Insomnia associated with thalamic involvement in E200K Creutzfeldt-Jakob disease

Advancements in dementia research, diagnostics, and care in Latin America: Highlights from the 2023 Alzheimer's Association International conference satellite symposium in Mexico City

INTRODUCTION

While Latin America (LatAm) is facing an increasing burden of dementia due to the rapid aging of the population, it remains underrepresented in dementia research, diagnostics, and care.

METHODS

In 2023, the Alzheimer's Association hosted its eighth satellite symposium in Mexico, highlighting emerging dementia research, priorities, and challenges within LatAm.

RESULTS

Significant initiatives in the region, including intracountry support, showcased their efforts in fostering national and international collaborations; genetic studies unveiled the unique genetic admixture in LatAm; researchers conducting emerging clinical trials discussed ongoing culturally specific interventions; and the urgent need to harmonize practices and studies, improve diagnosis and care, and use affordable biomarkers in the region was highlighted.

DISCUSSION

The myriad of topics discussed at the 2023 AAIC satellite symposium highlighted the growing research efforts in LatAm, providing valuable insights into dementia biology, genetics, epidemiology, treatment, and care.

Prospective 25-year surveillance of prion diseases in France, 1992 to 2016: a slow waning of epidemics and an increase in observed sporadic forms

BackgroundPrion diseases are rare, fatal disorders that have repeatedly raised public health concerns since the early 1990s. An active prion disease surveillance network providing national level data was implemented in France in 1992.AimWe aimed to describe the epidemiology of sporadic, genetic and infectious forms of prion diseases in France since surveillance implementation.MethodsWe included all suspected cases notified from January 1992 to December 2016, and cases who died during the period with a definite or probable prion disease diagnosis according to EuroCJD criteria. Demographic, clinical, genetic, neuropathological and biochemical data were collected.ResultsIn total, 25,676 suspected cases were notified and 2,907 were diagnosed as prion diseases, including 2,510 (86%) with sporadic Creutzfeldt-Jakob disease (sCJD), 240 (8%) genetic and 157 (6%) with infectious prion disease. Suspected cases and sCJD cases increased over time. Younger sCJD patients (≤ 50 years) showed phenotypes related to a distinct molecular subtype distribution vs those above 50 years. Compared to other European countries, France has had a higher number of cases with iatrogenic CJD after growth hormone treatment and variant CJD (vCJD) linked to bovine spongiform encephalopathy (second after the United Kingdom), but numbers slowly decreased over time.ConclusionWe observed a decrease of CJD infectious forms, demonstrating the effectiveness of measures to limit human exposure to exogenous prions. However, active surveillance is needed regarding uncertainties about future occurrences of vCJD, possible zoonotic potential of chronic wasting diseases in cervids and increasing trends of sCJD observed in France and other countries.

Thalamic-insomnia phenotype in E200K Creutzfeldt-Jakob disease: A PET/MRI study

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gCJD with PRNP E200K mutations frequently manifested as a thalamic-insomnia phenotype.

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Some features of the E200K phenotype are somewhere in between typical CJD and FFI.

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PET is a sensitive approach to help identify the functional changes in prion disease.

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.

Proposal of new diagnostic criteria for fatal familial insomnia

Background

The understanding of fatal familial insomnia (FFI), a rare neurodegenerative autosomal dominant prion disease, has improved in recent years as more cases were reported. This work aimed to propose new diagnostic criteria for FFI with optimal sensitivity, specificity, and likelihood ratio.

Methods

An international group of experts was established and 128 genetically confirmed FFI cases and 281 non-FFI prion disease controls are enrolled in the validation process. The new criteria were proposed based on the following steps with two-round expert consultation: (1) Validation of the 2018 FFI criteria. (2) Diagnostic item selection according to statistical analysis and expert consensus. (3) Validation of the new criteria.

Results

The 2018 criteria for possible FFI had a sensitivity of 90.6%, a specificity of 83.3%, with a positive likelihood ratio (PLR) of 5.43, and a negative likelihood ratio (NLR) of 0.11; and the probable FFI criteria had a sensitivity of 83.6%, specificity of 92.9%, with a PLR of 11.77, and a NLR of 0.18. The new criteria included more specific and/or common clinical features, two exclusion items, and summarized a precise and flexible diagnostic hierarchy. The new criteria for possible FFI had therefore reached a better sensitivity and specificity (92.2% and 96.1%, respectively), a PLR of 23.64 and a NLR of 0.08, whereas the probable FFI criteria showed a sensitivity of 90.6%, a specificity of 98.2%, with a PLR of 50.33 and a NLR of 0.095.

Conclusions

We propose new clinical diagnostic criteria for FFI, for a better refining of the clinical hallmarks of the disease that ultimately would help an early recognition of FFI and a better differentiation from other prion diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11135-6.

The insomnia phenotype in genetic Creutzfeldt-Jakob disease based on the E200K mutation

The aim of the presented study was to reveal the frequency of insomnia spells in E200K genetic Creutzfeldt-Jakob disease (gCJD) patients. Clinical records of 22 subjects diagnosed with E200K gCJD were retrospectively reviewed. The patients w/wo insomnia (n = 4, 18%/n = 18, 82%) did not differ in age, sex and the duration of the symptomatic phase. Analysis of the clinical features in the groups yielded differences in the clinical signs in the early phase of the disorder, proportion of homozygotes (Met/Met) at codon 129, MRI changes in the thalamus and the typical EEG abnormality. The study suggests that apart from traditional clinical features, the insomnia is not a rare early symptom in phenotype of E200K gCJD based on early thalamic involvement.

The genetic Creutzfeldt-Jakob disease with E200K mutation: analysis of clinical, genetic and laboratory features of 30 Chinese patients

Genetic Creutzfeldt-Jakob disease (gCJD) with E200K mutation is one of the common subtypes of human genetic prion diseases worldwide. In this study, we systematically analyzed 30 Chinese E200K gCJD cases for their epidemiological, clinical, laboratory and genetic features. The patients came from 12 different provinces, majority in northern part of China. The onset age varied from 42 to 71 year-old (y), with the median of was 57 y. The CYP4X1 gene rs9793471 SNP was tested. Only one patient’s rs9793471 genotype was GA and the others’ were AA. The gender ratio (M: F) was 1:1.73 (11:19). The foremost symptoms and clinical progression of Chinese E200K gCJD patients were quite similar as sporadic CJD cases. Only a few cases (4/30) recalled clearly disease related family history. 74.1% (20/27), 86.7% (26/30) and 50.0% (13/26) of the cases were CSF 14-3-3 positive, sCJD associated abnormalities on MRI and special PSWC on EEG, respectively. The median clinical duration was 9 months (varying from 2 to 26 months). All 30 Chinese E200K gCJD patients were M129M and E219E homozygous. 21 members from 3 families conducted PRNP sequencing and 16 asymptomatic carriers of E200K mutation with M129M and E219E homozygous were identified. This is the largest study on E200K gCJD patients in China, which would benefit to the knowledge of E200K gCJD.

Fatal familial insomnia and sporadic fatal insomnia

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 resPrP^TSE 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 PrP^TSE. The thalamus is the brain region first affected. A similar mechanism triggered spontaneously may underlie sFI.

Genetic Creutzfeldt-Jakob disease

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

Sleep Pathology in Creutzfeldt-Jakob Disease

STUDY OBJECTIVES

Associations between sleep and neurodegenerative diseases have become increasingly evident. This study aims to characterize the prevalence and type of sleep pathology in Creutzfeldt-Jakob disease (CJD), a rapidly progressive, fatal neurodegenerative disease.

METHODS

In this observational cross-sectional cohort study, we performed a retrospective analysis of sleep signs and symptoms in a consecutive group of patients with definite CJD at a tertiary care medical center (n = 28). Polysomnography was performed in 14 patients.

RESULTS

Although only 5 of 28 patients carried a premorbid sleep diagnosis, signs/symptoms of sleep pathology were present in 25 patients. Eleven reported hypersomnia whereas 13 reported insomnia. Seven had restless legs symptoms and/or periodic limb movements of sleep, and nine reported parasomnias. Of the 14 patients who underwent polysomnography, 1 did not show sleep, 9 (69%) had poorly formed or absent sleep spindles and/or K-complexes, and 10 (77%) had sleep-disordered breathing. Of the 8 patients who experienced rapid eye movement (REM) sleep during the polysomnography, 3 (38%) showed REM sleep without atonia, and 2 patients met criteria for REM sleep behavior disorder. Median total sleep time was 226 (interquartile range [IQR] = 195-282) min. Median sleep efficiency was 58.5% (IQR = 41-65.5 %). Median REM time was 0.35% (IQR = 0-7.125%). Five patients (38%) demonstrated periodic limb movements during polysomnography. One case is presented.

CONCLUSIONS

Sleep pathology is common in CJD, and screening for sleep pathology is indicated in the evaluation of patients with rapidly progressive dementias. Early identification and treatment of sleep pathology may provide an intervenable target for CJD.

Early pathology in sleep studies of patients with familial Creutzfeldt-Jakob disease

In this study, we aimed to assess sleep function in patients with recent-onset familial Creutzfeldt-Jakob disease (fCJD). The largest cluster of fCJD patients is found in Jews of Libyan origin, linked to the prion protein gene (PRNP) E200K mutation. The high index of suspicion in these patients often leads to early diagnosis, with complaints of insomnia being a very common presenting symptom of the disease. The study included 10 fCJD patients diagnosed by clinical manifestations, magnetic resonance imaging (MRI) scan of the brain, elevated tau protein in the cerebrospinal fluid (CSF) and positive PRNP E200K mutation. Standard polysomnography was performed after a brief interview confirming the presence of sleep disturbances. All patients showed a pathological sleep pattern according to all scoring evaluation settings. The sleep stages were characterized by (i) disappearance of sleep spindles; (ii) outbursts of periodic sharp waves and shallowing of sleep consisting in increased Stage 2 and wake periods during the night, as well as decrease of slow-wave sleep and rapid eye movement (REM) sleep. Recordings of respiratory functions reported irregular breathing with central and obstructive apnea and hypopnea. The typical hypotonia occurring during the night and atonia during REM sleep were replaced by hyperactive sleep consisting of multiple jerks, movements and parasomnia (mainly talking) throughout the night. In conclusion, we report unique pathological sleep patterns in early fCJD associated with the E200K mutation. Specific respiratory disturbances and lack of atonia could possibly serve as new, early diagnostic tools in the disease.

Unusual presentations in patients with E200K familial Creutzfeldt-Jakob disease

BACKGROUND AND PROPOSE

Familial Creutzfeldt-Jakob disease (fCJD) in Jews of Libyan ancestry is caused by an E200K mutation in the PRNP gene. The typical presenting symptoms include cognitive decline, behavioral changes and gait disturbances; however, some patients may have an unusual presentation such as a stroke-like presentation, alien hand syndrome or visual disturbances. The aim of this paper is to describe uncommon presentations in our series of consecutive patients with E200K fCJD.

METHODS

The study group included consecutive fCJD patients followed up as part of a longitudinal prospective study ongoing since 2003 or hospitalized since 2005. The clinical diagnosis of probable CJD was based on accepted diagnostic criteria and supported by typical magnetic resonance imaging, electroencephalographic findings, elevated cerebrospinal fluid tau protein levels and by genetic testing for the E200K mutation. Disease symptoms and signs were retrieved from the medical files.

RESULTS

The study population included 77 patients (42 men) with a mean age of disease onset of 60.6 ± 7.2 years. The most prevalent presenting symptoms were cognitive decline followed by gait impairment and behavioral changes. However, six patients had an unusual presentation including auditory agnosia, monoparesis, stroke-like presentation, facial nerve palsy, pseudobulbar syndrome and alien hand syndrome.

CONCLUSIONS

Our case series illustrates the wide phenotypic variability of the clinical presentation of patients with fCJD and widens the clinical spectrum of the disease. A high level of clinical suspicion may prove useful in obtaining early diagnosis and therefore avoiding costly and inefficient diagnostic and therapeutic strategies.

Characterization of sleep disorders in patients with E200K familial Creutzfeldt-Jakob disease

The largest cluster of E200K familial Creutzfeldt-Jakob disease (fCJD) which occurs is in Jews of Libyan origin in Israel. Insomnia is a very common early complaint in those patients and may even be the presenting symptom. The aim of this study was to assess and characterize sleep pathology in E200K fCJD patients. To do so, sleep studies of 10 consecutive fCJD patients were compared with those of 39 age and gender-matched controls. All patients presented pathological sleep characterized by fragmentation of sleep, loss of sleep spindles and reduced REM sleep amount. Respiration was characterized by irregular rhythm, periodic breathing, apneas and hypopneas, either central or obstructive. EMG recordings revealed repeated movements in sleep, with loss of REM atonia. Comparing to controls, a significant decrease of total sleep time, sleep efficacy and slow-wave sleep as well as a significant increase in the number of awakenings, apnea-hypopnea index and mixed and central apneas were evident in CJD patients. Comparison of two sequential sleep studies in one patient revealed a 40 % reduction of the total sleep time, a 40 % reduction in sleep efficacy and a 40-fold increase of the number of arousals in the second study. A significant correlation was found between the disease severity, as reflected by the CJD Neurological Scale and Periodic leg movement index. These definite and characteristic sleep pathologies in patients with fCJD associated with the E200K mutation may serve as a new diagnostic tool in the disease.

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

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

Creutzfeldt-Jakob disease surveillance in Argentina, 1997-2008

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Sporadic fatal insomnia in a young woman: a diagnostic challenge: case report

Background

Sporadic fatal insomnia (sFI) and fatal familial insomnia (FFI) are rare human prion diseases.

Case Presentation

We report a case of a 33-year-old female who died of a prion disease for whom the diagnosis of sFI or FFI was not considered clinically. Following death of this patient, an interview with a close family member indicated the patient's illness included a major change in her sleep pattern, corroborating the reported autopsy diagnosis of sFI. Genetic tests identified no prion protein (PrP) gene mutation, but neuropathological examination and molecular study showed protease-resistant PrP (PrP^res) in several brain regions and severe atrophy of the anterior-ventral and medial-dorsal thalamic nuclei similar to that described in FFI.

Conclusions

In patients with suspected prion disease, a characteristic change in sleep pattern can be an important clinical clue for identifying sFI or FFI; polysomnography (PSG), genetic analysis, and nuclear imaging may aid in diagnosis.

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

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

The genetics of prion diseases

Prion diseases are a rare group of fatal neurodegenerative disorders of humans and animals that manifest primarily as progressive dementia and ataxia. Unique to these diseases is the prion, a misfolded isoform of the prion protein that can transmit disease from cell to cell or host to host by associating with, and transforming, normal prion protein into the misfolded isoform (the pathogenic scrapie-inducing form). Although the majority of cases occur on a sporadic basis, and rarely result from exposure to prions, such as mad cow disease, 10-15% are attributable to the presence of an autosomal dominant mutation of the prion protein gene (PRNP). Single base pair changes, or the insertion of one or more multiples of a 24 base pair repeat segment, make up the known sequence alterations of PRNP associated with genetic prion disease. The common polymorphic codon 129 of PRNP also plays an important and complex role in risk and phenotype of sporadic and genetic prion disease. This review will focus on the clinical and histopathologic features of the genetic prion diseases. Selected mutations will be highlighted as a way to illustrate general phenotype-genotype correlations.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Thalamo-striatal diffusion reductions precede disease onset in prion mutation carriers

Human prion diseases present substantial scientific and public health challenges. They are unique in being sporadic, infectious and inherited, and their pathogen is distinct from all other pathogens in lacking nucleic acids. Despite progress in understanding the molecular structure of prions, their initial cerebral pathophysiology and the loci of cerebral injury are poorly understood. As part of a large prospective study, we analysed early diffusion MRI scans of 14 patients with the E200K genetic form of Creutzfeldt-Jakob Disease, 20 healthy carriers of this mutation that causes the disease and 20 controls without the mutation from the same families. Cerebral diffusion was quantified by the Apparent Diffusion Coefficient, and analysed by voxel-wise statistical parametric mapping technique. Compared to the mutation-negative controls, diffusion was significantly reduced in a thalamic-striatal network, comprising the putamen and mediodorsal, ventrolateral and pulvinar thalamic nuclei, in both the patients and the healthy mutation carriers. With disease onset, these diffusion reductions intensified, but did not spread to other areas. The caudate nucleus was reduced only after symptomatic onset. These findings indicate that cerebral diffusion reductions can be detected early in the course of Creutzfeldt-Jakob Disease, and years before symptomatic onset in mutation carriers, in a distinct subcortical network. We suggest that this network is centrally involved in the pathogenesis of Creutzfeldt-Jakob Disease, and its anatomical connections are sufficient to account for the common symptoms of this disease. Further, we suggest that the abnormalities in healthy mutation-carrying subjects may reflect the accumulation of abnormal prion protein and/or associated vacuolation at this time, temporally close to disease onset.

Mutations in the amino terminus of foamy virus Gag disrupt morphology and infectivity but do not target assembly

Foamy viruses (FVs) assemble using pathways distinct from those of orthoretroviruses. FV capsid assembly takes place near the host microtubule-organizing center (MTOC). Assembled capsids then migrate by an unknown mechanism to the trans-Golgi network to colocalize with the FV glycoprotein, Env. Interaction with Env is required for FV capsid egress from cells; the amino terminus of FV Gag contains a cytoplasmic targeting/retention signal that is responsible for targeting assembly to the MTOC. A mutant Gag was constructed by addition of a myristylation (M) signal in an attempt to target assembly to the plasma membrane and potentially overcome the dependence upon Env for budding (S. W. Eastman and M. L. Linial, J. Virol. 75:6857-6864, 2001). Using this and additional mutants, we now show that assembly is not redirected to the plasma membrane. Addition of an M signal leads to gross morphological defects. The aberrant particles still assemble near the MTOC but do not produce infectious virus. Although extracellular Gag can be detected in a pelletable form in the absence of Env, the mutant particles contain very little genomic RNA and are less dense. Our analyses indicate that the amino terminus of Gag contains an Env interaction domain that is critical for bona fide egress of assembled capsids.

Physiology of the prion protein

Prion diseases are transmissible spongiform encephalopathies (TSEs), attributed to conformational conversion of the cellular prion protein (PrP(C)) into an abnormal conformer that accumulates in the brain. Understanding the pathogenesis of TSEs requires the identification of functional properties of PrP(C). Here we examine the physiological functions of PrP(C) at the systemic, cellular, and molecular level. Current data show that both the expression and the engagement of PrP(C) with a variety of ligands modulate the following: 1) functions of the nervous and immune systems, including memory and inflammatory reactions; 2) cell proliferation, differentiation, and sensitivity to programmed cell death both in the nervous and immune systems, as well as in various cell lines; 3) the activity of numerous signal transduction pathways, including cAMP/protein kinase A, mitogen-activated protein kinase, phosphatidylinositol 3-kinase/Akt pathways, as well as soluble non-receptor tyrosine kinases; and 4) trafficking of PrP(C) both laterally among distinct plasma membrane domains, and along endocytic pathways, on top of continuous, rapid recycling. A unified view of these functional properties indicates that the prion protein is a dynamic cell surface platform for the assembly of signaling modules, based on which selective interactions with many ligands and transmembrane signaling pathways translate into wide-range consequences upon both physiology and behavior.

Sleep and temperature rhythms in two sisters with P102L Gerstmann-Sträussler-Scheinker (GSS) disease

BACKGROUND

Sleep disorders are increasingly recognized in the symptomatology of many neurodegenerative diseases. Gerstmann-Sträussler-Scheinker (GSS) disease is a hereditary prion disease featuring cerebellar ataxia, akinetic parkinsonism, pyramidal signs and cognitive decline.

METHODS

We performed a polysomnographic study (PSG) of sleep and body core temperature (BcT degrees ) in two sisters with GSS.

RESULTS

Our study showed protracted nocturnal awakenings, reduced sleep efficiency and brief daytime naps but also qualitatively preserved slow-wave and REM sleep and substantially normal arousal and periodic limb movements in sleep indices and BcT degrees rhythm.

CONCLUSIONS

These findings conflict with those in multiple system atrophy and other prion diseases such as fatal familial insomnia, which enter the differential diagnosis of GSS and are characterized by prominently disrupted sleep-wake and BcT degrees cycles.

Familial Creutzfeldt-Jakob Disease with a codon 200 mutation presenting as thalamic syndrome: diagnosis by single photon emission computed tomography using (99m)Tc-ethyl cysteinate dimer

The clinical features of familial Creutzfeldt-Jakob disease with a codon 200 point mutation [fCJD (E200K)] are similar to those of sporadic CJD (sCJD). MRI diffusion-weighted imaging (MRI-DWI) has been reported to be useful for the early diagnosis of CJD. We describe a Japanese fCJD (E200K) case in which thalamic symptoms were the initial manifestations. On admission, electroencephalography (ECG) showed no periodic synchronous discharge (PSD), and MRI showed no abnormalities. However, single photon emission computed tomography (SPECT) using (99m)Tc-ethyl cysteinate dimer ((99m)Tc-ECD) revealed hypoperfusion in the right thalamus. We conclude that the thalamic form of CJD tends to show no high-intensity area (HIA) by MRI-DWI, and that SPECT may be more useful for visualizing the affected area responsible for the thalamic symptoms at an early stage.

Two different clinical phenotypes of Creutzfeldt-Jakob disease with a M232R substitution

OBJECTIVE

To describe the clinical features of Creutzfeldt-Jakob disease with a substitution of arginine for methionine (M232R substitution) at codon 232 (CJD232) of the prion protein gene (PRNP).

PATIENTS AND METHODS

We evaluated the clinical and laboratory features of 20 CJD232 patients: age of onset, initial symptoms, duration until becoming akinetic and mute, duration until occurrence of periodic sharp and wave complexes on EEG (PSWC), MRI findings, and the presence of CSF 14-3-3 protein. Immunohistochemically, prion protein (PrP) deposition was studied.

RESULTS

None of the patients had a family history of CJD. We recognized two clinical phenotypes: a rapidly progressive type (rapidtype) and a slowly progressive type (slow-type). Out of 20 patients, 15 became akinetic and mute, demonstrated myoclonus, and showed PSWC within a mean duration of 3.1, 2.4, and 2.8 months, respectively (rapid-type). Five showed slowly progressive clinical courses (slow-type). Five became akinetic and mute and four demonstrated myoclonus within a mean duration of 20.6 and 15.3 months, respectively, which were significantly longer than those in the rapid-type. Only one demonstrated PSWC 13 months after the onset. Diffuse synaptic-type deposition was demonstrated in four rapidtype patients, and perivacuolar and diffuse synaptic-type deposition in two, and diffuse synaptic-type deposition in one slow-type patient. Three of 50 suspected but non-CJD patients had the M232R substitution.

CONCLUSIONS

Patients with CJD232 had no family history like patients with sCJD, and showed two different clinical phenotypes in spite of having the same PRNP genotype. More studies are needed to determine whether M232R substitution causes the disease and influences the disease progression.

Fatal familial insomnia: a model disease in sleep physiopathology

Fatal Familial Insomnia (FFI) is characterized by loss of sleep, oneiric stupor with autonomic/motor hyperactivity and somato-motor abnormalities (pyramidal signs, myoclonus, dysarthria/dysphagia, ataxia). Positon emission tomography (PET) disclosed thalamic hypometabolism and milder involvement of the cortex; neuropathology severe neuronal loss in the thalamic nuclei variably affecting the caudate, gyrus cinguli and fronto-temporal cortices. Genetic analysis disclosed a mutation in the PRNP gene and FFI was transmitted to experimental animals, thus classifying FFI within the prion diseases. Rare Sporadic Fatal Insomnia (SFI) cases occur without PRNP mutation but with features similar to FFI. FFI represents a model disease for the study of sleep-wake regulation: (I) the profound thalamic hypometabolism/atrophy associated with lack of sleep spindles and delta sleep implicate the thalamus in the origin of slow wave sleep (SWS); (II) loss of SWS is associated with marked autonomic and motor hyperactivity; termed 'agrypnia excitata', this association has been proposed as a useful clinical concept representative of thalamo-limbic dysfunction; (III) lack of SWS occurs with substantial preservation of stage 1 NREM sleep, implying that the latter has mechanisms different from SWS and unaffected by thalamic atrophy; accordingly, conflating stage 1 NREM with SWS into NREM sleep is inappropriate.

Sporadic fatal insomnia with spongiform degeneration in the thalamus and widespread PrPSc deposits in the brain

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.

Comparison of the neuropathological characteristics of bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) in mice

Bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) belong to a group of diseases called the transmissible spongiform encephalopathies (TSEs). Transmission studies in inbred mice (strain typing) provided overwhelming evidence that vCJD arose from BSE. In this study, we compare the patterns of neuropathology in a panel of three inbred mouse strains (RIII, C57BL and VM) and one cross (C57BL x VM) infected with either vCJD or BSE. For each mouse strain, patterns of abnormal prion protein (PrPres) deposition, astrocytosis and vacuolation were similar in the vCJD- and BSE-challenged mice. Prion protein (PrP)-positive plaques were prominent in the VM and C57BL x VM mice in addition to diffuse PrPres accumulation, whereas only diffuse PrPres labelling was observed in the RIII and C57BL mice. The hippocampus was targeted in all mouse strains, as was the cochlear nucleus in the medulla, both showing consistent severe vacuolation and heavy PrPres deposition. Although the targeting of PrPres was similar in the BSE- and vCJD-infected brains, the amount and intensity of PrPres observed in the brains treated with formic acid during fixation was reduced considerably. The distribution of astrocytosis was similar to the targeting of PrPres deposition in the brain, although some differences were observed in the hippocampi of mice challenged with vCJD. We conclude that there are no significant differences in the targeting of neuropathological changes observed in the BSE- and vCJD-infected mice, consistent with the previous evidence of a link between BSE and vCJD.

Hereditary Creutzfeldt-Jakob disease and fatal familial insomnia

Studies on hereditary CJD and FFI have contributed greatly to the understanding of all forms of prion disease. Most importantly, they have provided strong support for the prion hypothesis [2]. The linkage of pathogenic PRNP mutations to human prion disease strengthens the notion that a change in PrP conformation is a key event that triggers the development of the disease. Although hereditary CJD and FFI account for only 10% of all cases of human prion disease, they provide a unique opportunity for studying disease pathogenesis initiated by perturbation in the PrP structure. An understanding of the events that accompany a change in PrP conformation has far-reaching implications for sCJD (the most common form of the disease) and for sporadic fatal insomnia. A wealth of available evidence indicates that a common pathway in disease pathogenesis may be shared by both the sporadic and the hereditary forms of prion disease, except that the initiating events are stochastic in the former, rather than predetermined by the presence of a germ-line mutation. In addition, investigations of hereditary CJD and FFI have provided plausible mechanisms of phenotypic heterogeneity in prion disease, a phenomenon analogous to the "prion strain" diversity in animal prion disease. Although many other neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis, and Huntington's chorea are fairly homogeneous in disease phenotype, prion disease includes many clinically and pathologically distinct disease entities. In hereditary prion disease, the disease phenotype is likely to be determined by the combined effect of pathogenic mutations, codon 129 polymorphism, and the type of PrPSc. The pathogenic mutations include point mutations that are located mostly in the central and C-terminal region of PrP, and deletion and insertion mutations that are located in the N-terminal region. It is conceivable that these distinct types of mutations may result in differential changes in conformation or stability of PrP. The codon 129 polymorphism plays a twofold role in modulating the disease outcome. On the mutant allele, it determines the basic features of the disease phenotype--as in the case of FFI and CJD178--that result respectively from the coupling of M or V at codon 129 with the D178N mutation. On the normal allele, it may modulate the severity of the phenotype. A PrPSc subtype is encoded by the PRNP haplotype, and subsequently is generated by a conformational conversion process that transforms the cellular isoform to the pathogenic protein. The site for the formation of a specific PrPSc conformer and its accumulation in different brain regions are likely to contribute to the clinical features and pathologic lesions. The phenotypic homogeneity in other neurologic diseases, including Alzheimer's disease, may be due, in part, to the lack of a powerful genetic modifier such as the codon 129 polymorphism in the PrP gene, and the lack of the ability of affected gene products such as PrP to assume multiple protein conformations. Clearly, the remaining issue in the understanding of pathogenesis of prion disease is a detailed and accurate knowledge of the in vivo processes and conditions for the formation of PrPSc that inevitably lead to the development and expression of the disease. This knowledge will enable the development of a rational and effective strategy for therapeutic intervention.