Familial Creutzfeldt-Jakob disease with a V180I mutation: comparative analysis with pathological findings and diffusion-weighted images

Prion Mutations in Republic of Republic of Korea, China, and Japan

Prion gene (PRNP) mutations are associated with diverse disease phenotypes, including familiar Creutzfeldt-Jakob Disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS), and fatal familial insomnia (FFI). Interestingly, PRNP mutations have been reported in patients diagnosed with Alzheimer's disease, dementia with Lewy bodies, Parkinson's disease, and frontotemporal dementia. In this review, we describe prion mutations in Asian countries, including Republic of Republic of Korea, China, and Japan. Clinical phenotypes and imaging data related to these mutations have also been introduced in detail. Several prion mutations are specific to Asians and have rarely been reported in countries outside Asia. For example, PRNP V180I and M232R, which are rare in other countries, are frequently detected in Republic of Korea and Japan. PRNP T188K is common in China, and E200K is significantly more common among Libyan Jews in Israel. The A117V mutation has not been detected in any Asian population, although it is commonly reported among European GSS patients. In addition, V210I or octapeptide insertion is common among European CJD patients, but relatively rare among Asian patients. The reason for these differences may be geographical or ethical isolation. In terms of clinical phenotypes, V180I, P102L, and E200K present diverse clinical symptoms with disease duration, which could be due to other genetic and environmental influences. For example, rs189305274 in the ACO1 gene may be associated with neuroprotective effects in cases of V180I mutation, leading to longer disease survival. Additional neuroprotective variants may be possible in cases featuring the E200K mutation, such as KLKB1, KARS, NRXN2, LAMA3, or CYP4X1. E219K has been suggested to modify the disease course in cases featuring the P102L mutation, as it may result in the absence of prion protein-positive plaques in tissue stained with Congo red. However, these studies analyzed only a few patients and may be too preliminary. The findings need to be verified in studies with larger sample sizes or in other populations. It would be interesting to probe additional genetic factors that cause disease progression or act as neuroprotective factors. Further studies are needed on genetic modifiers working with prions and alterations from mutations.

Systematic Review of Clinical and Pathophysiological Features of Genetic Creutzfeldt-Jakob Disease Caused by a Val-to-Ile Mutation at Codon 180 in the Prion Protein Gene

Genetic Creutzfeldt-Jakob disease (gCJD) is a subtype of genetic prion diseases (gPrDs) caused by the accumulation of mutated pathological prion proteins (PrPSc). gCJD has a phenotypic similarity with sporadic CJD (sCJD). In Japan, gCJD with a Val to Ile substitution at codon 180 (V180I-gCJD) is the most frequent gPrD, while the mutation is extremely rare in countries other than Japan and Korea. In this article, we aim to review previously elucidated clinical and biochemical features of V180I-gCJD, expecting to advance the understanding of this unique subtype in gCJD. Compared to classical sCJD, specific clinical features of V180I-gCJD include older age at onset, a relatively slow progression of dementia, and a lower positivity for developing myoclonus, cerebellar, pyramidal signs, and visual disturbance. Diffuse edematous ribboning hyperintensity of the cerebral cortex, without occipital lobes in diffusion-weighted magnetic resonance imaging, is also specific. Laboratory data reveal the low positivity of PrPSc in the cerebrospinal fluid and periodic sharp wave complexes on an electroencephalogram. Most patients with V180I-gCJD have been reported to have no family history, probably due to the older age at onset, and clinical and biochemical features indicate the specific phenotype associated with the prion protein gene mutation.

A patient with spastic paralysis finally diagnosed as V180I genetic Creutzfeldt-Jakob disease 9 years after onset

Genetic Creutzfeldt-Jakob disease (gCJD) with a mutation in codon 180 of the prion protein gene (V180I gCJD) is the most common form of gCJD in Japan, but only a few cases have been reported in Europe and the United States. It is clinically characterized by occurring in the elderly and presenting as slowly progressive dementia, although it generally shows less cerebellar and pyramidal symptoms than sporadic CJD. Here, we report a patient with V180I gCJD who initially presented with slowly progressive spastic paralysis with neither cerebrospinal fluid (CSF) nor magnetic resonance imaging (MRI) abnormalities. His symptoms progressed gradually, and after 9 years, he displayed features more typical of CJD. Diffusion-weighted MRI revealed high-intensity signals in the cortical gyrus, and there was a marked increase of 14-3-3 protein and total tau protein in the CSF, but he was negative for the real-time quaking-induced conversion assay. Although the time course was more consistent with Gerstmann-Sträussler-Scheinker disease than CJD, genetic testing revealed V180I gCJD. This is the first report of a patient with V180I gCJD who initially presented with spastic paralysis, and also the first to reveal that it took 9 years from disease onset for cortical dysfunction to develop and for MRI and CSF abnormalities to be detectable. In conclusion, we should screen for V180I gCJD in elderly patients presenting with slowly progressive spastic paralysis.

Clinical Laboratory Tests Used To Aid in Diagnosis of Human Prion Disease

Prion diseases are a group of rapidly progressive and always fatal neurodegenerative disorders caused by misfolded prion protein in the brain. Although autopsy remains the gold-standard diagnostic tool, antemortem laboratory testing can be performed to aid in the diagnosis of prion disease. This review is meant to help laboratory directors and physicians in their interpretation of test results. Laboratory assays to detect both nonspecific biomarkers of prion disease and prion-specific biomarkers can be used. The levels of nonspecific biomarkers in cerebrospinal fluid (CSF) are elevated when rapid neurodegeneration is occurring in the patient, and these markers include 14-3-3, tau, neuron-specific enolase, S100B, and alpha-synuclein. These markers have various sensitivities and specificities but are overall limited, as the levels of any of these analytes can be elevated in nonprion disease that is causing rapid damage of brain tissue. Prion-specific assays used in clinical laboratory testing are currently limited to two options. The first option is second-generation real-time quaking-induced conversion (RT-QuIC) performed on CSF, and the second option is Western blotting of a brain biopsy specimen used to detect protease-resistant prion protein. Although both tests have exquisite specificity, RT-QuIC has a sensitivity of 92 to 97.2% in symptomatic individuals, compared to the brain biopsy Western blot sensitivity of 20 to 60%. RT-QuIC was added to the Centers for Disease Control and Prevention's diagnostic criteria for prion disease in 2018. Other caveats of laboratory testing need to be considered, as sporadic, genetic, and acquired forms of prion disease have different clinical and laboratory presentations, and these caveats are discussed. Laboratory testing plays an important role in the diagnosis of prion disease, which is often challenging to diagnose.

Characterization of mutations in PRNP (prion) gene and their possible roles in neurodegenerative diseases

Abnormal prion proteins are responsible for several fatal neurodegenerative diseases in humans and in animals, including Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker disease, and fatal familial insomnia. Genetics is important in prion diseases, but in the most cases, cause of diseases remained unknown. Several mutations were found to be causative for prion disorders, and the effect of mutations may be heterogeneous. In addition, different prion mutations were suggested to play a possible role in additional phenotypes, such as Alzheimer's type pathology, spongiform encephalopathy, or frontotemporal dementia. Pathogenic nature of several prion mutations remained unclear, such as M129V and E219K. These two polymorphic sites were suggested as either risk factors for different disorders, such as Alzheimer's disease (AD), variant CJD, or protease-sensitive prionopathy, and they can also be disease-modifying factors. Pathological overlap may also be possible with AD or progressive dementia, and several patients with prion mutations were initially diagnosed with AD. This review also introduces briefly the diagnosis of prion diseases and the issues with their diagnosis. Since prion diseases have quite heterogeneous phenotypes, a complex analysis, a combination of genetic screening, cerebrospinal fluid biomarker analysis and imaging technologies could improve the early disease diagnosis.

Preserved regional cerebral blood flow in the occipital cortices, brainstem, and cerebellum of patients with V180I-129M genetic Creutzfeldt-Jakob disease in serial SPECT studies

Creutzfeldt-Jakob disease (CJD) with a causative point mutation of valine to isoleucine at codon 180 (V180I) is one of the major types of genetic CJD (gCJD) in Japan. V180I gCJD is rarely accompanied by a family history, and its clinical characteristics include late-onset, long disease duration, and edematous cortical hyperintensity in diffusion, fluid attenuate inversion and T2-weighted MRI. We performed serial imaging with single-photon emission computed tomography (SPECT) and MRI in three V180I gCJD cases over long-term observation. All cases were characterized by progressive dementia, parkinsonism, and the absence of cerebellar signs or cortical visual dysfunction in their clinical courses. Moreover, during the end-stage, SPECT findings showed preserved regional cerebral blood flow (rCBF) in the occipital cortices, brainstem, and cerebellum. Similarly, no apparent atrophy or increased signal intensities were observed in MRI images of the occipital and cerebellar regions. In conclusion, we report a decrease in rCBF predominantly in the frontal and temporal cortices during the early-stage, which became more widespread as the disease progressed. Importantly, rCBF was preserved in the occipital cortices, brainstem, and cerebellar regions until the end-stage, which may be distinct to V180I gCJD cases.

Genomic Characteristics of Genetic Creutzfeldt-Jakob Disease Patients with V180I Mutation and Associations with Other Neurodegenerative Disorders

Inherited prion diseases (IPDs), including genetic Creutzfeldt-Jakob disease (gCJD), account for 10–15% of cases of prion diseases and are associated with several pathogenic mutations, including P102L, V180I, and E200K, in the prion protein gene (PRNP). The valine to isoleucine substitution at codon 180 (V180I) of PRNP is the most common pathogenic mutation causing gCJD in East Asian patients. In this study, we conducted follow-up analyses to identify candidate factors and their associations with disease onset. Whole-genome sequencing (WGS) data of five gCJD patients with V180I mutation and 145 healthy individuals were used to identify genomic differences. A total of 18,648,850 candidate variants were observed in only the patient group, 29 of them were validated as variants. Four of these validated variants were nonsense mutations, six were observed in genes directly or indirectly related to neurodegenerative disorders (NDs), such as LPA, LRRK2, and FGF20. More than half of validated variants were categorized in Gene Ontology (GO) terms of binding and/or catalytic activity. Moreover, we found differential genome variants in gCJD patients with V180I mutation, including one uniquely surviving 10 years after diagnosis of the disease. Elucidation of the relationships between gCJD and Alzheimer’s disease or Parkinson’s disease at the genomic level will facilitate further advances in our understanding of the specific mechanisms mediating the pathogenesis of NDs and gold standard therapies for NDs.

Do prion protein gene polymorphisms induce apoptosis in non-mammals?

Genetic variations such as single nucleotide polymorphisms (SNPs) in prion protein coding gene, Prnp, greatly affect susceptibility to prion diseases in mammals. Here, the coding region of Prnp was screened for polymorphisms in redeared turtle, Trachemys scripta. Four polymorphisms, L203V, N205I, V225A and M237V, were common in 15 out of 30 turtles; in one sample, three SNPs, L203V, N205I and M237V, and in the remaining 14 samples, only L203V and N205I polymorphisms, were investigated. Besides, C658T, C664T, C670A and C823A SNPs were silent mutations. To elucidate the relationship between the SNPs and apoptosis, TUNEL assays and active caspase-3 immunodetection techniques in brain sections of the polymorphic samples were performed. The results revealed that TUNEL-positive cells and active caspase-3-positive cells in the turtles with four polymorphisms were significantly increased compared with those of the turtles with two polymorphisms (P less than 0.01 and P less than 0.05, respectively). In conclusion, this study provides preliminary information about the possible relationship between SNPs within the Prnp locus and apoptosis in a non-mammalian species, Trachemys scripta, in which prion disease has never been reported.

Creutzfeldt-Jakob Disease with a prion protein gene codon 180 mutation presenting asymmetric cortical high-intensity on magnetic resonance imaging

Here we report a genetically confirmed case of Creutzfeldt-Jakob disease with a prion protein gene codon 180 mutation presenting atypical magnetic resonance imaging findings. The present case exhibited an acute onset and lateralized neurologic signs, and progressive cognitive impairment. No myoclonus or periodic synchronous discharges on electroencephalography were observed. Diffusion-weighted images revealed areas of high signal intensity in the right frontal and temporal cortices at onset that extended to the whole cortex and basal ganglia of the right cerebral hemisphere at 3 months. Although the cerebrospinal fluid (CSF) was initially negative for neuron specific enolase, tau protein, 14-3-3 protein, and abnormal prion protein, the CSF was positive for these brain-derived proteins at 3 months after onset.

Rare V180I mutation in PRNP gene of a Chinese patient with Creutzfeldt-Jakob disease

Abstract Here, we reported a Chinese case of Creutzfeldt-Jakob disease (CJD) with a rare mutation in the prion protein gene (PRNP) leading to an exchange of amino acid from valine (V) to isoleucine (I) at codon 180 (V180I). The 72 year-old Chinese women started with gradual memory loss. On admission, she did not present special abnormality during clinical examinations except bradykinesia in her lower extremities. Myoclonic jerks and increased muscle tone were noticed 3 months after the onset. No periodic activity was recorded at electroencephalography (EEG) and 14-3-3 protein was negative in the cerebrospinal fluid (CSF) sample. Brain diffusion weighted images (DWI) demonstrated high signal intensities in bilateral frontal, parietal, temporal and occipital cortices, especially on the left hemisphere, and high signal intensities were also seen in the left caudate nucleus and the putamen. The patient had no family history of similar symptoms. Her general condition was gradually deteriorative, but the patient was still alive when we performed the follow-up 12 months after onset.

White matter involvement in sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease is considered primarily a disease of grey matter, although the extent of white matter involvement has not been well described. We used diffusion tensor imaging to study the white matter in sporadic Creutzfeldt-Jakob disease compared to healthy control subjects and to correlated magnetic resonance imaging findings with histopathology. Twenty-six patients with sporadic Creutzfeldt-Jakob disease and nine age- and gender-matched healthy control subjects underwent volumetric T₁-weighted and diffusion tensor imaging. Six patients had post-mortem brain analysis available for assessment of neuropathological findings associated with prion disease. Parcellation of the subcortical white matter was performed on 3D T₁-weighted volumes using Freesurfer. Diffusion tensor imaging maps were calculated and transformed to the 3D-T₁ space; the average value for each diffusion metric was calculated in the total white matter and in regional volumes of interest. Tract-based spatial statistics analysis was also performed to investigate the deeper white matter tracts. There was a significant reduction of mean (P = 0.002), axial (P = 0.0003) and radial (P = 0.0134) diffusivities in the total white matter in sporadic Creutzfeldt-Jakob disease. Mean diffusivity was significantly lower in most white matter volumes of interest (P < 0.05, corrected for multiple comparisons), with a generally symmetric pattern of involvement in sporadic Creutzfeldt-Jakob disease. Mean diffusivity reduction reflected concomitant decrease of both axial and radial diffusivity, without appreciable changes in white matter anisotropy. Tract-based spatial statistics analysis showed significant reductions of mean diffusivity within the white matter of patients with sporadic Creutzfeldt-Jakob disease, mainly in the left hemisphere, with a strong trend (P = 0.06) towards reduced mean diffusivity in most of the white matter bilaterally. In contrast, by visual assessment there was no white matter abnormality either on T₂-weighted or diffusion-weighted images. Widespread reduction in white matter mean diffusivity, however, was apparent visibly on the quantitative attenuation coefficient maps compared to healthy control subjects. Neuropathological analysis showed diffuse astrocytic gliosis and activated microglia in the white matter, rare prion deposition and subtle subcortical microvacuolization, and patchy foci of demyelination with no evident white matter axonal degeneration. Decreased mean diffusivity on attenuation coefficient maps might be associated with astrocytic gliosis. We show for the first time significant global reduced mean diffusivity within the white matter in sporadic Creutzfeldt-Jakob disease, suggesting possible primary involvement of the white matter, rather than changes secondary to neuronal degeneration/loss.

Sporadic Creutzfeldt-Jakob disease (sCJD) is considered primarily a disease of grey matter. However, Caverzasi et al. now show a global decrease in mean diffusivity in white matter. The changes appear to be associated with reactive astrocytic gliosis and activated microglia, and suggest primary involvement of the white matter in sCJD.

Clinical features of genetic Creutzfeldt-Jakob disease with V180I mutation in the prion protein gene

OBJECTIVES

Genetic 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.

DESIGN

We analysed clinical symptoms, prion protein genetics, biomarkers in cerebrospinal fluid (CSF) and MRI of patients.

PARTICIPANTS

186 Japanese patients with the V180I mutation in PRNP.

RESULTS

Our 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 PrP(Sc) in the CSF, genetic analysis was often required for a differential diagnosis from slowly progressive dementia.

CONCLUSIONS

We 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.

The role of neuroimaging in evaluating patients affected by Creutzfeldt-Jakob disease: a systematic review of the literature

Diagnosis of Creutzfeldt-Jakob disease during life can be challenging since the huge variability of the symptoms which can be observed, especially in its early stages, may simulate other common forms of dementia. In latest years, noninvasive techniques such as magnetic resonance, positron emission tomography, and single-photon emission tomography have been evaluated to help clinical neurologists to provide a definite diagnosis. We here provide a systematic review of the current knowledge of neuroimaging in CJD in order to establish the actual state of the art.

Discriminant analysis of prion sequences for prediction of susceptibility

Prion diseases, including ovine scrapie, bovine spongiform encephalopathy (BSE), human kuru and Creutzfeldt-Jakob disease (CJD), originate from a conformational change of the normal cellular prion protein (PrP(C)) into abnormal protease-resistant prion protein (PrP(Sc)). There is concern regarding these prion diseases because of the possibility of their zoonotic infections across species. Mutations and polymorphisms of prion sequences may influence prion-disease susceptibility through the modified expression and conformation of proteins. Rapid determination of susceptibility based on prion-sequence polymorphism information without complex structural and molecular biological analyses may be possible. Information regarding the effects of mutations and polymorphisms on prion-disease susceptibility was collected based on previous studies to classify the susceptibilities of sequences, whereas the BLOSUM62 scoring matrix and the position-specific scoring matrix were utilised to determine the distance of target sequences. The k-nearest neighbour analysis was validated with cross-validation methods. The results indicated that the number of polymorphisms did not influence prion-disease susceptibility, and three and four k-objects showed the best accuracy in identifying the susceptible group. Although sequences with negative polymorphisms showed relatively high accuracy for determination, polymorphisms may still not be an appropriate factor for estimating variation in susceptibility. Discriminant analysis of prion sequences with scoring matrices was attempted as a possible means of determining susceptibility to prion diseases. Further research is required to improve the utility of this method.

Prions in variably protease-sensitive prionopathy: an update

Human prion diseases, including sporadic, familial, and acquired forms such as Creutzfeldt-Jakob disease (CJD), are caused by prions in which an abnormal prion protein (PrP^Sc) derived from its normal cellular isoform (PrP^C) is the only known component. The recently-identified variably protease-sensitive prionopathy (VPSPr) is characterized not only by an atypical clinical phenotype and neuropathology but also by the deposition in the brain of a peculiar PrP^Sc. Like other forms of human prion disease, the pathogenesis of VPSPr also currently remains unclear. However, the findings of the peculiar features of prions from VPSPr and of the possible association of VPSPr with a known genetic prion disease linked with a valine to isoleucine mutation at residue 180 of PrP reported recently, may be of great importance in enhancing our understanding of not only this atypical human prion disease in particular, but also other prion diseases in general. In this review, we highlight the physicochemical and biological properties of prions from VPSPr and discuss the pathogenesis of VPSPr including the origin and formation of the peculiar prions.

Spreading brain lesions in a familial Creutzfeldt-Jakob disease with V180I mutation over 4 years

BACKGROUND

We report a female patient with familial Creutzfeldt-Jakob disease with V180I mutation (fCJD with V180I), who was serially followed up with magnetic resonance imaging (MRI) and electroencephalogram (EEG) for up to four years.

CASE PRESENTATION

At 6 months after the onset, diffusion-weighted images (DWI) and fluid-attenuated inversion recovery (FLAIR) of brain MRI revealed an increased signal intensity in the bilateral frontal, temporal, and parietal cerebral cortex with left dominancy except for the occipital lobe. However, her follow-up MRI at four years showed the high-signal regions spreading to the occipital cerebral cortex in DWI and FLAIR images, and bilateral frontal cerebral white matter in FLAIR images. EEG showed a progressive and general slow high-voltage rhythm from 7-8 to 3-5 c/s over four years, without evidence of periodic synchronous discharge. These findings correspond to the symptom progression even after akinetic mutism at 18 months.

CONCLUSION

We suggest that serial MRI and EEG examinations are useful for early diagnosis of fCJD with V180I and for monitoring disease progression.

Early detection of familial Creutzfeldt-Jakob disease on diffusion-weighted imaging before symptom onset

Familial Creutzfeldt-Jakob disease (CJD) with V180I shows different clinical characteristics from classical CJD and is difficult to diagnose in the early stage. We report a CJD180 patient in whom results of diffusion-weighted imaging (DWI) led us to suspect CJD before symptoms started. A 68-year-old woman presented to our hospital with headache and nausea and underwent magnetic resonance imaging. DWI showed cortical hyperintensity. Three months later, cognitive function started to decline and CJD180 was diagnosed following genetic examination. In the early stage, ADC values were not decreased and single positron emission computed tomography demonstrated a decreased pattern like Alzheimer disease.

Pathogenic mutations in the hydrophobic core of the human prion protein can promote structural instability and misfolding

Transmissible spongiform encephalopathies, or prion diseases, are caused by misfolding and aggregation of the prion protein PrP. These diseases can be hereditary in humans and four of the many disease-associated missense mutants of PrP are in the hydrophobic core: V180I, F198S, V203I and V210I. The T183A mutation is related to the hydrophobic core mutants as it is close to the hydrophobic core and known to cause instability. We used extensive molecular dynamics simulations of these five PrP mutants to compare their dynamics and conformations to those of the wild type PrP. The simulations highlight the changes that occur upon introduction of mutations and help to rationalize experimental findings. Changes can occur around the mutation site, but they can also be propagated over long distances. In particular, the F198S and T183A mutations lead to increased flexibility in parts of the structure that are normally stable, and the short β-sheet moves away from the rest of the protein. Mutations V180I, V210I and, to a lesser extent, V203I cause changes similar to those observed upon lowering the pH, which has been linked to misfolding. Early misfolding is observed in one V180I simulation. Overall, mutations in the hydrophobic core have a significant effect on the dynamics and stability of PrP, including the propensity to misfold, which helps to explain their role in the development of familial prion diseases.

Prospective 10-year surveillance of human prion diseases in Japan

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.