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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.

Creutzfeldt–Jakob disease (CJD) is a rapidly progressive, fatal and transmissible neurodegenerative disease associated with the accumulation of misfolded prion protein in the CNS. International CJD surveillance programmes have been active since the emergence, in the mid-1990s, of variant CJD (vCJD), a disease linked to bovine spongiform encephalopathy. Control measures have now successfully contained bovine spongiform encephalopathy and the incidence of vCJD has declined, leading to questions about the requirement for ongoing surveillance. However, several lines of evidence have raised concerns that further cases of vCJD could emerge as a result of prolonged incubation and/or secondary transmission. Emerging evidence from peripheral tissue distribution studies employing high-sensitivity assays suggests that all forms of human prion disease carry a theoretical risk of iatrogenic transmission. Finally, emerging diseases, such as chronic wasting disease and camel prion disease, pose further risks to public health. In this Review, we provide an up-to-date overview of the transmission of prion diseases in human populations and argue that CJD surveillance remains vital both from a public health perspective and to support essential research into disease pathophysiology, enhanced diagnostic tests and much-needed treatments.Despite the declining incidence of variant Creutzfeldt–Jakob disease, prion diseases remain a threat to public health. In this Review, Suvankar Pal and colleagues provide an up-to-date overview of the transmission of prion diseases in human populations and argue that CJD surveillance is still vital.

Variant Creutzfeldt–Jakob disease was identified in a technician who had cut her thumb while handling brain sections of mice infected with adapted BSE 7.5 years earlier. The long incubation period was similar to that of the transfusion-transmitted form of the disease.

The diagnosis of prion-associated diseases such as variant Creutzfeldt–Jakob disease remains difficult. In this study, cases of variant Creutzfeldt–Jakob disease were identified by means of a technique that amplifies minute quantities of the prion protein in urine. Prion diseases are fatal neurodegenerative disorders for which no therapy or definitive noninvasive intravital diagnosis is available. 1 These diseases affect humans and animals. Creutzfeldt–Jakob disease in humans and scrapie, bovine spongiform encephalopathy, and chronic wasting disease in animals are the most common forms of transmissible spongiform encephalopathies. The infectious agent in transmissible spongiform encephalopathies appears to be composed exclusively of the misfolded form of the prion protein (termed PrPSc), which self-propagates in the absence of nucleic acid. 2 , 3 PrPSc replicates in infected persons by acting as a template for the misfolding of the cellular prion protein (PrPC). When . . .

Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common form of prion diseases. The causes of sCJD are still unknown and exogenous factors may play a role. Worldwide, the number of patients with sCJD has progressively increased over time. This increase can be partly explained by increasing life expectancy and better case ascertainment, but a true increase in the number of sCJD cases cannot be excluded. We estimated mortality rates from sCJD in France (1992–2016) and studied variation in mortality rates by age, period, and time. We included all cases aged 45–89 years old who died with a probable/definite sCJD diagnosis based on the French national surveillance network. We used age-period-cohort (APC) Poisson regression models to study variation in mortality rates by sex, age, period, and time. A total of 2475 sCJD cases aged 45–89 years were included. Mortality rates increased with age, reached a peak between 75 and 79 years, and decreased thereafter. Mortality rates were higher in women than men at younger ages and lower at older ages. The full APC model with a sex×age interaction provided the best fit to the data, thus in favour of sex, age, period, and cohort effects on mortality rates. In particular, mortality rates increased progressively with successive birth cohorts. Based on 25 years of active surveillance in France, we show evidence for sex, age, period, and cohort effects on sCJD mortality. The identification of cohort effects suggests that environmental exposures may play a role in sCJD etiology.

Abeta deposits and tau pathology were investigated in 24 French patients that died from iatrogenic Creutzfeldt–Jakob disease after exposure to cadaver-derived human growth hormone (c-hGH) in the 1980s. Abeta deposits were found only in one case that had experienced one of the longest incubation periods. Three cases had also intracellular tau accumulation. The analysis of 24 batches of c-hGH, produced between 1974 and 1988, demonstrated for the first time the presence of Abeta and tau contaminants in c-hGH (in 17 and 6 batches, respectively). The incubation of prion disease was shorter in the French patients than the incubation times reported in two previously published British series. We interpreted the low incidence of Abeta in this French series as a consequence of the shorter incubation period observed in France, as compared to that observed in the United Kingdom. This concept suggested that a mean incubation period for the development of detectable Abeta deposits would be longer than 18 years after the first exposure. Moreover, we hypothesized that tau pathology might also be transmissible in humans.

Background Spinocerebellar ataxia type 27B (SCA27B), caused by a GAA repeat expansion in FGF14, is a recently described genetic etiology of idiopathic late‐onset cerebellar ataxia (ILOCA). Downbeat nystagmus (DBN) is increasingly recognized as a clinical hallmark of this condition. We aimed to assess the diagnostic value of video‐oculography (VOG) in detecting SCA27B and its role in monitoring response to 4‐aminopyridine (4‐AP) in a real‐world clinical setting. Methods We retrospectively analyzed patients with ILOCA referred to Fondation Rothschild Hospital (Paris, France) from February 2023 to January 2024. All underwent clinical, MRI, and VOG assessments, with genetic testing for FGF14‐GAA expansions. Clinical and oculomotor features of carriers (≥ 200 repeats) and non‐carriers were compared. A subset of symptomatic carriers received 4‐AP and were evaluated at baseline, 2 months, and 8 months using the Scale for the Assessment and Rating of Ataxia (SARA) and VOG. Results Twelve of 34 tested patients (35%) were FGF14‐GAA expansion carriers. DBN was significantly more frequent in carriers than in non‐carriers (92% vs. 33%, p = 0.003), often associated with gaze‐evoked nystagmus (75% vs. 19%, p = 0.005). MRI did not distinguish carriers from non‐carriers. Of the nine patients treated, all reported enhanced balance, which is corroborated by the improvement in the SARA score from a median of 5.5–3 at 2 months (p = 0.015), with sustained benefit at 8 months. Conclusions VOG is a key diagnostic tool for detecting DBN, which is strongly associated with SCA27B, facilitating targeted genetic testing. 4‐AP is an effective symptomatic treatment.

The presence of pathology related to the deposition of amyloid-β (Aβ) has been recently reported in iatrogenic Creutzfeldt-Jakob disease (iCJD) acquired from inoculation of growth hormone (GH) extracted from human cadaveric pituitary gland or use of cadaveric dura mater (DM) grafts. To investigate this phenomenon further, a cohort of 27 iCJD cases – 21 with adequate number of histopathological sections – originating from Australia, France, Italy, and the Unites States, were examined by immunohistochemistry, amyloid staining, and Western blot analysis of the scrapie prion protein (PrP Sc ), and compared with age-group matched cases of sporadic CJD (sCJD), Alzheimer disease (AD) or free of neurodegenerative diseases (non-ND). Cases of iCJD and sCJD shared similar profiles of proteinase K-resistant PrP Sc with the exception of iCJD harboring the “MMi” phenotype. Cerebral amyloid angiopathy (CAA), either associated with, or free of, Thioflavin S-positive amyloid core plaques (CP), was observed in 52% of 21 cases of iCJD, which comprised 37.5% and 61.5% of the cases of GH- and DM-iCJD, respectively. If only cases younger than 54 years were considered, Aβ pathology affected 41%, 2% and 0% of iCJD, sCJD and non-ND, respectively. Despite the patients’ younger age CAA was more severe in iCJD than sCJD, while Aβ diffuse plaques, in absence of Aβ CP, populated one third of sCJD. Aβ pathology was by far most severe in AD. Tau pathology was scanty in iCJD and sCJD. In conclusion, (i) despite the divergences in the use of cadaveric GH and DM products, our cases combined with previous studies showed remarkably similar iCJD and Aβ phenotypes indicating that the occurrence of Aβ pathology in iCJD is a widespread phenomenon, (ii) CAA emerges as the hallmark of the Aβ phenotype in iCJD since it is observed in nearly 90% of all iCJD with Aβ pathology reported to date including ours, and it is shared by GH- and DM-iCJD, (iii) although the contributions to Aβ pathology of other factors, including GH deficiency, cannot be discounted, our findings increase the mounting evidence that this pathology is acquired by a mechanism resembling that of prion diseases.

Objective To describe peripheral neuropathy associated with familial Creutzfeldt‐Jakob disease. Methods We report two unrelated patients with genetic Creutzfeldt–Jakob disease with demyelinating peripheral neuropathy as initial presentation, with a comprehensive clinical, electrophysiological and neuropathological description. Results Both patients exhibited gait disturbance and paresthesia. Electrodiagnostic studies revealed demyelinating abnormalities with motor conduction blocks suggestive of chronic inflammatory demyelinating polyradiculoneuropathy, with abnormal plexus MRI and elevated CSF protein levels. One of them had pes cavus and a late‐onset Charcot–Marie‐Tooth (CMT) disease was also initially hypothesized. Central nervous system involvement manifested 1–2 years after the onset of peripheral symptoms. Both patients had a heterozygous E200K mutation in the PRNP gene. Postmortem neuropathological examinations showed PrPSc deposits in the peripheral nervous system, particularly in Schwann cells. Interpretation: Peripheral neuropathy in E200K genetic forms of Creutzfeldt‐Jakob disease can be inaugural and mimic chronic inflammatory demyelinating polyradiculoneuropathy.

In prion diseases, a major issue in therapeutic research is the variability of the effect between strains. Stimulated by the report of an antiprion effect in a scrapie model and by ongoing international clinical trials using doxycycline, we studied the efficacy of cyclines against the propagation of human prions. First, we successfully propagated various Creutzfeldt-Jakob disease (CJD) isolates (sporadic, variant, and iatrogenic CJD) in neuronal cultures expressing the human prion protein. Then, we found that doxycycline was the most effective compound, with important variations between isolates. Isolates from sporadic CJD, the most common form of prion disease, showed the highest sensitivity.