Fatal Familial Insomnia Cases Research Articles

Proposal of new clinical diagnostic criteria for fatal familial insomnia

AbstractBackgroundEarly and accurate diagnosis of fatal familial insomnia (FFI) is critical for effective screening; however, this rare disease remains difficult to recognize. This work aimed to propose a new diagnostic criterion for fatal familial insomnia (FFI) with optimal sensitivity, specificity, and likelihood ratio.MethodsAn international group of experts was established and 128 genetically confirmed FFI cases and 281 non‐FFI prion disease controls are enrolled in the validation process. The new criteria were proposed based on the following steps with 2‐round expert consultation: 1) Validation of the 2018 FFI criteria. 2) Diagnostic item selection according to statistical analysis and expert consensus. 3) Validation of the new criteria.ResultsThe 2018 criteria for possible FFI had a sensitivity of 90.6%, specificity of 83.3%, the positive likelihood ratio (PLR) of 5.43, and negative likelihood ratio (NLR) of 0.11; the probable FFI criteria had a sensitivity of 83.6%, specificity of 92.9%, the PLR of 11.77, and NLR of 0.18. The new criteria included more specific and/or common clinical features, 2 exclusion items, and summarized a precise and flexible diagnostic hierarchy. The new criteria for possible FFI had a sensitivity of 92.2%, specificity of 96.1%, a PLR of 23.64, and NLR of 0.08, while the probable FFI criteria had a sensitivity of 90.6%, specificity of 98.2%, the PLR of 50.33, and NLR of 0.095.ConclusionA new clinical diagnostic criteria was proposed for FFI, which will be practical at the clinic for early recognition of FFI and differentiation from other prion diseases then help further referral and genetic test.

From parasomnia to agrypnia excitata - An illustrative case on diagnostic approach

The diagnostic approach to sleep-related movements disorders is seldom discussed. We report a case of fatal familial insomnia who initially presented with persistent limb movements in sleep, which later progressed to a state of agrypnia excitata. Here, the evaluation of abnormal movements in sleep is discussed using a step-by-step diagnostic approach. Although no cure is available for fatal familial insomnia, prompt recognition of this condition is important to facilitate proper management, including the involvement of interdisciplinary neuropalliative care.

Clinical profiles and ethnic heterogeneity of sporadic fatal insomnia.

This study was undertaken to elucidate the clinical profile of sporadic fatal insomnia (sFI), assess the similarities and differences between sFI and fatal familial insomnia (FFI), and evaluate the influence of ethnicity on the phenotype of sFI patients. The data of sFI and FFI patients were retrieved from our case series and through literature review. The clinical and diagnostic features of sFI and FFI were compared, as were the phenotypes of Asian and Caucasian sFI patients. We identified 44 sFI and 157 FFI cases. The prevalence of sleep-related, neuropsychiatric, and autonomic symptoms among the sFI patients were 65.9%, 100.0%, and 43.2%, respectively. Compared to FFI, sFI exhibited longer disease duration and a higher proportion of neuropsychiatric symptoms, whereas FFI was characterized by a higher incidence of sleep-related and autonomic symptoms in the early stages of the disease or throughout its course. In addition, a higher proportion of the sFI patients showed hyperintensity on magnetic resonance imaging (MRI) and periodic sharp wave complexes on electroencephalography compared to the FFI patients, especially those presenting with pathological changes associated with MM2-cortical type sporadic Creutzfeldt-Jakob disease. The Asian sFI patients had a higher proportion of males and positivity for cerebrospinal fluid 14-3-3 protein, and fewer sleep-related symptoms compared to Caucasian sFI patients. The age at onset and duration of sFI differed between ethnic groups, but the difference failed to reach statistical significance. Despite its similarities to FFI, sFI is characterized by longer disease duration, higher proportion of neuropsychiatric symptoms, and hyperintensity on MRI, along with differences in the clinical characteristics based on ethnicity.

Proposal of new diagnostic criteria for fatal familial insomnia

BackgroundThe understanding of fatal familial insomnia (FFI), a rare neurodegenerative autosomal dominant prion disease, has improved in recent years as more cases were reported. This work aimed to propose new diagnostic criteria for FFI with optimal sensitivity, specificity, and likelihood ratio.MethodsAn international group of experts was established and 128 genetically confirmed FFI cases and 281 non-FFI prion disease controls are enrolled in the validation process. The new criteria were proposed based on the following steps with two-round expert consultation: (1) Validation of the 2018 FFI criteria. (2) Diagnostic item selection according to statistical analysis and expert consensus. (3) Validation of the new criteria.ResultsThe 2018 criteria for possible FFI had a sensitivity of 90.6%, a specificity of 83.3%, with a positive likelihood ratio (PLR) of 5.43, and a negative likelihood ratio (NLR) of 0.11; and the probable FFI criteria had a sensitivity of 83.6%, specificity of 92.9%, with a PLR of 11.77, and a NLR of 0.18. The new criteria included more specific and/or common clinical features, two exclusion items, and summarized a precise and flexible diagnostic hierarchy. The new criteria for possible FFI had therefore reached a better sensitivity and specificity (92.2% and 96.1%, respectively), a PLR of 23.64 and a NLR of 0.08, whereas the probable FFI criteria showed a sensitivity of 90.6%, a specificity of 98.2%, with a PLR of 50.33 and a NLR of 0.095.ConclusionsWe propose new clinical diagnostic criteria for FFI, for a better refining of the clinical hallmarks of the disease that ultimately would help an early recognition of FFI and a better differentiation from other prion diseases.

Defining the Prion Type of Fatal Familial Insomnia.

Fatal familial insomnia (FFI) belongs to the genetic human transmissible spongiform encephalopathies (TSE), such as genetic Creutzfeldt-Jakob disease (CJD) or Gerstmann-Straeussler-Scheinker syndrome (GSS). Here, we analyzed the properties of the pathological prion protein in six FFI cases by Western blot analysis, a protein aggregate stability assay, and aggregate deposition characteristics visualized with the paraffin-embedded tissue blot. While in all cases the unglycosylated fragment in Western blot analysis shared the same size with sporadic CJD prion type 2, the reticular/synaptic deposition pattern of the prion aggregates resembled the ones found in sporadic CJD type 1 (CJD types according to the Parchi classification from 1999). Regarding the conformational stability against denaturation with GdnHCl, FFI prion aggregates resembled CJD type 1 more than type 2. Our results suggest that the size of the proteinase-K-resistant fragments is not a valid criterion on its own. Additional criteria supplying information about conformational differences or similarities need to be taken into account. FFI may resemble a prion type with its own conformation sharing properties partly with type 1 and type 2 prions.

Genetic Prion Disease: Insight from the Features and Experience of China National Surveillance for Creutzfeldt-Jakob Disease.

Human genetic prion diseases (gPrDs) are directly associated with mutations and insertions in the PRNP (Prion Protein) gene. We collected and analyzed the data of 218 Chinese gPrD patients identified between Jan 2006 and June 2020. Nineteen different subtypes were identified and gPrDs accounted for 10.9% of all diagnosed PrDs within the same period. Some subtypes of gPrDs showed a degree of geographic association. The age at onset of Chinese gPrDs peaked in the 50-59 year group. Gerstmann-Sträussler-Scheinker syndrome (GSS) and fatal familial insomnia (FFI) cases usually displayed clinical symptoms earlier than genetic Creutzfeldt-Jakob disease (gCJD) patients with point mutations. A family history was more frequently recalled in P105L GSS and D178N FFI patients than T188K and E200K patients. None of the E196A gCJD patients reported a family history. The gCJD cases with point mutations always developed clinical manifestations typical of sporadic CJD (sCJD). EEG examination was not sensitive for gPrDs. sCJD-associated abnormalities on MRI were found in high proportions of GSS and gCJD patients. CSF 14-3-3 positivity was frequently detected in gCJD patients. Increased CSF tau was found in more than half of FFI and T188K gCJD cases, and an even higher proportion of E196A and E200K gCJD patients. 63.6% of P105L GSS cases showed a positive reaction in cerebrospinal fluid RT-QuIC. GSS and FFI cases had longer durations than most subtypes of gCJD. This is one of the largest studies of gPrDs in East Asians, and the illness profile of Chinese gPrDs is clearly distinct. Extremely high proportions of T188K and E196A occur among Chinese gPrDs; these mutations are rarely reported in Caucasians and Japanese.

Insomnia as a benign presentation of fatal familial insomnia (FFI). A case report from Malaysia

Fatal familial insomnia (FFI) is an extremely rare autosomal dominant prion disease. The chief clinical features include an organic sleep disorder associated with sympathetic overdrive, motor and bulbar compromise as well as progressive cognitive decline. Death ensures in 100% of cases with a mean survival duration of 18 months from time of symptom onset. Treatment strategies in the management of FFI remains largely symptomatic with greater emphasis placed on palliative care services. We report a case of a 31-year old gentleman (Mr G) who presented with insomnia, sleep behavior disturbances, diplopia, myoclonus and transient global amnesia. A family history of a paternal aunt with similar presentation who passed away raised the suspicion of probable FFI, which was subsequently confirmed by genetic testing. Mr G is the first reported definitive FFI case of Malaysian Chinese descent. Standard MRI imaging and CSF analyses are insufficient in the workup of an individual with probable FFI. PET scan, polysomnogram and genetic studies are required for cases with high index of suspicion. In view of the rapid progression of the disease with significant cognitive impairment within months of symptom onset, we advocate for early diagnosis and a biopsychosocial patient-centered treatment approach.

A clinical case of fatal familial insomnia with a transient positive response to corticosteroids

Fatal familial insomnia (FFI) is a rare genetic human prion disease with an autosomal dominant pattern of inheritance caused by a D178N mutation in the PRNP gene. FFI is characterized by a variable clinical presentation and subacute manifestation. The latter prompts to consider autoimmune encephalitis as a differential diagnosis in the diagnostically challenging patients. Here, we present a clinical case of FFI that was initially misdiagnosed with autoimmune encephalitis. A 26-year-old woman presented with rapid development of diverse neurological features, autonomic and endocrine disturbances, which initially were considered as manifestations of an autoimmune disease due to the lack of clear indications of positive family history. She was started on corticosteroids with temporary stabilization and even with a mild improvement for several months. Progressive deterioration of her symptoms with development of the psychiatric and cognitive impairment, as well as subsequently received additional information regarding positive family history, prompted us to perform a PRNP gene test that revealed a D178N mutation and confirmed an FFI diagnosis.

Different post-mortem brain regions from three Chinese FFI patients induce different reactive profiles both in the first and second generation RT-QuIC assays

ABSTRACT Fatal Familial Insomnia (FFI) is one of the most popular genetic prion disease (gPrD) in China. Unlike the other types of human prion diseases, FFI patients show distinctive neuropathological characteristics, such as less deposition of PrPSc, low tissue infectivity and severe neuron losses in some special brain regions. Compared with other gPrDs, the positive reactions of cerebrospinal fluid (CSF) RT-QuIC of FFI patients were markedly low. However, the reactivities of RT-QuIC of the brain tissues, particularly different brain regions, of FFI cases are rarely described. In this study, three different brain regions from three FFI patients were subjected into two kinds of RT-QuIC assays using recombinant hamster PrP23-231 (rHaPrP23-231) and PrP90-231 (rHaPrP90-231) as the substrates, respectively. The results showed that the general RT-QuIC reactivities of the brains from FFI cases were significantly lower than that of sCJD. Analyses of the positive rates and the reactivities (lag time and rfu peak) of RT-QuIC identified that the homogenates of frontal lobe induced the most active reaction, followed by thalamus and callosum. The RT-QuIC reactivity in the tested brain sample was closely associated with the intensity of PK-resistant PrPSc. Moreover, we also verified that the sensitivity of the RT-QuIC of rHaPrP90-231 was much higher than that of rHaPrP23-231. Those data confirm that brain tissues of FFI patients are able to convert positive reactions in RT-QuIC and show regional-associated positive converting capacities.

Clinical features and genetic characteristics of two Chinese pedigrees with fatal family insomnia

ABSTRACTBackground: Fatal familial insomnia (FFI) is a rare autosomal-dominant inherited prion disease characterized clinically by severe sleep disorder, motor signs, dysautonomia and abnormal behaviour. FFI is caused by a missense mutation at codon 178 of the prion protein gene (PRNP). Our study is aimed to explore typical clinical and genetic features of two Chinese pedigrees with FFI and review the related literatures.Methods: Two FFI cases with family histories were recruited in our study. The main clinical features, genetic features and possible pathophysiologic mechanisms of these two FFI cases were analysed.Results: The foremost symptoms seemed to be sleep disturbances and psychosis. Progressive sympathetic symptoms, movement disturbances and memory loss were frequently observed as well. Electroencephalography (EEG) showed a minor slowing without periodic triphasic waves. Polysomnography (PSG) showed reduction in total sleep time and disturbance of sleep-related respiratory. Brain magnetic resonance imaging (MRI) did not reveal obvious abnormality. Genetic analysis disclosed the prion protein gene mutation at codon 178 (D178N), with methionine (Met) homozygosity at the polymorphic position 129 (Met129Met).Conclusions: The major clinical features of Chinese FFI are sleep dysfunction, psychiatric symptoms and sympathetic symptoms. Our patients have similar clinical characteristics as that of the typical FFI cases.

Fatal Familial Insomnia Initially Developing Parkinsonism Mimicking Dementia with Lewy Bodies

We report a rare case of fatal familial insomnia in a 58-year-old man who initially developed parkinsonism, secondary dementia, and visual hallucinations that were suspected to be due to dementia with Lewy bodies. We evaluated the function of the striatum via dopamine transporter single-photon emission computed tomography (DAT SPECT) using 123I-ioflupane and found marked presynaptic dopamine dysfunction in the bilateral striatum. This is the first reported case in which the initial symptom of fatal familial insomnia was parkinsonism and in which the dopamine transporter function was evaluated by DAT SPECT.

The associations of two SNPs in miRNA-146a and one SNP in ZBTB38-RASA2 with the disease susceptibility and the clinical features of the Chinese patients of sCJD and FFI

ABSTRACTPrion diseases are a group of fatal neurodegenerative disorders that affect humans and animals. Besides of the pathological agent, prion, there are some elements that can influence or determine susceptibility to prion infection and the clinical phenotype of the diseases, e.g., the polymorphism in PRNP gene. Another polymorphism in ZBTB38–RASA2 has been observed to be associated with the susceptibility of sporadic Creutzfeldt-Jacob disease (sCJD) in UK. MicroRNAs are endogenous small noncoding RNAs that control gene expression by targeting mRNAs and triggering either translation repression or RNA degradation. In this study, two polymorphic loci in miR-146a (rs2910164 and rs57095329) and one locus in ZBTB38-RASA2 (rs295301) of 561 Chinese patients of sCJD and 31 cases of fatal familial insomnia (FFI) were screened by PCR and sequencing. Our data did not figure out any association of those three SNPs with the susceptibility of sCJD. However, a significant association of the SNP of rs57095329 in miR-146a showed the association with the susceptibility of FFI. Additionally, the SNP of rs57095329 showed statistical significances with the appearances of mutism and the positive of cerebrospinal fluid (CSF) protein 14-3-3 in sCJD patients, while the SNP of ZBTB38-RASA2 was significantly related with the appearance of myoclonus in sCJD patients. It indicates that the SNPs of ZBTB38-RASA2 and miR-146a are not associated with the susceptibility of the Chinese sCJD patients, but may influence the appearances of clinical manifestations somehow.

An invivo 11C-PK PET study of microglia activation in Fatal Familial Insomnia.

ObjectivePostmortem studies reported significant microglia activation in association with neuronal apoptosis in Fatal Familial Insomnia (FFI), indicating a specific glial response, but negative evidence also exists. An in vivo study of local immune responses over FFI natural course may contribute to the understanding of the underlying pathogenesis.MethodsWe included eight presymptomatic subjects (mean ± SD age:44.13 ± 3.83 years) carrying the pathogenic D178N‐129met FFI mutation, one symptomatic patient (male, 45 yrs. old), and nine healthy controls (HC) (mean ± SD age: 44.00 ± 11.10 years.) for comparisons. 11C‐(R)‐PK11195 PET allowed the measurement of Translocator Protein (TSPO) overexpression, indexing microglia activation. A clustering algorithm was adopted to define subject‐specific reference regions. Voxel‐wise statistical analyses were performed on 11C‐(R)‐PK11195 binding potential (BP) images both at the group and individual level.ResultsThe D178N‐129met/val FFI patient showed significant 11C‐(R)‐PK11195 BP increases in the midbrain, cerebellum, anterior thalamus, anterior cingulate cortex, orbitofrontal cortex, and anterior insula, bilaterally. Similar TSPO increases, but limited to limbic structures, were observed in four out of eight presymptomatic carriers. The only carrier with the codon 129met/val polymorphism was the only one showing an additional TSPO increase in the anterior thalamus.InterpretationIn comparison to nonprion neurodegenerative diseases, the observed lack of a diffuse brain TSPO overexpression in preclinical and the clinical FFI cases suggests the presence of a different microglia response. The involvement of limbic structures might indicate a role for microglia activation in these key pathologic regions, known to show the most significant neuronal loss and functional deafferentation in FFI.

Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) Correlation of Histopathology and MRI in Prion Disease.

Creutzfeldt-Jakob disease (CJD) and other prion diseases are rapidly progressive spongiform encephalopathies that are invariably fatal. Clinical features and magnetic resonance imaging, electroencephalogram, and cerebrospinal fluid abnormalities may suggest prion disease, but a definitive diagnosis can only be made by means of neuropathologic examination. Fluorodeoxyglucose positron emission tomography (FDG-PET) is not routinely used to evaluate patients with suspected prion disease. This study includes 11 cases of definite prion disease in which FDG-PET scans were obtained. There were 8 sporadic CJD cases, 2 genetic CJD cases, and 1 fatal familial insomnia case. Automated FDG-PET analysis revealed parietal region hypometabolism in all cases. Surprisingly, limbic and mesolimbic hypermetabolism were also present in the majority of cases. When FDG-PET hypometabolism was compared with neuropathologic changes (neuronal loss, astrocytosis, spongiosis), hypometabolism was predictive of neuropathology in 80.6% of cortical regions versus 17.6% of subcortical regions. The odds of neuropathologic changes were 2.1 times higher in cortical regions than subcortical regions (P=0.0265). A similar discordance between cortical and subcortical regions was observed between FDG-PET hypometabolism and magnetic resonance imaging diffusion weighted imaging hyperintensity. This study shows that there may be a relationship between FDG-PET hypometabolism and neuropathology in cortical regions in prion disease but it is unlikely to be helpful for diagnosis.

Fatal familial insomnia: mitochondrial and protein synthesis machinery decline in the mediodorsal thalamus.

The expression of subunits of mitochondrial respiratory complexes and components of the protein synthesis machinery from the nucleolus to the ribosome was analyzed in the mediodorsal thalamus in seven cases of fatal familial insomnia (FFI) compared with age-matched controls. NDUFB8 (complex I subunit), SDHB (complex II subunit), UQCRC2 (complex III subunit), COX2 (complex IV subunit), and ATP50 (complex V subunit) expression levels, as revealed by western blotting, were reduced in FFI. Voltage-dependent anion channel (VDAC) and ATP5H were also reduced due to the marked depopulation of neurons. In contrast, a marked increase in superoxide dismutase 2 (SOD2) was found in reactive astrocytes thus suggesting that astrocytes are key factors in oxidative stress responses. The histone-binding chaperones nucleolin and nucleoplasmin 3, and histone H3 di-methylated K9 were markedly reduced together with a decrease in the expression of protein transcription elongation factor eEF1A. These findings show severe impairment in the expression of crucial components of mitochondrial function and protein synthesis in parallel with neuron loss in mediodorsal thalamus at terminal stages of FFI. Therapeutic measures must be taken long before the appearance of clinical symptoms to prevent the devastating effects of FFI.

Gait disorders in fatal familial insomnia

Fatal familial insomnia (FFI) is a hereditary autosomal-dominant prion disease linked to a mutation of the prion protein gene and characterized by sleep and autonomic abnormalities at onset followed by motor disturbances. We describe gait abnormalities in 13 FFI cases with different disease durations. Clinical records and corresponding videos of 13 FFI cases were regularly monitored from disease onset to death. Gait disturbances appeared in all FFI subjects 5 ± 2 months after disease onset following a distinct progression for the 2 genetic FFI variants. Homozygous patients developed only a cautious gait with some difficulties in turning and in tandem gait; heterozygous patients showed a clear progressive worsening of equilibrium with latero/retropulsion ultimately preventing standing and walking unaided. The severity and features of gait dysfunction in FFI are related to the duration of the disease, which in turn is a result of the genotype. The evolving gait dysfunction in the disease course may mirror the spread of neuronal degeneration from the thalamus to other brain areas involved in the control of gait or may be the functional effect of a disturbed neuronal network in which the thalamus is a crucial relay.

Brain microglia were activated in sporadic CJD but almost unchanged in fatal familial insomnia and G114V genetic CJD

BackgroundMicroglial activations have been described in different subtypes of human prion diseases such as sporadic Creutzfeldt-Jakob disease (CJD), variant CJD, Kuru and Gerstmann-Sträussler-Scheinker disease (GSS). However, the situation of microglia in other genetic prion diseases such as fatal familial insomnia (FFI) and familial CJD remains less understood. The brain microglia was evaluated comparatively between the FFI, G114V and sCJD cases in the study.MethodsSpecific Western blots, immunohistochemical and immunofluorescent assays were used to detect the changes of microglia and ELISA tests were used for levels of inflammatory cytokines.ResultsWestern blots, immunohistochemical and immunofluorescent assays illustrated almost unchanged microglia in the temporal lobes of FFI and G114V gCJD, but obviously increased in those of sCJD. The Iba1-levels maintained comparable in six different brain regions of FFI and G114V cases, including thalamus, cingulate gyrus, frontal cortex, parietal cortex, occipital cortex and temporal cortex. ELISA tests for inflammatory cytokines revealed significantly up-regulated IL-1β, IL-6 and TNF-α in the brain homogenates from sCJD, but not in those from FFI and G114V gCJD.ConclusionData here demonstrates silent brain microglia in FFI and G114V gCJD but obviously increased in sCJD, which reflects various pathogenesis of different human prion diseases subtypes.

Analyses of the Survival Time and the Influencing Factors of Chinese Patients with Prion Diseases Based on the Surveillance Data from 2008–2011

BackgroundPrion diseases are kinds of progressive, incurable neurodegenerative disorders. So far, survival time of the patients with these diseases in China is unclear.MethodsBased upon the surveillance data from Chinese Creutzfeldt-Jakob disease (CJD) surveillance network from January 2008 to December 2011, a retrospective follow-up survey was performed. The survival times of Chinese patients with prion diseases and the possible influencing factors were analyzed.ResultsMedian survival time of 121 deceased patients was 7.1 months, while those for sporadic CJD (sCJD), familial CJD (fCJD) and fatal familial insomnia (FFI) cases were 6.1, 3.1 and 8.2 months, respectively. 74.0% of sCJD patients, 100% of fCJD cases and 91.7% FFI cases died within one year. The general socio-demographic factors, abnormalities in clinical examinations, clinical manifestations, and social factors did not significantly influence the survival times of Chinese prion patients.ConclusionsSurvival time of Chinese patients with prion diseases was comparable with that of many Western countries, but obviously shorter than that of Japan. Patients with acute onset and rapid progression had significantly short survival times.

Early Detection of Abnormal Prion Protein in Genetic Human Prion Diseases Now Possible Using Real-Time QUIC Assay

IntroductionThe definitive diagnosis of genetic prion diseases (gPrD) requires pathological confirmation. To date, diagnosis has relied upon the finding of the biomarkers 14-3-3 protein and total tau (t-tau) protein in the cerebrospinal fluid (CSF), but many researchers have reported that these markers are not sufficiently elevated in gPrD, especially in Gerstmann-Sträussler-Scheinker syndrome (GSS). We recently developed a new in vitro amplification technology, designated “real-time quaking-induced conversion (RT-QUIC)”, to detect the abnormal form of prion protein in CSF from sporadic Creutzfeldt-Jakob disease (sCJD) patients. In the present study, we aimed to investigate the presence of biomarkers and evaluate RT-QUIC assay in patients with gPrD, as the utility of RT-QUIC as a diagnostic tool in gPrD has yet to be determined.Method/Principal Findings56 CSF samples were obtained from gPrD patients, including 20 cases of GSS with P102L mutation, 12 cases of fatal familial insomnia (FFI; D178N), and 24 cases of genetic CJD (gCJD), comprising 22 cases with E200K mutation and 2 with V203I mutation. We subjected all CSF samples to RT-QUIC assay, analyzed 14-3-3 protein by Western blotting, and measured t-tau protein using an ELISA kit. The detection sensitivities of RT-QUIC were as follows: GSS (78%), FFI (100%), gCJD E200K (87%), and gCJD V203I (100%). On the other hand the detection sensitivities of biomarkers were considerably lower: GSS (11%), FFI (0%), gCJD E200K (73%), and gCJD V203I (67%). Thus, RT-QUIC had a much higher detection sensitivity compared with testing for biomarkers, especially in patients with GSS and FFI.Conclusion/SignificanceRT-QUIC assay is more sensitive than testing for biomarkers in gPrD patients. RT-QUIC method would thus be useful as a diagnostic tool when the patient or the patient's family does not agree to genetic testing, or to confirm the diagnosis in the presence of a positive result for genetic testing.

Comparison of the pathologic and pathogenic features in six different regions of postmortem brains of three patients with fatal familial insomnia

Fatal familial insomnia (FFI) is an autosomal dominant prion disease clinically characterized by rapidly progressive insomnia, prominent autonomic alterations and behavioral disturbance. The D178N mutation of the prion protein gene (PRNP) on chromosome 20 in conjunction with methionine at codon129 is a molecular feature. Although the neuropathological characteristics of FFI are well documented, the neuropathologic and pathogenic features of FFI patients remain poorly understood. Six brain regions of postmortem brains from 3 FFI patients were examined using immunohistochemistry, western blot analyses and quantitative real-time PCR. In all 3 brain specimens, reactive astrogliosis was found to be more severe in the thalamus than in the cortex regions. Western blot analyses showed that all three brains expressed PrP, but only 2 were associated with significantly weak proteinase K (PK) resistance. However, the conformational stabilities of PrPSc in the 3 FFI brains were significantly weaker than those presented in a G114V genetic Creutzfeldt-Jakob disease (gCJD) case. Immunohistochemistry and western blot analyses showed comparable amounts of neuron-specific enolase (NSE)-positive stained cells and NSE protein among the different regions in the three brains. In addition, the transcriptional levels of glial fibrillary acidic protein (GFAP) and NSE-specific mRNAs were coincident with the expression of these proteins. In conclusion, in the present study, we described the detailed regional neuropathology of FFI cases.