Evidence-based guideline: diagnostic accuracy of CSF 14-3-3 protein in sporadic Creutzfeldt-Jakob disease: report of the guideline development subcommittee of the American Academy of Neurology

Early onset cerebral amyloid angiopathy following childhood exposure to cadaveric dura

Amyloid-β transmission has been described in patients both with and without iatrogenic Creutzfeldt-Jakob disease; however, there is little information regarding the clinical impact of this acquired amyloid-β pathology during life. Here, for the first time, we describe in detail the clinical and neuroimaging findings in 3 patients with early onset symptomatic amyloid-β cerebral amyloid angiopathy following childhood exposure to cadaveric dura (by neurosurgical grafting in 2 patients and tumor embolization in a third). Our observations provide further in vivo evidence that cerebral amyloid angiopathy might be caused by transmission of amyloid-β seeds (prions) present in cadaveric dura and have diagnostic relevance for younger patients presenting with suspected cerebral amyloid angiopathy. Ann Neurol 2019; 1-7 ANN NEUROL 2019;85:284-290.

The worst is yet to come: probable sporadic Creutzfeldt-Jakob disease in a well-controlled HIV patient

We describe a case of probable sporadic Creutzfeldt-Jakob disease in the setting of well-controlled HIV and discuss whether exist, in fact, HIV-related factors that may predispose to the development of prion disease. To the best of our knowledge, this is the third report of this association.

Drug-induced Creutzfeldt-Jakob disease-like syndrome: early CSF analysis as useful tool for differential diagnosis

We report the case of a 78-year-old man who showed a subacute onset of severe cognitive impairment, ataxia, tremor, stimulus sensitive myoclonus and hypophonia. Since a few weeks, he received a treatment with a combination of tricyclic antidepressants for mood disorder. The clinical picture mimicked Creutzfeldt-Jakob disease (CJD), but we could rule out this diagnosis by means of cerebrospinal fluid (CSF) analysis, which showed normal level of tau protein and Aβ_1-42, being also negative for CSF 14-3-3 protein. A complete clinical recovery was observed after the discontinuation of antidepressants. So far, some cases of drug-induced CJD-like syndrome have been described. In our experience, early CSF analysis shows high diagnostic usefulness in order to exclude CJD.

Review: Fluid biomarkers in the human prion diseases

The human prion diseases are a diverse set of often rapidly progressive neurodegenerative conditions associated with abnormal forms of the prion protein. We review work to establish diagnostic biomarkers and assays that might fill other important roles, particularly those that could assist the planning and interpretation of clinical trials. The field now benefits from highly sensitive and specific diagnostic biomarkers using cerebrospinal fluid: detecting by-products of rapid neurodegeneration or specific functional properties of abnormal prion protein, with the second generation real time quaking induced conversion (RT-QuIC) assay being particularly promising. Blood has been a more challenging analyte, but has now also yielded valuable biomarkers. Blood-based assays have been developed with the potential to screen for variant Creutzfeldt-Jakob disease, although it remains uncertain whether these will ever be used in practice. The very rapid neurodegeneration of prion disease results in strong signals from surrogate protein markers in the blood that reflect neuronal, axonal, synaptic or glial pathology in the brain: notably the tau and neurofilament light chain proteins. We discuss early evidence that such tests, applied alongside robust diagnostic biomarkers, may have potential to add value as clinical trial outcome measures, predictors of future disease course (including for asymptomatic individuals at high risk of prion disease), and as rapidly accessible and sensitive markers to aid early diagnosis.

Prion Diseases

Prions diseases are uniformly fatal neurodegenerative diseases that occur in sporadic, genetic, and acquired forms. Acquired prion diseases, caused by infectious transmission, are least common. Most prion diseases are not infectious, but occur spontaneously through misfolding of normal prion proteins or genetic mutations in the prion protein gene. Although most prion diseases are not caused by infection, they can be transmitted accidentally. Certain infection control protocols should be applied when handling central nervous system and other high-risk tissues. New diagnostic methods are improving premortem and earlier diagnosis. Treatment trials have not shown improved survival, but therapies may be available soon.

Sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease (CJD), the most common human prion disease, is generally regarded as a spontaneous neurodegenerative illness, arising either from a spontaneous PRNP somatic mutation or a stochastic PrP structural change. Alternatively, the possibility of an infection from animals or other source remains to be completely ruled out. Sporadic CJD is clinically characterized by rapidly progressive dementia with ataxia, myoclonus, or other neurologic signs and, neuropathologically, by the presence of aggregates of abnormal prion protein, spongiform change, neuronal loss, and gliosis. Despite these common features the disease shows a wide phenotypic variability which was recognized since its early descriptions. In the late 1990s the identification of key molecular determinants of phenotypic expression and the availability of a large series of neuropathologically verified cases led to the characterization of definite clinicopathologic and molecular disease subtypes and to an internationally recognized disease classification. By showing that these disease subtypes correspond to specific agent strain-host genotype combinations, recent transmission studies have confirmed the biologic basis of this classification. The introduction of brain magnetic resonance imaging techniques such as fluid-attenuated inversion recovery and diffusion-weighted imaging sequences and cerebrospinal fluid biomarker assays for the detection of brain-derived proteins as well as real-time quaking-induced conversion assay, allowing the specific detection of prions in accessible biologic fluids and tissues, has significantly contributed to the improved accuracy of the clinical diagnosis of sporadic CJD in recent years.

14-3-3 and enolase abundances in the CSF of Prion diseased rats

Creutzfeldt-Jakob disease (CJD) is characterized by an extended asymptomatic preclinical phase followed by rapid neurodegeneration. There are no effective treatments. CJD diagnosis is initially suspected based upon the clinical presentation of the disease and the exclusion of other etiologies. Neurologic symptoms are assessed in combination with results from cerebrospinal fluid (CSF) biomarker abundances, electroencephalography (EEG), magnetic resonance imaging (MRI), and in some countries, real-time quaking-induced conversion (RT-QuIC). Inconsistencies in sensitivities and specificities of prion disease biomarker abundance in CSF have been described, which can affect diagnostic certainty, but the utility of biomarkers for prognosis has not been fully explored. The clinical presentation of CJD is variable, and factors such as prion protein polymorphic variants, prion strain, and other genetic or environmental contributions may affect the disease progression, confounding the appearance or abundance of biomarkers in the CSF. These same factors may also affect the appearance or abundance of biomarkers, further confounding diagnosis. In this study, we controlled for many of these variables through the analysis of serial samples of CSF from prion-infected and control rats. Prion disease in laboratory rodents follows a defined disease course as the infection route and time, prion strain, genotype, and environmental conditions are all controlled. We measured the relative abundance of 14-3-3 and neuron-specific enolase (NSE) in CSF during the course of prion infection in rats. Even when disease-related, environmental and genetic variables were controlled, CSF 14-3-3 and NSE abundances were variable. Our study emphasizes the considerable diagnostic and prognostic limitations of these prion biomarkers.

[Human prion diseases: current issues]

Prion diseases, or transmissible spongiform encephalopathies, are a group of neurodegenerative diseases with progressive dementia and movement disorders. There are three variants of prion diseases pathogenesis: direct contamination, genetic and sporadic forms. The following clinical forms are known: Creutzfeldt-Jakob disease (common type), variant Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker disease, variably protease-sensitive prionopathy, fatal insomnia and fatal familial insomnia, kuru, prion disease associated with diarrhea and autonomic neuropathy. Clinical characteristic of prion diseases, molecular-genetic aspects of their pathogenesis and current diagnostic approaches are discussed. Because of the lack of effective treatment, prevention of both alimentary prion infections (consumption of contaminated meat products) and transmissible iatrogenic infections (the use of biopreparations from animal tissues) is important. The safety of such biopreparations should be ensured by modern manufacturing technologies and specially developed procedures that meet international requirements and standards.

Case series of Creutzfeldt-Jakob disease in a third-level hospital in Quito

BACKGROUND

Creutzfeldt-Jakob disease is a rare and fatal neurodegenerative disorder that affects mammals and humans. The prevalence of this disease in the United States is 0.5 to 1 per million inhabitants. So far in Ecuador, we do not know what the prevalence or incidence is, and only one case report has been written.

CASE PRESENTATION

We present a case series of Creutzfeldt-Jakob disease in a third-level hospital in Quito. The average age of symptom onset in our patients was 58.8 years. The male to female ratio was 1:1. Two patients began with cognitive/behavioral symptoms, while 4 patients began with focal neurological signs; 1 case with ataxia, 2 with gait disorders and 1 with vertigo and headache. All of the patients had the clinical features established by the World Health Organization. In addition, the entire cohort was positive for the 14-3-3 protein in cerebrospinal fluid, and had high signal abnormalities in caudate and putamen nucleus in DWI and FLAIR IRM. Only in one case, did we reach a definitive diagnosis through a pathological study. All other cases had a probable diagnosis. In this series of cases, 6 out of 6 patients died. The average time from the onset of the symptoms to death in this cohort was 13 months.

CONCLUSION

This is the first report of a series of cases of Creutzfeldt-Jakob disease in Quito. Although definitive diagnosis must be histopathological, there are ancillary tests currently available that have allowed us to obtain a diagnosis of the disease.

Cerebrospinal Fluid Levels of 14-3-3 Gamma: What Does It Tell Us About Sporadic Creutzfeldt-Jakob Disease?

Clinical diagnosis of Creutzfeldt-Jakob disease (CJD) can be supported by the analysis of Tau and 14-3-3 in the cerebrospinal fluid (CSF). In this short report, we report about a retrospective analysis performed on 2,296 routinely collected CSF samples, and 44 samples with a ratio of phosphoTau181/Tau <0.075 were selected. Analysis was performed with a novel 14-3-3 gamma CircuLex Elisa. We show that control levels were around 6,000 AU/mL and samples from Alzheimer patients were not different from those collected from healthy controls. Four cases of verified CJD had 14-3-3 CSF levels of >100,000 AU/mL, while 10 out of 12 suspected CJD samples with 14-3-3 CSF levels between 50,000-100,000 AU/mL were CJD positive. All samples with 14-3-3 levels between 15,000 and 50,000 AU/mL were not CJD cases but disorders with complex neuropathology. In conclusion, our data suggests that in CSF samples with a phospho-Tau-181/Tau ratio <0.075 CSF levels of 14-3-3 should be analyzed. Our data suggests a very high risk for CJD with 14-3-3 levels above 100,000 AU/mL and a probable diagnosis of CJD based on laboratory parameters above 50,000 AU/mL.

Three sporadic cases of Creutzfeldt-Jakob disease in China and their clinical analysis

The present study described the characteristics of three cases of Creutzfeldt-Jakob disease (CJD) in China and analyzed their clinical presentations. The clinical information of the three cases was collected and analyzed. Blood and cerebrospinal fluid (CSF) specimens of the patients were collected for detection of the prion protein (PRNP) gene and 14-3-3 protein levels. Dynamic changes of electroencephalograms (EEGs) and brain magnetic resonance images (MRIs) were also observed. All the three cases were sporadic CJD cases. They presented with symptoms including hyposthenia, progressive memory loss, truncal and limb ataxia, dysarthria, lowered vision acuity, bucking, language disorders, myoclonia and akinetic mutism state. One of the three cases was associated with a prolonged duration of >6 years. The EEG of two cases showed slow biphasic waves. The diffusion-weighted MRI sequence revealed abnormal hyperintensity and bilateral ribboning in the cortex. Two patients tested positive for the 14-3-3 protein in the CSF. All patients were of methionine homozygosity at codon 129 in the gene encoding PRNP protein and one patient had a mutation. The CJD cases showed differences in terms of symptoms and disease duration. Subacute onset was common and with attentive nursing and supportive treatments, one of the patients had a prolonged survival time of >6 years.

Dysregulation of 14-3-3 proteins in neurodegenerative diseases with Lewy body or Alzheimer pathology

Objective

The highly conserved 14‐3‐3 proteins interact with key players involved in Parkinson's disease (PD) and other neurodegenerative disorders. We recently demonstrated that 14‐3‐3 phosphorylation is increased in PD models and that increased 14‐3‐3 phosphorylation reduces the neuroprotective effects of 14‐3‐3 proteins. Here, we investigated whether 14‐3‐3 phosphorylation is altered in postmortem brains from control, PD, Alzheimer's Disease (AD), Alzheimer's with Lewy Bodies (ADLB), Dementia with Lewy Bodies (DLB), and Progressive Supranuclear Palsy (PSP) subjects at three conserved sites: serine 58 (S58), serine 185 (S185), and serine 232 (S232).

Methods

S58, S185, and S232 phosphorylation was measured by western blot analysis of Triton X‐100 soluble and insoluble fractions from postmortem temporal cortex.

Results

The ratio of soluble phospho‐S232 to insoluble phospho‐S232 was reduced by 32%, 60%, 37%, and 52% in PD, AD, ADLB, and DLB, respectively. S185 and S58 phosphorylation were mildly elevated in the soluble fraction in DLB. We also noted a dramatic reduction in soluble pan 14‐3‐3 levels by ~35% in AD, ADLB, and DLB. Lower ratios of soluble to insoluble S232 phosphorylation (pointing to higher insoluble pS232) correlated with lower soluble pan 14‐3‐3 levels, suggesting that S232 phosphorylation may promote insolubilization of 14‐3‐3s. The phospho‐S232 ratio and soluble pan 14‐3‐3 levels correlated with clinical and pathological severity.

Interpretation

These data reveal dysregulation of 14‐3‐3 proteins in neurodegeneration associated with Lewy body or Alzheimer pathology. S232 phosphorylation may drive insolubilization of 14‐3‐3s and thus contribute to the pathophysiology in neurodegenerative disorders associated with Lewy body or Alzheimer pathology.

Prion-specific and surrogate CSF biomarkers in Creutzfeldt-Jakob disease: diagnostic accuracy in relation to molecular subtypes and analysis of neuropathological correlates of p-tau and Aβ42 levels

The differential diagnosis of Creutzfeldt-Jakob disease (CJD) from other, sometimes treatable, neurological disorders is challenging, owing to the wide phenotypic heterogeneity of the disease. Real-time quaking-induced prion conversion (RT-QuIC) is a novel ultrasensitive in vitro assay, which, at variance with surrogate neurodegenerative biomarker assays, specifically targets the pathological prion protein (PrP^Sc). In the studies conducted to date in CJD, cerebrospinal fluid (CSF) RT-QuIC showed good diagnostic sensitivity (82–96%) and virtually full specificity. In the present study, we investigated the diagnostic value of both prion RT-QuIC and surrogate protein markers in a large patient population with suspected CJD and then evaluated the influence on CSF findings of the CJD type, and the associated amyloid-β (Aβ) and tau neuropathology. RT-QuIC showed an overall diagnostic sensitivity of 82.1% and a specificity of 99.4%. However, sensitivity was lower in CJD types linked to abnormal prion protein (PrP^Sc) type 2 (VV2, MV2K and MM2C) than in typical CJD (MM1). Among surrogate proteins markers (14-3-3, total (t)-tau, and t-tau/phosphorylated (p)-tau ratio) t-tau performed best in terms of both specificity and sensitivity for all sCJD types. Sporadic CJD VV2 and MV2K types demonstrated higher CSF levels of p-tau when compared to other sCJD types and this positively correlated with the amount of tiny tau deposits in brain areas showing spongiform change. CJD patients showed moderately reduced median Aβ42 CSF levels, with 38% of cases having significantly decreased protein levels in the absence of Aβ brain deposits. Our results: (1) support the use of both RT-QuIC and t-tau assays as first line laboratory investigations for the clinical diagnosis of CJD; (2) demonstrate a secondary tauopathy in CJD subtypes VV2 and MV2K, correlating with increased p-tau levels in the CSF and (3) provide novel insight into the issue of the accuracy of CSF p-tau and Aβ42 as markers of brain tauopathy and β-amyloidosis.

Neuroradiology of human prion diseases, diagnosis and differential diagnosis

Human transmissible spongiform encephalopathies (TSEs), or prion diseases, are invariably fatal conditions associated with a range of clinical presentations. TSEs are classified as sporadic [e.g. sporadic Creutzfeldt-Jakob disease (sCJD), which is the most frequent form], genetic (e.g. Gerstmann-Straussler-Scheinker disease, fatal familial insomnia, and inherited CJD), and acquired or infectious (e.g. Kuru, iatrogenic CJD, and variant CJD). In the past, brain imaging played a supporting role in the diagnosis of TSEs, whereas nowadays magnetic resonance imaging (MRI) plays such a prominent role that MRI findings have been included in the diagnostic criteria for sCJD. Currently, MRI is required for all patients with a clinical suspicion of TSEs. Thus, MRI semeiotics of TSEs should become part of the cultural baggage of any radiologist. The purposes of this update on the neuroradiology of CJD are to (i) review the pathophysiology and clinical presentation of TSEs, (ii) describe both typical and atypical MRI findings of CJD, and (iii) illustrate diseases mimicking CJD, underlining the MRI key findings useful in the differential diagnosis.

Naturalistic study of guideline implementation tool use via evaluation of website access and physician survey

Background

Clinical guidelines support decision-making at the point-of-care but the onus is often on individual users such as physicians to implement them. Research shows that the inclusion of implementation tools in or with guidelines (GItools) is associated with guideline use. However, there is little research on which GItools best support implementation by individual physicians. The purpose of this study was to investigate naturalistic access and use of GItools produced by the American Academy of Neurology (AAN) to inform future tool development.

Methods

Website accesses over six months were summarized for eight AAN guidelines and associated GItools published between July 2012 and August 2013. Academy members were surveyed about use of tools accompanying the sport concussion guideline. Data were analyzed using summary statistics and the Chi-square test.

Results

The clinician summary was accessed more frequently (29.0%, p < 0.001) compared with the slide presentation (26.8%), patient summary (23.2%) or case study (20.9%), although this varied by guideline topic. For the sport concussion guideline, which was accompanied by a greater variety of GItools, the mobile phone quick reference check application was most frequently accessed, followed by the clinician summary, patient summary, and slide presentation. For the sports concussion guideline survey, most respondents (response rate 21.8%, 168/797) were aware of the guideline (88.1%) and had read the guideline (78.6%). For GItool use, respondents indicated reading the reference card (51.2%), clinician summary (45.2%), patient summary (28.0%), mobile phone application (26.2%), and coach/athletic trainer summary (20.2%). Patterns of sports concussion GItool use were similar between respondents who said they had and had not yet implemented the guideline.

Conclusions

Developers faced with resource limitations may wish to prioritize the development of printable or mobile application clinician summaries, which were accessed significantly more than other types of GItools. Further research is needed to understand how to optimize the design of such GItools.

Related or not? Development of spontaneous Creutzfeldt-Jakob disease in a patient with chronic, well-controlled HIV: A case report and review of the literature

BACKGROUND

We report a novel case of a rare disease: spontaneous Creutzfeldt-Jakob disease in a patient with well-controlled HIV. We explore the relationship between spontaneous Creutzfeldt-Jakob disease and HIV.

CASE REPORT

A 66-year-old man with long-standing, well-controlled HIV infection presented with 3 months of progressive, subacute neurocognitive decline. His symptoms included conceptual apraxia, apathy, memory impairment, and gait disturbance, and were initially attributed to depressive "pseudo-dementia." Unfortunately, the patient's symptoms rapidly progressed and he ultimately succumbed to his illness. Autopsy confirmed the clinical diagnosis of spontaneous Creutzfeldt-Jakob disease.

DISCUSSION

This case highlights spontaneous Creutzfeldt-Jakob disease as a rare terminal illness in the setting of well-controlled chronic HIV. To our knowledge, this is the first report of a patient with chronic and previously well-controlled HIV infection dying from a prion disease. Despite the very different epidemiology and pathophysiology of HIV and spontaneous Creutzfeldt-Jakob disease, this case does raise questions of whether certain host genetic factors could predispose to both conditions, albeit currently, there is no clear causal link between HIV and spontaneous Creutzfeldt-Jakob disease.

Prion Diseases

PURPOSE OF REVIEW

This article presents an update on the clinical aspects of human prion disease, including the wide spectrum of their presentations.

RECENT FINDINGS

Prion diseases, a group of disorders caused by abnormally shaped proteins called prions, occur in sporadic (Jakob-Creutzfeldt disease), genetic (genetic Jakob-Creutzfeldt disease, Gerstmann-Sträussler-Scheinker syndrome, and fatal familial insomnia), and acquired (kuru, variant Jakob-Creutzfeldt disease, and iatrogenic Jakob-Creutzfeldt disease) forms. This article presents updated information on the clinical features and diagnostic methods for human prion diseases. New antemortem potential diagnostic tests based on amplifying prions in order to detect them are showing very high specificity. Understanding of the diversity of possible presentations of human prion diseases continues to evolve, with some genetic forms progressing slowly over decades, beginning with dysautonomia and neuropathy and progressing to a frontal-executive dementia with pathology of combined prionopathy and tauopathy. Unfortunately, to date, all human prion disease clinical trials have failed to show survival benefit. A very rare polymorphism in the prion protein gene recently has been identified that appears to protect against prion disease; this finding, in addition to providing greater understanding of the prionlike mechanisms of neurodegenerative disorders, might lead to potential treatments.

SUMMARY

Sporadic Jakob-Creutzfeldt disease is the most common form of human prion disease. Genetic prion diseases, resulting from mutations in the prion-related protein gene (PRNP), are classified based on the mutation, clinical phenotype, and neuropathologic features and can be difficult to diagnose because of their varied presentations. Perhaps most relevant to this Continuum issue on neuroinfectious diseases, acquired prion diseases are caused by accidental transmission to humans, but fortunately, they are the least common form and are becoming rarer as awareness of transmission risk has led to implementation of measures to prevent such occurrences.

Development of a dot blot assay with antibodies to recombinant "core" 14-3-3 protein: Evaluation of its usefulness in diagnosis of Creutzfeldt-Jakob disease

BACKGROUND AND PURPOSE

Definitive diagnosis of Creutzfeldt-Jakob disease (CJD) requires demonstration of infective prion protein (PrP(Sc)) in brain tissues by immunohistochemistry or immunoblot, making antemortem diagnosis of CJD difficult. The World Health Organization (WHO) recommends detection of 14-3-3 protein in cerebrospinal fluid (CSF) in cases of dementia, with clinical correlation, as a useful diagnostic marker for CJD, obviating the need for brain biopsy. This facility is currently available in only a few specialized centers in the West and no commercial kit is available for clinical diagnostic use in India. Hence the objective of this study was to develop an in-house sensitive assay for quantitation of 14-3-3 protein and to evaluate its diagnostic potential to detect 14-3-3 proteins in CSF as a biomarker in suspected cases of CJD.

MATERIALS AND METHODS

A minigene expressing the "core" 14-3-3 protein was synthesized by overlapping polymerase chain reaction (PCR) and the recombinant protein was produced by employing a bacterial expression system. Polyclonal antibodies raised in rabbit against the purified recombinant protein were used for developing a dot blot assay with avidin-biotin technology for signal amplification and quantitation of 14-3-3 protein in CSF.

RESULTS

The results in the present study suggest the diagnostic potential of the dot blot method with about 10-fold difference (P< 0.001) in the CSF levels of 14-3-3 protein between the CJD cases (N= 50) and disease controls (N= 70). The receiver operating characteristic (ROC) analysis of the results suggested an optimal cutoff value of 2 ng/mL.

CONCLUSIONS

We have developed an indigenous, economical, and sensitive dot blot method for the quantitation of 14-3-3 protein in CSF.

Case Studies Illustrating Focal Alzheimer's, Fluent Aphasia, Late-Onset Memory Loss, and Rapid Dementia

Many dementia subtypes have more shared signs and symptoms than defining ones. We review 8 cases with 4 overlapping syndromes and demonstrate how to distinguish the cases. These include focal cortical presentations of Alzheimer's disease (AD; posterior cortical atrophy and corticobasal syndrome [CBS]), fluent aphasia (semantic dementia and logopenic aphasia), late-onset slowly progressive dementia (hippocampal sclerosis and limbic predominant AD) and rapidly progressive dementia (Creutzfeldt-Jakob disease and limbic encephalitis). Recognizing the different syndromes can help the clinician to improve their diagnostic skills, leading to improved patient outcomes by early and accurate diagnosis, prompt treatment, and appropriate counseling and guidance.

Biomarkers for sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare but fatal type of spongiform encephalopathy with unknown cause. Unfortunately, definitive diagnosis of this disease can only be done by examination of postmortem brain tissue. Presumptive diagnosis is done through a combination of clinical manifestations, radiology results, and cerebrospinal fluid (CSF) testing for CSF 14-3-3. Even with these guidelines, premortem diagnosis of sCJD can be unreliable with high rates of misdiagnosis. This calls for more reliable biomarkers of the disease, allowing for better diagnosis as well as understanding the pathogenesis of sCJD. This review compiles potential genetic, protein, biomolecular, and imaging biomarker studies for sCJD since 2010, highlighting the promise of proteins, cytokines, and composite biomarkers for improving the diagnosis as well as understanding the pathogenesis of this mysterious ailment.

A rare case of rapidly progressive dementia with elevated RT-QuIC and negative 14-3-3 and tau proteins

Creutzfeldt-Jakob disease (CJD) is characterized by rapidly progressing dementia with death usually occurring within 6 months. There is no verified disease-specific pre-mortem diagnostic test besides brain biopsy. We describe a 66 y old previously high functioning male who presented with a 5 month history of rapidly progressive dementia. Neurological examination revealed a score of 19/30 on MOCA testing. An extensive workup into various causes of dementia including electroencephalography and imaging studies was unremarkable. The cerebrospinal fluid was sent to National Prion Disease Center and it revealed elevated RT-QuIC levels with negative 14-3-3 and T tau proteins. Based on literature review, our case is one of few living subjects with elevated RT-QuIC levels and negative 14-3-3 and tau proteins.

Partial verification bias and incorporation bias affected accuracy estimates of diagnostic studies for biomarkers that were part of an existing composite gold standard

OBJECTIVE

To investigate how choice of gold standard biases estimates of sensitivity and specificity in studies reassessing the diagnostic accuracy of biomarkers that are already part of a lifetime composite gold standard (CGS).

STUDY DESIGN AND SETTING

We performed a simulation study based on the real-life example of the biomarker "protein 14-3-3" used for diagnosing Creutzfeldt-Jakob disease. Three different types of gold standard were compared: perfect gold standard "autopsy" (available in a small fraction only; prone to partial verification bias), lifetime CGS (including the biomarker under investigation; prone to incorporation bias), and "best available" gold standard (autopsy if available, otherwise CGS).

RESULTS

Sensitivity was unbiased when comparing 14-3-3 with autopsy but overestimated when using CGS or "best available" gold standard. Specificity of 14-3-3 was underestimated in scenarios comparing 14-3-3 with autopsy (up to 24%). In contrast, overestimation (up to 20%) was observed for specificity compared with CGS; this could be reduced to 0-10% when using the "best available" gold standard.

CONCLUSION

Choice of gold standard affects considerably estimates of diagnostic accuracy. Using the "best available" gold standard (autopsy where available, otherwise CGS) leads to valid estimates of specificity, whereas sensitivity is estimated best when tested against autopsy alone.

Sporadic Creutzfeldt-Jakob disease diagnostic accuracy is improved by a new CSF ELISA 14-3-3γ assay

Protein 14-3-3 is a reliable marker of rapid neuronal damage, specifically increased in cerebrospinal fluid (CSF) of sporadic Creutzfeldt-Jakob disease (sCJD) patients. Its detection is usually performed by Western Blot (WB), prone to methodological issues. Our aim was to evaluate the diagnostic performance of a recently developed quantitative enzyme-linked immunosorbent (ELISA) assay for 14-3-3γ, in comparison with WB and other neurodegeneration markers. CSF samples from 145 patients with suspicion of prion disease, later classified as definite sCJD (n=72) or Non-prion diseases (Non-CJD; n=73) comprised our population. 14-3-3 protein was determined by WB and ELISA. Total Tau (t-Tau) and phosphorylated Tau (p-Tau) were also evaluated. Apolipoprotein E gene (ApoE) and prionic protein gene (PRNP) genotyping was assessed. ELISA 14-3-3γ levels were significantly increased in sCJD compared to Non-CJD patients (p<0.001), showing very good accuracy (AUC=0.982; sensitivity=97%; specificity=94%), and matching WB results in 81% of all cases. It strongly correlated with t-Tau and p-Tau (p<0.0001), showing slightly higher specificity (14-3-3 WB - 63%; Tau - 90%; p-Tau/t-Tau ratio - 88%). From WB inconclusive results (n=44), ELISA 14-3-3γ correctly classified 41 patients. Additionally, logistic regression analysis selected ELISA 14-3-3γ as the best single predictive marker for sCJD (overall accuracy=93%). ApoE and PRNP genotypes did not influence ELISA 14-3-3γ levels. Despite specificity for 14-3-3γ isoform, ELISA results not only match WB evaluation but also help discrimination of inconclusive results. Our results therefore reinforce this assay as a single screening test, allowing higher sample throughput and unequivocal results.

Characteristics of Korean patients with suspected Creutzfeldt-Jakob disease with 14-3-3 protein in cerebrospinal fluid: Preliminary study of the Korean Creutzfeldt-Jakob disease active surveillance program

Although Korea had a national surveillance system for Creutzfeldt-Jakob disease (CJD), it was mainly dependent on attending physician's reports. Thus, little prospective data about the epidemiology, characteristics, and final diagnoses of suspected patients were available. We have established a nationwide network for the active surveillance of patients with suspected CJD. When the requested cerebrospinal fluid (CSF) samples tested positive for 14-3-3 protein, we investigated the clinical characteristics of the corresponding patients and followed them until their final diagnoses were confirmed. A total of 218 samples were requested for CSF assays from May 2010 to August 2012, and 106 (48.6%) were positive for 14-3-3 protein. In 89 patients with complete clinical data, 38 (42.7%) were diagnosed with probable CJD and the estimated annual occurrence of CJD was 16.3 persons-per-year. The most common diagnoses of the remainder were central nervous system infection and any-cause encephalopathy. Non-CJD subjects showed worse initial consciousness levels than CJD patients. This preliminary study showed that the number of reported cases of CJD and the true positivity rates of CSF 14-3-3 protein assays were both low in Korea. An active surveillance system is urgently needed to provide the latest nationwide epidemiological data of CJD.

Clinical update of Jakob-Creutzfeldt disease

PURPOSE OF REVIEW

The present review discusses recent clinical data on diagnosis, new forms, and treatment of human prion diseases, and briefly summarizes research suggesting prion-like mechanisms in other neurodegenerative diseases.

RECENT FINDINGS

When proper sequences are performed, MRI has high diagnostic utility in prion disease, but there are issues with interpretation of images. The spectrum of MRI's utility for diagnosis and understanding human prion disease is still being explored. Two recent diffusion tensor imaging studies quantified changes in the gray and white matter in sporadic Jakob-Creutzfeldt disease, with unexpected results. The diagnostic utility of cerebrospinal fluid biomarkers has been controversial. A few studies showed that amplification methods can detect prions in either cerebrospinal fluid, olfactory epithelium, blood and/or urine in various human prion diseases. Additional cases of variably protease-sensitive prionopathy have led to a broader understanding of this novel sporadic prion disease. A few new mutations causing genetic prion disease, one with a very atypical presentation, have been identified. Although recent human prion disease treatment trials did not show benefit, they have improved our understanding, and led to better quantification, of the progression of these disorders. Lastly, we briefly summarize the increasing evidence that many nonprion neurodegenerative proteinopathies might spread in the brain by a prion-like mechanism.

SUMMARY

New prion detection methods appear promising, but need to be replicated with larger sample sizes. Identification of novel forms of human prion disease might better elucidate the full spectrum of prion diseases and expand our understanding of their pathogenesis.

A genome-wide association study on amyotrophic lateral sclerosis in the Taiwanese Han population

Identification of mutations in patients with amyotrophic lateral sclerosis (ALS) in a genome-wide association study can reveal possible biomarkers of such a rapidly progressive and fatal neurodegenerative disease. It was observed that significant single nucleotide polymorphisms vary when the tested population changes from one ethnic group to another. To identify new loci associated with ALS susceptibility in the Taiwanese Han population, we performed a genome-wide association study on 94 patients with sporadic ALS and 376 matched controls. We uncovered two new susceptibility loci at 13q14.3 (rs2785946) and 11q25 (rs11224052). In addition, we analyzed the functions of all the associated genes among 54 significant single nucleotide polymorphisms using Gene Ontology annotations, and the results showed several statistically significant neural- and muscle-related Gene Ontology terms and the associated diseases.

How many biomarkers to discriminate neurodegenerative dementia?

A number of cerebrospinal fluid (CSF) biomarkers are currently used for the diagnosis of dementia. Opposite changes in the level of amyloid-β(1-42) versus total tau and phosphorylated-tau181 in the CSF reflect the specific pathology of Alzheimer's disease (AD) in the brain. This panel of biomarkers has proven to be effective to differentiate AD from controls and from the major types of neurodegenerative dementia, and to evaluate the progression from mild cognitive impairment to AD. In the absence of specific biomarkers reflecting the pathologies of the other most common forms of dementia, such as Lewy Body disease, Frontotemporal lobar degeneration, Creutzfeldt-Jakob disease, etc., the evaluation of biomarkers of AD pathology is used, attempting to exclude rather than to confirm AD. Other biomarkers included in the common clinical practice do not clearly relate to the underlying pathology: progranulin (PGRN) is a selective marker of frontotemporal dementia with mutations in the PGRN gene; the 14-3-3 protein is a highly sensitive and specific marker for Creutzfeldt-Jakob disease, but has to be used carefully in differentiating rapid progressive dementia; and α-synuclein is an emerging candidate biomarker of the different forms of synucleinopathy. This review summarizes several biomarkers of neurodegenerative dementia validated based on the neuropathological processes occurring in brain tissue. Notwithstanding the paucity of pathologically validated biomarkers and their high analytical variability, the combinations of these biomarkers may well represent a key and more precise analytical and diagnostic tool in the complex plethora of degenerative dementia.

The use of cerebrospinal fluid and neuropathologic studies in neuropsychiatry practice and research

The gold standard for diagnosis of neurodegenerative diseases (ie, Alzheimer disease, frontotemporal dementia, Parkinson disease, dementia with Lewy bodies, amyotrophic lateral sclerosis) is neuropathologic examination at autopsy. As such, laboratory studies play a central role in antemortem diagnosis of these conditions and their differentiation from the neuroinflammatory, infectious, toxic, and other nondegenerative etiologies (eg, rapidly progressive dementias) that are encountered in neuropsychiatric practice. This article summarizes the use of cerebrospinal fluid (CSF) laboratory studies in the diagnostic evaluation of dementia syndromes and emerging CSF biomarkers specific for underlying neuropathology in neurodegenerative disease research.

Brain imaging in the differential diagnosis of young-onset dementias

Young-onset dementia is a broad category of diseases that affect adults before the age of 65, with devastating effects on individuals and families. Neuroimaging plays a clear and ever-expanding role in the workup of these diseases. MRI demonstrates classic patterns of atrophy that help to confirm the clinical diagnosis and may predict the underlying disease. Functional nuclear imaging, such as PET, demonstrates areas of brain dysfunction even in the absence of visible atrophy. These techniques can inform important aspects of the care of young-onset dementia, such as the underlying pathologic condition, treatment, and prognosis.

Proteinase-activated receptor 2 and disease biomarkers in cerebrospinal fluid in cases with autopsy-confirmed prion diseases and other neurodegenerative diseases

BACKGROUND

Proteinase-activated receptor 2 (PAR-2) has been shown to promote both neurotoxic and neuroprotective effects. Similarly, other routinely used nonspecific markers of neuronal damage can be found in cerebrospinal fluid (CSF) and can be used as biomarkers for different neurodegenerative disorders.

METHODS

Using enzyme-linked immunosorbent assays and western blotting we assessed PAR-2, total-tau, phospho-tau, beta-amyloid levels, and protein 14-3-3 in the CSF of former patients who had undergone a neuropathological autopsy after death and who had been definitively diagnosed with a prion or other neurodegenerative disease.

RESULTS

We did not find any significant correlation between levels of PAR-2 and other biomarkers, nor did we find any differences in PAR-2 levels between prion diseases and other neurodegenerative conditions. However, we confirmed that very high total-tau levels were significantly associated with definitive prion diagnoses and exhibited greater sensitivity and specificity than protein 14-3-3, which is routinely used as a marker.

CONCLUSIONS

Our study showed that PAR-2, in CSF, was not specifically altered in prion diseases compared to other neurodegenerative conditions. Our results also confirmed that very high total-tau protein CSF levels were significantly associated with a definitive Creutzfeldt-Jakob disease (CJD) diagnosis and should be routinely tested as a diagnostic marker. Observed individual variability in CSF biomarkers provide invaluable feedback from neuropathological examinations even in "clinically certain" cases.

Comparing CSF biomarkers and brain MRI in the diagnosis of sporadic Creutzfeldt-Jakob disease

We assessed the diagnostic utility of 3 CSF biomarkers-14-3-3 protein, total tau (T-tau), and neuron-specific enolase (NSE)-from the same lumbar puncture to distinguish between participants with neuropathologically confirmed sporadic Creutzfeldt-Jakob disease (sCJD, n = 57) and controls with nonprion rapidly progressive dementia (npRPD, n = 41). Measures of diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value, as well as logistic regression and area under the receiver operator curve (AUC), were used to assess the ability of these CSF biomarkers, alone or concomitantly, to predict diagnosis. In a subcohort with available MRI (sCJD n = 57, npRPD = 32), we compared visual assessment of diffusion-weighted imaging MRI sequences to these CSF biomarkers. MRI was the best predictor, with an AUC of 0.97 (confidence interval [CI] 0.92-1.00) and a diagnostic accuracy of 97% (CI 90%-100%). Of the CSF biomarkers, T-tau had a higher diagnostic accuracy (79.6%) than 14-3-3 (70.4%, CI for difference 8.7%, 9.7%; p = 0.048) or NSE (71.4%, CI for difference 7.6%, 8.7%; p = 0.03).

A study of clinical profile, radiological and electroencephalographic characteristics of suspected Creutzfeldt-Jakob disease in a tertiary care centre in South India

Introduction:

Creutzfeldt-Jakob disease (CJD) is a progressive, fatal, neurodegenerative disease classified under transmissible spongiform encephalopathies (TSE) or prion diseases. It is characterized by long asymptomatic period followed by rapid clinical deterioration leading to the death within months. The disease is still under-reported in India.

Objective:

The aim of this study was to describe the clinical, radiological and electroencephalographic characteristics of eight cases of CJD encountered in MS Ramaiah Medical college and Hospital, Bangalore over the past 3 years (2010-2013). This was retrospective, observational, hospital-based study.

Results:

The mean age of patients was 66.6 years (range: 54-82) and there was female predominance (five patients). The main clinical manifestations were cognitive disturbance (8/8) and myoclonus (8/8), followed by behavioral disturbance (5/8), ataxia (5/8) and extra-pyramidal symptoms/signs (4/8). Time interval (mean) between onset of disease to death was 6.6 months (range: 3-14). Brain MRI abnormalities were noted in 6 patients: Fluid-attenuated inversion recovery hyperintensities with restriction on diffusion-weighted image/apparent diffusion coefficient (DWI/ADC) in caudate and putamen, and diffusion hyperintensities without restriction on ADC in parieto-occipital, frontal and temporal regions. Classical electroencephalogram (EEG) changes of periodic triphasic waves were seen in 87% of patients. The CSF 14-3-3 protein assay was positive in two patients (out of four). Seven cases were probable CJD and one was possible CJD.

Conclusion:

A strong clinical suspicion aided by characteristic brain MRI and EEG abnormalities is essential for timely diagnosis of this fatal disease.

Magnetic resonance imaging findings in probable Creutzfeld-Jacob disease: comparison with electroencephalography and cerebrospinal fluid characteristics

BACKGROUND

Creutzfeld-Jacob disease (CJD) is a rare, progressive disease that has a vast clinical manifestation range. Cranial magnetic resonance imaging (MRI), electroencephalography (EEG), and measurement of 14-3-3 in cerebrospinal fluid (CSF) may offer a pragmatic approach in the diagnosis of CJD as an alternative to histopathological confirmation.

PURPOSE

To present the symptoms and signs of the CJD patients in regard to radiological and neurophysiological findings.

MATERIAL AND METHODS

We collected all cases with the diagnosis of probable CJD admitted to our neurology department between June 2010 and June 2014. The medical records and laboratory data, clinical features, results of MRI (including diffusion weighted images), EEG and CSF evaluations, and other laboratory data to exclude other possible diagnoses were recorded. None of the patients underwent biopsy or autopsy for histological diagnosis.

RESULTS

Of 20 patients, 11 (55%) were men and nine (45%) were women. The mean age at disease onset was 60.0 ± 9.5 years (age range, 47-80 years). All patients without exception had characteristic abnormalities in DWI and/or FLAIR on admission, about 4 months after the initial symptom. Periodic complexes on EEGs characteristic for CJD were detected only in 10 patients (50%) on admission and in 13 patients (65%) during disease course. Out of 14 patients who underwent CSF examination, 11 (78.5%) were positive for 14-3-3 protein.

CONCLUSION

Although the definite diagnosis of CJD is made histopathologically, we aimed to discuss the value of magnetic resonance imaging in the diagnosis of CJD in respect to EEG findings and protein 14-3-3 levels in CSF.

Prionic diseases

Prion diseases are neurodegenerative illnesses due to the accumulation of small infectious pathogens containing protein but apparently lacking nucleic acid, which have long incubation periods and progress inexorably once clinical symptoms appear. Prions are uniquely resistant to a number of normal decontaminating procedures. The prionopathies [Kuru, Creutzfeldt-Jakob disease (CJD) and its variants, Gerstmann-Sträussler-Scheinker (GSS) syndrome and fatal familial insomnia (FFI)] result from accumulation of abnormal isoforms of the prion protein in the brains of normal animals on both neuronal and non-neuronal cells. The accumulation of this protein or fragments of it in neurons leads to apoptosis and cell death. There is a strong link between mutations in the gene encoding the normal prion protein in humans (PRNP) - located on the short arm of chromosome 20 - and forms of prion disease with a familial predisposition (familial CJD, GSS, FFI). Clinically a prionopathy should be suspected in any case of a fast progressing dementia with ataxia, myoclonus, or in individuals with pathological insomnia associated with dysautonomia. Magnetic resonance imaging, identification of the 14-3-3 protein in the cerebrospinal fluid, tonsil biopsy and genetic studies have been used for in vivo diagnosis circumventing the need of brain biopsy. Histopathology, however, remains the only conclusive method to reach a confident diagnosis. Unfortunately, despite numerous treatment efforts, prionopathies remain short-lasting and fatal diseases.

Determination of neuronal antibodies in suspected and definite Creutzfeldt-Jakob disease

IMPORTANCE

Creutzfeldt-Jakob disease (CJD) and autoimmune encephalitis with antibodies against neuronal surface antigens (NSA-abs) may present with similar clinical features. Establishing the correct diagnosis has practical implications in the management of care for these patients.

OBJECTIVE

To determine the frequency of NSA-abs in the cerebrospinal fluid of patients with suspected CJD and in patients with pathologically confirmed (ie, definite) CJD.

DESIGN, SETTING, AND PARTICIPANTS

A mixed prospective (suspected) and retrospective (definite) CJD cohort study was conducted in a reference center for detection of NSA-abs. The population included 346 patients with suspected CJD and 49 patients with definite CJD.

MAIN OUTCOMES AND MEASURES

Analysis of NSA-abs in cerebrospinal fluid with brain immunohistochemistry optimized for cell-surface antigens was performed. Positive cases in the suspected CJD group were further studied for antigen specificity using cell-based assays. All definite CJD cases were comprehensively tested for NSA-abs, with cell-based assays used for leucine-rich glioma-inactivated 1 (LGI1), contactin-associated protein-like 2 (CASPR2), N-methyl-d-aspartate (NMDA), and glycine (GlY) receptors.

RESULTS

Neuronal surface antigens were detected in 6 of 346 patients (1.7%) with rapid neurologic deterioration suggestive of CJD. None of these 6 patients fulfilled the diagnostic criteria for probable or possible CJD. The target antigens included CASPR2, LGI1, NMDAR, aquaporin 4, Tr (DNER [δ/notch-like epidermal growth factor-related receptor]), and an unknown protein. Four of the patients developed rapidly progressive dementia, and the other 2 patients had cerebellar ataxia or seizures that were initially considered to be myoclonus without cognitive decline. The patient with Tr-abs had a positive 14-3-3 test result. Small cell lung carcinoma was diagnosed in the patient with antibodies against an unknown antigen. All patients improved or stabilized after appropriate treatment. None of the 49 patients with definite CJD had NSA-abs.

CONCLUSIONS AND RELEVANCE

A low, but clinically relevant, number of patients with suspected CJD had potentially treatable disorders associated with NSA-abs. In contrast, none of 49 patients with definite CJD had NSA-abs, including NMDAR-abs, GlyR-abs, LGI1-abs, or CASPR2-abs. These findings suggest that cerebrospinal fluid NSA-abs analysis should be included in the diagnostic workup of patients with rapidly progressive central nervous system syndromes, particularly when they do not fulfill the diagnostic criteria of probable or possible CJD.

A low-molecular-weight ferroxidase is increased in the CSF of sCJD cases: CSF ferroxidase and transferrin as diagnostic biomarkers for sCJD

AIMS

Most biomarkers used for the premortem diagnosis of sporadic Creutzfeldt-Jakob disease (CJD) are surrogate in nature, and provide suboptimal sensitivity and specificity.

RESULTS

We report that CJD-associated brain iron dyshomeostasis is reflected in the cerebrospinal fluid (CSF), providing disease-specific diagnostic biomarkers. Analysis of 290 premortem CSF samples from confirmed cases of CJD, Alzheimer's disease, and other dementias (DMs), and 52 non-DM (ND) controls revealed a significant difference in ferroxidase (Frx) activity and transferrin (Tf) levels in sporadic Creutzfeldt-Jakob disease (sCJD) relative to other DM and ND controls. A combination of CSF Frx and Tf discriminated sCJD from other DMs with a sensitivity of 86.8%, specificity of 92.5%, accuracy of 88.9%, and area-under-the receiver-operating-characteristic (ROC) curve of 0.94. This combination provided a similar diagnostic accuracy in discriminating CJD from rapidly progressing cases who died within 6 months of sample collection. Surprisingly, ceruloplasmin and amyloid precursor protein, the major brain Frxs, displayed minimal activity in the CSF. Most of the Frx activity was concentrated in the <3-kDa fraction in normal and diseased CSF, and resisted heat and proteinase-K treatment.

INNOVATION

(i) A combination of CSF Frx and Tf provides disease-specific premortem diagnostic biomarkers for sCJD. (ii) A novel, nonenzymatic, nonprotein Frx predominates in human CSF that is distinct from the currently known CSF Frxs.

CONCLUSION

The underlying cause of iron imbalance is distinct in sCJD relative to other DMs associated with the brain iron imbalance. Thus, change in the CSF levels of iron-management proteins can provide disease-specific biomarkers and insight into the cause of iron imbalance in neurodegenerative conditions.

A multidisciplinary approach to study a couple of monozygotic twins discordant for the chronic fatigue syndrome: a focus on potential salivary biomarkers

BACKGROUND

Chronic Fatigue Syndrome (CFS) is a severe, systemic illness characterized by persistent, debilitating and medically unexplained fatigue. The etiology and pathophysiology of CFS remains obscure, and diagnosis is formulated through the patient's history and exclusion of other medical causes. Thereby, the availability of biomarkers for CFS could be useful for clinical research. In the present study, we used a proteomic approach to evaluate the global changes in the salivary profile in a couple of monozygotic twins who were discordant for CFS. The aim was to evaluate differences of salivary protein expression in the CFS patient in respect to his healthy twin.

METHODS

Saliva samples were submitted to two-dimensional electrophoresis (2DE). The gels were stained with Sypro, and a comparison between CFS subject and the healthy one was performed by the software Progenesis Same Spot including the Analysis of variance (ANOVA test). The proteins spot found with a ≥2-fold spot quantity change and p<0.05 were identified by Nano-liquid chromatography electrospray ionization tandem mass spectrometry. To validate the expression changes found with 2DE of 5 proteins (14-3-3 protein zeta/delta, cyclophilin A, Cystatin-C, Protein S100-A7, and zinc-alpha-2-glycoprotein), we used the western blot analysis. Moreover, proteins differentially expressed were functionally analyzed using the Ingenuity Pathways Analysis software with the aim to determine the predominant canonical pathways and the interaction network involved.

RESULTS

The analysis of the protein profiles allowed us to find 13 proteins with a different expression in CFS in respect to control. Nine spots were up-regulated in CFS and 4 down-regulated. These proteins belong to different functional classes, such as inflammatory response, immune system and metabolism. In particular, as shown by the pathway analysis, the network built with our proteins highlights the involvement of inflammatory response in CFS pathogenesis.

CONCLUSIONS

This study shows the presence of differentially expressed proteins in the saliva of the couple of monozygotic twins discordant for CFS, probably related to the disease. Consequently, we believe the proteomic approach could be useful both to define a panel of potential diagnostic biomarkers and to shed new light on the comprehension of the pathogenetic pathways of CFS.