The impact of the introduction of the 14-3-3 protein assay in the surveillance of sporadic Creutzfeldt-Jakob disease in Catalonia

Human prion disease surveillance in Spain, 1993-2018: an overview

In Spain, human transmissible spongiform encephalopathies (TSEs) have been undergoing continuous surveillance for over 25 years. In 1995, the system was launched as an EU Concerted Action, with EU surveillance network procedures being incorporated from 2002 onwards. The aim of this report was to describe performance and outcomes of this surveillance system across the period 1993–2018. Neurology and public health specialists from every region reported cases to a central hub at the Carlos III Health Institute, Madrid. In all, eight accidentally transmitted cases and five definite variant Creutzfeldt-Jakob disease (vCJD) patients were reported. All vCJD cases were diagnosed between 2005 and 2008. Two of these were family/dietary-related and spatially linked to a third. Yearly incidence of sporadic CJD per million was 1.25 across the period 1998–2018, and displayed a north-south gradient with the highest incidence in La Rioja, Navarre and the Basque Country. Genetic TSEs were observed to be clustered in the Basque Country, with a 4-fold incidence over the national rate. A total of 120 (5.6%) non-TSE sporadic, conformational, rapidly progressing neurodegenerative and vascular brain disorders were reported as suspect CJD. We conclude that TSEs in Spain displayed geographically uneven, stable medium incidences for the sporadic and genetic forms, a temporal and spatial family cluster for vCJD, and decreasing numbers for dura-mater-associated forms. The vCJD surveillance, framed within the EU network, might require continuing to cover all prion disorders. There is need for further strategic surveillance research focusing on case definition of rapid-course, conformational encephalopathies and surgical risk.

Heightened incidence of sporadic Creutzfeldt-Jakob disease is associated with a shift in clinicopathological profiles

Incidences of human transmissible spongiform encephalopathies are monitored by national registries in the majority of countries in Western Europe. During the past 13 years incidences for Creutzfeldt-Jakob disease (CJD) in Switzerland fluctuated between 0.4 and 2.63 cases/10(6) inhabitants. We have compared clinicpathological patient profiles including geographic and gender distribution, age at disease onset, duration of disease, clinical symptoms, and recognized or hypothetical risk factors for CJD, genetic risk factors, biochemical and histopathological data for two cohorts of Swiss sporadic CJD patients from years of regular sporadic CJD incidence (1996-2000, mean incidence 1.3 cases/10(6) inhabitants, n = 47) to Swiss sporadic CJD patients from years of elevated sporadic CJD incidence (2001-2004, mean incidence 2.3 cases/10(6) inhabitants, n = 73). Sporadic CJD patients from the cohort with elevated sporadic CJD incidence presented with a higher frequency of rare sporadic CJD subtypes. Patients of these subtypes were significantly older and showed a skewed male/female ratio when compared to published patients of identical sporadic CJD-types or to patients from the 1996-2000 cohort and indicates that improved detection of rare sporadic CJD subtypes may have contributed to increased incidence.

Human transmissible spongiform encephalopathies in eleven countries: diagnostic pattern across time, 1993-2002

BACKGROUND

The objective of this study was to describe the diagnostic panorama of human transmissible spongiform encephalopathies across 11 countries.

METHODS

From data collected for surveillance purposes, we describe annual proportions of deaths due to different human transmissible spongiform encephalopathies in eleven EUROCJD-consortium countries over the period 1993-2002, as well as variations in the use of diagnostic tests. Using logistic models we quantified international differences and changes across time.

RESULTS

In general, pre-mortem use of diagnostic investigations increased with time. International differences in pathological confirmation of sporadic Creutzfeldt-Jakob disease, stable over time, were evident. Compared to their counterparts, some countries displayed remarkable patterns, such as: 1) the high proportion, increasing with time, of variant Creutzfeldt-Jakob disease in the United Kingdom, (OR 607.99 95% CI 84.72-4363.40), and France (OR 18.35, 95% CI 2.20-152.83); 2) high, decreasing proportions of iatrogenic Creutzfeldt-Jakob disease in France, (OR 5.81 95% CI 4.09-8.24), and the United Kingdom, (OR 1.54 95% CI 1.03-2.30); and, 3) high and stable ratios of genetic forms in Slovakia (OR 21.82 95% CI 12.42-38.33) and Italy (OR 2.12 95% CI 1.69-2.68).

CONCLUSION

Considerable international variation in aetiological subtypes of human transmissible spongiform encephalopathies was evident over the observation period. With the exception of variant Creutzfeldt-Jakob disease and iatrogenic Creutzfeldt-Jakob disease in France and the United Kingdom, these differences persisted across time.

Phenotypic variability in familial prion diseases due to the D178N mutation

BACKGROUND

Between January 1993 and December 2003, 19 patients with familial prion diseases due to the D178N mutation were referred to the regional epidemiological registry for spongiform encephalopathies in the Basque Country in Spain, a small community of some 2,100,000 inhabitants.

METHODS

Ten further patients belonging to the same pedigrees were retrospectively ascertained through neurological or neuropathological records. In four of the patients, the diagnosis was confirmed by analysing DNA obtained from paraffin blocks. In this article, we report on the clinical, genetic, and pathological features of the 23 patients carrying the D178N mutation confirmed by genetic molecular analysis. Haplotyping studies suggest a founder effect among Basque born families, explaining in part this unusually high incidence of the D178N mutation in a small community. Only two patients (8%) lack familial antecedents.

RESULTS

We have observed a phenotypic variability even among homozygous 129MM patients. Our findings challenge the currently accepted belief that MM homozygosity in codon 129 is always related to a fatal familial insomnia (FFI) phenotype. Indeed, seven out of 17 patients with a 129MM genotype in this series presented with a Creutzfeldt-Jakob disease (CJD) clinicopathological picture.

CONCLUSIONS

The considerable clinical and pathological overlapping observed among homozygous 129MM patients favours the view that FFI and CJD178 are the extremes of a spectrum rather than two discrete and separate entities. Other genetic or environmental factors apart from the polymorphism in codon 129 may play a role in determining the phenotypic expression of the D178N mutation in the PRNP gene.

Clinical and genetic features of human prion diseases in Catalonia: 1993-2002

We describe the clinical and genetic characteristics of the 85 definite or probable human prion diseases cases died between January 1993 and December 2002 in Catalonia (an autonomous community of Spain, 6 million population). Seventy-three (86%) cases were sporadic Creutzfeld-Jakob diseases (sCJD) (49 definite, 24 probable), with a median age at onset of 66 years. The clinical presentation was dementia in 29 cases, ataxia in 14 and visual symptoms in five. The median survival was 3 months. The 14-3-3 assay was positive in 93% cases, 62% presented periodic sharp wave complexes (PSWC) in EEG but only 18% the typical signs on MRI. Forty-eight sCJD were studied for codon 129 PRNP polymorphism: 69% were methionine/methionine (M/M), 14.5% valine/valine (V/V) and 16.5% M/V. Six out of seven V/V cases did not present PSWC and in two survival was longer than 20 months. Eleven cases (13%) were genetic: five familial fatal insomnia and six familial CJD (fCJD). Up to four (67%) fCJD lacked family history of disease, two presented seizures early at onset and one neurosensorial deafness. The only iatrogenic case was related to a dura mater graft. No case of variant CJD was registered. The study confirms in our population the consistent pattern reported worldwide on human prion diseases. Atypical features were seen more frequently in sporadic 129 V/V CJD and fCJD cases.

Human prion diseases: epidemiology and integrated risk assessment

Human prion diseases are devastating and incurable, but are very rare. Fears that the bovine spongiform encephalopathy epizootic would lead to a large epidemic of its presumed human counterpart, variant Creutzfeldt-Jakob disease (vCJD), have not been realised. Yet a feeling of uncertainty prevails in the general public and in the biomedical world. The lack of data on the prevalence of asymptomatic carriers of vCJD compounds this uncertainty. In addition to this problem, Switzerland is currently faced with another issue of major public concern: a recent rise in the incidence of CJD. Here we examine the plausibility of several scenarios that may account for the increase in CJD incidence, including ascertainment bias due to improved reporting of CJD, iatrogenic transmission, and transmission of a prion zoonosis. In addition, we present the design and current status of a Swiss population-wide study of subclinical vCJD prevalence.

14-3-3 Protein isoforms and atypical patterns of the 14-3-3 assay in the diagnosis of Creutzfeldt-Jakob disease

A positive 14-3-3 assay is a criterion for probable Creutzfeldt-Jakob disease (CJD). Cerebrospinal fluid (CSF) 14-3-3 is usually detected by immunoblot using an antibody that recognizes all of the 14-3-3 isoforms. In a few cases, the antibody recognizes an inferior band and this pattern is associated with false positive results. We analyzed 43 CSF (26 CJD, 17 controls) samples using antibodies against specific isoforms (beta, epsilon, gamma, tau, xi) and compared the results with those obtained with the standard antibody. The anti-gamma and anti-beta antibody achieved similar results but the presence of atypical patterns made the standard antibody more accurate for the CJD diagnosis. To study the nature of the inferior band, CSF samples were probed with antibodies against light chain immunoglobulins, and immunoblots of human IgG with the standard antibody. The experiments suggested a cross-reaction of the anti-14-3-3 antibody with light chain immunoglobulins.