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Sporadic Creutzfeldt-Jakob disease is a fatal neurodegenerative disease caused by misfolded prion proteins (PrPSc). Effective therapeutics are currently not available and accurate diagnosis can be challenging. Clinical diagnostic criteria use a combination of characteristic neuropsychiatric symptoms, CSF proteins 14-3-3, MRI, and EEG. Supportive biomarkers, such as high CSF total tau, could aid the diagnostic process. However, discordant studies have led to controversies about the clinical value of some established surrogate biomarkers. Development and clinical application of disease-specific protein aggregation and amplification assays, such as real-time quaking induced conversion (RT-QuIC), have constituted major breakthroughs for the confident pre-mortem diagnosis of sporadic Creutzfeldt-Jakob disease. Updated criteria for the diagnosis of sporadic Creutzfeldt-Jakob disease, including application of RT-QuIC, should improve early clinical confirmation, surveillance, assessment of PrPSc seeding activity in different tissues, and trial monitoring. Moreover, emerging blood-based, prognostic, and potentially pre-symptomatic biomarker candidates are under investigation.

Real-time quaking-induced conversion (RT-QuIC) allows the amplification of miniscule amounts of scrapie prion protein (PrP Sc ). Recent studies applied the RT-QuIC methodology to cerebrospinal fluid (CSF) for diagnosing human prion diseases. However, to date, there has not been a formal multi-centre assessment of the reproducibility, validity and stability of RT-QuIC in this context, an indispensable step for establishment as a diagnostic test in clinical practice. In the present study, we analysed CSF from 110 prion disease patients and 400 control patients using the RT-QuIC method under various conditions. In addition, “blinded” ring trials between different participating sites were performed to estimate reproducibility. Using the previously established cut-off of 10,000 relative fluorescence units (rfu), we obtained a sensitivity of 85 % and a specificity of 99 %. The multi-centre inter-laboratory reproducibility of RT-QuIC revealed a Fleiss’ kappa value of 0.83 (95 % CI: 0.40–1.00) indicating an almost perfect agreement. Moreover, we investigated the impact of short-term CSF storage at different temperatures, long-term storage, repeated freezing and thawing cycles and the contamination of CSF with blood on the RT-QuIC seeding response. Our data indicated that the PrP Sc seed in CSF is stable to any type of storage condition but sensitive to contaminations with blood (>1250 erythrocytes/μL), which results in a false negative RT-QuIC response. Fresh blood-contaminated samples (3 days) can be rescued by removal of erythrocytes. The present study underlines the reproducibility and high stability of RT-QuIC across various CSF storage conditions with a remarkable sensitivity and specificity, suggesting RT-QuIC as an innovative and robust diagnostic method.

At present, the testing of 14-3-3 protein in cerebrospinal fluid (CSF) is a standard biomarker test in suspected sporadic Creutzfeldt-Jakob disease (sCJD) diagnosis. Increasing 14-3-3 test referrals in CJD reference laboratories in the last years have led to an urgent need to improve established 14-3-3 test methods. The main result of our study was the validation of a commercially available 14-3-3 ELISA next to the commonly used Western blot method as a high-throughput screening test. Hereby, 14-3-3 protein expression was quantitatively analyzed in CSF of 231 sCJD and 2035 control patients. We obtained excellent sensitivity/specificity values of 88 and 96 % that are comparable to the established Western blot method. Since standard protocols and preanalytical sample handling have become more important in routine diagnostic, we investigated in a further step the reproducibility and stability of 14-3-3 as a biomarker for human prion diseases. Ring trial data from 2009 to 2013 revealed an increase of Fleiss’ kappa from 0.51 to 0.68 indicating an improving reliability of 14-3-3 protein detection. The stability of 14-3-3 protein under short-term and long-term storage conditions at various temperatures and after repeated freezing/thawing cycles was confirmed. Contamination of CSF samples with blood appears likely to be an important factor at a concentration of more than 2500 erythrocytes/μL. Hemolysis of erythrocytes with significant release of 14-3-3 protein started after 2 days at room temperature. We first define clear standards for the sample handling, short- and long-term storage of CSF samples as well as the handling of blood- contaminated samples which may result in artificially elevated CSF levels of 14-3-3.

Introduction Prion diseases are mortal neurodegenerative disorders, which include Creutzfeldt-Jakob disease (CJD). Due to its heterogenous clinical presentation diagnosis uncertainties are common. In this paper we explore CJD diagnostic challenges focusing on differential diagnosis and diagnostic delays. Methods We report a case of a patient who was misclassified and evaluated by several medical specialties before the CJD suspicion. A systematic review of the literature of the CJD case reports focused on the timely and differential diagnosis was carried out in Medline and Embase until May 2023. Results Patient with diagnosis was made due to the form of presentation and clinical evolution, neuroimaging and the presence of protein 14-3-3. In systematic review, fifteen articles were selected, who reported 31 cases of CJD with problems in the timely diagnosis and incorrect initial diagnosis, the main initial differential diagnoses were psychiatry exacerbation, myelopathy, epilepsy, stroke, parkinsonism, cerebellar ataxia and autoimmune encephalitis. The most common clinical onset was psychobehavioral disturbances (apathy, confusion and sleep disturbance), extrapyramidal signs and cognitive impairment. The diagnosis delay was from one to eighteen months. Conclusion A discussion of the case report and the diagnostic challenges reported in the literature was made. Patients can present a wide range of symptoms. It is recommended to consider CJD for the differential diagnosis in patients with behavioral symptoms, and cognitive impairment.

In contrast to other neurodegenerative diseases, sporadic Creutzfeldt–Jakob disease (sCJD) is rarely diagnosed in patients older than 75 years. Data describing the characteristics of sCJD in the very old are rare and inconclusive. Therefore, a historical cohort study was designed to evaluate clinical, cerebrospinal fluid (CSF), electroencephalography (EEG), and magnetic resonance imaging (MRI) features of this group. Patients older than 75 years identified via the German surveillance program from 2001 to 2012 ( n  = 73) were compared to a random subsample of sCJD patients younger than 75 ( n  = 73) from the same time period using an historical cohort design. Older patients showed a faster disease progression represented by an earlier point of diagnosis and a shorter survival time ( p  < 0.001). In the early stages of disease, older patients presented slightly more often with dementia ( p  = 0.127) or dysarthria ( p  = 0.238), whereas disorders of the extrapyramidal ( p  = 0.056) and visual system ( p  = 0.015) were more common in the younger group. Atypical MRI profiles such as MRI lesions restricted to one hemisphere ( p  < 0.001) or cortical lesions only ( p  = 0.258) were found more frequently in patients older than 75 years, whereas typical cortical and basal ganglia hyperintensities were more common in the younger group ( p  = 0.001). We demonstrated for the first time that patients with late-onset sCJD differ from younger sCJD patients with respect to MRI profiles and initial clinical presentation, but not among CSF markers. Misclassification of Creutzfeldt–Jakob disease cases in patients older than 75 years seems likely due to atypical clinical and radiological presentation. This might contribute to lower sCJD incidence rates in this age group.

We report a case of iatrogenic Creutzfeldt-Jakob disease (iCJD) after a 48.3-year incubation period in a patient treated with cadaveric human growth hormone. iCJD was pathologically confirmed; genetic analysis was negative for pathogenic mutations. Clinicians should consider iCJD in patients with progressive neurologic signs who had received cadaveric human growth hormone treatment.

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.

ObjectiveTo compare the diagnostic accuracy and the prognostic value of blood and cerebrospinal fluid (CSF) tests across prion disease subtypes.MethodsWe used a single-molecule immunoassay to measure tau and neurofilament light chain (NfL) protein levels in the plasma and assessed CSF total(t)-tau, NfL and protein 14-3-3 levels in patients with prion disease (n=336), non-prion rapidly progressive dementias (n=106) and non-neurodegenerative controls (n=37). We then evaluated each plasma and CSF marker for diagnosis and their association with survival, taking into account the disease subtype, which is a strong independent prognostic factor in prion disease.ResultsPlasma tau and NfL concentrations were higher in patients with prion disease than in non-neurodegenerative controls and non-prion rapidly progressive dementias. Plasma tau showed higher diagnostic value than plasma NfL, but a lower accuracy than the CSF proteins t-tau and 14-3-3. In the whole prion cohort, both plasma (tau and NfL) and CSF (t-tau, 14-3-3 and NfL) markers were significantly associated with survival and showed similar prognostic values. However, the intrasubtype analysis revealed that only CSF t-tau in sporadic Creutzfeldt-Jakob disease (sCJD) MM(V)1, plasma tau and CSF t-tau in sCJD VV2, and plasma NfL in slowly progressive prion diseases were significantly associated with survival after accounting for covariates.ConclusionsPlasma markers have lower diagnostic accuracy than CSF biomarkers. Plasma tau and NfL and CSF t-tau are significantly associated with survival in prion disease in a subtype-specific manner and can be used to improve clinical trial stratification and clinical care.

ObjectiveTo review clinical and investigation findings in patients referred to a specialist prion clinic who were suspected to have sporadic Creutzfeldt-Jakob disease (sCJD) and yet were found to have an alternative final diagnosis.MethodsReview the clinical findings and investigations in 214 patients enrolled into the UK National Prion Monitoring Cohort Study between October 2008 and November 2015 who had postmortem confirmed sCJD and compare these features with 50 patients referred over the same period who had an alternative final diagnosis (CJD mimics).ResultsPatients with an alternative diagnosis and those with sCJD were of similar age, sex and frequency of dementia but CJD mimics had a longer clinical history. Myoclonus, rigidity and hallucinations were more frequent in patients with sCJD but these features were not helpful in classifying individual patients. Alzheimer’s disease, dementia with Lewy bodies and genetic neurodegenerative disorders were alternative diagnoses in more than half of the CJD mimic cases, and 10% had an immune-mediated encephalopathy; lymphoma, hepatic encephalopathy and progressive multifocal leukoencephalopathy were seen more than once. Diffusion-weighted MRI was the most useful readily available test to classify cases correctly (92% CJD, 2% CJD mimics). The CSF cell count, 14-3-3 protein detection and S100B were of limited value. A positive CSF RT-QuIC test, introduced during the course of the study, was found in 89% of tested CJD cases and 0% CJD mimics.ConclusionThe combination of diffusion-weighted MRI analysis and CSF RT-QuIC allowed a perfect classification of sCJD versus its mimics in this study.

Definitive diagnosis of prion disease currently requires postmortem brain tissue. Now, Ryuichiro Atarashi and colleagues have discovered an assay that can identify prions in human cerebrospinal fluid. This assay could allow for diagnosis of disease in living humans. The development of technologies for the in vitro amplification of abnormal conformations of prion protein (PrP Sc ) has generated the potential for sensitive detection of prions. Here we developed a new PrP Sc amplification assay, called real-time quaking-induced conversion (RT-QUIC), which allows the detection of ≥1 fg of PrP Sc in diluted Creutzfeldt-Jakob disease (CJD) brain homogenate. Moreover, we assessed the technique first in a series of Japanese subjects and then in a blind study of 30 cerebrospinal fluid specimens from Australia, which achieved greater than 80% sensitivity and 100% specificity. These findings indicate the promising enhanced diagnostic capacity of RT-QUIC in the antemortem evaluation of suspected CJD.