Inga Zerr

Classification of sporadic Creutzfeldt‐Jakob disease based on molecular and phenotypic analysis of 300 subjects

Phenotypic heterogeneity in sporadic Creutzfeldt‐Jakob disease (sCJD) is well documented, but there is not yet a systematic classification of the disease variants. In a previous study, we showed that the polymorphic codon 129 of the prion protein gene (PRNP), and two types of protease‐resistant prion protein (PrPSc) with distinct physicochemical properties, are major determinants of these variants. To define the full spectrum of variants, we have examined a series of 300 sCJD patients. Clinical features, PRNP genotype, and PrPSc properties were determined in all subjects. In 187, we also studied neuropathological features and immunohistochemical pattern of PrPSc deposition. Seventy percent of subjects showed the classic CJD phenotype, PrPSc type 1, and at least one methionine allele at codon 129; 25% of cases displayed the ataxic and kuru‐plaque variants, associated to PrPSc type 2, and valine homozygosity or heterozygosity at codon 129, respectively. Two additional variants, which included a thalamic form of CJD and a phenotype characterized by prominent dementia and cortical pathology, were linked to PrPSc type 2 and methionine homozygosity. Finally, a rare phenotype characterized by progressive dementia was linked to PrPSc type 1 and valine homozygosity. The present data demonstrate the existence of six phenotypic variants of sCJD. The physicochemical properties of PrPSc in conjunction with the PRNP codon 129 genotype largely determine this phenotypic variability, and allow a molecular classification of the disease variants. Ann Neurol 1999;46:224–233

Updated clinical diagnostic criteria for sporadic Creutzfeldt-Jakob disease

Several molecular subtypes of sporadic Creutzfeldt–Jakob disease have been identified and electroencephalogram and cerebrospinal fluid biomarkers have been reported to support clinical diagnosis but with variable utility according to subtype. In recent years, a series of publications have demonstrated a potentially important role for magnetic resonance imaging in the pre-mortem diagnosis of sporadic Creutzfeldt–Jakob disease. Magnetic resonance imaging signal alterations correlate with distinct sporadic Creutzfeldt–Jakob disease molecular subtypes and thus might contribute to the earlier identification of the whole spectrum of sporadic Creutzfeldt–Jakob disease cases. This multi-centre international study aimed to provide a rationale for the amendment of the clinical diagnostic criteria for sporadic Creutzfeldt–Jakob disease. Patients with sporadic Creutzfeldt–Jakob disease and fluid attenuated inversion recovery or diffusion-weight imaging were recruited from 12 countries. Patients referred as ‘suspected sporadic Creutzfeldt–Jakob disease’ but with an alternative diagnosis after thorough follow up, were analysed as controls. All magnetic resonance imaging scans were assessed for signal changes according to a standard protocol encompassing seven cortical regions, basal ganglia, thalamus and cerebellum. Magnetic resonance imaging scans were evaluated in 436 sporadic Creutzfeldt–Jakob disease patients and 141 controls. The pattern of high signal intensity with the best sensitivity and specificity in the differential diagnosis of sporadic Creutzfeldt–Jakob disease was identified. The optimum diagnostic accuracy in the differential diagnosis of rapid progressive dementia was obtained when either at least two cortical regions (temporal, parietal or occipital) or both caudate nucleus and putamen displayed a high signal in fluid attenuated inversion recovery or diffusion-weight imaging magnetic resonance imaging. Based on our analyses, magnetic resonance imaging was positive in 83% of cases. In all definite cases, the amended criteria would cover the vast majority of suspected cases, being positive in 98%. Cerebral cortical signal increase and high signal in caudate nucleus and putamen on fluid attenuated inversion recovery or diffusion-weight imaging magnetic resonance imaging are useful in the diagnosis of sporadic Creutzfeldt–Jakob disease. We propose an amendment to the clinical diagnostic criteria for sporadic Creutzfeldt–Jakob disease to include findings from magnetic resonance imaging scans.

Iatrogenic Creutzfeldt–Jakob disease at the millennium

Article abstract The causes and geographic distribution of 267 cases of iatrogenic Creutzfeldt–Jakob disease (CJD) are here updated at the millennium. Small numbers of still-occurring cases result from disease onsets after longer and longer incubation periods following infection by cadaveric human growth hormone or dura mater grafts manufactured and distributed before the mid-1980s. The proportion of recipients acquiring CJD from growth hormone varies from 0.3 to 4.4% in different countries, and acquisition from dura mater varies between 0.02 and 0.05% in Japan (where most cases occurred). Incubation periods can extend up to 30 years, and cerebellar onsets predominate in both hormone and graft recipients (in whom the site of graft placement had no effect on the clinical presentation). Homozygosity at codon 129 of the PRNP gene is over-represented in both forms of disease; it has no effect on the incubation period of graft recipients, but may promote shorter incubation periods in hormone cases. Knowledge about potential high-risk sources of contamination gained during the last quarter century, and the implementation of methods to circumvent them, should minimize the potential for iatrogenic contributions to the current spectrum of CJD.

Analysis of EEG and CSF 14-3-3 proteins as aids to the diagnosis of Creutzfeldt–Jakob disease

Objective: To improve diagnostic criteria for sporadic Creutzfeldt–Jakob disease (CJD). Methods: Pooled data on initial and final diagnostic classification of suspected CJD patients were accumulated, including results of investigations derived from a coordinated multinational study of CJD. Prospective analysis for a comparison of clinical and neuropathologic diagnoses and evaluation of the sensitivity and specificity of EEG and 14-3-3 CSF immunoassay were conducted. Results: Data on 1,003 patients with suspected CJD were collected using a standard questionnaire. After follow-up was carried out, complete clinical data and neuropathologic diagnoses were available in 805 cases. In these patients, the sensitivity of the detection of periodic sharp wave complexes in the EEG was 66%, with a specificity of 74%. The detection of 14-3-3 proteins in the CSF correlated with the clinical diagnosis in 94% (sensitivity). The specificity (84%) was higher than that of EEG. A combination of both investigations further increased the sensitivity but decreased the specificity. Conclusions: Incorporation of CSF 14-3-3 analysis in the diagnostic criteria for CJD significantly increases the sensitivity of case definition. Amended diagnostic criteria for CJD are proposed.

Elevated levels of tau-protein in cerebrospinal fluid of patients with Creutzfeldt–Jakob disease

Creutzfeldt-Jakob disease (CJD) is a rare, fatal, neurodegenerative disease caused by a transmissible agent designated as proteinaceous infectious agent (prion). Searching for biochemical markers of CJD, we analysed cerebrospinal fluid (CSF) samples of 53 patients for tau-protein using an enzyme linked immunoassay (ELISA). In a group of 21 patients with definite CJD seen in the German case control study for CJD, tau-protein concentrations in CSF were significantly higher than in two control-groups of patients with other diseases (median 13,153 pg/ml, range 1,533-27,648 pg/ml; P = 0.0001). One group comprised 19 patients who were seen in the same study and were diagnosed as having other dementing diseases (tau concentration: median 558 pg/ml, range 233-1,769 pg/ml). The second control group comprised 13 patients from our hospital with no dementing disease (tau concentration: median 296 pg/ml, range 109-640 pg/ml). We conclude that determination of tau protein levels in CSF is a useful marker for laboratory diagnosis of CJD.

Genetic prion disease: the EUROCJD experience

A total of 10–15% of human transmissible spongiform encephalopathies (TSEs) or prion diseases are characterised by disease-specific mutations in the prion protein gene (PRNP). We examined the phenotype, distribution, and frequency of genetic TSEs (gTSEs) in different countries/geographical regions. We collected standardised data on gTSEs between 1993 and 2002 in the framework of the EUROCJD collaborative surveillance project. Our results show that clinicopathological phenotypes include genetic Creutzfeldt–Jakob disease (gCJD), fatal familial insomnia (FFI), and Gerstmann–Sträussler–Scheinker disease (GSS). Genetic TSE patients with insert mutation in the PRNP represent a separate group. Point and insertional mutations in the PRNP gene varies significantly in frequency between countries. The commonest mutation is E200K. Absence of a positive family history is noted in a significant proportion of cases in all mutation types (12–88%). FFI and GSS patients develop disease earlier than gCJD. Base pair insertions associated with the Creutzfeldt–Jakob disease (CJD) phenotype, GSS, and FFI cases have a longer duration of illness compared to cases with point mutations and gCJD. Cerebrospinal fluid 14-3-3 immunoassay, EEG, and MRI brain scan are useful in the diagnosis of CJD with point mutations, but are less sensitive in the other forms. Given the low prevalence of family history, the term “gTSE” is preferable to “familial TSE”. Application of genetic screening in clinical practice has the advantage of early diagnosis and may lead to the identification of a risk of a TSE.

Mortality from Creutzfeldt–Jakob disease and related disorders in Europe, Australia, and Canada

Background: An international study of the epidemiologic characteristics of Creutzfeldt–Jakob disease (CJD) was established in 1993 and included national registries in France, Germany, Italy, the Netherlands, Slovakia, and the United Kingdom. In 1997, the study was extended to Australia, Austria, Canada, Spain, and Switzerland. Methods: Data were pooled from all participating countries for the years 1993 to 2002 and included deaths from definite or probable CJD of all etiologic subtypes. Results: Four thousand four hundred forty-one cases were available for analysis and included 3,720 cases of sporadic CJD, 455 genetic cases, 138 iatrogenic cases, and 128 variant cases. The overall annual mortality rate between 1999 and 2002 was 1.67 per million for all cases and 1.39 per million for sporadic CJD. Mortality rates were similar in all countries. There was heterogeneity in the distribution of cases by etiologic subtype with an excess of genetic cases in Italy and Slovakia, of iatrogenic cases in France and the UK, and of variant CJD in the UK. Conclusions: This study has established overall epidemiologic characteristics for Creutzfeldt–Jakob disease (CJD) of all types in a multinational population–based study. Intercountry comparisons did not suggest any relative change in the characteristics of sporadic CJD in the United Kingdom, and the evidence in this study does not suggest the occurrence of a novel form of human bovine spongiform encephalopathy infection other than variant CJD. However, this remains a possibility, and countries currently unaffected by variant CJD may yet have cases.

CSF tests in the differential diagnosis of Creutzfeldt-Jakob disease.

Objectives: To analyze the diagnostic sensitivity and specificity of various brain-derived proteins (14-3-3, Tau, neuron specific enolase [NSE], and S100b) in the CSF of patients with Creutzfeldt-Jakob disease (CJD) and to analyze biologic factors that modify these parameters. Methods: CSF was tested for 14-3-3, Tau, NSE, and S100b in 1,859 patients with sporadic, genetic, iatrogenic, and variant CJD, and in 1,117 controls. Results: The highest sensitivity was achieved for 14-3-3 and Tau in sporadic CJD (85% and 86%), and a combined determination of 14-3-3 and Tau, S100b, or NSE increased the sensitivity to over 93%. A multivariate analysis showed that the sensitivity of all tests was highest in patients with the shortest disease duration, age at onset >40 years, and homozygosity at codon 129 of the prion protein gene. In a group of patients with repeated lumbar punctures, a second test also increased the diagnostic sensitivity. Conclusions: The detection of elevated levels of brain-derived proteins in the CSF in patients with suspected Creutzfeldt-Jakob disease is a valuable diagnostic test. A second lumbar puncture may be of value in patients with atypical clinical course in whom the first test was negative.

Decreased β-amyloid1-42 in cerebrospinal fluid of patients with Creutzfeldt-Jakob disease

Objectives: Decreased levels of Aβ1-42 are found in CSF of patients with AD. Because early stages of Creutzfeldt-Jakob disease (CJD) and AD share several clinical features, we investigated Aβ1-42 levels in CSF of these groups, inferring that this might give additional help in differentiating patients with CJD from AD patients. Methods: We investigated 27 patients with CJD, 14 patients with AD, 19 patients with other dementias, and 20 nondemented controls (NDC) for Aβ1-42 in CSF. Twenty-four of the 27 CJD patients were neuropathologically verified. All the neuropathologically verified patients presented with a type 1 prion protein pattern. CJD patients were all homozygous for methionine at codon 129. Except in five CJD patients, no β-amyloid plaques were seen. Additionally, APOE status was determined in patients with CJD. Results: Levels of Aβ1-42 in CSF were decreased in patients with AD as well as in CJD. Levels of Aβ1-42 in CSF of patients with CJD and AD were significantly different from the other dementia and NDC groups. There was no substantial difference between the CJD and AD groups (p = 0.66). Decreased levels of Aβ1-42 did not correlate with the APOE ε4 load in patients with CJD. Conclusion: Low levels of Aβ1-42 in CSF do not exclude a diagnosis of CJD. Decreased levels of Aβ1-42 in CSF can occur without β-amyloid plaque formation in the brain. However, the underlying mechanism of this phenomenon must be elucidated.

Case-control study of risk factors of Creutzfeldt-Jakob disease in Europe during 1993-95

BACKGROUND Creutzfeldt-Jakob disease (CJD) is a transmissible spongiform encephalopathy. Genetic and iatrogenic forms have been recognised but most are sporadic and of unknown cause. We have studied risk factors for CJD as part of the 1993-95 European Union collaborative studies of CJD in Europe. METHODS The 405 patients with definite or probable CJD who took part in our study had taken part in population-based studies done between 1993 and 1995 in Belgium, France, Germany, Italy, the Netherlands, and the UK. Data on putative risk factors from these patients were compared with data from 405 controls. FINDINGS We found evidence for familial aggregation of CJD with dementia due to causes other than CJD (relative risk [RR] 2.26, 95% CI 1.31-3.90). No significant increased risk of CJD in relation to a history of surgery and blood transfusion was shown. There was no evidence for an association between the risk of CJD and the consumption of beef, veal, lamb, cheese, or milk. No association was found with occupational exposure to animals or leather. The few positive findings of the study include increased risk in relation to consumption of raw meat (RR 1.63 [95% CI 1.18-2.23]) and brain (1.68 [1.18-2.39]), frequent exposure to leather products (1.94 [1.13-3.33]), and exposure to fertiliser consisting of hoofs and horns (2.32 [1.38-2.91]). Additional analyses, for example stratification by country and of exposures pre-1985 and post-1985, suggest that these results should be interpreted with great caution. INTERPRETATION Within the limits of the retrospective design of the study, our findings suggest that genetic factors other than the known CJD mutations may play an important part in CJD. Iatrogenic transmission of disease seems rare in this large population-based sample of patients with CJD. There is little evidence for an association between the risk of CJD and either animal exposure, or consumption of processed bovine meat or milk products for the period studied.