No Adaptation of the Prion Strain in a Heterozygous Case of Variant Creutzfeldt-Jakob Disease.

We investigated a clinical case of variant Creutzfeldt-Jakob Disease in a person heterozygous for methionine/valine at codon 129 of the prion protein gene and identified the same strain properties in variant Creutzfeldt-Jakob disease in methionine homozygous persons and in bovine spongiform encephalopathy. These results indicate no adaptation of the agent in a different genetic background.

Variant Creutzfeldt-Jakob disease strain is identical in individuals of two PRNP codon 129 genotypes.

In 2004, a subclinical case of variant Creutzfeldt-Jakob disease in a PRNP 129 methionine/valine heterozygous individual infected via blood transfusion was reported, and we established that the spleen from this individual was infectious. Since host genetics is an important factor in strain modification, the identification of variant Creutzfeldt-Jakob disease infection in a PRNP 129 methionine/valine heterozygous individual has raised the possibility that the properties of the variant Creutzfeldt-Jakob disease agent could change after transmission to this different genetic background and concerns that this could lead to a more virulent strain of variant Creutzfeldt-Jakob disease. The variant Creutzfeldt-Jakob disease strain has to date been characterized only in methionine homozygous individuals, therefore to establish whether the strain characteristics of variant Creutzfeldt-Jakob disease had been modified by the host genotype, spleen material with prion protein deposition from a PRNP 129 methionine/valine individual was inoculated into a panel of wild-type mice. Three passages in mice were undertaken to allow stabilization of the strain characteristics following its passage into mice. In each passage, a combination of clinical signs, neuropathology (transmissible spongiform encephalopathy vacuolation and prion protein deposition) were analysed and biochemical analysis carried out. While some differences were observed at primary and first subpassage, following the second subpassage, strain characteristics in the methionine/valine individual were totally consistent with those of variant Creutzfeldt-Jakob disease transmitted to 129 methionine/methionine individuals thus demonstrated no alteration in strain properties were imposed by passage through the different host genotype. Thus we have demonstrated variant Creutzfeldt-Jakob disease strain properties are not affected by transmission through an individual with the PRNP methionine/valine codon 129 genotype and thus no alteration in virulence should be associated with the different host genotype.

Sporadic Fatal Insomnia in Europe: Phenotypic Features and Diagnostic Challenges.

OBJECTIVE: Comprehensively describe the phenotypic spectrum of sporadic fatal insomnia (sFI) to facilitate diagnosis and management of this rare and peculiar prion disorder. METHODS: A survey among major prion disease reference centers in Europe identified 13 patients diagnosed with sFI in the past 20 years. We undertook a detailed analysis of clinical and histopathological features and the results of diagnostic investigations. RESULTS: Mean age at onset was 43 years, and mean disease duration 30 months. Early clinical findings included psychiatric, sleep, and oculomotor disturbances, followed by cognitive decline and postural instability. In all tested patients, video-polysomnography demonstrated a severe reduction of total sleep time and/or a disorganized sleep. Cerebrospinal fluid (CSF) levels of proteins 14-3-3 and t-tau were unrevealing, the concentration of neurofilament light protein (NfL) was more consistently increased, and the real-time quaking-induced conversion assay (RT-QuIC) revealed a positive prion seeding activity in 60% of cases. Electroencephalography and magnetic resonance imaging showed nonspecific findings, whereas fluorodeoxyglucose positron emission tomography (FDG-PET) demonstrated a profound bilateral thalamic hypometabolism in 71% of cases. Molecular analyses revealed PrPSc type 2 and methionine homozygosity at PRNP codon 129 in all cases. INTERPRETATION: sFI is a disease of young or middle-aged adults, which is difficult to reconcile with the hypothesis of a spontaneous etiology related to stochastic, age-related PrP misfolding. The combination of psychiatric and/or sleep-related symptoms with oculomotor abnormalities represents an early peculiar clinical feature of sFI to be valued in the differential diagnosis. Video-polysomnography, FDG-PET, and especially CSF prion RT-QuIC and NfL constitute the most promising supportive diagnostic tests in vivo. Ann Neurol 2018;84:347-360.

Diagnosis of Methionine/Valine Variant Creutzfeldt-Jakob Disease by Protein Misfolding Cyclic Amplification.

A patient with a heterozygous variant of Creutzfeldt-Jakob disease (CJD) with a methionine/valine genotype at codon 129 of the prion protein gene was recently reported. Using an ultrasensitive and specific protein misfolding cyclic amplification-based assay for detecting variant CJD prions in cerebrospinal fluid, we discriminated this heterozygous case of variant CJD from cases of sporadic CJD.

Similarities of Variant Creutzfeldt-Jakob Disease Strain in Mother and Son in Spain to UK Reference Case.

We investigated transmission characteristics of variant Creutzfeldt-Jakob disease in a mother and son from Spain. Despite differences in patient age and disease manifestations, we found the same strain properties in these patients as in UK vCJD cases. A single strain of agent appears to be responsible for all vCJD cases to date.

Sporadic Creutzfeldt-Jakob Disease in 2 Plasma Product Recipients, United Kingdom.

Sporadic Creutzfeldt-Jakob disease (sCJD) has not been previously reported in patients with clotting disorders treated with fractionated plasma products. We report 2 cases of sCJD identified in the United Kingdom in patients with a history of extended treatment for clotting disorders; 1 patient had hemophilia B and the other von Willebrand disease. Both patients had been informed previously that they were at increased risk for variant CJD because of past treatment with fractionated plasma products sourced in the United Kingdom. However, both cases had clinical and investigative features suggestive of sCJD. This diagnosis was confirmed in both cases on neuropathologic and biochemical analysis of the brain. A causal link between the treatment with plasma products and the development of sCJD has not been established, and the occurrence of these cases may simply reflect a chance event in the context of systematic surveillance for CJD in large populations.

Prion infectivity in the spleen of a PRNP heterozygous individual with subclinical variant Creutzfeldt-Jakob disease.

Blood transfusion has been identified as a source of human-to-human transmission of variant Creutzfeldt-Jakob disease. Three cases of variant Creutzfeldt-Jakob disease have been identified following red cell transfusions from donors who subsequently developed variant Creutzfeldt-Jakob disease and an asymptomatic red cell transfusion recipient, who did not die of variant Creutzfeldt-Jakob disease, has been identified with prion protein deposition in the spleen and a lymph node, but not the brain. This individual was heterozygous (MV) at codon 129 of the prion protein gene (PRNP), whereas all previous definite and probable cases of variant Creutzfeldt-Jakob disease have been methionine homozygotes (MM). A critical question for public health is whether the prion protein deposition reported in peripheral tissues from this MV individual correlates with infectivity. Additionally it is important to establish whether the PRNP codon 129 genotype has influenced the transmission characteristics of the infectious agent. Brain and spleen from the MV blood recipient were inoculated into murine strains that have consistently demonstrated transmission of the variant Creutzfeldt-Jakob disease agent. Mice were assessed for clinical and pathological signs of disease and transmission data were compared with other transmission studies in variant Creutzfeldt-Jakob disease, including those on the spleen and brain of the donor to the index case. Transmission of variant Creutzfeldt-Jakob disease was observed from the MV blood recipient spleen, but not from the brain, whereas there was transmission from both spleen and brain tissues from the red blood cell donor. Longer incubation times were observed for the blood donor spleen inoculum compared with the blood donor brain inoculum, suggesting lower titres of infectivity in the spleen. The distribution of vacuolar pathology and abnormal prion protein in infected mice were similar following inoculation with both donor and recipient spleen homogenates, providing initial evidence of similar transmission properties after propagation in PRNP codon 129 MV and MM individuals. These studies demonstrate that spleen tissue from a PRNP MV genotype individual can propagate the variant Creutzfeldt-Jakob disease agent and that the infectious agent can be present in the spleen without CNS involvement.

Real time quaking-induced conversion analysis of cerebrospinal fluid in sporadic Creutzfeldt-Jakob disease.

OBJECTIVE: Current cerebrospinal fluid (CSF) tests for sporadic Creutzfeldt-Jakob disease (sCJD) are based on the detection of surrogate markers of neuronal damage such as CSF 14-3-3, which are not specific for sCJD. A number of prion protein conversion assays have been developed, including real time quaking-induced conversion (RT-QuIC). The objective of this study is to investigate whether CSF RT-QuIC analysis could be used as a diagnostic test in sCJD. METHODS: An exploratory study was undertaken that analyzed 108 CSF samples from patients with neuropathologically confirmed sCJD or from control patients. Of the 108 CSF samples, 56 were from sCJD patients (30 female, 26 male; aged 31-84 years; mean age, 62.3 ± 13.5 years), and 52 were from control patients (26 female, 26 male; aged 43-84 years; mean age, 67.8 ± 10.4 years). A confirmatory group of 118 patients was subsequently examined that consisted of 67 cases of neuropathologically confirmed sCJD (33 female, 34 male; aged 39-82 years; mean age, 67.5 ± 9.0 years) and 51 control cases (26 female, 25 male; aged 36-87 years; mean age, 63.5 ± 11.6 years). RESULTS: The exploratory study showed that RT-QuIC analysis had a sensitivity of 91% and a specificity of 98% for the diagnosis of sCJD. These results were confirmed in the confirmatory study, which showed that CSF RT-QuIC analysis had a sensitivity and specificity of 87% and 100%, respectively. INTERPRETATION: This study shows that CSF RT-QuIC analysis has the potential to be a more specific diagnostic test for sCJD than current CSF tests.

Intensity of human prion disease surveillance predicts observed disease incidence.

BACKGROUND: Prospective national screening and surveillance programmes serve a range of public health functions. Objectively determining their adequacy and impact on disease may be problematic for rare disorders. We undertook to assess whether objective measures of disease surveillance intensity could be developed for the rare disorder sporadic Creutzfeldt-Jakob disease (CJD) and whether such measures correlate with disease incidence. METHOD: From 10 countries with national human prion disease surveillance centres, the annual number of suspected prion disease cases notified to each national unit (n=17,610), referrals for cerebrospinal fluid (CSF) 14-3-3 protein diagnostic testing (n=28,780) and the number of suspect cases undergoing diagnostic neuropathological examination (n=4885) from 1993 to 2006 were collected. Age and survey year adjusted incidence rate ratios with 95% CIs were estimated using Poisson regression models to assess risk factors for sporadic, non-sporadic and all prion disease cases. RESULTS: Age and survey year adjusted analysis showed all three surveillance intensity measures (suspected human prion disease notifications, 14-3-3 protein diagnostic test referrals and neuropathological examinations of suspect cases) significantly predicted the incidence of sporadic CJD, non-sporadic CJD and all prion disease. CONCLUSIONS: Routine national surveillance methods adjusted as population rates allow objective determination of surveillance intensity, which correlates positively with reported incidence for human prion disease, especially sporadic CJD, largely independent of national context. The predictive relationship between surveillance intensity and disease incidence should facilitate more rapid delineation of aberrations in disease occurrence and assessment of the adequacy of disease monitoring by national registries.

Defining sporadic Creutzfeldt-Jakob disease strains and their transmission properties.

The biological determinants of the phenotypic variation in sporadic Creutzfeldt-Jakob disease (sCJD) are unknown. To categorize sCJD cases, the prion protein (PrP) codon 129 genotype and the biochemical characteristics of the disease-associated form of PrP (PrP(Sc)) can be combined to form six subgroups (MM1, MM2, MV1, MV2, VV1, and VV2). This classification largely correlates with the known variation in the clinical and pathological features of sCJD, with the MM1 and MV1 cases representing the "classic" phenotype of sCJD. To address how this classification relates to different strains of sCJD we have inoculated each subgroup of sCJD to a panel of mice expressing different forms of the human PRNP gene (129MM, 129VV, and 129MV). We have established that all subtypes are transmissible to at least one genotype of mouse, and both agent and host factors determine transmission efficiency and the form of PrP(Sc) deposited in the brain. Moreover, we have identified four distinct strains of sCJD using our in vivo strain typing panel.

Constant transmission properties of variant Creutzfeldt-Jakob disease in 5 countries.

Variant Creutzfeldt-Jakob disease (vCJD) has been reported in 12 countries. We hypothesized that a common strain of agent is responsible for all vCJD cases, regardless of geographic origin. To test this hypothesis, we inoculated strain-typing panels of wild-type mice with brain material from human vCJD case-patients from France, the Netherlands, Italy, and the United States. Mice were assessed for clinical disease, neuropathologic changes, and glycoform profile; results were compared with those for 2 reference vCJD cases from the United Kingdom. Transmission to mice occurred from each sample tested, and data were similar between non-UK and UK cases, with the exception of the ranking of mean clinical incubation times of mouse lines. These findings support the hypothesis that a single strain of infectious agent is responsible for all vCJD infections. However, differences in incubation times require further subpassage in mice to establish any true differences in strain properties between cases.

Iatrogenic Creutzfeldt-Jakob disease, final assessment.

The era of iatrogenic Creutzfeldt-Jakob disease (CJD) has nearly closed; only occasional cases with exceptionally long incubation periods are still appearing. The principal sources of these outbreaks are contaminated growth hormone (226 cases) and dura mater grafts (228 cases) derived from human cadavers with undiagnosed CJD infections; a small number of additional cases are caused by neurosurgical instrument contamination, corneal grafts, gonadotrophic hormone, and secondary infection with variant CJD transmitted by transfusion of blood products. No new sources of disease have been identified, and current practices, which combine improved recognition of potentially infected persons with new disinfection methods for fragile surgical instruments and biological products, should continue to minimize the risk for iatrogenic disease until a blood screening test for the detection of preclinical infection is validated for human use.

Sensitive and specific detection of sporadic Creutzfeldt-Jakob disease brain prion protein using real-time quaking-induced conversion.

Real-time quaking-induced conversion (RT-QuIC) is an assay in which disease-associated prion protein (PrP) initiates a rapid conformational transition in recombinant PrP (recPrP), resulting in the formation of amyloid that can be monitored in real time using the dye thioflavin T. It therefore has potential advantages over analogous cell-free PrP conversion assays such as protein misfolding cyclic amplification (PMCA). The QuIC assay and the related amyloid seeding assay have been developed largely using rodent-passaged sheep scrapie strains. Given the potential RT-QuIC has for Creutzfeldt-Jakob disease (CJD) research and human prion test development, this study characterized the behaviour of a range of CJD brain specimens with hamster and human recPrP in the RT-QuIC assay. The results showed that RT-QuIC is a rapid, sensitive and specific test for the form of abnormal PrP found in the most commonly occurring forms of sporadic CJD. The assay appeared to be largely independent of species-related sequence differences between human and hamster recPrP and of the methionine/valine polymorphism at codon 129 of the human PrP gene. However, with the same conditions and substrate, the assay was less efficient in detecting the abnormal PrP that characterizes variant CJD brain. Comparison of these QuIC results with those previously obtained using PMCA suggested that these two seemingly similar assays differ in important respects.

Sensitivity to biases of case-control studies on medical procedures, particularly surgery and blood transfusion, and risk of Creutzfeldt-Jakob disease.

BACKGROUND: Evidence of risk of Creutzfeldt-Jakob disease (CJD) associated with medical procedures, including surgery and blood transfusion, is limited by susceptibility to bias in epidemiological studies. METHODS: Sensitivity to bias was explored using a central-birth-cohort model using data from 18 case-control studies obtained after a review of 494 reports on medical procedures and risk of CJD, systematic for the period January 1, 1989 to December 31, 2011. RESULTS: The validity of the findings in these studies may have been undermined by: recall; control selection; exposure assessment in life-time periods of different duration, out of time-at-risk of effect, or asymmetry in case/control data; and confounding by concomitant blood transfusion at the time of surgery. For sporadic CJD (sCJD), a history of surgery or blood transfusion was associated with risk in some, but not all, recent studies at a ≥10 year lag time, when controls were longitudinally sampled. Space-time aggregation of surgical events was not seen. Surgery at early clinical onset might be overrepresented among cases. Neither surgical history nor blood transfusion unlabelled for donor status, dental treatments or endoscopic examinations were linked to variant CJD (vCJD). CONCLUSIONS: These results indicate the need for further research. Common challenges within these studies include access to and content of past medical/dental treatment records for diseases with long incubation periods.

A polymorphism in the regulatory region of PRNP is associated with increased risk of sporadic Creutzfeldt-Jakob disease.

BACKGROUND: Creutzfeldt-Jakob disease (CJD) is a rare transmissible neurodegenerative disorder. An important determinant for CJD risk and phenotype is the M129V polymorphism of the human prion protein gene (PRNP), but there are also other coding and non-coding polymorphisms inside this gene. METHODS: We tested whether three non-coding polymorphism located inside the PRNP regulatory region (C-101G, G310C and T385C) were associated with risk of CJD and with age at onset in a United Kingdom population-based sample of 131 sporadic CJD (sCJD) patients and 194 controls. RESULTS: We found no disease association for either PRNP C-101G or PRNP T385C. Although the crude analysis did not show a significant association between PRNP G310C and sCJD (OR: 1.5; 95%CI = 0.7 to 2.9), after adjusting by PRNP M129V genotype, it resulted that being a C allele carrier at PRNP G310C was significantly (p = 0.03) associated with a 2.4 fold increased risk of developing sCJD (95%CI = 1.1 to 5.4). Additionally, haplotypes carrying PRNP 310C coupled with PRNP 129M were significantly overrepresented in patients (p = 0.02) compared to controls. Cases of sCJD carrying a PRNP 310C allele presented at a younger age (on average 8.9 years younger than those without this allele), which was of statistical significance (p = 0.05). As expected, methionine and valine homozygosity at PRNP M129V increased significantly the risk of sCJD, alone and adjusted by PRNP G310C (OR MM/MV = 7.3; 95%CI 3.9 to 13.5 and OR VV/MV = 4.0; 95%CI 1.7 to 9.3). CONCLUSIONS: Our findings support the hypothesis that genetic variations in the PRNP promoter may have a role in the pathogenesis of sCJD.

Validation of diagnostic criteria for variant Creutzfeldt-Jakob disease.

OBJECTIVE: Variant Creutzfeldt-Jakob disease (vCJD), a novel form of human prion disease, was recognized in 1996. The disease affected a younger cohort than sporadic CJD, and the early clinical course was dominated by psychiatric and sensory symptoms. In an attempt to aid diagnosis and establish standardization between surveillance networks, diagnostic criteria were established. These were devised from the features of a small number of cases and modified in 2000 as the clinical phenotype was established. Since then, only minor changes have been introduced; revalidation of the criteria in the current format is overdue. METHODS: Included in this study are autopsy/cerebral biopsy-proven cases of vCJD referred to the National CJD Surveillance Unit (NCJDSU) between 1995 and 2004 and suspect cases in which an alternative diagnosis was identified following autopsy/cerebral biopsy. RESULTS: Over the 10-year period, 106 definite cases of vCJD and 45 pathologically confirmed "noncases" were identified from the archives of the NCJDSU. The median age at onset of the cases was significantly younger than that of the noncases (27 years [range, 12-74 years] vs 43 years [range, 10-64 years]), and the median duration of illness was significantly shorter (14 months [range, 6-39 months] vs 22 months [range, 2-139 months]). The most commonly identified core clinical feature in cases was dementia; persistent painful sensory symptoms were the least frequent. Eighty-eight of 106 (83%) vCJD cases were retrospectively classified as probable in life, 6 cases were classified as possible. Most cases were classified as probable on the basis of core clinical features and brain magnetic resonance imaging. To date, the diagnostic criteria remain 100% specific, with no autopsy/cerebral biopsy-proven noncases classified as probable in life. INTERPRETATION: This study confirms that the diagnostic criteria for vCJD are sensitive and specific and provide a useful standard framework for case classification in a surveillance setting.

Is there evidence of vertical transmission of variant Creutzfeldt-Jakob disease?

OBJECTIVES: The possibility of vertical transmission of variant Creutzfeldt-Jakob disease (vCJD) has been raised because of the widespread distribution of infectivity in vCJD and the demonstration that this condition can be transmitted through blood transfusion. The aim of this study is to search for evidence of this type of transmission of vCJD. METHODS: A national surveillance system for CJD has been established in the UK since 1990. Through this register, details were extracted of all children born to vCJD cases up to March 2009. This list was checked against the CJD register and cases identified through the UK study of Progressive Intellectual and Neurological Deterioration in children to determine whether any of the children of vCJD cases had themselves developed a progressive neurological disorder or vCJD. RESULTS: 125 children were born to parents with a diagnosis of vCJD. Nine of these children were born to females with vCJD who were symptomatic at conception, birth or within a year of clinical onset. Only one woman was known to have breast fed her child. None of the children of vCJD cases have been referred to the National CJD Surveillance Unit as suspected vCJD and none have been classified as suffering from a progressive neurodegenerative disorder through the Progressive Intellectual and Neurological Deterioration study. One of the children has been investigated by the National Prion Unit (see accompanying case report). INTERPRETATION: To date there is no evidence of vertical transmission of vCJD. However, the incubation period through this mechanism might be prolonged and it will be many years before observational data can exclude this possibility.

Variant Creutzfeldt-Jakob disease in France and the United Kingdom: Evidence for the same agent strain.

OBJECTIVE: Variant Creutzfeldt-Jakob disease (vCJD) was first reported in the United Kingdom in 1996. Since then, the majority of cases have been observed in the United Kingdom where there was a major epidemic of bovine spongiform encephalopathy. France was the second country affected. To address the hypothesis of the involvement of a common strain of agent, we have compared clinical, neuropathological, and biochemical data on vCJD patients from both countries. METHODS: In France and the United Kingdom, epidemiological and clinical data were obtained from analysis of medical records and direct interview of the family of the patients using the same standardized questionnaire in both countries. When brain material was available, we performed with similar methods a comparative study of brain lesions and PrP(res) glycoform ratios in both vCJD populations. RESULTS: Clinical data, genetic background, neuropathological finding, and biochemical findings in the 185 patients observed in France (n = 23) and the United Kingdom (n = 162) were similar except for age at death. Currently, blood transfusion is a risk factor identified only in the United Kingdom. INTERPRETATION: The close similarity between the cases of vCJD in France and the United Kingdom supports the hypothesis that a common strain of infectious agent is involved in both countries. The 5-year delay in the peak that we observed in France compared with the United Kingdom fits well with the increase in the importation of beef products to France from the United Kingdom between 1985 and 1995.

PRNP variation in UK sporadic and variant Creutzfeldt Jakob disease highlights genetic risk factors and a novel non-synonymous polymorphism.

BACKGROUND: Genetic analysis of the human prion protein gene (PRNP) in suspect cases of Creutzfeldt-Jakob disease (CJD) is necessary for accurate diagnosis and case classification. Previous publications on the genetic variation at the PRNP locus have highlighted the presence of numerous polymorphisms, in addition to the well recognised one at codon 129, with significant variability between geographically distinct populations. It is therefore of interest to consider their influence on susceptibility or the clinico-pathological disease phenotype. This study aimed to characterise the frequency and effect of PRNP open reading frame polymorphisms other than codon 129 in both disease and control samples sourced from the United Kingdom population. METHODS: DNA was extracted from blood samples and genetic data obtained by full sequence analysis of the prion protein gene or by restriction fragment length polymorphism analysis using restriction enzymes specific to the gene polymorphism under investigation. RESULTS: 147 of 166 confirmed cases of variant CJD (vCJD) in the UK have had PRNP codon 129 genotyping and all are methionine homozygous at codon 129; 118 have had full PRNP gene sequencing. Of the latter, 5 cases have shown other polymorphic loci: at codon 219 (2, 1.69%), at codon 202 (2, 1.69%), and a 24 bp deletion in the octapeptide repeat region (1, 0.85%). E219K and D202D were not found in sporadic CJD (sCJD) cases and therefore may represent genetic risk factors for vCJD.Genetic analysis of 309 confirmed UK sCJD patients showed codon 129 genotype frequencies of MM: 59.5% (n = 184), MV: 21.4% (n = 66), and VV: 19.1% (n = 59). Thirteen (4.2%) had the A117A polymorphism, one of which also had the P68P polymorphism, four (1.3%) had a 24 bp deletion, and a single patient had a novel missense variation at codon 167. As the phenotype of this latter case is similar to sCJD and in the absence of a family history of CJD, it is unknown whether this is a form of genetic CJD, or simply a neutral polymorphism. CONCLUSIONS: This analysis of PRNP genetic variation in UK CJD patients is the first to show a comprehensive comparison with healthy individuals (n = 970) from the same population, who were genotyped for the three most common variations (codon 129, codon 117, and 24 bp deletion). These latter two genetic variations were equally frequent in UK sCJD or vCJD cases and a normal (healthy blood donor) UK population.