disease cases with available fresh-frozen samples referred to the Danish Reference Center over the past 40 years, putting a special emphasis on the molecular characterization of novel disease subtypes. Investigation of the Danish prion diseases cohort revealed rare sporadic Creutzfeldt-Jakob disease cases with mixed subtypes and subtypes with previously uncharacterized white matter plaques, a new case of sporadic fatal insomnia, and 3 novel mutations, including 2 large octapeptide repeat insertions, and a point mutation in the prion protein gene. The evaluation of methionine and valine distribution at codon 129 among the prion disease patients in the cohort revealed the increased prevalence of methionine homozygotes compared to the general population. This observation was in line with the prevalence reported in other Caucasian prion disease cohort studies. Reclassification of the old prion diseases cohort revealed unique cases, the molecular characterization of which improves prion diseases classification, diagnostic accuracy, genetic counseling of affected families, and the understanding of disease biology.
... Based on more recent transmission studies and PrP genotypes, five major strains of sCJD including MM1/MV1, MV2/VV2. MM2 cortical (MM2c), MM2 thalamic (MM2t), and VV1 have been proposed (Parch et al., 2010, 2012Bishop et al., 2010Moda et al., 2012). It should be noted that all the sporadic and acquired human prion diseases have been transmitted to laboratory animals, although this is not the case for all of the inherited forms (Asante et al., 2013). ...
Incidences of iatrogenic Creutzfeldt-Jakob disease (iCJD) are caused by transplantation of prion-contaminated hormones, cornea and dura mater as well as contact with prion- contaminated medical devices, such as stereotactic electrodes, used in neurosurgery. Because prions are highly resistant and difficult to inactivate, prion contamination is a severe risk when medical instruments are reused after surgical procedures involving suspicious and confirmed cases of patients with prion diseases. Therefore, when high-risk procedures such as cerebral surgery, craniotomy surgery, orthopaedic spinal surgery and ophthalmic surgery are performed for high-risk patients or individuals with prion diseases, it is neces- sary to appropriately treat the medical devices using scientifically proven prion inactivation methods. In this chapter, we introduce fundamental aspects of prion inactivation methods, looking specifically at the practical issues involved in their implementation.
... These sCJD biochemical subtypes are defined by the genotype at PRNP polymorphic codon 129 (encoding methionine [M] or valine [V]) in combination with the molecular weight of the unglycosylated PrP res found in brain tissue samples and scored by western blot (WB) with an anti-PrP monoclonal antibody [6,7] (Type 1 = 19 kDa, Type 2 = 21 kDa). Animal studies have shown that these six sCJD subtypes comprise four major human strains of prions (M1, M2, V1, V2) as defined by the length of incubation time, susceptibility and disease phenotype in selected inbred strains of mice as well as the conservation of characteristic neuropathological lesion patterns upon serial passage in the same host [8,9]. ...
Sporadic Creutzfeldt-Jakob disease (sCJD) is a transmissible, rapidly progressive and fatal neurodegenerative disease. The transmissible agent linked to sCJD is composed of the misfolded form of the host-encoded prion protein. The combination of histopathological and biochemical analyses has allowed the identification and sub-classification of six sCJD subtypes. This classification depends on the polymorphic variability of codon 129 of the prion protein gene and the PrPres isotype, and appears to be associated with neuropathological and clinical features. Currently, sCJD subtyping is only fully achievable post mortem. However, a rapid and non-invasive method for discriminating sCJD subtypes in vita would be invaluable for the clinical management of affected individuals, and for the selection of participants for clinical trials. The CSF analysis by Real Time Quaking Induced Conversion (RT-QuIC) reaction is the most sensitive and specific ante mortem sCJD diagnostic test available to date, and it is used by a number of laboratories internationally. RT-QuIC takes advantage of the natural replication mechanisms of prions by template-induced misfolding, employing recombinant prion protein as reaction substrate. We asked whether epitope mapping, of the RT-QuIC reaction products obtained from seeding RT-QuIC with brain and CSF samples from each of the six molecular subtypes of sCJD could be employed to distinguish them and therefore achieve in vita sCJD molecular subtyping. We found that it is possible to distinguish the RT-QuIC products generated by sCJD biological samples from the ones generated by spontaneous conversion in the negative controls, but that different sCJD subtypes generate very similar, if not identical RT-QuIC reaction products. We concluded that whilst RT-QuIC has demonstrable diagnostic value it has limited prognostic value at this point in time.
... Transmission properties of the six sCJD subgroups also have been examined systematically, and five prion strains have been recognized based on the distinctive transmission properties, namely M1 (sCJD-MM/MV1), M2C (sCJD-MM2C), M2T (sCJD-MM2T), V1 (sCJD-VV1), or V2 (sCJD-VV2 and -MV2) strain. 6,7 Co-occurrence of different prion strains in the same brain is possible and results in the presentation of mixed neuropathologic features and more than one PrP Sc type. 3,8e12 The most frequently observed mixed subgroup is co-occurrence of M1 and M2C prion strains (ie, sCJD-MM/MV1þ2C), which accounts for 26% of the total sCJD cases. ...
Six subgroups of sporadic Creutzfeldt-Jakob disease have been identified by distinctive clinicopathologic features, genotype at polymorphic codon 129 [methionine (M)/valine (V)] of the PRNP gene, and type of abnormal prion proteins (type 1 or 2). In addition to the pure subgroups, mixed neuropathologic features and the coexistence of two types of abnormal prion proteins in the same patient also have been reported. Here, we found that a portion of the patients previously diagnosed as MM1 had neuropathologic characteristics of the MM2 thalamic form (ie, neuronal loss of the inferior olivary nucleus of the medulla). Furthermore, coexistence of biochemical features of the MM2 thalamic form also was confirmed in the identified cases. In addition, in transmission experiments using prion protein–humanized mice, the brain material from the identified case showed weak infectivity and generated characteristic abnormal prion proteins in the inoculated mice resembling those after inoculation with brain material of MM2 thalamic form. Taken together, these results show that the co-occurrence of MM1 and MM2 thalamic form is a novel entity of sporadic Creutzfeldt-Jakob disease prion strain co-occurrence. The present study raises the possibility that the co-occurrence of the MM2 thalamic form might have been overlooked so far because of the scarcity of abnormal prion protein accumulation and restricted neuropathology.
... Based on more recent transmission studies and PrP genotypes, five major strains of sCJD including MM1/MV1, MV2/VV2. MM2 cortical (MM2c), MM2 thalamic (MM2t), and VV1 have been proposed (Parch et al., 2010, 2012Bishop et al., 2010Moda et al., 2012). It should be noted that all the sporadic and acquired human prion diseases have been transmitted to laboratory animals, although this is not the case for all of the inherited forms (Asante et al., 2013). ...
... Five out of six of these major sCJD variants were shown to propagate in syngeneic hosts as distinct prion strains [2,17,23]. These are defined as natural isolates of infectious prions characterized by distinctive clinical and neuropathological features, which are faithfully recapitulated upon serial passage within the same host genotype [3,4]. ...
Amyloid plaques formed by abnormal prion protein (PrPSc) aggregates occur with low frequency in Creutzfeldt-Jakob disease, but represent a pathological hallmark of three relatively rare disease histotypes, namely variant CJD, sporadic CJDMV2K (methionine/valine at PRNP codon 129, PrPSc type 2 and kuru-type amyloid plaques) and iatrogenic CJDMMiK (MM at codon 129, PrPSc of intermediate type and kuru plaques). According to recent studies, however, PrP-amyloid plaques involving the subcortical and deep nuclei white matter may also rarely occur in CJDMM1 (MM at codon 129 and PrPSc type 1), the most common CJD histotype.
To further characterize the phenotype of atypical CJDMM1 with white matter plaques (p-CJDMM1) and unravel the basis of amyloid plaque formation in such cases, we compared clinical and histopathological features and PrPSc physico-chemical properties between 5 p-CJDMM1 and 8 typical CJDMM1 brains lacking plaques. Furthermore, transmission properties after bioassay in two genetic lines of bank voles were also explored in the two groups.
All 5 p-CJDMM1 cases had a disease duration longer than one year. Three cases were classified as sporadic CJDMM1, one as sporadic CJDMM1 + 2C and one as genetic CJDE200K-MM1. Molecular mass, protease sensitivity and thermo-solubilization of PrPSc aggregates did not differ between p-CJDMM1 and classical CJDMM1 cases. Likewise, transmission properties such as incubation time, lesion profile and PrPSc properties in bank voles also matched in the two groups.
The present data further define the clinical-pathologic phenotype of p-CJDMM1, definitely establish it as a distinctive CJD histotype and demonstrate that PrP-plaque formation in this histotype is not a strain-specific feature. Since cases lacking amyloid plaques may also manifest a prolonged (i.e. > than one year) disease course, unidentified, host-specific factors likely play a significant role, in addition to disease duration, in generating white matter PrP-amyloid plaques in p-CJDMM1.
Electronic supplementary material
The online version of this article (10.1186/s40478-017-0496-7) contains supplementary material, which is available to authorized users.
... Specifically, current evidence indicate that five out of six sCJD subtypes (MM1, MM2C, MM2T, VV1 and VV2) behave as distinct prion strains after serial transmission into animal models. As the only exception, the VV2 and MV2K variants showed the same transmission properties, indicating a host-genotype (codon 129) effect [12][13][14][15] . ...
An early and accurate in vivo diagnosis of rapidly progressive dementia remains challenging, despite its critical importance for the outcome of treatable forms, and the formulation of prognosis. Real-Time Quaking-Induced Conversion (RT-QuIC) is an in vitro assay that, for the first time, specifically discriminates patients with prion disease. Here, using cerebrospinal fluid (CSF) samples from 239 patients with definite or probable prion disease and 100 patients with a definite alternative diagnosis, we compared the performance of the first (PQ-CSF) and second generation (IQ-CSF) RT-QuIC assays, and investigated the diagnostic value of IQ-CSF across the broad spectrum of human prions. Our results confirm the high sensitivity of IQ-CSF for detecting human prions with a sub-optimal sensitivity for the sporadic CJD subtypes MM2C and MM2T, and a low sensitivity limited to variant CJD, Gerstmann-Sträussler-Scheinker syndrome and fatal familial insomnia. While we found no difference in specificity between PQ-CSF and IQ-CSF, the latter showed a significant improvement in sensitivity, allowing prion detection in about 80% of PQ-CSF negative CJD samples. Our results strongly support the implementation of IQ-CSF in clinical practice. By rapidly confirming or excluding CJD with high accuracy the assay is expected to improve the outcome for patients and their enrollment in therapeutic trials.
... Distinct human prion strains, such as sCJD, vCJD, kuru, iCJD, VPSPr and sporadic Fatal Insomnia, not only differ in their biochemical and neuropathological patterns, but also have characteristic transmission and propagation properties which have been extensively studied in transgenic humanised mouse models [3,18,19,90,111,122,129,183,186]. The knowledge gained through these studies is important particularly from a public health point of view, as this can help identifying and characterising the origins of any new atypical strains. ...
The understanding of the pathogenesis and mechanisms of diseases requires a multidisciplinary approach, involving clinical observation, correlation to pathological processes, and modelling of disease mechanisms. It is an inherent challenge, and arguably impossible to generate model systems that can faithfully recapitulate all aspects of human disease. It is, therefore, important to be aware of the potentials and also the limitations of specific model systems. Model systems are usually designed to recapitulate only specific aspects of the disease, such as a pathological phenotype, a pathomechanism, or to test a hypothesis. Here, we evaluate and discuss model systems that were generated to understand clinical, pathological, genetic, biochemical, and epidemiological aspects of prion diseases. Whilst clinical research and studies on human tissue are an essential component of prion research, much of the understanding of the mechanisms governing transmission, replication, and toxicity comes from in vitro and in vivo studies. As with other neurodegenerative diseases caused by protein misfolding, the pathogenesis of prion disease is complex, full of conundra and contradictions. We will give here a historical overview of the use of models of prion disease, how they have evolved alongside the scientific questions, and how advancements in technologies have pushed the boundaries of our understanding of prion biology.
... Prion transmission (susceptibility, incubation period and phenotype) can be considered as an interaction between agent strain and host genotype, mediated in part by the related properties of abnormal prion protein conformation (for which PrP res type is a surrogate marker) and the PRNP polymorphism that the encodes the residue at position 129 of the prion protein (either M or V). At present, five sCJD prion strains (designated M1, M2(c), M2(t), V1 and V2) have been distinguished by transmission studies in PRNP humanised transgenic mice and nonhuman primates and the V2 strain has been proposed to account for both MV2 and VV2 sCJD [3,21,24]. The surfeit of PRNP codon 129 MM hGH-iCJD cases in France, compared to the predominance of PRNP codon 129 VV hGH-iCJD cases in the UK as of 2003 was suggested to be attributable to different contamination events by different strains of agent [4]. ...
Creutzfeldt?Jakob disease (CJD) is the prototypic human prion disease that occurs most commonly in sporadic and genetic forms, but it is also transmissible and can be acquired through medical procedures, resulting in iatrogenic CJD (iCJD). The largest numbers of iCJD cases that have occurred worldwide have resulted from contaminated cadaveric pituitary-derived human growth hormone (hGH) and its use to treat primary and secondary growth hormone deficiency. We report a comprehensive, tissue-based and molecular genetic analysis of the largest series of UK hGH-iCJD cases reported to date, including in vitro kinetic molecular modelling of genotypic factors influencing prion transmission. The results show the interplay of prion strain and host genotype in governing the molecular, pathological and temporal characteristics of the UK hGH-iCJD epidemic and provide insights into the adaptive mechanisms involved when prions cross genotypic barriers. We conclude that all of the available evidence is consistent with the hypothesis that the UK hGH-iCJD epidemic resulted from transmission of the V2 human prion strain, which is associated with the second most common form of sporadic CJD.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-016-1638-x) contains supplementary material, which is available to authorized users.
... Cite this article as Cold Spring Harb Perspect Med 2017;7:a024364 nized in terms of both clinical and neuropathological findings ( Ironside et al. 2005). Recently, the co-occurrence of mixed PrP res types (e.g., types 1 and 2) in individual cases of sCJD has been recognized in 30% of cases, which has necessitated review of the classification system described above ( Parchi et al. 2009); the variability of phenotype in sCJD may also be linked to different causative prion strains ( Bishop et al. 2010;Moda et al. 2012). ...
Human prion diseases are rare neurodegenerative diseases that have become the subject of public and scientific interest because of concerns about interspecies transmission and the unusual biological properties of the causal agents: prions. These diseases are unique in that they occur in sporadic, hereditary, and infectious forms that are characterized by an extended incubation period between exposure to infection and the development of clinical illness. Silent infection can be present in peripheral tissues during the incubation period, which poses a challenge to public health, especially because prions are relatively resistant to standard decontamination procedures. Despite intense research efforts, no effective treatment has been developed for human prion diseases, which remain uniformly fatal.
Sporadic or idiopathic prion diseases account for over 90% of all human prion diseases, and sporadic Creutzfeldt–Jakob disease (sCJD) is by far the most common. The heterogeneity of the sCJD clinical features, which was noted soon after a significant number of cases became available, led to the introduction of increasing number of “forms” or phenotypes under descriptive labels, such as myoclonic, ataxic, and amaurotic. In the 90s, Gambetti, Parchi and colleagues proposed a molecular mechanism based on the pairing of the prion protein (PrP) genotype at the methionine (M)/valine (V) polymorphic codon 129, and the type 1 or 2, of the disease-associated PrP (PrPD). This mechanism led to a rational and robust classification of sporadic prion diseases that, with some adjustments to the increasing complexities of the sporadic prion diseases, is currently in use worldwide, and has been the subject of several reviews. Recent data, however, have highlighted an additional mechanism of phenotypic heterogeneity that pertains to the sCJD subtypes heterozygous at codon 129 denoted as MV2C, MV2K, and MV1, and have further characterized the sCJDVV1 subtype as well as sporadic fatal insomnia and variably protease-sensitive prionopathy, the two prion diseases recently set apart from sCJD. This review focuses on these new data that further support and expand the molecular mechanism of phenotypic heterogeneity originally proposed. We also review a novel application of magnetic resonance imaging to identify in vivo the brain region initially impacted (epicenter) and the subsequent propagation pathway of the disease process in the major subtypes of sCJD. It is hoped that a better understanding of phenotypic heterogeneity and strain determination coupled with technologies leading to early and accurate diagnosis of sCJD subtype in vivo will lead to early and targeted therapeutics.
У науковій монографії викладено сучасні погляди на пріони та пріонні хвороби тварин і людини. Автори, ґрунтуючись на наукових працях
і сучасних розробках щодо діагностики, розповсюдження і профілактики
пріонних захворювань розкривають значення цих хвороб в епізоотології
й епідеміології, наводять загальні закономірності й тенденції їх поширення, розкривають сучасні відомості про пріони, розкривають питання
зоонозного потенціалу пріонних захворювань. Наведено характеристики
й особливості перебігу пріонних хвороб тварин і людини, описані епізоотологічні й епідеміологічні їх особливості, викладено сучасні методи
діагностики (у тому числі методи білкової ампліфікації) й заходи захисту
від цих хвороб.
Наукова монографія розрахована на спеціалістів районних і обласних
управлінь, лікарень ветеринарної медицини, слухачів інститутів і факультетів післядипломного навчання, викладачів та студентів факультетів
ветеринарної медицини вищих навчальних аграрних закладів і загал практичних фахівців ветеринарної медицини.
The scientific monograph presents current views on prions and animal and human prion diseases. Authors based on scientific works
and modern developments in diagnosis, distribution and prevention
of prion diseases reveal the importance of these diseases in epizootology
and epidemiology, state the general patterns and trends of their distribution, reveal modern information about prions, reveal questions
zoonotic potential of prion diseases.
The scientific monograph is intended for district and regional specialists
departments, hospitals of veterinary medicine, students of institutes and faculties of postgraduate studies, teachers and students of faculties
of veterinary medicine of higher educational agrarian institutions and general practitioners of veterinary medicine.
Prion diseases are fatal neurodegenerative disorders that affect humans and animals, and can also be transmitted from animals to humans. A fundamental event in prion disease pathogenesis is the conversion of normal host prion protein (PrPC) to a disease-associated misfolded form (PrPSc). Whether or not an animal prion disease can infect humans cannot be determined a priori. There is a consensus that classical bovine spongiform encephalopathy (C-type BSE) in cattle transmits to humans, and that classical sheep scrapie is of little or no risk to human health. However, the zoonotic potential of more recently identified animal prion diseases, such as atypical scrapie, H-type and L-type BSE and chronic wasting disease (CWD) in cervids, remains an open question. Important components of the zoonotic barrier are (i) physiological differences between humans and the animal in question, (ii) amino acid sequence differences of the animal and human PrPC, and (iii) the animal prion strain, enciphered in the conformation of PrPSc. Historically, the direct inoculation of experimental animals has provided essential information on the transmissibility and compatibility of prion strains. More recently, cell-free molecular conversion assays have been used to examine the molecular compatibility on prion replication and zoonotic potential. One such assay is Protein Misfolding Cyclic Amplification (PMCA), in which a small amount of infected tissue homogenate, containing PrPSc, is added as a seed to an excess of normal tissue homogenate containing PrPC, and prion conversion is accelerated by cycles of incubation and ultrasonication. PMCA has been used to measure the molecular feasibility of prion transmission in a range of scenarios using genotypically homologous and heterologous combinations of PrPSc seed and PrPC substrate. Furthermore, this method can be used to speculate on the molecular profile of PrPSc that might arise from a zoonotic transmission. We discuss the experimental approaches that have been used to model both the intra- and inter-species molecular compatibility of prions, and the factors affecting PrPc to PrPSc conversion and zoonotic potential. We conclude that cell-free prion protein conversion assays, especially PMCA, are useful, rapid and low-cost approaches for elucidating the mechanisms of prion propagation and assessing the risk of animal prions to humans.
Five sporadic Creutzfeldt–Jakob disease (CJD) strains have been identified to date, based on differences in clinicopathological features of the patients, the biochemical properties of abnormal prion proteins, and transmission properties. Recent advances in our knowledge about iatrogenic transmission of sporadic CJD have raised the possibility that the infectivity of sporadic CJD strains through peripheral routes is different from that of intracranial infection. To test this possibility, here we assessed systematically the infectivity of sporadic CJD strains through the peripheral route for the first time using a mouse model expressing human prion protein. Although the infectivity of the V2 and M1 sporadic CJD strains is almost the same in intracerebral transmission studies, the V2 strain infected more efficiently than the M1 strain through the peripheral route. The other sporadic CJD strains examined lacked infectivity. Of note, both the V2 and M1 strains showed preference for mice with the valine homozygosity at the PRNP polymorphic codon. These results indicate that the V2 strain is the most infectious sporadic CJD strain for infection through peripheral routes. In addition, these findings raise the possibility that individuals with the valine homozygosity at the PRNP polymorphic codon might have higher risks of infection through peripheral routes compared with the methionine homozygotes. Thus, preventive measures against the transmission of the V2 sporadic CJD strain will be important for the eradication of iatrogenic CJD transmission through peripheral routes.
Genetic Creutzfeldt-Jakob disease (gCJD) with a methionine to arginine substitution at codon 232 of the prion protein gene (gCJD-M232R) is rare and has only been reported in Japan. We report an autopsy case of gCJD-M232R showing alleles of codon 129 that were homozygous for methionine and the presence of multiple strains of the protease-resistant, abnormal isoform of prion protein (PrPSc ), M1 + M2C + M2T. The patient, a 54-year-old Japanese man, died after a clinical course of 21 months characterized by slowly progressive dementia and sleep disturbance. At autopsy, the neuropil of the cerebral neocortex showed a widespread and severe spongiform change. Grape-like clusters of large confluent vacuoles were admixed with fine vacuoles. Neuronal loss was moderate, but reactive astrocytosis was mild. The dorsomedial nucleus of the thalamus and the inferior olivary nucleus showed moderate and severe neuronal loss, respectively. Many amyloid plaques were present in the cerebellar molecular layer. PrPSc deposition pattern was predominantly the synaptic type in the cerebrum and corresponded to the plaques in the cerebellum. Perivacuolar deposition was also seen. Western blot analysis of PrPSc revealed the predominance of type 2. Moreover, by employing Western blot analysis in combination with the protein misfolding cyclic amplification (PMCA) method, which selectively amplifies the minor M2T prion strain, we demonstrated the presence of M2T, in addition to M1 and M2C strains, in the brain of the patient. PMCA was a powerful method for demonstrating the presence of the M2T strain, although the amount is often small and the transmission is difficult.
Prions are pathogenic infectious agents responsible for fatal, incurable neurodegenerative diseases in animals and humans. Prions are composed exclusively of an aggregated and misfolded form (PrPSc) of the cellular prion protein (PrPC). During the propagation of the disease, PrPSc recruits and misfolds PrPC into further PrPSc. In human, iatrogenic prion transmission has occurred with incompletely sterilized medical material because of the unusual resistance of prions to inactivation. Most commercial prion disinfectants validated against the historical, well-characterized laboratory strain of 263K hamster prions were recently shown to be ineffective against variant Creutzfeldt-Jakob disease human prions. These observations and previous reports support the view that any inactivation method must be validated against the prions for which they are intended to be used. Strain-specific variations in PrPSc physico-chemical properties and conformation are likely to explain the strain-specific efficacy of inactivation methods. Animal bioassays have long been used as gold standards to validate prion inactivation methods, by measuring reduction of prion infectivity. Cell-free assays such as the real-time quaking-induced conversion (RT-QuIC) assay and the protein misfolding cyclic amplification (PMCA) assay have emerged as attractive alternatives. They exploit the seeding capacities of PrPSc to exponentially amplify minute amounts of prions in biospecimens. European and certain national medicine agencies recently implemented their guidelines for prion inactivation of non-disposable medical material; they encourage or request the use of human prions and cell-free assays to improve the predictive value of the validation methods. In this review, we discuss the methodological and technical issues regarding the choice of (i) the cell-free assay, (ii) the human prion strain type, (iii) the prion-containing biological material. We also introduce a new optimized substrate for high-throughput PMCA amplification of human prions bound on steel wires, as translational model for prion-contaminated instruments.
Objective
To clinically diagnose MM2-cortical (MM2C) and MM2-thalamic (MM2T)-type sporadic Creutzfeldt-Jakob disease (sCJD) at early stage with high sensitivity and specificity.
Methods
We reviewed the results of Creutzfeldt-Jakob disease Surveillance Study in Japan between April 1999 and September 2019, which included 254 patients with pathologically confirmed prion diseases, including 9 with MM2C-type sCJD (MM2C-sCJD) and 10 with MM2T-type sCJD (MM2T-sCJD), and 607 with non-prion diseases.
Results
According to the conventional criteria of sCJD, 4 of 9 patients with MM2C- and 7 of 10 patients with MM2T-sCJD could not be diagnosed with probable sCJD until their death. Compared with other types of sCJD, patients with MM2C-sCJD showed slower progression of the disease and cortical distribution of hyperintensity lesions on diffusion-weighted images of brain MRI. Patients with MM2T-sCJD also showed relatively slow progression and negative results for most of currently established investigations for diagnosis of sCJD. To clinically diagnose MM2C-sCJD, we propose the new criteria; diagnostic sensitivity and specificity to distinguish ‘probable’ MM2C-sCJD from other subtypes of sCJD, genetic or acquired prion diseases and non-prion disease controls were 77.8% and 98.5%, respectively. As for MM2T-sCJD, clinical and laboratory features are not characterised enough to develop its diagnostic criteria.
Conclusions
MM2C-sCJD can be diagnosed at earlier stage using the new criteria with high sensitivity and specificity, although it is still difficult to diagnose MM2T-sCJD clinically.
Fatal familial insomnia is a genetic prion disease which is associated with the aspartic acid to asparagine substitution at codon 178 of the prion protein gene. Although the hallmark pathologic feature is thalamic and olivary degeneration, there is an atypical fatal familial insomnia patient without the hallmark feature. The cause of the pathologic variability is unclear. We analyzed a Japanese fatal familial insomnia kindred and compared one atypical clinicopathological fatal familial insomnia phenotype case and typical fatal familial insomnia phenotype cases with transmission studies using multiple lines of knock-in mice and with protein misfolding cyclic amplification. We also analyzed the transmissibility and the amplification properties of sporadic fatal insomnia. Transmission studies revealed that the typical fatal familial insomnia with thalamic and olivary degeneration showed successful transmission only using knock-in mice expressing human-mouse chimeric prion protein gene. The atypical fatal familial insomnia with spongiform changes showed successful transmission only using knock-in mice expressing bank vole prion protein gene. Two sporadic fatal insomnia cases with thalamic and olivary degeneration showed the same transmissibility as the typical fatal familial insomnia phenotype. Interestingly, one sporadic fatal insomnia case with thalamic/olivary degeneration and spongiform changes showed transmissibility of both the typical and atypical fatal familial insomnia phenotypes. protein misfolding cyclic amplification could amplify both typical fatal familial insomnia cases and sporadic fatal insomnia cases but not the atypical fatal familial insomnia phenotype or other sporadic Creutzfeldt-Jakob disease subtypes. In addition to clinical findings and neuropathological features, the transmission properties and the amplification properties were also different between the typical and atypical fatal familial insomnia phenotypes. It is suggested that two distinct prions were associated with the diversity in the fatal familial insomnia phenotype, and these two prions could be detected also in sporadic fatal insomnia.
Les maladies à prions sont des maladies neurodégénératives et transmissibles. Elles sont à l'origine de formes infectieuses comme la maladie de Creutzfeldt-Jakob iatrogène secondaire à un traitement par hormone de croissance d'origine humaine (MCJ post-hGH). La compréhension des facteurs gouvernant la physiopathologie de ces formes demeure parcellaire. Notre objectif a été de les étudier en analysant la cohorte des patients français exposés à l'hGH. Les analyses épidémiologiques, ont montré, à partir de données quantifiées, pour la première fois chez l'homme, une relation entre la dose d'exposition et le risque de développer la maladie d'une part et la durée de la période d'incubation d'autre part. La modélisation de la période d'incubation, a permis d'estimer que 95% des cas sont déjà apparus et d'évaluer l'influence du polymorphisme au codon 129 du gène codant la protéine prion sur la période d'incubation. L'étude descriptive a montré des similarités clinico-pathologiques entre tous les cas de maladies à prion humaines par contamination périphérique laissant supposer un rôle important de la voie d'exposition. Les expériences de transmission à la souris transgénique devraient permettre de valider les hypothèses que nous avons émises sur l'identité des souches présentes dans les lots contaminés. Ce travail a donc permis de mieux caractériser les facteurs impliqués dans la transmission des maladies à prions chez l'homme et de fournir un cadre méthodologique et des informations qui pourraient être utiles pour évaluer le risque de transmission potentielle des autres protéinopathies du système nerveux central pour lesquelles un mécanisme " prion like " a été proposé.
Prion diseases (e.g., Creutzfeldt-Jakob disease) are rapidly progressive neurodegenerative diseases that are invariably fatal and caused by three potential etiologies: sporadic, genetic, and acquired. The majority of cases have a survival time of 4–6 months from illness onset until death and the mean age at disease onset is in the early 60s. The clinical symptoms of prion disease typically include dementia, cerebellar, visual, pyramidal, and extrapyramidal symptoms, and myoclonus but the clinical phenotype can vary widely and often differs between and within different disease etiologies. The diagnosis of prion disease can be difficult due to the large differential diagnosis of rapidly progressive dementias, some of which are treatable. Although the only definitive manner in which to diagnosis prion disease is via neuropathologic examination (e.g., biopsy or autopsy), antemortem diagnosis can be achieved with reliability by recognizing the clinical symptoms and using several diagnostic tests that can be suggestive of prion disease. Several diagnostic tests that are discussed in this chapter include electroencephalogram (EEG), brain magnetic resonance imaging (MRI), and various cerebrospinal fluid tests. Unfortunately, there is no treatment for prion disease and care and management of affected patients is supportive and addresses symptoms of the illness. The reader of this chapter will be able to recognize the common symptoms of prion disease, apply the appropriate work-up for its diagnosis, and be able to offer supportive care and management strategies to patients affected by this disease.
The production of transgenic mice expressing different forms of the prion protein (PrP) or devoid of PrP has enabled researchers to study the role of PrP in the infectious process of a prion disease and its normal function in the healthy individual. A wide range of transgenic models have been produced ranging from PrP null mice, normal expression levels to overexpression models, models expressing different species of the Prnp gene and different mutations and polymorphisms within the gene. Using this range of transgenic models has allowed us to define the influence of PrP expression on disease susceptibility and transmission, assess zoonotic potential, define strains of human prion diseases, elucidate the function of PrP, and start to unravel the mechanisms involved in chronic neurodegeneration. This chapter focuses mainly on the use of the gene targeted transgenic models and summarizes the ways in which they have allowed us to study the role of PrP in prion disease and the insights they have provided into the mechanisms of neurodegenerative diseases.
Transmissible Spongiform Encephalopathy (TSE) or prion disease is caused by the infectious agent prion or scrapie prion protein (PrPSC). In animals, prion disease includes scrapie in sheep and goat; mink spongiform encephalopathy in mink; chronic wasting disease in elk and deer, and bovine spongiform encephalopathy (BSE), a.k.a. mad cow disease in cattle. Human TSE includes, Kuru; Creutzfeldt-Jakob Disease (CJD); Gerstmann-Str�ussler-Scheinker Disease (GSS) and more recently, variant CJD, which is thought to be caused by the transmission of BSE to human. The search for the transmissible agent of TSE went through many decades of uncertainty. In contrast to all other known pathogens, the TSE agent was shown to lack nucleic acids and appeared to co-purify with proteins. It was not until the 1980s that the infectious agent of TSE was shown to be a protein. Remarkably, the gene encoding for this protein is present in normal mammals. Subsequently, the word "prion", an acronym for "proteinases infectious particle" was coined to explain this conundrum. It was postulated that the central event in the pathogenesis of prion diseases is the conversion of the normal cellular prion protein (PrPC) into an intermediate isoform (PrP*) and finally the pathological, protease-resistant and infectious, PrPSC. While the concept of "protein only hypothesis" is firmly established, the processes by which the conversion occurs, and the mechanisms by which PrPSC causes pathogenesis remain incompletely understood. Furthermore, despite exhaustive investigations, the normal physiologic functions of PrPC remain elusive. It is clear, however, that expression of PrPC in the central nervous system (CNS) is required for the neurotoxicity of PrPSC as prnp null mice do not develop neurodegeneration. As a rare neurodegeneration disease, prion disease occurs with 1-3 cases in a million people per year, among which approximately 85% is sporadic without known agents, 10%-15% is genetic due to somatic mutations of the PRNP gene, and less than 1% is infectious. It is likely that the first occurrence of mad cow disease in England was caused by feeding meat and bone meal (MBM) contaminated by prions. How the first prion strain causing scrapie, chronic wasting disease, and transmissible mink encephalopathy remains obscure. For the past years, an international ban on MBM feeding has greatly reduced the occurrence of prion diseases, however, several reasons indicate that prion diseases will not be eradicated. First, somatic mutations of PRNP naturally occur, albeit at a rare frequency. Second, prions can adapt to new hosts, thus increasing their host range and overcoming the transmission barrier. Third, prions remaining in the field are infectious, and in some cases may become more infectious after binding to soil, as evidenced by the spread of chronic wasting disease among otherwise healthy deer populations. Fourth, samples from asymptomatic CJD patients or patients who are misdiagnosed under certain situations can contaminate medical instruments or be transplanted unintentionally, thus causing prion disease. More recently, it is postulated that the prion phenomenon, as defined by "the conversion of a normal protein to become an infectious protein" may also contribute to other neurodegenerative diseases. Hence, studying the pathogenesis of prion disease may provide novel insights into the underlying mechanisms of more common neurodegenerative diseases, such as Alzheimer's disease and Parkinson's diseases. � 2016, Science Press. All right reserved.
A 51-year-old man presented with progressive difficulty walking that developed over 1 month shortly after he ran a marathon. He frequently fell and had difficulty climbing the stairs. He stated he had hearing problems, but with further questioning, it was discovered he actually had difficulty deciphering speech. He did not have dizziness on standing nor bowel or bladder incontinence. He did not take medications, and he drank socially. He had no family history of imbalance problems. He still worked full-time as a lawyer.
Prion diseases are believed to propagate by the mechanism involving self-perpetuating conformational conversion of the normal form of the prion protein, PrP(C), to the misfolded, pathogenic state, PrP(Sc). One of the most intriguing aspects of these disorders is the phenomenon of prion strains. It is believed that strain properties are fully encoded in distinct conformations of PrP(Sc). Strains are of practical relevance to human prion diseases as their diversity may explain the unusual heterogeneity of these disorders. The first insight into the molecular mechanisms underlying heterogeneity of human prion diseases was provided by the observation that two distinct disease phenotypes and their associated PrP(Sc) conformers co-distribute with distinct PrP genotypes as determined by the methionine/valine polymorphism at codon 129 of the PrP gene. Subsequent studies identified six possible combinations of the three genotypes (determined by the polymorphic codon 129) and two common PrP(Sc) conformers (named types 1 and 2) as the major determinants of the phenotype in sporadic human prion diseases. This scenario implies that each 129 genotype-PrP(Sc) type combination would be associated with a distinct disease phenotype and prion strain. However, notable exceptions have been found. For example, two genotype-PrP(Sc) type combinations are linked to the same phenotype, and conversely, the same combination was found to be associated with two distinct phenotypes. Furthermore, in some cases, PrP(Sc) conformers naturally associated with distinct phenotypes appear, upon transmission, to lose their phenotype-determining strain characteristics. Currently it seems safe to assume that typical sporadic prion diseases are associated with at least six distinct prion strains. However, the intrinsic characteristics that distinguish at least four of these strains remain to be identified.
Six subtypes of sporadic Creutzfeldt-Jakob disease with distinctive clinico-pathological features have been identified largely based on two types of the abnormal prion protein, PrPSc, and the methionine (M)/valine (V) polymorphic codon 129 of the prion protein. The existence of affected subjects showing mixed phenotypic features and concurrent PrPSc types has been reported but with inconsistencies among studies in both results and their interpretation. The issue currently complicates diagnosis and classification of cases and also has implications for disease pathogenesis. To explore the issue in depth, we carried out a systematic regional study in a large series of 225 cases. PrPSc types 1 and 2 concurrence was detected in 35% of cases and was higher in MM than in MV or VV subjects. The deposition of either type 1 or 2, when concurrent, was not random and always characterized by the coexistence of phenotypic features previously described in the pure subtypes. PrPSc type 1 accumulation and related pathology predominated in MM and MV cases, while the type 2 phenotype prevailed in VVs. Neuropathological examination best identified the mixed types 1 and 2 features in MMs and most MVs, and also uniquely revealed the co-occurrence of pathological variants sharing PrPSc type 2. In contrast, molecular typing best detected the concurrent PrPSc types in VV subjects and MV cases with kuru plaques. The present data provide an updated disease classification and are of importance for future epidemiologic and transmission studies aimed to identify etiology and extent of strain variation in sporadic Creutzfeldt-Jakob disease.
The biological determinants of the phenotypic variation in sporadic Creutzfeldt-Jakob disease (sCJD) are unknown. To categorize sCJD cases, the prion protein (PrP) codon 129 genotype and the biochemical characteristics of the disease-associated form of PrP (PrP(Sc)) can be combined to form six subgroups (MM1, MM2, MV1, MV2, VV1, and VV2). This classification largely correlates with the known variation in the clinical and pathological features of sCJD, with the MM1 and MV1 cases representing the "classic" phenotype of sCJD. To address how this classification relates to different strains of sCJD we have inoculated each subgroup of sCJD to a panel of mice expressing different forms of the human PRNP gene (129MM, 129VV, and 129MV). We have established that all subtypes are transmissible to at least one genotype of mouse, and both agent and host factors determine transmission efficiency and the form of PrP(Sc) deposited in the brain. Moreover, we have identified four distinct strains of sCJD using our in vivo strain typing panel.
Five phenotypically distinct subtypes have been identified in sporadic Creutzfeldt-Jakob disease (sCJD), based on the methionine/valine polymorphic genotype of codon 129 of the prion protein (PrP) gene and the presence of either one of the two protease K-resistant scrapie prion protein (PrP(Sc)) types identified as 1 and 2. The infrequent co-existence of both PrP(Sc) types in the same case has been known for a long time. Recently, it has been reported, using type-specific antibodies, that the PrP(Sc) type 1 is present in all cases of sCJD carrying PrP(Sc) type 2. The consistent co-occurrence of both PrP(Sc) types complicates the diagnosis and the current classification of sCJD, and has implications for the pathogenesis of naturally occurring prion diseases. In the present study, we investigated the prevalence of PrP(Sc) types 1 and 2 co-occurrence, along with its effects on the disease phenotype and PrP(Sc) strain characteristics, comparatively analysing 34 cases of sCJD, all methionine homozygous at codon 129 of the PrP gene (sCJDMM). To minimize overestimating the prevalence of the sCJDMM cases carrying PrP(Sc) types 1 and 2 (sCJDMM1-2), we used proteinase K concentrations designed to hydrolyse all fragments resulting from an incomplete digestion, while preserving the protease-resistant PrP(Sc) core. Furthermore, we used several antibodies to maximize the detection of both PrP(Sc) types. Our data show that sCJDMM cases associated exclusively with either PrP(Sc) type 1 (sCJDMM1) or PrP(Sc) type 2 (sCJDMM2) do exist; we estimate that they account for approximately 56% and 5% of all the sCJDMM cases, respectively; while in 39% of the cases, both PrP(Sc) types 1 and 2 are present together (sCJDMM1-2) either mixed in the same anatomical region or separate in different regions. Clinically, sCJDMM1-2 had an average disease duration intermediate between the other two sCJDMM subtypes. The histopathology was also intermediate, except for the cerebellum where it resembled that of sCJDMM1. These features, along with the PrP immunostaining pattern, offer a diagnostic clue. We also observed a correlation between the disease duration and the prevalence of PrP(Sc) type 2 and sCJDMM2 phenotypes. The use of different antibodies and of the conformational stability immunoassay indicated that the co-existence of types 1 and 2 in the same anatomical region may confer special conformational characteristics to PrP(Sc) types 1 and 2. All of these findings indicate that sCJDMM1-2 should be considered as a separate entity at this time.
Six subtypes of sporadic Creutzfeldt-Jakob disease with distinctive clinico-pathological features have been identified largely based on two types of the abnormal prion protein, PrP(Sc), and the methionine (M)/valine (V) polymorphic codon 129 of the prion protein. The existence of affected subjects showing mixed phenotypic features and concurrent PrP(Sc) types has been reported but with inconsistencies among studies in both results and their interpretation. The issue currently complicates diagnosis and classification of cases and also has implications for disease pathogenesis. To explore the issue in depth, we carried out a systematic regional study in a large series of 225 cases. PrP(Sc) types 1 and 2 concurrence was detected in 35% of cases and was higher in MM than in MV or VV subjects. The deposition of either type 1 or 2, when concurrent, was not random and always characterized by the coexistence of phenotypic features previously described in the pure subtypes. PrP(Sc) type 1 accumulation and related pathology predominated in MM and MV cases, while the type 2 phenotype prevailed in VVs. Neuropathological examination best identified the mixed types 1 and 2 features in MMs and most MVs, and also uniquely revealed the co-occurrence of pathological variants sharing PrP(Sc) type 2. In contrast, molecular typing best detected the concurrent PrP(Sc) types in VV subjects and MV cases with kuru plaques. The present data provide an updated disease classification and are of importance for future epidemiologic and transmission studies aimed to identify etiology and extent of strain variation in sporadic Creutzfeldt-Jakob disease.
Prion diseases are characterized by the presence of the abnormal prion protein PrPSc, which is believed to be generated by the conversion of the α-helical structure that predominates in the normal PrP isoform into a β-sheet structure resistant to proteinase K (PK). In human prion diseases, two major types of PrPSc, type 1 and 2, can be distinguished based on the difference in electrophoretic migration of the PK-resistant core fragment. In this study, protein sequencing was used to identify the PK cleavage sites of PrPSc in 36 cases of prion diseases. We demonstrated two primary cleavage sites at residue 82 and residue 97 for type 1 and type 2 PrPSc, respectively, and numerous secondary cleavages distributed along the region spanning residues 74–102. Accordingly, we identify three regions in PrPSc: one N-terminal (residues 23–73) that is invariably PK-sensitive, one C-terminal (residues 103–231) that is invariably PK-resistant, and a third variable region (residues 74–102) where the site of the PK cleavage, likely reflecting the extent of the β-sheet structure, varies mostly as a function of the PrP genotype at codon 129.
Gerstmann-Sträussler syndrome is a rare familial neurodegenerative condition that is vertically transmitted, in an apparently autosomal dominant way. It can also be horizontally transmitted to non-human primates and rodents through intracerebral inoculation of brain homogenates from patients with the disease. The exact incidence of the syndrome is unknown but is estimated to be between one and ten per hundred million. Patients initially suffer from ataxia or dementia and deteriorate until they die, in one to ten years. Protease-resistant prion protein (PrP) and PrP-immunoreactive amyloid plaques with characteristic morphology accumulate in the brains of these patients. Current diagnostic criteria for Gerstmann-Sträussler syndrome incorporate clinical and neuropathological features, as animal transmission studies can be unreliable. PrP is implicated in the pathogenesis and transmission of the condition and in scrapie, an equivalent animal disease. It was discovered by enriching scrapie-infected hamster brain fractions for infectivity. Because there is compelling evidence that the scrapie isoform of PrP is a necessary component of the infectious particle, it seemed possible that the PrP gene on the short arm of human chromosome 20 in Gerstmann-Sträussler syndrome might be abnormal. We show here that PrP codon 102 is linked to the putative gene for the syndrome in two pedigrees, providing the best evidence to date that this familial condition is inherited despite also being infectious, and that substitution of leucine for proline at PrP codon 102 may lead to the development of Gerstmann-Sträussler syndrome.
We report here the case of a 53-year-old man who presented with progressive insomnia and dysautonomia (pyrexia, diaphoresis, miosis, and sphincter disturbances). Dreamlike status, dysarthria, tremor, and myoclonus subsequently developed and led to coma and death after nine months. Two sisters of the patient and many relatives over three generations had died of a similar disease. Pathological studies of the brains of the patient and one of his sisters showed severe neuronal degeneration, with reactive astrocytosis limited to the anterior and dorsomedial thalamic nuclei and without spongiosis or vascular or inflammatory changes. These cases document the existence of a degenerative disease confined to the thalamus and emphasize the role of the anterior and dorsomedial thalamic formations in the regulation of the sleep-wake cycle and other autonomic functions.
The human prion diseases include Creutzfeldt–Jakob disease, Gerstmann–Straussler–Scheinker disease, fatal familial insomnia, and the recently described new variant of Creutzfeldt–Jakob disease. Much evidence argues that a post-translational, noncovalent modification of prion protein is the fundamental event in the mechanism underlying these diseases.1 The normal cellular isoform of the prion protein (PrPC) is predominantly α-helical, is detergent soluble, and is readily digested by proteases. In contrast, the pathogenic isoform (PrPSc) has a substantially β-sheet structure, is insoluble in nondenaturing detergents, and shows relative resistance to proteolytic digestion.2–4 The protease-resistant core of PrPSc, designated PrP27–30, is usually detectable . . .
Phenotypic heterogeneity of sporadic Creutzfeldt-Jakob disease (CJD) has been linked to biochemically distinct types of the protease-resistant form of the prion protein (type 1 and type 2 PrP(Sc)). We investigated 14 cases of sporadic CJD and found that both type 1 and type 2 PrP(Sc) coexisted in 5 subjects. The distinct PrP(Sc) isoforms were associated with different patterns of PrP deposition and severity of spongiform changes, suggesting that the PrP(Sc) type plays a central role in determining the neuropathologic profile of CJD.
The phenotype of human sporadic prion diseases is affected by patient genotype at codon 129 of the prion protein (PrP) gene,
the site of a common methionine/valine polymorphism, and by the type of the scrapie PrP (PrPSc), which likely reflects the prion strain. However, two distinct disease phenotypes, identified as sporadic Creutzfeldt-Jakob
disease (M/M2 sCJD) and sporadic fatal insomnia (sFI), share methionine homozygosity at codon 129 and PrPSc type 2. One-dimensional gel electrophoresis and immunoblotting reveal no difference between the M/M2 sCJD and sFI species
of PrPSc in gel mobility and glycoform ratio. In contrast, the two-dimensional immunoblot demonstrates that in M/M2 sCJD the full-length
PrPSc form is overrepresented and carries glycans that are different from those present in the PrPScof sFI. Because the altered glycans are detectable only in the PrPSc and not in the normal or cellular PrP (PrPC), they are likely to result from preferential conversion to PrPSc of rare PrPC glycoforms. This is the first evidence that a qualitative difference in glycans contributes to prion diversity.
Molecular typing in Creutzfeldt-Jakob disease (CJD) relies on the detection of distinct protease-resistant prion protein (PrP(Sc)) core fragments, which differ in molecular mass or glycoform ratio. However, the definition and correct identification of CJD cases with a co-occurrence of PrP(Sc) types remains a challenge. With antibodies recognizing a linear epitope in the octapeptide repeat PrP region, supposed to distinguish between the two major PrP(Sc) isoforms (ie, types 1 and 2), it was recently shown that all type 2 cases display an associated band with a type 1 migration pattern, which led to the conclusion that multiple PrP(Sc) types regularly coexist in CJD. We studied brain samples from 53 sporadic CJD and 4 variant CJD subjects using a high-resolution electrophoresis, a wide range of proteinase K (PK) activities, the 'type 1-selective' antibody 12B2, and several unselective antibodies. We found that the type 1-like band detected by 12B2 in all CJD subtypes associated with PrP(Sc) type 2 is not a PK-resistant PrP(Sc) core but rather matches the physicochemical properties of partially cleaved fragments, which result from the several PK cleavage sites included in the N-terminal portion of PrP(Sc). Furthermore, using gels with high resolution and a relatively high PK activity, we were able to increase the detection sensitivity of either type 1 or 2, when coexisting, to amount corresponding to 3-5% of the total PrP(Sc) signal (ie, weak band of one type/total PrP(Sc)). Our results show that there are many pitfalls associated with the use of 'type 1 selective' antibodies for CJD typing studies and that co-occurrence of PrP(Sc) types in CJD is not the rule. The present results further validate the rationale basis of current CJD classification and the qualitative nature of molecular typing in CJD.
Epidemiological surveillance of Creutzfeldt-Jakob disease (CJD) was reinstituted in the UK in 1990 to identify any changes in the occurrence of this disease after the epidemic of bovine spongiform encephalopathy (BSE) in cattle.
Case ascertainment of CJD was mostly by direct referral from neurologists and neuropathologists. Death certificates on which CJD was mentioned were also obtained. Clinical details were obtained for all referred cases, and information on potential risk factors for CJD was obtained by a standard questionnaire administered to patients' relatives. Neuropathological examination was carried out on approximately 70% of suspect cases. Epidemiological studies of CJD using similar methodology to the UK study have been carried out in France, Germany, Italy, and the Netherlands between 1993 and 1995.
Ten cases of CJD have been identified in the UK in recent months with a new neuropathological profile. Other consistent features that are unusual include the young age of the cases, clinical findings, and the absence of the electroencephalogram features typical for CJD. Similar cases have not been identified in other countries in the European surveillance system.
These cases appear to represent a new variant of CJD, which may be unique to the UK. This raises the possibility that they are causally linked to BSE. Although this may be the most plausible explanation for this cluster of cases, a link with BSE cannot be confirmed on the basis of this evidence alone. It is essential to obtain further information on the current and past clinical and neuropathological profiles of CJD in the UK and elsewhere.
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 PrPSc 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 PrPSc 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. One of the many challenging features of the prion diseases or transmissible spongiform encephalopathies (TSEs) is the prominent heterogeneity. While the pathology of other conformational diseases of the central nervous system, such as Alzheimer’s disease, Huntington’s chorea and Parkinson’s disease, are rather homogenous, prion diseases include a wide spectrum of histopathological phenotypes. The heterogeneity of prion diseases is compounded by several factors. First, prion diseases are unique among conformational diseases as being infectious. At variance with other neurodegenerative diseases, prion diseases include three forms: sporadic, familial and acquired by infection (Table 1). Second, according to the infection portal of entry or the origin of the exogenous infectious prion, the form of prion diseases acquired by infection may display phenotypes that are quite different. This is the case with the iatrogenic Creutzfeldt-Jakob disease (CJD) and the new variant CJD that display quite different pathological features. Third, there are a large number of mutations that are genetically distinct and often are associated with quite different disease phenotypes. Fourth, the sporadic
Prions are unprecedented infectious pathogens that cause a group of
invariably fatal neurodegenerative diseases by an entirely novel
mechanism. Prion diseases may present as genetic, infectious, or
sporadic disorders, all of which involve modification of the prion
protein (PrP). Bovine spongiform encephalopathy (BSE), scrapie of
sheep, and Creutzfeldt–Jakob disease (CJD) of humans are among the
most notable prion diseases. Prions are transmissible particles that
are devoid of nucleic acid and seem to be composed exclusively of a
modified protein (PrPSc). The normal, cellular PrP
(PrPC) is converted into PrPSc through a
posttranslational process during which it acquires a high β-sheet
content. The species of a particular prion is encoded by the sequence
of the chromosomal PrP gene of the mammals in which it last replicated.
In contrast to pathogens carrying a nucleic acid genome, prions appear
to encipher strain-specific properties in the tertiary structure of
PrPSc. Transgenetic studies argue that PrPSc
acts as a template upon which PrPC is refolded into a
nascent PrPSc molecule through a process facilitated by
another protein. Miniprions generated in transgenic mice expressing
PrP, in which nearly half of the residues were deleted, exhibit unique
biological properties and should facilitate structural studies of
PrPSc. While knowledge about prions has profound
implications for studies of the structural plasticity of proteins,
investigations of prion diseases suggest that new strategies for the
prevention and treatment of these disorders may also find application
in the more common degenerative diseases.
Phenotypic heterogeneity in sporadic Creutzfeldt-Jakob disease (sCJD) is well documented, but there is not yet a systematic classification of the disease variants. In a previous study, we showed that the polymorphic codon 129 of the prion protein gene (PRNP), and two types of protease-resistant prion protein (PrPSc) with distinct physicochemical properties, are major determinants of these variants. To define the full spectrum of variants, we have examined a series of 300 sCJD patients. Clinical features, PRNP genotype, and PrPSc properties were determined in all subjects. In 187, we also studied neuropathological features and immunohistochemical pattern of PrPSc deposition. Seventy percent of subjects showed the classic CJD phenotype, PrPSc type 1, and at least one methionine allele at codon 129; 25% of cases displayed the ataxic and kuru-plaque variants, associated to PrPSc type 2, and valine homozygosity or heterozygosity at codon 129, respectively. Two additional variants, which included a thalamic form of CJD and a phenotype characterized by prominent dementia and cortical pathology, were linked to PrPSc type 2 and methionine homozygosity. Finally, a rare phenotype characterized by progressive dementia was linked to PrPSc type 1 and valine homozygosity. The present data demonstrate the existence of six phenotypic variants of sCJD. The physicochemical properties of PrPSc in conjunction with the PRNP codon 129 genotype largely determine this phenotypic variability, and allow a molecular classification of the disease variants. Ann Neurol 1999;46:224–233
The genesis of the lesions of scrapie in 3 strains of mice under comparable circumstances was investigated, using a system of scoring the brain pathology which depended on an assessment of the intensity of neuronal vacuolation and status spongiosus in paraffin sections stained with haematoxylin and eosin. By applying this method to narrowly defined areas of the brain a quantitative analysis of the distribution of lesions and total brain damage could be arrived at, allowing precise comparisons to be made.There were differences between mouse strains in the rate of development of the lesions, the distribution and intensity of which was characteristic of each strain. Within a single strain, however, the distribution of lesions during the incubatin period was closely similar to the distribution at the end point, differing only in intensity.
We sequenced the prion protein gene and studied the biochemical characteristics and the intracerebral distribution of protease-resistant prion protein with Western blot and immunohistochemistry in 19 cases of sporadic Creutzfeldt-Jakob disease. We identified four groups of subjects defined by the genotype at codon 129 of the prion protein gene, the site of a common methionine/valine polymorphism, and two types of protease-resistant prion proteins that differed in size and glycosylation. The four Creutzfeldt-Jakob disease groups showed distinct clinicopathological features that corresponded to previously described variants. The typical Creutzfeldt-Jakob disease phenotype or myoclonic variant and the Heidenhain variant were linked to methionine homozygosity at codon 129 and to "type 1" protease-resistant prion protein. The atypical and rarer variants such as that with dementia of long duration, the ataxic variant, and the variant with kuru plaques were linked to different genotypes at codon 129 and shared the "type 2" protease-resistant prion protein. Our data indicate that the sporadic form of Creutzfeldt-Jakob disease comprises a limited number of variants. The methionine/valine polymorphism at codon 129 of the prion protein gene and two types of protease-resistant prion proteins are the major determinants of these variants. These findings suggest the existence of prion strains in humans and provide the molecular basis for a novel classification of sporadic Creutzfeldt-Jakob disease.
2 and asked to refer any suspect cases to the CJD Surveillance Unit in Edinburgh. The young age of those with nvCJD at death (currently mean 30 years, range 19-50 years) has been a characteristic of nvCJD and since March, 1996, there has been an increase in the number of referrals of cases of suspect CJD under the age of 50 years. Excluding familial and iatrogenic cases, up to Feb 28, 1997, 37 cases of suspect CJD aged less than 50 years have been referred since March, 1996, at a rate of 1-5 per month, with no increase in the rate of referral during this period. Neuropathological examination is essential for the definite diagnosis of nvCJD. 11 of the referred cases have died and necropsy has been done in nine. Of these nine, one has been confirmed as nvCJD, one classic CJD, and three as other conditions. The results of necropsy are awaited in four cases. In one patient who died without necropsy, the diagnosis of nvCJD was confirmed by brain biopsy and the one patient who died without necropsy or brain biopsy has been classified as probable nvCJD on the basis of clinical features and investigations. The diagnosis of nvCJD has been confirmed by brain biopsy in two patients who are still alive. Four of the 37 referred cases aged less than 50 years have been classified as nvCJD and one as probable nvCJD (table). In the remaining 24 referred cases still alive (excluding the two confirmed as nvCJD on brain biopsy), the diagnosis is uncertain, although in the great majority nvCJD is very unlikely because of alternative clinical diagnoses (12), clinical recovery (3), clinical improvement (1), or lack of clinical progression over several months (2). In two of the cases with recovery, the initial clinical presentation was highly suggestive of nvCJD. The diagnosis of nvCJD was confirmed within 3 months of referral in the four neuropathologically verified cases and 12 of the outstanding cases were referred more than 4 months ago. The relatively low proportion of cases diagnosed as nvCJD reflects the importance of
Prions are unprecedented infectious pathogens that cause a group of invariably fatal neurodegenerative diseases by an entirely novel mechanism. Prion diseases may present as genetic, infectious, or sporadic disorders, all of which involve modification of the prion protein (PrP). Bovine spongiform encephalopathy (BSE), scrapie of sheep, and Creutzfeldt-Jakob disease (CJD) of humans are among the most notable prion diseases. Prions are transmissible particles that are devoid of nucleic acid and seem to be composed exclusively of a modified protein (PrPSc). The normal, cellular PrP (PrPC) is converted into PrPSc through a posttranslational process during which it acquires a high beta-sheet content. The species of a particular prion is encoded by the sequence of the chromosomal PrP gene of the mammals in which it last replicated. In contrast to pathogens carrying a nucleic acid genome, prions appear to encipher strain-specific properties in the tertiary structure of PrPSc. Transgenetic studies argue that PrPSc acts as a template upon which PrPC is refolded into a nascent PrPSc molecule through a process facilitated by another protein. Miniprions generated in transgenic mice expressing PrP, in which nearly half of the residues were deleted, exhibit unique biological properties and should facilitate structural studies of PrPSc. While knowledge about prions has profound implications for studies of the structural plasticity of proteins, investigations of prion diseases suggest that new strategies for the prevention and treatment of these disorders may also find application in the more common degenerative diseases.
To establish a variant of sporadic prion disease as the sporadic form of fatal familial insomnia (FFI).
FFI is a recently described prion disease characterized clinically by severe sleep impairment, dysautonomia, and motor signs, and pathologically by atrophy of thalamic nuclei, especially the medial dorsal and anterior ventral, and of the inferior olive. FFI is linked to the D178N mutation coupled with the methionine codon at position 129 in the prion protein gene (PRNP). It is also identified by the properties of the abnormal prion protein (PrP(Sc)), which has the relative molecular mass of 19 kDa, corresponding to the so-called type 2, and a marked underrepresentation of the unglycosylated form relative to the diglycosylated and monoglycosylated forms.
Clinical, pathologic, PrP(Sc), and PRNP data from 5 subjects with a sporadic prion disease phenotypically similar to FFI were collected and analyzed.
All 5 subjects had a disease clinically similar and histopathologically virtually identical to FFI. PrP(Sc) type 2 was present in all subjects in amount and distribution similar to those of FFI. However, the PrP(Sc) did not show the striking underrepresentation of the unglycosylated isoform of the protein that is characteristic of FFI. Moreover, none of the subjects had the D178N PRNP mutation but all were homozygous for methionine at codon 129.
This condition is likely to represent the sporadic form of FFI and the term "sporadic fatal insomnia" is proposed.
The neuropathological diagnosis of Creutzfeldt-Jakob disease relies on the immunohistochemical demonstration of the proteinase-K resistant form of the prion protein (PrPres) in the brain tissue. The antigenicity of PrPres is strongly reduced by the formalin solution widely used to fix the tissue, thus the PrPres immunoreactivity is inconsistently detectable in formalin-fixed tissue. A better PrPres immunostaining can be obtained by using Carnoy's fixing solution, which is composed of ethanol, chloroform and acetic acid (6:3:1). PrPres can easily be extracted from Carnoy's-fixed, paraplast-embedded tissue. Accordingly, Carnoy's-fixed tissue can prior to immunolabeling be subjected to proteinase K and guanidine thiocyanate, which respectively eliminate the normal cellular form of prion protein and promote protein denaturation. In comparison with the best protocols for formalin-fixed tissue (i.e.--hydrolytic autoclaving or autoclaving in distilled water followed by formic acid and guanidine thiocyanate), PrPres immunostaining carried out on sections cut from Carnoy's-fixed, paraplast-embedded tissue blocks and subjected to proteinase K and guanidine thiocyanate, proved more successful to detect and map both diffuse and focal PrPres immunoreactivity, and to correlate the immunoreactivity pattern with MV polymorphism at PRNP codon 129 and PrPres banding and glycosylation pattern revealed by Western blot.
A 58-year-old man died after a 27-month illness characterized by insomnia, confirmed by polysomnography. He was homozygous for methionine at codon 129 of the prion gene but had no mutation in the prion gene. Neuropathology showed thalamic and olivary atrophy and no spongiform changes. Paraffin-embedded tissue blotting demonstrated abnormal prion protein in the brain. This is the first case of the sporadic form of fatal familial insomnia with demonstration of the disorder by polysomnography. Ann Neurol 2000;48:665–668
Background:
Variant Creutzfeldt-Jakob disease (vCJD) has a pathogenesis distinct from other forms of human prion disease: disease-related prion protein (PrP(Sc)) is readily detectable in lymphoreticular tissues. Quantitation of risk of secondary transmission, and targeting of risk reduction strategies, is limited by lack of knowledge about relative prion titres in these and other peripheral tissues, the unknown prevalence of preclinical vCJD, and a transmission barrier which limits the sensitivity of bioassay. We aimed to improve immunoblotting methods for high sensitivity detection of PrP(Sc) to investigate the distribution of PrP(Sc) in a range of vCJD tissues.
Methods:
We obtained tissues at necropsy from four patients with neuropathologically confirmed vCJD and from individuals without neurological disease. Tissues were analysed by sodium phosphotungstic acid precipitation of PrP(Sc) and western blotting using high sensitivity enhanced chemiluminescence.
Findings:
We could reliably detect PrP(Sc) in the equivalent of 50 nL 10% vCJD brain homogenate, with a maximum limit of detection equivalent to 5 nl. PrP(Sc) could be detected in tissue homogenates when present at concentrations 10(4)-10(5) fold lower than those reported in brain. Tonsil, spleen, and lymph node were uniformly positive for PrP(Sc) at concentrations in the range of 0.1-15% of those found in brain: the highest concentrations were consistently seen in tonsil. PrP(Sc) was readily detected in the retina and proximal optic nerve of vCJD eye at levels of 2.5 and 25%, respectively of those found in brain. Other peripheral tissues studied were negative for PrP(Sc) with the exception of low concentrations in rectum, adrenal gland, and thymus from a single patient with vCJD. vCJD appendix and blood (Buffy coat fraction) were negative for PrP(Sc) at this level of assay sensitivity.
Interpretation:
We have developed a highly sensitive immunoblot method for detection of PrP(Sc) in vCJD tissues that can be used to provide an upper limit on PrP(Sc) concentrations in peripheral tissues, including blood, to inform risk assessment models. Rectal and other gastrointestinal tissues should be further investigated to assess risk of iatrogenic transmission via biopsy instruments. Ophthalmic surgical instruments used in procedures involving optic nerve and the posterior segment of the eye, in particular the retina, might represent a potential risk for iatrogenic transmission of vCJD. Tonsil is the tissue of choice for diagnostic biopsy and for population screening of surgical tissues to assess prevalence of preclinical vCJD infection within the UK and other populations.
Familial fatal insomnia (FFI)--a hereditary prion disease caused by a mutation at codon 178 of the prion-protein (PrP) gene (PRNP) that leads to a D178N substitution in the protein--and its sporadic form, sporadic fatal insomnia (SFI), have similar disease phenotypes. Both disorders have clinical features of disrupted sleep (loss of sleep spindles and slow-wave sleep and enacted dreams during rapid-eye-movement sleep), autonomic hyperactivation, and motor abnormalities (myoclonus, ataxia, dysarthria, dysphagia, and pyramidal signs). PET shows pronounced thalamic and limbic hypometabolism that becomes more widespread in later stages. Neuropathological assessment reveals severe neuronal loss and astrogliosis of the anterior medial thalamus and inferior olives, with later cerebral cortical and cerebellar involvement. Accumulation of an isoform of protease-resistant PrP fragment in FFI distinct from that found in a familial form of Creutzfeldt-Jakob disease with the same D178N mutation, shows the effect of the polymorphism at codon 129 of PRNP on phenotypic expression and the possibility of distinct prion "strains" with diverse pathological potential. Intriguing clinicopathological correlations in FFI and SFI suggest a role for the thalamolimbic system in the regulation of sleep and other circadian functions.
Human prion diseases are rare fatal neurodegenerative conditions that occur as acquired, familial, or idiopathic disorders. A key event in their pathogenesis is the accumulation of an altered form of the prion protein, termed PrP(Sc), in the central nervous system. A novel acquired human prion disease, variant Creutzfeldt-Jakob disease, is thought to result from oral exposure to the bovine spongiform encephalopathy agent. This disease differs from other human prion diseases in its neurological, neuropathological, and biochemical phenotype. We have used immunohistochemistry and Western blot techniques to analyze the tissue distribution and biochemical properties of PrP(Sc) in peripheral tissues in a unique series of nine cases of variant Creutzfeldt-Jakob disease. We have compared this with the distribution and biochemical forms found in all of the major subtypes of sporadic Creutzfeldt-Jakob disease and in a case of iatrogenic Creutzfeldt-Jakob disease associated with growth hormone therapy. The results show that involvement of the lymphoreticular system is a defining feature of variant Creutzfeldt-Jakob disease, but that the biochemical isoform of PrP(Sc) found is influenced by the cell type in which it accumulates.
Human prion diseases can occur as an idiopathic disorder (sporadic Creutzfeldt-Jakob disease) or can be acquired, as is the case for variant Creutzfeldt-Jakob disease. These disorders are characterized by the accumulation of a protease-resistant form of the host-encoded prion protein termed PrP(Sc) in the brains of affected individuals. PrP(Sc) has been proposed to be the principal, if not sole, component of the infectious agent, with its accumulation in the central nervous system the primary event leading to neurodegeneration. A major question remains as to whether self-propagating structural differences in PrP(Sc) might account for the clinicopathological diversity evident in Creutzfeldt-Jakob disease and whether different prion protein types underlie the existence of different strains of causative agent. Here, we describe the results of a large-scale biochemical study of PrP(Sc) from autopsy-proved cases of variant Creutzfeldt-Jakob disease (n = 59) and compare these with cases of sporadic Creutzfeldt-Jakob disease (n = 170) in the United Kingdom over the period 1991 to 2002. The results show PrP(Sc) in variant Creutzfeldt-Jakob disease to be remarkably stereotyped. In contrast, considerable heterogeneity in PrP(Sc) exists both between and within cases of sporadic Creutzfeldt-Jakob disease.
We report a case of human prion disease of 29 months duration in a 74-year-old Japanese man. The disease started with progressive sleeplessness and dementia. MRI showed gradually progressive cerebral atrophy. Neuronal loss, spongiform change and gliosis were evident in the thalamus and cerebral cortex, as well as in the striatum and amygdaloid nucleus. In the cerebellar cortex, mild-to-moderate depletion of Pukinje cells and spongiform change were observed. Mild neuronal loss in the inferior olivary nucleus was also seen. Immunohistochemistry revealed widespread perivacuolar deposits of abnormal prion protein (PrPsc) in the cerebral cortex, thalamus, basal ganglia, and brainstem, and minimal plaque-like deposits of PrPSc in the cerebellar cortex. In the cerebellar plaque-like deposits, the presence of amyloid fibrils was confirmed ultrastructurally. The entire pathology appeared to lie halfway between those of CJD and fatal insomnia, and further demonstrated the relationship between spongiform degeneration and PrPSc deposits, especially in the diseased thalamus. By immunoblotting, the thalamus was shown to contain the lowest amount of PrPSc among the brain regions examined. The PrPSc of type 2, in which the ratio of the three glycoforms was compatible with that of sporadic fatal insomnia (MM2-thalamic variant) reported previously, was also demonstrated. Analysis of the prion protein gene (PRNP) showed no mutation, and homozygosity for methionine at codon 129. In conclusion, we considered that this patient had been suffering from sporadic, pathologically atypical fatal insomnia.
The molecular typing of sporadic Creutzfeldt-Jakob disease (CJD) is based on the size and glycoform ratio of protease-resistant prion protein (PrP(Sc)), and on PRNP haplotype. On digestion with proteinase K, type 1 and type 2 PrP(Sc) display unglycosylated core fragments of 21 kDa and 19 kDa, resulting from cleavage around amino acids 82 and 97, respectively.
We generated anti-PrP monoclonal antibodies to epitopes immediately preceding the differential proteinase K cleavage sites. These antibodies, which were designated POM2 and POM12, recognise type 1, but not type 2, PrP(Sc).
We studied 114 brain samples from 70 patients with sporadic CJD and three patients with variant CJD. Every patient classified as CJD type 2, and all variant CJD patients, showed POM2/POM12 reactivity in the cerebellum and other PrP(Sc)-rich brain areas, with a typical PrP(Sc) type 1 migration pattern.
The regular coexistence of multiple PrP(Sc) types in patients with CJD casts doubts on the validity of electrophoretic PrP(Sc) mobilities as surrogates for prion strains, and questions the rational basis of current CJD classifications.
Molecular typing of the abnormal form of the prion protein (PrP(Sc)) has come to be regarded as a powerful tool in the investigation of the prion diseases. All evidence thus far presented indicates a single PrP(Sc) molecular type in variant Creutzfeldt-Jakob disease (termed type 2B), presumably resulting from infection with a single strain of the agent (bovine spongiform encephalopathy). Here we show for the first time that the PrP(Sc) that accumulates in the brain in variant Creutzfeldt-Jakob disease also contains a minority type 1 component. This minority type 1 PrP(Sc) was found in all 21 cases of variant Creutzfeldt-Jakob disease tested, irrespective of brain region examined, and was also present in the variant Creutzfeldt-Jakob disease tonsil. The quantitative balance between PrP(Sc) types was maintained when variant Creutzfeldt-Jakob disease was transmitted to wild-type mice and was also found in bovine spongiform encephalopathy cattle brain, indicating that the agent rather than the host specifies their relative representation. These results indicate that PrP(Sc) molecular typing is based on quantitative rather than qualitative phenomena and point to a complex relationship between prion protein biochemistry, disease phenotype and agent strain.
The outbreaks of iatrogenic Creutzfeldt-Jakob disease (CJD) from cadaveric human growth hormone and dura mater are winding down and, like the only other environmentally acquired form of CJD (variant CJD due to infection with the agent of bovine spongiform encephalopathy), iatrogenic disease seems to have reached its high water mark during the 1990s. The total number of cases has reached 405, and the diminishing number of new cases is due to extremely long incubation periods from infections acquired before 1985 (up to 23 years for dura mater and 36 years for growth hormone). Although no cases associated with surgical or other invasive procedures have been identified during the past several decades, the recent discovery of three transfusion-associated variant CJD infections has provoked new concerns about the possibility of further secondary transmissions from operative procedures as well as blood and tissue donations. Therefore, at least in those countries in which variant CJD has occurred, precautionary measures must continue for the indefinite future.
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.
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