Sporadic Creutzfeldt-Jakob disease VM1: phenotypic and molecular characterization of a novel subtype of human prion disease

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.

Novel histotypes of sporadic Creutzfeldt-Jakob disease linked to 129MV genotype

The MV1 and MV2 subtypes of sporadic Creutzfeldt-Jakob disease (sCJD) are linked to the heterozygous methionine (M)/valine (V) polymorphism at codon 129 of the prion protein (PrP) gene. MV2 is phenotypically heterogeneous, whereas MV1, due to its low prevalence, is one of the least well characterized subtypes. In this study, we investigated the biochemical properties of PrPSc and phenotypic expression of cases diagnosed as sCJD MV1 and MV2. We describe four MV2 histotypes: 2C, with cortical (C) coarse pathology; 2K, with kuru (K) plaque deposits; 2C-K, with co-existing C and K histotypic features; and the novel histotype 2C-PL that mimics 2C in the cerebral cortex and cerebellum, but exhibits plaque-like (PL) PrP deposits in subcortical regions (e.g., basal nuclei, thalamus and midbrain). Histotype prevalence is highest for 2C-K (55%), intermediate for 2C (31%), and lowest for 2C-PL and 2K (7%). Nearly every MV2 case expressed both PrPSc types, with T2 being the predominant type ("MV2-1"). MV1 cases typically show a rapid disease course (≤ 4 months), and feature the 1C histotype, phenotypically identical to sCJDMM1. Co-existing PrPSc types, with T1 significantly exceeding T2 ("MV1-2"), are detected in patients diagnosed as MV1 with longer disease courses. We observed four histotypes among MV1-2 cases, including two novel histotypes: 1V, reminiscent of sCJDVV1; 1C-2C, resembling sCJDMM1-2 with predominant MM1 histotypic component; and novel histotypes 1C-2PL and 1C-2K, overall mimicking 1C in the cerebral cortex, but harboring T2 and plaque-like PrP deposits in subcortical regions (1C-2PL), and T2 and kuru plaques in the cerebellum (1C-2K). Lesion profiles of 1C, 1V, and 1C-2C are similar, but differ from 1C-2PL and 1C-2K, as the latter two groups show prominent hippocampal and nigral degeneration. We believe that the novel "C-PL" histotypes are distinct entities rather than intermediate forms between "C" and "C-K" groups, and that 1C-2PL and 1C-2K histotypes may be characterized by different T1 variants of the same size.

A novel subtype of sporadic Creutzfeldt-Jakob disease with PRNP codon 129MM genotype and PrP plaques

The presence of amyloid kuru plaques is a pathological hallmark of sporadic Creutzfeldt-Jakob disease (sCJD) of the MV2K subtype. Recently, PrP plaques (p) have been described in the white matter of a small group of CJD (p-CJD) cases with the 129MM genotype and carrying resPrPD type 1 (T1). Despite the different histopathological phenotype, the gel mobility and molecular features of p-CJD resPrPD T1 mimic those of sCJDMM1, the most common human prion disease. Here, we describe the clinical features, histopathology, and molecular properties of two distinct PrP plaque phenotypes affecting the gray matter (pGM) or the white matter (pWM) of sCJD cases with the PrP 129MM genotype (sCJDMM). Prevalence of pGM- and pWM-CJD proved comparable and was estimated to be ~ 0.6% among sporadic prion diseases and ~ 1.1% among the sCJDMM group. Mean age at onset (61 and 68 years) and disease duration (~ 7 months) of pWM- and pGM-CJD did not differ significantly. PrP plaques were mostly confined to the cerebellar cortex in pGM-CJD, but were ubiquitous in pWM-CJD. Typing of resPrPD T1 showed an unglycosylated fragment of ~ 20 kDa (T120) in pGM-CJD and sCJDMM1 patients, while a doublet of ~ 21-20 kDa (T121-20) was a molecular signature of pWM-CJD in subcortical regions. In addition, conformational characteristics of pWM-CJD resPrPD T1 differed from those of pGM-CJD and sCJDMM1. Inoculation of pWM-CJD and sCJDMM1 brain extracts to transgenic mice expressing human PrP reproduced the histotype with PrP plaques only in mice challenged with pWM-CJD. Furthermore, T120 of pWM-CJD, but not T121, was propagated in mice. These data suggest that T121 and T120 of pWM-CJD, and T120 of sCJDMM1 are distinct prion strains. Further studies are required to shed light on the etiology of p-CJD cases, particularly those of T120 of the novel pGM-CJD subtype.

The Zoonotic Potential of Chronic Wasting Disease-A Review

Prion diseases are transmissible neurodegenerative disorders that affect humans and ruminant species consumed by humans. Ruminant prion diseases include bovine spongiform encephalopathy (BSE) in cattle, scrapie in sheep and goats and chronic wasting disease (CWD) in cervids. In 1996, prions causing BSE were identified as the cause of a new prion disease in humans; variant Creutzfeldt-Jakob disease (vCJD). This sparked a food safety crisis and unprecedented protective measures to reduce human exposure to livestock prions. CWD continues to spread in North America, and now affects free-ranging and/or farmed cervids in 30 US states and four Canadian provinces. The recent discovery in Europe of previously unrecognized CWD strains has further heightened concerns about CWD as a food pathogen. The escalating CWD prevalence in enzootic areas and its appearance in a new species (reindeer) and new geographical locations, increase human exposure and the risk of CWD strain adaptation to humans. No cases of human prion disease caused by CWD have been recorded, and most experimental data suggest that the zoonotic risk of CWD is very low. However, the understanding of these diseases is still incomplete (e.g., origin, transmission properties and ecology), suggesting that precautionary measures should be implemented to minimize human exposure.

Case report: Two clusters of Creutzfeldt-Jakob disease cases within 1 year in West Michigan

Background

Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive, and uniformly fatal neurodegenerative disease. The reported incidence of CJD is 1 to 2 per million people worldwide annually, with fewer than 1,000 cases in the United States per year. In this study, we report a unique case series on temporo-spatial clusters of CJD cases in West Michigan.

Methods

A total of five CJD cases consisting of two temporal clusters were seen from July 2021 to June 2022 at Corewell Health West hospitals. All patients had brain MRI, EEG, and CSF tests. Four patients underwent autopsies.

Results

All patients' MRIs showed characteristic CJD patterns. Four patients had positive CJD panels in CSF. One patient had typical CJD EEG findings. Four patients were confirmed as sporadic CJD by autopsy. All patients died within 3 months after CJD was suspected.

Discussion

All patients lived within a 90-mile radius of Grand Rapids, MI, and two lived in the same county. West Michigan has a population of 1.6 million people, and the four counties where five patients lived have a combined population of 395,104, indicating CJD's new case rate of 3.1 and 12.5 per million people, respectively. Corewell Health is one of the three major healthcare systems in West Michigan. The actual incidence of CJD in West Michigan is likely even higher. This dense temporal and spatial cluster of CJD cases poses a serious public health challenge and warrants urgent investigation.