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Gerstmann–Sträussler–Scheinker (GSS) disease is an inherited prion disease characterized by dementia, cerebellar ataxia, and painful sensory disturbances. GSS is pathologically defined by the presence of amyloid plaques comprised of prion protein predominantly localized in the cerebral cortex, cerebellar cortex, and basal ganglia, resulting from mutations in the prion protein gene. This study investigated five cases of GSS P102L [GSS caused by a leucine (L) substitution of proline (P) at position 102 of the prion protein gene] with L-dopa-resistant extrapyramidal symptoms and reduced dopamine transporter single-photon emission computed tomography (DAT-SPECT) uptake. Clinical findings revealed diverse manifestations, with all cases exhibiting parkinsonism, and four patients had a vertical gaze palsy. Notably, all patients showed reduced striatal DAT-SPECT uptake, indicating neurodegeneration of the nigrostriatal system. Autopsy findings in one case confirmed prion protein plaques and dopaminergic neuron loss in the substantia nigra of a patient with GSS P102L. Additionally, reduced DAT immunostaining was observed in the putamen compared with a control. While previous studies have identified reduced DAT-SPECT and positron emission tomography uptake in Creutzfeldt-Jakob disease and fatal familial insomnia owing to nigrostriatal neurodegeneration induced by abnormal prion protein deposition, similar phenomena in GSS P102L have not been reported. This study provides support for a correlation between abnormal prion protein deposition and nigrostriatal system degeneration in GSS P102L. Our results reveal the importance of considering GSS P102L in cases of atypical Parkinsonism and abnormal DAT-SPECT results, which would serve as a valuable indicator for subsequent prion genetic testing. [ABSTRACT FROM AUTHOR]

Gerstmann–Sträussler–Scheinker (GSS) disease is an inherited prion disease characterized by dementia, cerebellar ataxia, and painful sensory disturbances. GSS is pathologically defined by the presence of amyloid plaques comprised of prion protein predominantly localized in the cerebral cortex, cerebellar cortex, and basal ganglia, resulting from mutations in the prion protein gene. This study investigated five cases of GSS P102L [GSS caused by a leucine (L) substitution of proline (P) at position 102 of the prion protein gene] with L-dopa-resistant extrapyramidal symptoms and reduced dopamine transporter single-photon emission computed tomography (DAT-SPECT) uptake. Clinical findings revealed diverse manifestations, with all cases exhibiting parkinsonism, and four patients had a vertical gaze palsy. Notably, all patients showed reduced striatal DAT-SPECT uptake, indicating neurodegeneration of the nigrostriatal system. Autopsy findings in one case confirmed prion protein plaques and dopaminergic neuron loss in the substantia nigra of a patient with GSS P102L. Additionally, reduced DAT immunostaining was observed in the putamen compared with a control. While previous studies have identified reduced DAT-SPECT and positron emission tomography uptake in Creutzfeldt-Jakob disease and fatal familial insomnia owing to nigrostriatal neurodegeneration induced by abnormal prion protein deposition, similar phenomena in GSS P102L have not been reported. This study provides support for a correlation between abnormal prion protein deposition and nigrostriatal system degeneration in GSS P102L. Our results reveal the importance of considering GSS P102L in cases of atypical Parkinsonism and abnormal DAT-SPECT results, which would serve as a valuable indicator for subsequent prion genetic testing.

Background: Genetic prion diseases, including Gerstmann‐Sträussler‐Scheinker disease (GSS), are extremely rare, fatal neurodegenerative disorders, often associated with progressive ataxia and cognitive/neuropsychiatric symptoms. GSS typically presents as a rapidly progressive cerebellar ataxia, associated with cognitive decline. Late‐onset cases are rare. Objective: To compare a novel GSS phenotype with six other cases and present pathological findings from a single case. Methods: Case series of seven GSS patients, one proceeding to autopsy. Results: Case 1 developed slowly progressive gait difficulties at age 71, mimicking a spinocerebellar ataxia, with a family history of balance problems in old age. Genome sequencing revealed a heterozygous c.392G > A (p.G131E) pathogenic variant and a c.395A > G resulting in p.129 M/V polymorphism in the PRNP gene. Probability analyses considering family history, phenotype, and a similar previously reported point mutation (p.G131V) suggest p.G131E as a new pathogenic variant. Clinical features and imaging of this case are compared with those six additional cases harboring p.P102L mutations. Autopsy findings of a case are described and were consistent with the prion pathology of GSS. Conclusions: We describe a patient with GSS with a novel p.G131E mutation in the PRNP gene, presenting with a late‐onset, slowly progressive phenotype, mimicking a spinocerebellar ataxia, and six additional cases with the typical P102L mutation. [ABSTRACT FROM AUTHOR]

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Objectives: To elucidate and compare the genetic, clinical, ancillary diagnostic, and pathological characteristics across different Gerstmann-Sträussler-Scheinker disease (GSS) phenotypes and explore the underlying causes of the phenotypic heterogeneities. Methods: The genetic, clinical, ancillary diagnostic, and pathological profiles of GSS patients reported in the literature were obtained and analyzed. Additionally, 3 patients with genetically confirmed GSS from our unit were included. Based on clinical presentation, patients were classified into typical GSS, Creutzfeldt-Jakob disease (CJD)-like GSS, GSS with dementia, and other categories. Results: A total of 329 GSS cases were included with a 1.13:1 female-to-male ratio, median onset age 44, and median duration 4 years. Of the 294 categorized patients, 50.7% had typical GSS, 24.8% showed CJD-like GSS, and 16.3% presented with GSS with dementia. Clinical classification varied significantly based on genotype, with P102L more common in typical GSS and A117V prevalent in CJD-like GSS. Polymorphism at codon 129 has no effect on GSS phenotype, but the 129 M allele acts as a protective factor in GSS patients in Asia and North America. Moderate to severe spongiform degeneration and the presence of PK-resistant small fragments migrating at

ABSTRACTGerstmann–Sträussler–Scheinker (GSS) disease is an autosomal dominant neurodegenerative disease, and it is characterized by progressive cerebellar ataxia. Up to now, GSS cases with the p.P102L mutation have mainly been reported in Caucasian, but rarely in Asian populations. A 54-year-old female patient presented with an unstable gait in the hospital. Last year, she was unable to walk steadily and occasionally choked, could not even walk independently gradually. After taking her medical history, we found that she was misdiagnosed with schizophrenia before the gait problems. The patient’s father showed similar symptoms and was diagnosed with brain atrophy at the age of 56, but her daughter showed no similar symptoms at present. On arrival at the Neurology Department, the patient’s vital signs and laboratory examinations showed no abnormality. As the proband presented with cerebellar ataxia and had an obvious family history, we were sure that she had hereditary cerebellar ataxia. Then, patient’s brain MRI showed an abnormal signal in the right parietal cortex and bilateral small ischaemic lesions in the frontal lobe. A gene panel (including 142 ataxia-related genes) was performed, and a heterozygous mutation PRNP Exon2 c.305C>T p. (Pro102Leu) was identified. Her daughter had the same heterozygous mutation. The patient was diagnosed with GSS with mental disorders as initial symptoms. After 2 months of TCM treatment, the patient’s walking instability decreased, and her emotional fluctuations were less than before. In conclusion, we have reported a rare case of GSS in Sichuan, China, and the family with mental disorder as the first symptom was finally confirmed with GSS PRNP P102L mutation.

Prion diseases and the prion protein are only partially understood so far in many aspects. This explains the continued research on this topic, calling for an overview on the current state of knowledge. The main objective of the present review article is to provide a comprehensive up-to-date presentation of all major features of human prion diseases bridging the gap between basic research and clinical aspects. Starting with the prion protein, current insights concerning its physiological functions and the process of pathological conversion will be highlighted. Diagnostic, molecular, and clinical aspects of all human prion diseases will be discussed, including information concerning rare diseases like prion-associated amyloidoses and Huntington disease-like 1, as well as the question about a potential human threat due to the transmission of prions from prion diseases of other species such as chronic wasting disease. Finally, recent attempts to develop future therapeutic strategies will be addressed.

Deep functional and structural neuroimaging of a series of Gerstmann's syndrome patients required high accuracy, and our results avoided false overlaps of heterogeneous brain lesions by handling each case of our study subjects separately as an individual case regarding functional and neuroimaging tests. Six patients with Gerstmann tetrad (one with dominant acalculia, one with dominant left and right disorientation, two with writing disabilities and two with finger agnosia) and 6 control subjects with close ages were recruited in the current study. In the main phase, we assessed brain activation in response to experimental and interventional settings using neuroimaging techniques (FMRI-Functional Magnetic Resonance Imaging-where twelve pictures were taken on a Dell inspiration 3T all-body scanner with sequences of echo pictures, 80° angled, TE 35 ms) of the subject's brain to declare lesions existence and locations that might result in one of the four cognitive impairment domains of Gerstman's syndrome tetrad. We assessed statistically significant differences of patient images vs. control images as well as the images of patients presenting specific symptomatic cognitive dysfunction domain vs. the images of patients presenting the three other domains. Neuroimages were analyzed using multiple databases such as T1 weighted and free sequence types. Gerstmann's syndrome is mainly connected to injury in the dominant parietal lobe, so images comparisons and analysis were only restricted to the left parietal lobe region. P values <0.05 were only considered as statistically significant difference in comparisons of functional tests time and accuracy of patients vs. in addition to comparisons of brain images parameters of patient group vs. control group and specific symptomatic domain patients vs. other symptomatic domains patients. Regarding functional testing, Patients group took significantly higher time compared to control group. Regarding brain images parameters, patients in each domain showed significantly different lesions compared to other domains. Moreover, control subjects showed no lesions in the left parietal lobe compared to significant lesions in the patient groups. These results oppose the theory of Gerstmann that a common brain structural injury may result in the combination of all of the four symptomatic dysfunction domains. This may be due to the fact that Gerstmann examined incomplete cases which represent a considerable criticism to his scientific basis. Moreover, he excluded patients with speech difficulties and apraxia. [ABSTRACT FROM AUTHOR]

ABSTRACTGerstmann–Sträussler–Scheinker disease with a Pro-to-Leu substitution at codon 105 in the prion protein gene (GSS-P105L) is a rare variant of human genetic prion disease. Herein, we report the case of a patient with GSS-P105L, who showed serial changes in regional cerebral blood flow (rCBF) on single-photon emission computed tomography (SPECT). A 42-year-old woman, with an affected father presenting with similar symptoms, had a 1-year history of progressive gait disturbance, lower-limb spasticity, and psychiatric symptoms. Genetic analysis confirmed the diagnosis of GSS-P105L. Eleven months after disease onset, brain magnetic resonance imaging (MRI) showed bilateral frontal lobe-dominant cerebral atrophy without hyperintensity on diffusion-weighted imaging (DWI) sequences; meanwhile, SPECT revealed non-specific mild hypoperfusion. Follow-up MRI at 52 months after onset demonstrated progressive frontal lobe-dominant cerebral atrophy without hyperintensity on DWI, while SPECT revealed a marked decrease in rCBF in the bilateral right-dominant frontal lobe. Patients with GSS with a Pro-to-Leu substitution at codon 102 (GSS-P102L) have been reported to exhibit hyperintensity on DWI-MRI and a diffuse decrease in CBF with a mosaic-like pattern on SPECT, which is absent in patients with GSS-P105L, thereby possibly reflecting the differences in pathophysiology between GSS-P102L and GSS-P105L.

Although it is not yet universally accepted that all neurodegenerative diseases (NDs) are prion disorders, there is little disagreement that Alzheimer's disease (AD), Parkinson's disease, frontotemporal dementia (FTD), and other NDs are a consequence of protein misfolding, aggregation, and spread. This widely accepted perspective arose from the prion hypothesis, which resulted from investigations on scrapie, a common transmissible disease of sheep and goats. The prion hypothesis argued that the causative infectious agent of scrapie was a novel proteinaceous pathogen devoid of functional nucleic acids and distinct from viruses, viroids, and bacteria. At the time, it seemed impossible that an infectious agent like the one causing scrapie could replicate and exist as diverse microbiological strains without nucleic acids. However, aggregates of a misfolded host-encoded protein, designated the prion protein (PrP), were shown to be the cause of scrapie as well as Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker syndrome (GSS), which are similar NDs in humans. This review discusses historical research on diseases caused by PrP misfolding, emphasizing principles of pathogenesis that were later found to be core features of other NDs. For example, the discovery that familial prion diseases can be caused by mutations in PrP was important for understanding prion replication and disease susceptibility not only for rare PrP diseases but also for far more common NDs involving other proteins. We compare diseases caused by misfolding and aggregation of APP-derived Aβ peptides, tau, and α-synuclein with PrP prion disorders and argue for the classification of NDs caused by misfolding of these proteins as prion diseases. Deciphering the molecular pathogenesis of NDs as prion-mediated has provided new approaches for finding therapies for these intractable, invariably fatal disorders and has revolutionized the field.

This article discusses a rare genetic prion disease called Gerstmann‐Sträussler‐Scheinker disease (GSS) and its phenotypic variability. The authors describe three cases of early-onset GSS in patients aged 15, 17, and 18, which mimicked an anticipation phenomenon. The study conducted whole exome sequencing and identified a missense variant in the PRNP gene. The article highlights the challenges in predicting the age of onset for genetic prion diseases and the need for further research to understand the underlying mechanisms. [Extracted from the article]

When Gerstmann published the case report which later became known as the first case of Gerstmann syndrome, he did not claim the discovery of a new syndrome. It was only a few years later, after reporting on another two similar cases, that he isolated the famous tetrad of symptoms (finger agnosia, right-left disorientation, agraphia and acalculia) as a meaningful cluster with both localising and functional value. In this article, we provide the translation of key-excerpts of the second of Gerstmann's reports (Gerstmann, 1927) and a synoptic description of the symptoms as reported in the three original cases, which were later identified as cases of Gerstmann syndrome. The descriptions appear highly consistent across cases. Among symptoms, finger agnosia stands out for its pervasiveness, which may explain why Gerstmann considered this as the core symptom and speculated it could subtend all symptoms. However, no common functional denominator emerges from the original descriptions. [ABSTRACT FROM AUTHOR]

Prion diseases are immedicable neurodegenerative conditions affecting both animals and humans. The disease was first discovered by Stanley B. Prusiner and he defined Prions as infectious, transmissible proteinaceous particles that lack nucleic acid and are composed exclusively of a modified isoform of the non-infectious cellular prion protein (PrPC). The dentist must bear in mind of this disease because the Prions resist the standard sterilization procedures in normal clinical use and is barely completely eliminated by incineration. This article reviews current knowledge of the presence of prion within the mouth, risk of transmission and discusses infection control protocol for the patients with prion disease. [ABSTRACT FROM AUTHOR]

Although originally multi-ethnic in its structure, nowadays the Calabria region of southern Italy represents an area with low genetic heterogeneity and a high level of consanguinity that allows rare mutations to be maintained due to the founder effect. A complex research methodology—ranging from clinical activity to the genealogical reconstruction of families/populations across the centuries, the creation of databases, and molecular/genetic research—was modelled on the characteristics of the Calabrian population for more than three decades. This methodology allowed the identification of several novel genetic mutations or variants associated with neurodegenerative diseases. In addition, a higher prevalence of several hereditary neurodegenerative diseases has been reported in this population, such as Alzheimer's disease, frontotemporal dementia, Parkinson's disease, Niemann–Pick type C disease, spinocerebellar ataxia, Creutzfeldt–Jakob disease, and Gerstmann–Straussler–Scheinker disease. Here, we summarize and discuss the results of research data supporting the view that Calabria could be considered as a genetic isolate and could represent a model, a sort of outdoor laboratory—similar to very few places in the world—useful for the advancement of knowledge on neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Gerstmann–Sträussler–Scheinker disease (GSS) is a rare neurodegenerative illness that belongs to the group of hereditary or familial Transmissible Spongiform Encephalopathies (TSE). Due to the presence of different pathogenic alterations in the prion protein (PrP) coding gene, it shows an enhanced proneness to misfolding into its pathogenic isoform, leading to prion formation and propagation. This aberrantly folded protein is able to induce its conformation to the native counterparts forming amyloid fibrils and plaques partially resistant to protease degradation and showing neurotoxic properties. PrP with A117V pathogenic variant is the second most common genetic alteration leading to GSS and despite common phenotypic and neuropathological traits can be defined for each specific variant, strikingly heterogeneous manifestations have been reported for inter-familial cases bearing the same pathogenic variant or even within the same family. Given the scarcity of cases and their clinical, neuropathological, and biochemical variability, it is important to characterize thoroughly each reported case to establish potential correlations between clinical, neuropathological and biochemical hallmarks that could help to define disease subtypes. With that purpose in mind, this manuscript aims to provide a detailed report of the first Spanish GSS case associated with A117V variant including clinical, genetic, neuropathological and biochemical data, which could help define in the future potential disease subtypes and thus, explain the high heterogeneity observed in patients suffering from these maladies. [ABSTRACT FROM AUTHOR]

Gerstmann Syndrome is a rare neurological presentation due to a lesion in the left dominant parietal lobe, manifesting as a tetrad of agraphia, acalculia, finger agnosia and right-left disorientation. We present a case of a 52-year-old man, right hand dominant, who presented to the Emergency Department with acute confusion for one day. He was disorientated to time, place and person. Focused neurological examination revealed atypical signs of acute stroke, comprising agraphia, acalculia, finger agnosia and right-left disorientation. Stroke protocol was activated and he underwent computed tomography brain perfusion, which confirmed a large penumbra area at the left middle cerebral artery territory. Computed tomography angiogram of the carotid arteries showed a long segment thrombosis in the left internal carotid artery. Emergency thrombectomy was abandoned due to impenetrable hard thrombus. He was treated with dual antiplatelet therapy and discharged after three days with partial improvement in terms of following commands, simple calculations and reduced finger agnosia. He was scheduled for outpatient follow up. This case highlights Gerstmann syndrome as an atypical manifestation of acute stroke. [ABSTRACT FROM AUTHOR]

Attempts to model inherited human prion disorders such as familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker (GSS) disease, and fatal familial insomnia (FFI) using genetically modified mice have produced disappointing results. We recently demonstrated that transgenic (Tg) mice expressing wild-type bank vole prion protein (BVPrP) containing isoleucine at polymorphic codon 109 develop a spontaneous neurodegenerative disorder that exhibits many of the hallmarks of prion disease. To determine if mutations causing inherited human prion disease alter this phenotype, we generated Tg mice expressing BVPrP containing the D178N mutation, which causes FFI; the E200K mutation, which causes familial CJD; or an anchorless PrP mutation similar to mutations that cause GSS. Modest expression levels of mutant BVPrP resulted in highly penetrant spontaneous disease in Tg mice, with mean ages of disease onset ranging from ~120 to ~560 days. The brains of spontaneously ill mice exhibited prominent features of prion disease-specific neuropathology that were unique to each mutation and distinct from Tg mice expressing wild-type BVPrP. An ~8-kDa proteinase K-resistant PrP fragment was found in the brains of spontaneously ill Tg mice expressing either wild-type or mutant BVPrP. The spontaneously formed mutant BVPrP prions were transmissible to Tg mice expressing wild-type or mutant BVPrP as well as to Tg mice expressing mouse PrP. Thus, Tg mice expressing mutant BVPrP exhibit many of the hallmarks of heritable prion disorders in humans including spontaneous disease, protease-resistant PrP, and prion infectivity.

Introduction: Gerstmann-Sträussler-Scheinker disease (GSS) is a rare genetic prion disease. Unlike sporadic Creutzfeldt-Jakob disease, GSS has diverse clinical phenotypes, including slowly progressive cerebellar ataxia. Due to this clinical feature and the extreme rarity of GSS, the disease can be misdiagnosed as hereditary cerebellar ataxia.Case Report: We present the first familial cases of GSS in South Korea. Previously affected family members were misdiagnosed with hereditary cerebellar ataxia. Two siblings (patients #1 and #2) of this family were genetically diagnosed with P102L mutation GSS. Another sibling (patient #3) was not genetically confirmed, but based on the clinical course and diffusion-weighted imaging (DWI), the diagnosis of GSS will be certain. Despite the same genetic mutation, these siblings showed different clinical phenotypes of GSS.Conclusions: We genetically confirmed familial cases of GSS in South Korea. Although the disease is extremely rare, the PRNP gene test should be considered in undiagnosed autosomal dominant hereditary cerebellar ataxia. Phenotypical variability of GSS may be reflected in DWI of the early phase of the disease. [ABSTRACT FROM AUTHOR]

Prion diseases are a group of diseases caused by abnormally conformed infectious proteins, called prions. They can be sporadic (Jakob-Creutzfeldt disease [JCD]), genetic (genetic JCD, Gerstmann-Sträussler-Scheinker, and familial fatal insomnia), or acquired (kuru, variant JCD, and iatrogenic JCD). The clinical features associated with each form of prion disease, the neuroimaging findings, cerebrospinal fluid markers, and neuropathological findings are reviewed. Sporadic JCD is the most common form of human prion disease, and will be discussed in detail. Genetic prion diseases are caused by mutations in the prion-related protein gene (PRNP), and they are classified based on the mutation, clinical phenotype, and neuropathological features. Acquired prion diseases fortunately are becoming rarer, as awareness of transmission risk has led to implementation of measures to prevent such occurrences, but continued surveillance is necessary to prevent future cases. Treatment and management issues are also discussed.

The C-terminally truncated Y145Stop variant of prion protein (PrP23-144) has been linked to a heritable prionopathy in humans and is also capable of triggering a transmissible prion disease in mice. PrP23-144 can be converted from soluble monomeric form to amyloid under physiological conditions, providing an in vitro model for investigating the molecular basis of amyloid strains and cross-seeding barriers. Here, we use magic-angle spinning solid-state NMR to establish the sequential backbone and sidechain 13C and 15N chemical shift assignments for amyloid fibrils formed by the A117V and M129V mutants of human PrP23-144, which in the context of full length PrP in vivo are among the specific residues associated with development of Gerstmann–Straüssler–Scheinker disease. The chemical shift data are utilized to identify amino acids comprising the rigid amyloid core regions and to predict the protein secondary structures for human PrP23-144 A117V and M129V fibrils. [ABSTRACT FROM AUTHOR]

Eva Bagyinszky,1 Vo Van Giau,1 Young Chul Youn,2 Seong Soo A An,1 SangYun Kim3 1Department of Bionano Technology, Gachon Bionano Research Institute, Gachon University, Gyeonggi-do, South Korea; 2Department of Neurology, Chung-Ang University College of Medicine, Seoul, South Korea; 3Department of Neurology, Seoul National University College of Medicine & Neurocognitive Behavior Center, Seoul National University Bundang Hospital, Seongnam, South Korea Abstract: 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. Keywords: genetics, mutation, prion, PRNP gene, Creutzfeldt–Jakob disease, Gerstmann–Sträussler–Scheinker disease, fatal familial insomnia, Alzheimer’s disease, diagnosis

Prions are transmissible agents causing lethal neurodegenerative diseases that are composed of aggregates of misfolded cellular prion protein (PrPSc). Despite non-fibrillar oligomers having been proposed as the most infectious prion particles, prions purified from diseased brains usually consist of large and fibrillar PrPSc aggregates, whose protease-resistant core (PrPres) encompasses the whole C-terminus of PrP. In contrast, PrPSc from Gerstmann-Sträussler-Scheinker disease associated with alanine to valine substitution at position 117 (GSS-A117V) is characterized by a small protease-resistant core, which is devoid of the C-terminus. We thus aimed to investigate the role of this unusual PrPSc in terms of infectivity, strain characteristics, and structural features. We found, by titration in bank voles, that the infectivity of GSS-A117V is extremely high (109.3 ID50 U/g) and is resistant to treatment with proteinase K (109.0 ID50 U/g). We then purified the proteinase K-resistant GSS-A117V prions and determined the amount of infectivity and PrPres in the different fractions, alongside the morphological characteristics of purified PrPres aggregates by electron microscopy. Purified pellet fractions from GSS-A117V contained the expected N- and C-terminally cleaved 7 kDa PrPres, although the yield of PrPres was low. We found that this low yield depended on the low density/small size of GSS-A117V PrPres, as it was mainly retained in the last supernatant fraction. All fractions were highly infectious, thus confirming the infectious nature of the 7 kDa PrPres, with infectivity levels that directly correlated with the PrPres amount detected. Finally, electron microscopy analysis of these fractions showed no presence of amyloid fibrils, but only very small and indistinct, non-fibrillar PrPresparticles were detected and confirmed to contain PrP via immunogold labelling. Our study demonstrates that purified aggregates of 7 kDa PrPres, spanning residues ∼90-150, are highly infectious oligomers that encode the biochemical and biological strain features of the original sample. Overall, the autocatalytic behaviour of the prion oligomers reveals their role in the propagation of neurodegeneration in patients with Gerstmann-Sträussler-Scheinker disease and implies that the C-terminus of PrPSc is dispensable for infectivity and strain features for this prion strain, uncovering the central PrP domain as the minimal molecular component able to encode infectious prions. These findings are consistent with the hypothesis that non-fibrillar prion particles are highly efficient propagators of disease and provide new molecular and morphological constraints on the structure of infectious prions. [ABSTRACT FROM AUTHOR]

The largest kindred with inherited prion disease P102L, historically Gerstmann-Sträussler-Scheinker syndrome, originates from central England, with émigrés now resident in various parts of the English-speaking world. We have collected data from 84 patients in the large UK kindred and numerous small unrelated pedigrees to investigate phenotypic heterogeneity and modifying factors. This collection represents by far the largest series of P102L patients so far reported. Microsatellite and genealogical analyses of eight separate European kindreds support multiple distinct mutational events at a cytosine-phosphate diester-guanidine dinucleotide mutation hot spot. All of the smaller P102L kindreds were linked to polymorphic human prion protein gene codon 129M and were not connected by genealogy or microsatellite haplotype background to the large kindred or each other. While many present with classical Gerstmann-Sträussler-Scheinker syndrome, a slowly progressive cerebellar ataxia with later onset cognitive impairment, there is remarkable heterogeneity. A subset of patients present with prominent cognitive and psychiatric features and some have met diagnostic criteria for sporadic Creutzfeldt-Jakob disease. We show that polymorphic human prion protein gene codon 129 modifies age at onset: the earliest eight clinical onsets were all MM homozygotes and overall age at onset was 7 years earlier for MM compared with MV heterozygotes (P = 0.02). Unexpectedly, apolipoprotein E4 carriers have a delayed age of onset by 10 years (P = 0.02). We found a preponderance of female patients compared with males (54 females versus 30 males, P = 0.01), which probably relates to ascertainment bias. However, these modifiers had no impact on a semi-quantitative pathological phenotype in 10 autopsied patients. These data allow an appreciation of the range of clinical phenotype, modern imaging and molecular investigation and should inform genetic counselling of at-risk individuals, with the identification of two genetic modifiers.

Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are a group of neurodegenerative protein misfolding diseases that invariably cause death. TSEs occur when the endogenous cellular prion protein (PrPC) misfolds to form the pathological prion protein (PrPSc), which templates further conversion of PrPC to PrPSc, accumulates, and initiates a cascade of pathologic processes in cells and tissues. Different strains of prion disease within a species are thought to arise from the differential misfolding of the prion protein and have different clinical phenotypes. Different strains of prion disease may also result in differential accumulation of PrPSc in brain regions and tissues of natural hosts. Here, we review differential accumulation that occurs in the retinal ganglion cells, cerebellar cortex and white matter, and plexuses of the enteric nervous system in cattle with bovine spongiform encephalopathy, sheep and goats with scrapie, cervids with chronic wasting disease, and humans with prion diseases. By characterizing TSEs in their natural host, we can better understand the pathogenesis of different prion strains. This information is valuable in the pursuit of evaluating and discovering potential biomarkers and therapeutics for prion diseases.

Background and Purpose: The coast of Kyushu Island on Ariake Sea in Japan is known to be an accumulation area for patients with a proline-to-leucine substitution mutation at residue 102 (P102L) of the human prion protein gene ( PRNP ), which is associated with Gerstmann-Sträussler-Scheinker disease. We designated this geographical distribution as the "Ariake PRNP P102L variant." The purpose of this study was to characterize the clinical features of this variant., Methods: We enrolled patients with the PRNP P102L variant who were followed up at the Saga University Hospital from April 2002 to November 2019. The clinical information of patients were obtained from medical records, including clinical histories, brain magnetic resonance imaging (MRI), and electroencephalography (EEG). A brain autopsy was performed on one of the participants., Results: We enrolled 24 patients from 19 family lines, including 12 males. The mean age at symptom onset was 60.6 years (range, 41-77 years). The incidence rate of the Ariake PRNP P102L variant was 3.32/1,000,000 people per year in Saga city. The initial symptoms were ataxia (ataxic gait or dysarthria) in 19 patients (79.2%), cognitive impairment in 3 (12.5%), and leg paresthesia in 2 (8.3%). The median survival time from symptom onset among the 18 fatal cases was 63 months (range, 23-105 months). Brain MRI revealed no localized cerebellar atrophy, but sparse diffusion-weighted imaging abnormalities were detected in 16.7% of the patients. No periodic sharp-wave complexes were identified in EEG. Neuropathological investigations revealed uni- and multicentric prion protein (PrP) plaques in the cerebral cortex, putamen, thalamus, and cerebellum of one patient. Western blot analysis revealed 8-kDa proteinase-K-resistant PrP., Conclusions: This is the first report of the accumulation area of a PRNP P102L variant on the coast of Ariake Sea. The Ariake PRNP P102L variant can be characterized by a relatively long disease duration with sparse abnormalities in brain MRI and EEG relative to previous reports. Detailed interviews to obtain information on the birthplace and the family history of related symptoms are important to diagnosing a PRNP P102L variant., Competing Interests: The authors have no potential conflicts of interest to disclose., (Copyright © 2024 Korean Neurological Association.)

Gerstmann-Sträussler-Scheinker syndrome (GSS) with the P102L mutation is a rare genetic prion disease caused by a pathogenic mutation at codon 102 in the prion protein gene. Cluster analysis encompassing data from 7 Czech patients and 87 published cases suggests the existence of 4 clinical phenotypes (typical GSS, GSS with areflexia and paresthesia, pure dementia GSS, and Creutzfeldt-Jakob disease-like GSS); GSS may be more common than previously estimated. In making a clinical diagnosis or progression estimates of GSS, magnetic resonance imaging and real-time quaking-induced conversion may be helpful, but the results should be evaluated with respect to the overall clinical context. ANN NEUROL 2019;86:643-652. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate long-term virological failure (VF) and drug resistance among HIV-infected Ugandan children on first-line ART.Methods: In a multicentre prospective cohort study, viral load (VL) and drug resistance mutations (DRMs) were investigated at baseline and 6 monthly intervals in children (age ≤ 12 years). VF (two consecutive VLs >1000 copies/mL or death after 6 months of ART) was defined as early VF (0-24 months of ART) or late VF (25-48 months of ART). An active regimen was defined as partially active if the genotypic susceptibility score (GSS) was <3.Results: Between 2010 and 2011, 316 children were enrolled. Viral suppression was achieved in 75.8%, 71.5%, 72.6% and 69.2% at 12, 24, 36 and 48 months. VF occurred in 111/286 (38.8%), of which 67.6% was early and 32.4% late VF. Early VF was associated with a partially active regimen at baseline (OR 6.0, 95% CI 1.9-18.5), poor adherence (OR 3.1, 95% CI 1.3-7.4) and immunodeficiency (OR 3.3, 95% CI 1.1-10.2). Late VF was associated with age >3 years (OR 2.5, 95% CI 1.0-6.6) and WHO stage 3/4 (OR 4.2, 95% CI 1.4-13.4). Acquired DRMs were detected in 27.0% before 24 months, versus 14.4% after 24 months (P < 0.001). A total of 92.2% of the children with early VF, versus 56.2% with late VF, had a partially active regimen (P < 0.001).Conclusions: VF rates were high, occurred predominantly in the first 24 months and appeared to increase again in year four. Risk factors and patterns of early VF/DRMs were different from those of late VF/DRMs. Virological control may improve by close monitoring and prompt switching to second-line therapy in the first 24 months. Late VF may be prevented by early start of ART. [ABSTRACT FROM AUTHOR]

Objectives: To describe integrase strand transfer inhibitor (INSTI) resistance profiles and factors associated with resistance in antiretroviral-naive and -experienced patients failing an INSTI-based regimen in clinical practice.Methods: Data were collected from patients failing an INSTI-containing regimen in a multicentre French study between 2014 and 2017. Failure was defined as two consecutive plasma viral loads (VL) >50 copies/mL. Reverse transcriptase, protease and integrase coding regions were sequenced at baseline and failure. INSTI resistance-associated mutations (RAMs) included in the Agence Nationale de Recherches sur le SIDA genotypic algorithm were investigated.Results: Among the 674 patients, 359 were failing on raltegravir, 154 on elvitegravir and 161 on dolutegravir therapy. Overall, 90% were experienced patients and 389 (58%) patients showed no INSTI RAMs at failure. The strongest factors associated with emergence of at least one INSTI mutation were high VL at failure (OR = 1.2 per 1 log10 copies/mL increase) and low genotypic sensitivity score (GSS) (OR = 0.08 for GSS ≥3 versus GSS = 0-0.5). Patients failing dolutegravir also had significantly fewer INSTI RAMs at failure than patients failing raltegravir (OR = 0.57, P = 0.02) or elvitegravir (OR = 0.45, P = 0.005). Among the 68 patients failing a first-line regimen, 11/41 (27%) patients on raltegravir, 7/18 (39%) on elvitegravir and 0/9 on dolutegravir had viruses with emergent INSTI RAMs at failure.Conclusions: These results confirmed the robustness of dolutegravir regarding resistance selection in integrase in the case of virological failure in routine clinical care. [ABSTRACT FROM AUTHOR]

Prion diseases are progressive neurodegenerative disorders affecting humans and other mammalian species. The term prion, originally put forward to propose the concept that a protein could be infectious, refers to PrPSc, a misfolded isoform of the cellular prion protein (PrPC) that represents the pathogenetic hallmark of these disorders. The discovery that other proteins characterized by misfolding and seeded aggregation can spread from cell to cell, similarly to PrPSc, has increased interest in prion diseases. Among neurodegenerative disorders, however, prion diseases distinguish themselves for the broader phenotypic spectrum, the fastest disease progression and the existence of infectious forms that can be transmitted through the exposure to diseased tissues via ingestion, injection or transplantation. The main clinicopathological phenotypes of human prion disease include Creutzfeldt–Jakob disease, by far the most common, fatal insomnia, variably protease‐sensitive prionopathy, and Gerstmann–Sträussler–Scheinker disease. However, clinicopathological manifestations extend even beyond those predicted by this classification. Because of their transmissibility, the phenotypic diversity of prion diseases can also be propagated into syngenic hosts as prion strains with distinct characteristics, such as incubation period, pattern of PrPSc distribution and regional severity of histopathological changes in the brain. Increasing evidence indicates that different PrPSc conformers, forming distinct ordered aggregates, encipher the phenotypic variants related to prion strains. In this review, we summarize the most recent advances concerning the histo‐molecular pathology of human prion disease focusing on the phenotypic spectrum of the disease including co‐pathologies, the characterization of prion strains by experimental transmission and their correlation with the physicochemical properties of PrPSc aggregates. [ABSTRACT FROM AUTHOR]

Gerstmann‐Sträussler‐Scheinker disease (GSS) is a rare inherited prion disease that shows variable clinical symptoms, including cerebellar ataxia, dementia, and leg weakness. These symptoms may result in gait disturbance which frequently occurs in the early stage of the disease; however, precise descriptions focused on its phenomenology and etiology have been scarce. Here, we report a unique case of GSS presenting with gait apraxia as the initial symptom. Moreover, SPECT showed hypoperfusion in the bilateral superior frontal gyri, which suggests that dysfunction in the lesions is largely responsible for gait apraxia. [ABSTRACT FROM AUTHOR]

Background: Drug resistance mutations (DRMs) increasingly jeopardize paediatric HIV programmes in sub-Saharan Africa. As individual monitoring of DRMs and viral loads has limited availability, population data on DRMs are essential to determine first-line susceptibility. Paediatric data from sub-Saharan Africa are scarce and unavailable for Malawi.Objectives: To determine the prevalence of virological failure (VF) and DRMs among ART-naive HIV-infected Malawian children during the first year of first-line ART.Methods: In a prospective cohort of HIV-infected Malawian children, on first-line treatment, children were followed monthly; blood was collected for viral load testing (6 and 12 months) and genotypic resistance testing (12 months). VF was defined as at least one viral load >1000 copies/mL or death after 6 months of ART. DRMs were identified and susceptibility to NRTIs and NNRTIs was scored using the Stanford algorithm and by calculating genotypic susceptibility scores (GSSs).Results: VF occurred in 66% (23/35) of the children during 12 months of follow-up. DRMs were detected in 44% (15/34); all had NNRTI resistance and 12% (4/34) had dual-class NNRTI/NRTI resistance. Reduced susceptibility (DRMs and GSS <3) was seen in 41% (14/34) to their current first-line regimen. High-level resistance was most common for nevirapine [26% (9/34)].Conclusions: In this first report on VF and DRMs in children on first-line ART in Malawi, the rates of VF and DRMs were alarmingly high. Paediatric HIV programmes in sub-Saharan Africa should emphasize programmatic evaluation of VF and include detection of DRMs to adjust and design adequate first- and second-line regimens and prevent widespread resistance in children. [ABSTRACT FROM AUTHOR]

Objectives: To describe the prevalence of transmitted drug resistance (TDR) among 84 children newly diagnosed with HIV in France in 2006-17.Methods: HIV-1 resistance-associated mutations (RAMs) were characterized using both the 2009 Stanford list of mutations and the 2017 French National Agency for AIDS Research (ANRS) algorithm. A genotypic susceptibility score (GSS) was estimated for each first-line recommended ART combination.Results: Patients were mainly infected through mother-to-child transmission (MTCT) (73/84; 86.9%), but only 18 children (24.7% of vertically infected patients) were previously exposed to antiretroviral prophylaxis from MTCT. Non-B variants were identified in 90.5% (76/84) of patients. The frequency of TDR was 8.3% (7/84) using the 2009 Stanford list and 16.7% (14/84) using both the Stanford list and the 2017 ANRS algorithm. The prevalence of PI-, NRTI-, efavirenz/nevirapine-, etravirine/rilpivirine- and doravirine-associated RAMs was 0%, 3.6%, 6.0%, 11.9% and 2.4%, respectively. Single-, dual- and triple-class resistance was present in 15.5%, 1.2% and 0% of cases, respectively. Additionally, 3/60 (5%) strains had integrase inhibitor (INI)-related RAMs (an isolated E157Q mutation, which could mostly affect the susceptibility to raltegravir/elvitegravir rather than that to dolutegravir). Among the 18 children exposed to MTCT prophylaxis, RAMs were identified in only 1 case (5.6%). The proportion of fully active combinations (GSS = 3) was ≥97.6%, ≥94.1%, ≥92.9% and ≥89.3% for PI-, INI-, efavirenz/nevirapine- and rilpivirine-based regimens, respectively.Conclusions: The proportion of NRTI- and NNRTI-related TDR in children is lower in France than in low- and middle-income countries. However, we suggest favouring PI- or dolutegravir- over NNRTI-based combinations to treat newly diagnosed HIV-infected children, even in the absence of previous exposure to antiretroviral prophylaxis of MTCT. [ABSTRACT FROM AUTHOR]

Background and purpose Gerstmann-Sträussler-Scheinker syndrome is a rare hereditary neurodegenerative disorder with clinical heterogeneity. This study is aim to demonstrate the clinical spectrum and radiologic characteristics of patients caused by Pro102Leu mutation in PRNP. Materials and methods We retrospect clinical manifestations of five patients from four Japanese families, and comprehensively analyzed their brain MRI, SPECT (N-isopropyl-p-[123I] iodoamphetamine), and PET (18F-2-fluoro-2-deoxy- d -glucose) images. Results All patients developed ataxia of lower limbs and trunk, gait disturbance, dysesthesia in legs, and lower limb hyporeflexia. In the early clinical stage before dementia began, no noticeable abnormalities could be observed from brain MRI, but SPECT and PET revealed mosaic-like pattern of blood flow and glucose metabolism of the brain. Predominant abnormalities were found in the occipital and frontal lobes on SPECT and PET analysis, respectively. In SPECT analysis, blood flow of the anterior cerebellar lobes was lower than that of the posterior cerebellar lobes. Conclusions Clinical symptoms resulting from failure of dorsal horn of spinal cord and spinocerebellar tracts were observed in all cases. Radiologic findings revealed individual differences of involved region in their brain, which could produce clinical diversity. We identified a downtrend of blood flow in the anterior cerebellar lobes, a projection field of the spinocerebellar tracts, which is an important feature of Gerstmann-Sträussler-Scheinker syndrome. [ABSTRACT FROM AUTHOR]

Objectives: To assess, in a clinical cohort, the efficacy of switching current ART in virologically suppressed patients to a dolutegravir-based regimen, regardless of the genotypic susceptibility score (GSS).Patients and methods: This was an observational single-centre study assessing ART-treated patients with plasma viral load (pVL) <50 copies/mL who were switched to a dolutegravir-based regimen with 1 year of follow-up. PCR negative was defined as an undetected PCR signal. Trough plasma concentration (C24) was determined using UPLC-MS/MS.Results: Two hundred and thirty-nine patients initiated a dolutegravir-based regimen: 12%, 29% and 59% had a total GSS of 1 or 1.5 (group 1), 2 or 2.5 (group 2) and 3 (group 3), respectively. At switch initiation, the median time since first ART and the median duration with pVL <50 copies/mL were 13 years (IQR = 6-19) and 3 years (IQR = 1-6), respectively. Median times since last genotype were 9, 10 and 5 years for groups 1, 2 and 3, respectively. Twenty patients (8.4%) discontinued the dolutegravir-based regimen due to adverse events. During the study, 96.4% (n = 661/686) of all pVL were <50 copies/mL. Four patients (1.7%) experienced virological failure (two pVL >50 copies/mL) without emergence of resistance; these patients' GSSs were 2, 2.5, 3 and 3. The median dolutegravir C24 was 1545 ng/mL (IQR = 1150-2097). Of the patients with pVL <20 copies/mL, 72% were PCR negative during the follow-up, with no difference between the three groups of patients.Conclusions: This observational cohort study showed a high level of virological suppression maintenance in the first year following the switch to a dolutegravir-based regimen, even in patients with GSS ≤2. [ABSTRACT FROM AUTHOR]

Abstract: Truncating mutations in PRNP have been associated with heterogeneous phenotypes ranging from chronic diarrhea and neuropathy to dementia, either rapidly or slowly progressive. We identified novel PRNP stop‐codon mutations (p.Y163X, p.Y169X) in two Italian kindreds. Disease typically presented in the third or fourth decade with progressive autonomic failure and diarrhea. Moreover, one proband (p.Y163X) developed late cognitive decline, whereas some of his relatives presented with isolated cognitive and psychiatric symptoms. Our results strengthen the link between PRNP truncating mutations and systemic abnormal PrP deposition and support a wider application of PRNP screening to include unsolved cases of familial autonomic neuropathy. [ABSTRACT FROM AUTHOR]

Axons emerging from rat neural stem cell implants in the injured spinal cord of rat recipients are stimulated to grow by myelin. Myelin has been suggested to block regeneration of adult axons after spinal cord injury in mammals. In a new study, Poplawski et al. report that the outgrowth of axons from transplants of rat neural stem cells into sites of spinal cord injury in rat recipients may be stimulated by myelin, allowing axons to extend through the site of spinal cord injury. This growth depended in part on a cell adhesion molecule found on the surface of rodent NPCs called neuronal growth regulator 1 (Negr1). The finding that myelin may be able to stimulate neural repair in rodents suggests that this versatile substance should be investigated further for its potential to improve neural stem cell therapy for spinal cord injury. Axon regeneration after spinal cord injury (SCI) is attenuated by growth inhibitory molecules associated with myelin. We report that rat myelin stimulated the growth of axons emerging from rat neural progenitor cells (NPCs) transplanted into sites of SCI in adult rat recipients. When plated on a myelin substrate, neurite outgrowth from rat NPCs and from human induced pluripotent stem cell (iPSC)–derived neural stem cells (NSCs) was enhanced threefold. In vivo, rat NPCs and human iPSC–derived NSCs extended greater numbers of axons through adult central nervous system white matter than through gray matter and preferentially associated with rat host myelin. Mechanistic investigations excluded Nogo receptor signaling as a mediator of stem cell–derived axon growth in response to myelin. Transcriptomic screens of rodent NPCs identified the cell adhesion molecule neuronal growth regulator 1 (Negr1) as one mediator of permissive axon-myelin interactions. The stimulatory effect of myelin-associated proteins on rodent NPCs was developmentally regulated and involved direct activation of the extracellular signal–regulated kinase (ERK). The stimulatory effects of myelin on NPC/NSC axon outgrowth should be investigated further and could potentially be exploited for neural repair after SCI. [ABSTRACT FROM AUTHOR]

Translational neuroscience integrates the knowledge derived by basic neuroscience with the development of new diagnostic and therapeutic tools that may be applied to clinical practice in neurological diseases. This information can be used to improve clinical trial designs and outcomes that will accelerate drug development, and to discover novel biomarkers which can be efficiently employed to early recognize neurological disorders and provide information regarding the effects of drugs on the underlying disease biology. Alzheimer's disease (AD) and prion disease are two classes of neurodegenerative disorders characterized by incomplete knowledge of the molecular mechanisms underlying their occurrence and the lack of valid biomarkers and effective treatments. For these reasons, the design of therapies that prevent or delay the onset, slow the progression, or improve the symptoms associated to these disorders is urgently needed. During the last few decades, translational research provided a framework for advancing development of new diagnostic devices and promising disease-modifying therapies for patients with prion encephalopathies and AD. In this review, we provide present evidence of how supportive can be the translational approach to the study of dementias and show some results of our preclinical studies which have been translated to the clinical application following the 'bed-to-bench-and-back' research model. [ABSTRACT FROM AUTHOR]