We analysed the epidemiological data and clinical features of patients with prion diseases that had been registered by the Creutzfeldt-Jakob Disease Surveillance Committee, Japan, over the past 10 years, since 1999. We obtained information on 1685 Japanese patients suspected as having prion diseases and judged that 1222 patients had prion diseases, consisting of definite (n=180, 14.7%) and probable (n=1029, 84.2%) cases, except for dura mater graft-associated Creutzfeldt-Jakob disease which also included possible cases (n=13, 1.1%). They were classified into 922 (75.5%) with sporadic Creutzfeldt-Jakob disease, 216 (17.7%) with genetic prion diseases, 81 (6.6%) with acquired prion diseases, including 80 cases of dura mater graft-associated Creutzfeldt-Jakob disease and one case of variant Creutzfeldt-Jakob disease, and three cases of unclassified Creutzfeldt-Jakob disease (0.2%). The annual incidence rate of prion disease ranged from 0.65 in 1999 to 1.10 in 2006, with an average of 0.85, similar to European countries. Although methionine homozygosity at codon 129 polymorphism of the prion protein gene was reported to be very common (93%) in the general Japanese population, sporadic Creutzfeldt-Jakob disease in Japan was significantly associated with codon 129 homozygosity (97.5%), as reported in western countries. In sporadic Creutzfeldt-Jakob disease, MM1 type (Parchi's classification) is the most common, as in western countries. Among atypical sporadic Creutzfeldt-Jakob disease cases, the MM2 type appeared most common, probably related to the very high proportion of methionine allele in the Japanese population. As for iatrogenic Creutzfeldt-Jakob disease, only dura mater graft-associated Creutzfeldt-Jakob disease cases were reported in Japan and, combined with the data from previous surveillance systems, the total number of dura mater graft-associated Creutzfeldt-Jakob disease was 138, comprising the majority of worldwide dura mater graft-associated Creutzfeldt-Jakob disease patients. Regarding genetic prion diseases, the most common mutation of prion protein gene was V180I (41.2%), followed by P102L (18.1%), E200K (17.1%) and M232R (15.3%), and this distribution was quite different from that in Europe. In particular, V180I and M232R were quite rare mutations worldwide. Patients with V180I or M232R mutations rarely had a family history of prion diseases, indicating that a genetic test for sporadic cases is necessary to distinguish these from sporadic Creutzfeldt-Jakob disease. In conclusion, our prospective 10-year surveillance revealed a frequent occurrence of dura mater graft-associated Creutzfeldt-Jakob disease, and unique phenotypes of sporadic Creutzfeldt-Jakob disease and genetic prion diseases related to the characteristic distribution of prion protein gene mutations and polymorphisms in Japan, compared with those in western countries.

A national system for surveillance of prion diseases (PrDs) was established in Japan in April 1999. Here, we analyzed the relationships among prion protein gene (PRNP) mutations and the clinical features, cerebrospinal fluid (CSF) markers, and pathological characteristics of the major genotypes of genetic PrDs (gPrDs). We retrospectively analyzed age at onset and disease duration; the concentrations and incidences of 14-3-3 protein, tau protein, and abnormal prion protein (PrPSc) in the CSF of 309 gPrD patients with P102L, P105L, E200K, V180I, or M232R mutations; and brain pathology in 32 autopsied patients. Three clinical phenotypes were seen: rapidly progressive Creutzfeldt-Jakob disease (CJD), which included 100% of E200K cases, 70% of M232R, and 21% of P102L; slowly progressive CJD, which included 100% of V180I and 30% of M232R; and Gerstmann-Sträussler-Scheinker disease, which included 100% of P105L and 79% of P102L. PrPSc was detected in the CSF of more than 80% of patients with E200K, M232R, or P102L mutations but in only 39% of patients with V180I. V180I was accompanied by weak PrP immunoreactivity in the brain. Patients negative for PrPSc in the CSF were older at disease onset than positive patients. Patients with mutations associated with high 14-3-3 protein levels in the CSF typically had synaptic deposition of PrP in the brain and a rapid course of disease. The presence of small PrP protein fragments in brain homogenates was not correlated with other clinicopathological features. Positivity for PrPSc in the CSF may reflect the pathological process before or at disease onset, or abnormality in the secretion or metabolism of PrPSc. The amount of 14-3-3 protein in the CSF likely indicates the severity of the pathological process and accompanying neuronal damage. These characteristic features of the CSF in cases of gPrD will likely facilitate accurate diagnosis and clinicopathological study of the various disease subtypes.

ObjectivesGenetic Creutzfeldt-Jakob disease (CJD) due to V180I mutation in the prion protein gene (PRNP) is of great interest because of the differences from sporadic CJD and other genetic prion diseases in terms of clinical features, as well as pathological and biochemical findings. However, few systematic observations about the clinical features in patients with this unique mutation have been published. Therefore, the goal of this study was to relate this mutation to other forms of CJD from a clinical perspective.DesignWe analysed clinical symptoms, prion protein genetics, biomarkers in cerebrospinal fluid (CSF) and MRI of patients.Participants186 Japanese patients with the V180I mutation in PRNP.ResultsOur results indicate that the V180I mutation caused CJD at an older age, with a slower progression and a lower possibility of developing myoclonus, cerebellar, pyramidal signs and visual disturbance compared with classical sporadic CJD with methionine homozygosity at codon 129 of PRNP. Cognitive impairment was the major symptom. Diffuse hyperintensity of the cerebral cortex in diffusion-weighted MRI might be helpful for diagnosis. Owing to the low positivity of PrPSc in the CSF, genetic analysis was often required for a differential diagnosis from slowly progressive dementia.ConclusionsWe conclude that the V180I mutation in PRNP produces a late-developing and slow-developing, less severe form of CJD, whose lesions are uniquely distributed compared with sporadic and other genetic forms of CJD.

Surgery or blood transfusion had little effect on the incidence of sCJD.

No abstract

Up to February 2008, a total of 132 patients with dura mater graft-associated Creutzfeldt-Jakob disease (dCJD) have been identified in Japan, accounting for a majority of the world's patients with dCJD. The patients received dura mater grafts from 1978 to 1993. Lyodura (B. Braun, Melsungen, Germany) was used for all the patients in whom the brand name of the dura mater could be identified. After the incubation period of 1 to 25 years (mean, 11.8 years), CJD appeared from 1985 through to 2006. We analyzed clinical, pathological, and molecular features in 74 patients with dCJD who had been prospectively registered by the CJD Surveillance Committee. The cases of dCJD could be classified into two distinct clinicopathological phenotypes: a non-plaque type, showing typical features identical with those of classic CJD, and a plaque type, characterized by atypical features, including slow progression, lack of or late occurrence of periodic sharp wave complexes on EEG, and plaque formation in the brain. The plaque type accounted for one-third of the pathologically confirmed or clinically diagnosed cases of dCJD. The non-plaque type was associated with methionine homozygosity at codon 129 (129M/M) of the PrP gene in all patients, except for in one patient with the 129M/valine (V) genotype and type 1 protease-resistant PrP (PrP(res)), whereas the plaque type was always associated with the 129M/M genotype and the intermediate type between types 1 and 2 of PrP(res) in all cases. Thus, the clinicopathological and molecular features of the plaque type are distinct from those of the non-plaque type, suggesting contamination of the dura mater grafts with different prion strains.

Genome‐wide association studies demonstrated that polymorphisms in the CD33/sialic acid‐binding immunoglobulin‐like lectin 3 gene are associated with late‐onset Alzheimer's disease (AD). CD33 is expressed on myeloid immune cells and mediates inhibitory signaling through protein tyrosine phosphatases, but the exact function of CD33 in microglia is still unknown. Here, we analyzed CD33 knockout human THP1 macrophages and human induced pluripotent stem cell‐derived microglia for immunoreceptor tyrosine‐based activation motif pathway activation, cytokine transcription, phagocytosis, and phagocytosis‐associated oxidative burst. Transcriptome analysis of the macrophage lines showed that knockout of CD33 as well as knockdown of the CD33 signaling‐associated protein tyrosine phosphatase, nonreceptor type 6 (PTPN6) led to constitutive activation of inflammation‐related pathways. Moreover, deletion of CD33 or expression of Exon 2‐deleted CD33 (CD33ΔE2/CD33m) led to increased phosphorylation of the kinases spleen tyrosine kinase (SYK) and extracellular signal‐regulated kinase 1 and 2 (ERK1 and 2). Transcript analysis by quantitative real‐time polymerase chain reaction confirmed increased levels of interleukin (IL) 1B, IL8, and IL10 after knockout of CD33 in macrophages and microglia. In addition, upregulation of the gene transcripts of the AD‐associated phosphatase INPP5D was observed after knockout of CD33. Functional analysis of macrophages and microglia showed that phagocytosis of aggregated amyloid‐β1‐42 and bacterial particles were increased after knockout of CD33 or CD33ΔE2 expression and knockdown of PTPN6. Furthermore, the phagocytic oxidative burst during uptake of amyloid‐β1‐42 or bacterial particles was increased after CD33 knockout but not in CD33ΔE2‐expressing microglia. In summary, deletion of CD33 or expression of CD33ΔE2 in human macrophages and microglia resulted in putative beneficial phagocytosis of amyloid β1‐42, but potentially detrimental oxidative burst and inflammation, which was absent in CD33ΔE2‐expressing microglia.

Total tau protein (t-tau) levels in cerebrospinal fluid (CSF) (CSF-tau) are markedly elevated in patients with Creutzfeldt-Jakob disease (CJD). Some CSF-tau may leak into the blood. We evaluated t-tau levels in serum (serum-tau) as a possible marker for the differential diagnosis of CJD from Alzheimer's disease (AD) and other rapidly progressive dementias (RPD). Serum-and CSF-tau levels were determined in patients with sporadic CJD (n = 12), AD (n = 10) and RPD but no CJD (non-CJD-RPD; n =9) who showed RPD fulfilling the WHO criteria for possible CJD at onset and had a final diagnosis other than CJD. We also analyzed serum-tau levels in healthy volunteers as a control group (n = 10). Serum-as well as CSF-tau levels were significantly elevated in CJD group compared to those in AD, non-CJD-RPD and healthy control groups. Serumtau would be a simple and useful marker to distinguish CJD from AD and non-CJD-RPD, requiring further large study to confirm this.