Diagnostic accuracy of cerebrospinal fluid biomarkers in genetic prion diseases.

Genetic prion diseases are a rare and diverse group of fatal neurodegenerative disorders caused by pathogenic sequence variations in the prion protein gene, PRNP. Data on CSF biomarkers in patients with genetic prion diseases are limited and conflicting results have been reported for unclear reasons. Here, we aimed to analyse the diagnostic accuracy of CSF biomarkers currently used in prion clinical diagnosis in 302 symptomatic genetic prion disease cases from 11 prion diagnostic centres, encompassing a total of 36 different pathogenic sequence variations within the open reading frame of PRNP. CSF samples were assessed for the surrogate markers of neurodegeneration, 14-3-3 protein (14-3-3), total-tau protein (t-tau) and α-synuclein and for prion seeding activity through the real-time quaking-induced conversion assay. Biomarker results were compared with those obtained in healthy and neurological controls. For the most prevalent PRNP pathogenic sequence variations, biomarker accuracy and associations between biomarkers, demographic and genetic determinants were assessed. Additionally, the prognostic value of biomarkers for predicting total disease duration from symptom onset to death was investigated. High sensitivity of the four biomarkers was detected for genetic Creutzfeldt-Jakob disease associated with the E200K and V210I mutations, but low sensitivity was observed for mutations associated with Gerstmann-Sträussler-Scheinker syndrome and fatal familial insomnia. All biomarkers showed good to excellent specificity using the standard cut-offs often used for sporadic Creutzfeldt-Jakob disease. In genetic prion diseases related to octapeptide repeat insertions, the biomarker sensitivity correlated with the number of repeats. New genetic prion disease-specific cut-offs for 14-3-3, t-tau and α-synuclein were calculated. Disease duration in genetic Creutzfeldt-Jakob disease-E200K, Gerstmann-Sträussler-Scheinker-P102L and fatal familial insomnia was highly dependent on PRNP codon 129 MV polymorphism and was significantly associated with biomarker levels. In a large cohort of genetic prion diseases, the simultaneous analysis of CSF prion disease biomarkers allowed the determination of new mutation-specific cut-offs improving the discrimination of genetic prion disease cases and unveiled genetic prion disease-specific associations with disease duration.

Blood ß-Synuclein and Neurofilament Light Chain During the Course of Prion Disease.

BACKGROUND AND OBJECTIVES: For early diagnosis and disease monitoring of neurodegenerative diseases (NDs), reliable blood biomarkers are needed. Elevated levels of neurofilament light chain protein (NfL), an axonal damage marker, have been described across different NDs, with highest values in prion diseases and amyotrophic lateral sclerosis (ALS). Synaptic degeneration is a common early feature in most NDs and seems to precede neuronal degeneration in prion disease. However, synaptic markers in blood are still missing. Here, we investigated whether the brain-specific protein ß-synuclein might be a suitable blood biomarker for early diagnosis and evaluation of synaptic integrity in prion disease. METHODS: We analyzed blood ß-synuclein with a newly established digital ELISA and NfL with a single-molecule array in samples obtained from human participants and prion and ALS animal models. Furthermore, ß-synuclein was investigated in brain tissue of individuals with Creutzfeldt-Jakob disease (CJD) and controls. RESULTS: We investigated 308 patients, including 129 cases with prion disease, 8 presymptomatic PRNP variation carriers, 60 with ALS, 68 with other ND, and 43 control patients. In CJD symptomatic cases, ß-synuclein and NfL were markedly increased compared to all other diagnostic groups (p < 0.001). In the large majority of presymptomatic PRNP variation carriers, ß-synuclein and NfL levels were within normal ranges. In prion disease animal models, ß-synuclein and NfL displayed normal levels in the presymptomatic phase with a sudden elevation at disease onset and a plateau in the symptomatic phase. In contrast to NfL, ß-synuclein was not elevated in either symptomatic patients with ALS or an ALS animal model. In the discrimination between prion disease and all other groups, ß-synuclein (area under the curve 0.97, 95% CI 0.94-0.99, p < 0.001) was superior to NfL (area under the curve 0.91, 95% CI 0.88-0.94, p < 0.001). In addition, brain tissue ß-synuclein showed significantly reduced levels in patients with CJD compared to control patients (p < 0.001). DISCUSSION: Blood ß-synuclein was significantly elevated in patients with CJD, reflecting ongoing synaptic damage, and showed good discriminative characteristics. We therefore propose it as a candidate blood marker for early diagnosis and monitoring of synaptic integrity in prion disease. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that serum ß-synuclein concentration accurately distinguishes patients with symptomatic CJD from controls.

Genetic Risk Factors of Creutzfeldt-Jakob Disease in the Population of Newborns in Slovakia.

The most frequent human prion disease is Creutzfeldt-Jakob disease (CJD). It occurs as sporadic (sCJD), genetic (gCJD), iatrogenic (iCJD) form and as variant CJD. The genetic form represents about 10-15% of confirmed cases worldwide, in Slovakia as much as 65-75%. Focal accumulation of gCJD was confirmed in Orava region. The most common point mutation of the prion protein gene (PRNP) is E200K. CJD has a long asymptomatic phase and it is not known when the carriers of the mutation E200K become infectious. Precautions to prevent iCJD are focused especially on clinical CJD cases, but asymptomatic CJD-specific mutation carriers cannot be excluded, and represent a potential genetic CJD-risk group. The aim of this study was to determine the occurrence, frequency and geographic distribution of the E200K mutation among the newborns, comparing the areas of focal accumulation of gCJD with extra-focal ones, as well as distribution of the polymorphism M129V of the PRNP gene. A total of 2915 samples of dry blood spots from anonymous newborns were analyzed. We used RealTime PCR method to determine the presence of the E200K mutation and the M129V polymorphism. Genetic testing revealed 13 carriers of the E200K mutation. Investigation of the M129V polymorphism affirmed higher representation of methionine homozygotes (48% MM, 44% MV, 8% VV). Achieved results fully confirmed our previous observations concerning both the specific and nonspecific genetic CJD risk among the Slovak general population. The 48% of methionine homozygotes and 4 carriers of the E200K mutation among 1000 live-born children in Slovakia underline the benefits of genetic testing.

Autoantibodies against the prion protein in individuals with PRNP mutations.

OBJECTIVE: To determine whether naturally occurring autoantibodies against the prion protein are present in individuals with genetic prion disease mutations and controls, and if so, whether they are protective against prion disease. METHODS: In this case-control study, we collected 124 blood samples from individuals with a variety of pathogenic PRNP mutations and 78 control individuals with a positive family history of genetic prion disease but lacking disease-associated PRNP mutations. Antibody reactivity was measured using an indirect ELISA for the detection of human immunoglobulin G1-4 antibodies against wild-type human prion protein. Multivariate linear regression models were constructed to analyze differences in autoantibody reactivity between (1) PRNP mutation carriers vs controls and (2) asymptomatic vs symptomatic PRNP mutation carriers. Robustness of results was examined in matched cohorts. RESULTS: We found that antibody reactivity was present in a subset of both PRNP mutation carriers and controls. Autoantibody levels were not influenced by PRNP mutation status or clinical manifestation of prion disease. Post hoc analyses showed anti-PrPC autoantibody titers to be independent of personal history of autoimmune disease and other immunologic disorders, as well as PRNP codon 129 polymorphism. CONCLUSIONS: Pathogenic PRNP variants do not notably stimulate antibody-mediated anti-PrPC immunity. Anti-PrPC immunoglobulin G autoantibodies are not associated with the onset of prion disease. The presence of anti-PrPC autoantibodies in the general population without any disease-specific association suggests that relatively high titers of naturally occurring antibodies are well-tolerated. CLINICALTRIALSGOV IDENTIFIER: NCT02837705.

Cerebrospinal Fluid Total Prion Protein in the Spectrum of Prion Diseases.

Cerebrospinal fluid (CSF) total prion protein (t-PrP) is decreased in sporadic Creutzfeldt-Jakob disease (sCJD). However, data on the comparative signatures of t-PrP across the spectrum of prion diseases, longitudinal changes during disease progression, and levels in pre-clinical cases are scarce. T-PrP was quantified in neurological diseases (ND, n = 147) and in prion diseases from different aetiologies including sporadic (sCJD, n = 193), iatrogenic (iCJD, n = 12) and genetic (n = 209) forms. T-PrP was also measured in serial lumbar punctures obtained from sCJD cases at different symptomatic disease stages, and in asymptomatic prion protein gene (PRNP) mutation carriers. Compared to ND, t-PrP concentrations were significantly decreased in sCJD, iCJD and in genetic prion diseases associated with the three most common mutations E200K, V210I (associated with genetic CJD) and D178N-129M (associated with fatal familial insomnia). In contrast, t-PrP concentrations in P102L mutants (associated with the Gerstmann-Sträussler-Scheinker syndrome) remained unaltered. In serial lumbar punctures obtained at different disease stages of sCJD patients, t-PrP concentrations inversely correlated with disease progression. Decreased mean t-PrP values were detected in asymptomatic D178-129M mutant carriers, but not in E200K and P102L carriers. The presence of low CSF t-PrP is common to all types of prion diseases regardless of their aetiology albeit with mutation-specific exceptions in a minority of genetic cases. In some genetic prion disease, decreased levels are already detected at pre-clinical stages and diminish in parallel with disease progression. Our data indicate that CSF t-PrP concentrations may have a role as a pre-clinical or early symptomatic diagnostic biomarker in prion diseases as well as in the evaluation of therapeutic interventions.

Type J CBFbeta/MYH11 transcript in the M4Eo subtype of acute myeloid leukemia.

Acute myeloid leukemia (AML) carrying inversion or translocation of chromosome 16 is usually associated with the FAB M4Eo morphological subtype and belongs to AMLs with a relatively favorable prognosis. At the molecular level, it is associated with a disease-specific fusion gene, CBFbeta/MYH11. Previously, 10 different types of CBFbeta/MYH11 fusion transcripts have been described in the literature, 7 of them are still known as unique cases. In the current study, peripheral blood and/or bone marrow samples from 265 AML patients were tested for the presence of the CBFbeta/MYH11 fusion using RT-PCR and 12 (4.5%) positive cases were identified. The most common type A CBFbeta/MYH11 transcript was confirmed in 11 patients. The transcript in the remaining one (a 71-year-old female) was different and sequence analysis allowed us to classify it as CBFbeta/MYH11 type J. In contrast to the first type J case previously reported from Australia, this patient exhibited a typical FAB M4Eo morphology. The evidence of the second case indicates that the type J breakage might be a non-random event within the MYH11 gene.