Development and Validation of a Prognostic Model to Predict Overall Survival in Multiple System Atrophy.

Background: Multiple system atrophy (MSA) is a devastating disease characterized by a variable combination of motor and autonomic symptoms. Previous studies identified numerous clinical factors to be associated with shorter survival. Objective: To enable personalized patient counseling, we aimed at developing a risk model of survival based on baseline clinical symptoms. Methods: MSA patients referred to the Movement Disorders Unit in Innsbruck, Austria, between 1999 and 2016 were retrospectively analyzed. Kaplan-Meier curves and multivariate Cox regression analysis with least absolute shrinkage and selection operator penalty for variable selection were performed to identify prognostic factors. A nomogram was developed to estimate the 7 years overall survival probability. The performance of the predictive model was validated and calibrated internally using bootstrap resampling and externally using data from the prospective European MSA Study Group Natural History Study. Results: A total of 210 MSA patients were included in this analysis, of which 124 patients died. The median survival was 7 years. The following clinical variables were found to significantly affect overall survival and were included in the nomogram: age at symptom onset, falls within 3 years of onset, early autonomic failure including orthostatic hypotension and urogenital failure, and lacking levodopa response. The time-dependent area under curve for internal and external validation was >0.7 within the first 7 years of the disease course. The model was well calibrated showing good overlap between predicted and actual survival probability at 7 years. Conclusion: The nomogram is a simple tool to predict survival on an individual basis and may help to improve counseling and treatment of MSA patients.

"Dendroarchitectonics": From Santiago Ramón y Cajal to Enrique Ramón-Moliner or vice versa?

Here, we review the morphological taxonomy of neurons proposed by Enrique Ramón-Moliner in the vertebrate central nervous system based on "dendroarchitectonics" and compare these findings with Santiago Ramón y Cajal's work. Ramón-Moliner distinguished three main groups of nerve cells situated on a spectrum of dendritic configuration in the mammalian central nervous system with decreasing degree of morphological specialization, i.e., idiodendritic, allodendritic, and isodendritic neurons. Leptodendritic neurons would be an even more primitive type, and lophodendritic nerve cells would develop into pyramidal neurons. Using two developmental lines (i.e., telencephalic and rhombencephalic trends), Ramón-Moliner reconstructed the probable course of events in the phylogenetic history that led to the dendroarchitectonic families. While an increasing morphological specialization is associated with the projected phylogenetic development as an abstract "whole," phylogenetically "primitive neurons" such as the reticular formation may be present in later phylogenetic stages, and vice versa, phylogenetical "new arrivals," such as the cortical pyramidal cell, may be found early in phylogeny. Thus, Ramón-Moliner adopted the notion of an in-parallel neuronal development during phylogeny and ontogeny. In contrast, Cajal argued earlier in favor of the idea that ontogeny recapitulates phylogeny, focusing on the pyramidal neuron. In ontogeny, the early developmental features show a higher degree of similarity than the comparison of their adult forms. These results corroborate the rejection of the interpretative framework of ontogeny as a simple, speedy repetition of the phylogeny. Understanding morphological findings with the change in their interpretation and the historic underpinnings provide a framework for refined scientific hypotheses.

Premorbid de novo artistic creativity in frontotemporal dementia (FTD) syndromes.

The emergence of new artistic activities or shifts in artistic style in patients with frontotemporal dementia (FTD) syndromes is well documented at or after disease onset. However, a closer look in the literature reveals emerging artistic creativity also before FTD onset, although the significance and underlying pathology of such creative endeavors remain elusive. Here, we systematically review relevant studies and report an additional FTD case to elaborate on artistic activities that developed years before disease manifestation by paying particular attention to the sequence of events in individual patients' biography and clinical history. We further discuss the FTD patient's creative activities in the context of their life events, other initial or "premorbid" dementia symptoms or risk factors described in the literature such as mental illness and mild behavioral impairment (MBI), as well as changes in neuronal systems (i.e., neuroimaging and neuropathology). In addition to our FTD patient, we identified five published cases with an FTD syndrome, including three with FTD, one with primary progressive aphasia (PPA), and one with the behavioral variant of PPA (bvPPA). Premorbid novel creativity emerged across different domains (visual, musical, writing), with the FTD diagnosis ensuing artistic productivity by a median of 8 years. Data on late-life and pre-dementia life events were available in four cases. The late creative phase in our case was accompanied by personality changes, accentuation of personality traits, and cessation of painting activities occurred with the onset of memory complaints. Thus, premorbid personality changes in FTD patients can be associated with de novo creative activity. Stressful life events may also contribute to the burgeoning of creativity. Moreover, primary neocortical areas that are largely spared by pathology at early FTD stages may facilitate the engagement in artistic activities, offering a window of opportunity for art therapy and other therapeutic interventions during the MBI stage or even earlier.

Emergent creativity in frontotemporal dementia.

Numerous papers report on connections between creative work and dementing illness, particularly in frontotemporal dementia (FTD), which may combine with motor neuron disease (FTD-MND). However, the emergence of FTD(-MND) patients' de novo artistic activities is rarely reported and underappreciated. Therefore, the present review summarizes relevant case studies' outcomes, capturing creativity's multifaceted nature. Here, we systematically searched for case reports by paying particular attention to the chronological development of individual patients' clinical symptoms, signs, and life events. We synoptically compared the various art domains to the pattern of brain atrophy, the clinical and pathological FTD subtypes. 22 FTD(-MND) patients were identified with creativity occurring either at the same time (41%) or starting after the disease onset (59%); the median lag between the first manifestation of disease and the beginning of creativity was two years. In another five patients, novel artistic activity was developed by a median of 8 years before the start of dementia symptoms. Artistic activity usually evolved over time with a peak in performance, followed by a decline that was further hampered by physical impairment during disease progression. Early on, the themes and objects depicted were often concrete and realistic, but they could become more abstract or symbolic at later stages. Emergent artistic processes may occur early on in the disease process. They appear to be a communication of inner life and may also reflect an attempt of compensation or "self-healing". The relative preservation of primary neocortical areas such as the visual, auditory, or motor cortex may enable the development of artistic activity in the face of degeneration of association cortical areas and subcortical, deeper central nervous system structures. It is crucial to understand the differential loss of function and an individual's creative abilities to implement caregiver-guided, personalized therapeutic strategies such as art therapy.

Neocortical ß-amyloid area is associated with dementia and APOE in the oldest-old.

OBJECTIVE: Apolipoprotein E (APOE) ε2 carriers may be protected from dementia because of reduced levels of cortical ß-amyloid. In the oldest-old, however, APOE ε2 carriers have high ß-amyloid plaque scores and preserved cognition. We compared different measures of ß-amyloid pathology across APOE genotypes in the oldest-old, and their relationship with dementia. METHODS: The study included 96 participants from The 90+ Study. Using all information, dementia diagnoses were made. Neuropathological examination included staging for amyloid plaques and ß-amyloid cortical percent area stained by NAB228 antibody. RESULTS: Both APOE ε2 and APOE ε4 carriers had high Consortium to Establish a Registry for Alzheimer's Disease plaque scores. However, APOE ε2 carriers had low cortical ß-amyloid percent areas. ß-amyloid percent area was associated with dementia across APOE genotypes. CONCLUSIONS: Lower levels of percent area in APOE ε2 carriers may reflect lower total ß-amyloid and may contribute to APOE ε2 carriers' decreased risk of dementia, despite high ß-amyloid plaque scores. The relationship between ß-amyloid plaques and dementia in the oldest-old may vary by APOE genotype.

The natural history of multiple system atrophy: a prospective European cohort study.

BACKGROUND: Multiple system atrophy (MSA) is a fatal and still poorly understood degenerative movement disorder that is characterised by autonomic failure, cerebellar ataxia, and parkinsonism in various combinations. Here we present the final analysis of a prospective multicentre study by the European MSA Study Group to investigate the natural history of MSA. METHODS: Patients with a clinical diagnosis of MSA were recruited and followed up clinically for 2 years. Vital status was ascertained 2 years after study completion. Disease progression was assessed using the unified MSA rating scale (UMSARS), a disease-specific questionnaire that enables the semiquantitative rating of autonomic and motor impairment in patients with MSA. Additional rating methods were applied to grade global disease severity, autonomic symptoms, and quality of life. Survival was calculated using a Kaplan-Meier analysis and predictors were identified in a Cox regression model. Group differences were analysed by parametric tests and non-parametric tests as appropriate. Sample size estimates were calculated using a paired two-group t test. FINDINGS: 141 patients with moderately severe disease fulfilled the consensus criteria for MSA. Mean age at symptom onset was 56·2 (SD 8·4) years. Median survival from symptom onset as determined by Kaplan-Meier analysis was 9·8 years (95% CI 8·1-11·4). The parkinsonian variant of MSA (hazard ratio [HR] 2·08, 95% CI 1·09-3·97; p=0·026) and incomplete bladder emptying (HR 2·10, 1·02-4·30; p=0·044) predicted shorter survival. 24-month progression rates of UMSARS activities of daily living, motor examination, and total scores were 49% (9·4 [SD 5·9]), 74% (12·9 [8·5]), and 57% (21·9 [11·9]), respectively, relative to baseline scores. Autonomic symptom scores progressed throughout the follow-up. Shorter symptom duration at baseline (OR 0·68, 0·5-0·9; p=0·006) and absent levodopa response (OR 3·4, 1·1-10·2; p=0·03) predicted rapid UMSARS progression. Sample size estimation showed that an interventional trial with 258 patients (129 per group) would be able to detect a 30% effect size in 1-year UMSARS motor examination decline rates at 80% power. INTERPRETATION: Our prospective dataset provides new insights into the evolution of MSA based on a follow-up period that exceeds that of previous studies. It also represents a useful resource for patient counselling and planning of multicentre trials.

TDP-43 skeins show properties of amyloid in a subset of ALS cases.

Aggregation of TDP-43 proteins to form intracellular inclusions is the primary pathology in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) with TDP-43 inclusions (FTLD-TDP). Histologically, in the cerebral cortex and limbic regions of affected ALS and FTLD-TDP patients, these pathologies occur as a variety of cytoplasmic, neuritic and intranuclear TDP-43 inclusions. In the spinal cord and lower brainstem of ALS patients, the lesions form cytoplasmic dashes or complex filamentous and spherical profiles in addition to skein-like inclusions (SLI). Ultrastructurally, the morphology of TDP-43 inclusions is heterogeneous but mainly composed of loose bundles of 10- to 20-nm-diameter straight filaments associated with electron-dense granular material. All of these TDP-43 inclusions are generally described as disordered amorphous aggregations unlike the amyloid fibrils that characterize protein accumulations in neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. We here report that Thioflavin-S positive SLI are present in a subset of ALS cases, while TDP-43 inclusions outside the spinal cord lack the chemical properties of amyloid. Further, we examine the differential enrichment of fibrillar profiles in SLI of ALS cases by TDP-43 immuno-electron microscopy (immuno-EM). The demonstration that pathological TDP-43 can be amyloidogenic in situ suggests the following conclusions: (1) the conformational changes associated with TDP-43 aggregation are more complex than previously thought; (2) Thioflavin-S positive SLI may be composed primarily of filamentous ultrastructures.

The Unified Multiple System Atrophy Rating Scale: intrarater reliability.

BACKGROUND: The Unified Multiple System Atrophy Rating Scale (UMSARS) was developed to provide a surrogate measure of disease progression in multiple system atrophy. In the present study, the intrarater agreement of the motor examination part of the UMSARS was determined. METHODS: All patients were first examined face to face, while being video-recorded, by two senior and two junior investigators. The patients' videotaped examinations were reevaluated after 3 months. Intrarater reliability for each item was analyzed by kappa statistics. RESULTS: Overall weighted kappa (κ) values were at least substantial or excellent for all UMSARS motor examination items, except for ocular motor dysfunction, which showed only moderate intrarater agreement. Intrarater reliability was comparable between senior and junior raters, with all κ differences being ≤ 0.22. CONCLUSIONS: The motor examination part of the UMSARS was found to have satisfactory intrarater reliability in the present cohort.

Microglial activation and TDP-43 pathology correlate with executive dysfunction in amyotrophic lateral sclerosis.

While cognitive deficits are increasingly recognized as common symptoms in amyotrophic lateral sclerosis (ALS), the underlying histopathologic basis for this is not known, nor has the relevance of neuroinflammatory mechanisms and microglial activation to cognitive impairment (CI) in ALS been systematically analyzed. Staining for neurodegenerative disease pathology, TDP-43, and microglial activation markers (CD68, Iba1) was performed in 102 autopsy cases of ALS, and neuropathology data were related to clinical and neuropsychological measures. ALS with dementia (ALS-D) and ALS with impaired executive function (ALS-Ex) patients showed significant microglial activation in middle frontal and superior or middle temporal (SMT) gyrus regions, as well as significant neuronal loss and TDP-43 pathology in these regions. Microglial activation and TDP-43 pathology in middle frontal and superior or middle temporal regions were highly correlated with measures of executive impairment, but not with the MMSE. In contrast, only one ALS-D patient showed moderate Alzheimer's disease (AD) pathology. Tau and Aß pathology increased with age. A lower MMSE score correlated with tau pathology in hippocampus and SMT gyrus, and with Aß pathology in limbic and most cortical regions. Tau and Aß pathology did not correlate with executive measures. We conclude that microglial activation and TDP-43 pathology in frontotemporal areas are determinants of FTLD spectrum dementia in ALS and correlate with neuropsychological measures of executive dysfunction. In contrast, AD pathology in ALS is primarily related to increasing age and associated with a poorer performance on the MMSE.

Neocortical and hippocampal amyloid-ß and tau measures associate with dementia in the oldest-old.

The emergence of longevity in the modern world has brought a sense of urgency to understanding age-related neurodegenerative diseases such as Alzheimer's disease. Unfortunately, there is a lack of consensus regarding the correlation between the pathological substrates of neurodegeneration and dementia status, particularly in the oldest-old. To better understand the pathological correlates of dementia in the oldest-old, we characterized the topographical spread and severity of amyloid-ß, tau, TDP-43 and α-synuclein pathologies in the 90+ Study, a prospective longitudinal population-based study of ageing and dementia. Neuropathological analysis with immunohistochemically labelled sections was carried out blind to clinical diagnosis on the first 108 participants of the 90+ Study who came to autopsy including participants with dementia (n = 66) and without dementia (n = 42). We used quantitative and/or semi-quantitative measures to assess the burden of amyloid-ß, tau, TDP-43 and α-synuclein pathologies as well as hippocampal sclerosis. Amyloid-ß and tau were the predominant pathologies in the 90+ Study cohort and both amyloid-ß area and tau area occupied measures were strongly associated with the presence of dementia, as was Braak staging but semi-quantitative plaque scores were not. Notably, TDP-43 pathology also correlated with dementia, while α-synuclein distribution did not. In addition, hippocampal sclerosis was specific to participants with dementia and correlated with the presence of limbic TDP-43. In contrast to previous reports, we found that tau and amyloid-ß continue to be robust pathological correlates of dementia, even in the oldest-old. While individuals with no dementia had limited hippocampal tau and neocortical amyloid-ß pathology, dementia associated with an expansion in pathology, including increased neocortical tau and hippocampal amyloid-ß plaques, more abundant neocortical amyloid-ß deposition and hippocampal sclerosis with its attendant TDP-43 pathology.

Motor neuron disease clinically limited to the lower motor neuron is a diffuse TDP-43 proteinopathy.

Motor neuron disease (MND) may present as an isolated lower motor neuron (LMN) disorder. Although the significance of pathological 43 kDa transactive responsive sequence DNA binding protein (TDP-43) for amyotrophic lateral sclerosis (ALS) was appreciated only recently, the topographical distribution of TDP-43 pathology in MND clinically isolated to the LMN versus normal controls (COs) is only incompletely described. Therefore, we performed longitudinal clinical evaluation and retrospective chart review of autopsied patients diagnosed with isolated LMN disease. Cases with a disease duration over 4 years were designated as progressive muscular atrophy (PMA), and those with a more rapid course as MND/LMN. Immunohistochemistry was employed to identify neuronal and glial TDP-43 pathology in the central nervous system (CNS) in patients and COs. We examined 19 subjects including six patients (i.e., four with MND/LMN and two with PMA) and 13 COs. All patients showed significant TDP-43 linked degeneration of LMNs, and five cases showed a lesser degree of motor cortex degeneration. Additional brain areas were affected in varying degrees, ranging from predominantly brainstem pathology to significant involvement of the whole CNS including neocortical and limbic areas. Pathological TDP-43 was present only rarely in the CO group. We conclude that MND limited to the LMN and PMA is part of a disease continuum that includes ALS and FTLD-TDP, all of which are characterized by widespread TDP-43 pathology. Hence, we suggest that the next revision of the El Escorial criteria for the diagnosis of ALS include MND patients with disease clinically limited to the LMN and PMA as variants of ALS, which like classical ALS, are TDP-43 proteinopathies.

Risk genotypes at TMEM106B are associated with cognitive impairment in amyotrophic lateral sclerosis.

TMEM106B has recently been identified as a genetic risk factor for frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP). Amyotrophic lateral sclerosis (ALS), like FTLD-TDP, is characterized by pathological TDP-43 inclusions. We therefore investigated whether FTLD-TDP-associated risk genotypes at TMEM106B (1) contribute to risk of developing ALS or (2) modify the clinical presentation in ALS. Detailed clinical and pathological information from 61 postmortem ALS patients was collected by database query, retrospective chart review, and histopathological slide review. DNA from these patients, as well as 24 additional ALS patients, was genotyped for three TMEM106B single nucleotide polymorphisms known to confer increased risk of FTLD-TDP. Associations between TMEM106B genotype and ALS were investigated by comparing TMEM106B genotypes in ALS patients (n = 85) and normal controls (n = 553), and associations between TMEM106B genotype and clinical and pathologic features were explored using linear regression. Multivariate linear models were used to evaluate the contributions of TMEM106B genotype and TDP-43 pathology to cognitive performance in ALS as measured by a phonemic verbal fluency test. We found that TMEM106B genotypes did not differ between ALS patients and normal controls. However, protective alleles at TMEM106B were significantly associated with preserved cognition in ALS patients, with the strongest association seen under a major-allele-dominant genetic model. While lower TDP-43 pathology scores and protective alleles at TMEM106B both correlated with better cognitive scores, these factors were not correlated with each other and demonstrated independent effects. These findings implicate the FTLD-TDP risk gene TMEM106B in the development of cognitive impairment in ALS.

Presentation, diagnosis, and management of multiple system atrophy in Europe: final analysis of the European multiple system atrophy registry.

Multiple system atrophy (MSA) is a Parkinson's Disease (PD)-like α-synucleinopathy clinically characterized by dysautonomia, parkinsonism, cerebellar ataxia, and pyramidal signs in any combination. We aimed to determine whether the clinical presentation of MSA as well as diagnostic and therapeutic strategies differ across Europe and Israel. In 19 European MSA Study Group centres all consecutive patients with a clinical diagnosis of MSA were recruited from 2001 to 2005. A standardized minimal data set was obtained from all patients. Four-hundred thirty-seven MSA patients from 19 centres in 10 countries were included. Mean age at onset was 57.8 years; mean disease duration at inclusion was 5.8 years. According to the consensus criteria 68% were classified as parkinsonian type (MSA-P) and 32% as cerebellar type (MSA-C) (probable MSA: 72%, possible MSA: 28%). Symptomatic dysautonomia was present in almost all patients, and urinary dysfunction (83%) more common than symptomatic orthostatic hypotension (75%). Cerebellar ataxia was present in 64%, and parkinsonism in 87%, of all cases. No significant differences in the clinical presentation were observed between the participating countries. In contrast, diagnostic work up and therapeutic strategies were heterogeneous. Less than a third of patients with documented orthostatic hypotension or neurogenic bladder disturbance were receiving treatment. This largest clinical series of MSA patients reported so far shows that the disease presents uniformly across Europe. The observed differences in diagnostic and therapeutic management including lack of therapy for dysautonomia emphasize the need for future guidelines in these areas.

Pathological 43-kDa transactivation response DNA-binding protein in older adults with and without severe mental illness.

BACKGROUND: Major psychiatric diseases such as schizophrenia and mood disorders have not been linked to a specific pathology, but their clinical features overlap with some aspects of the behavioral variant of frontotemporal lobar degeneration. Although the significance of pathological 43-kDa (transactivation response) DNA-binding protein (TDP-43) for frontotemporal lobar degeneration was appreciated only recently, the prevalence of TDP-43 pathology in patients with severe mental illness vs controls has not been systematically addressed. OBJECTIVE: To examine patients with chronic psychiatric diseases, mainly schizophrenia, for evidence of neurodegenerative TDP-43 pathology in comparison with controls. DESIGN: Prospective longitudinal clinical evaluation and retrospective medical record review, immunohistochemical identification of pathological TDP-43 in the central nervous system, and genotyping for gene alterations known to cause TDP-43 proteinopathies including the TDP-43 (TARDBP) and progranulin (GRN) genes. SETTING: University health system. PARTICIPANTS: One hundred fifty-one subjects including 91 patients with severe mental illness (mainly schizophrenia) and 60 controls. MAIN OUTCOME MEASURES: Clinical medical record review, neuronal and glial TDP-43 pathology, and TARDP and GRN genotyping status. RESULTS: Significant TDP-43 pathology in the amygdala/periamygdaloid region or the hippocampus/transentorhinal cortex was absent in both groups in subjects younger than 65 years but present in elderly subjects (29% [25 of 86] of the psychiatric patients and 29% [10 of 34] of control subjects). Twenty-three percent (8 of 35) of the positive cases showed significant TDP-43 pathology in extended brain scans. There were no evident differences between the 2 groups in the frequency, degree, or morphological pattern of TDP-43 pathology. The latter included (1) subpial and subependymal, (2) focal, or (3) diffuse lesions in deep brain parenchyma and (4) perivascular pathology. A new GRN variant of unknown significance (c.620T>C, p.Met207Thr) was found in 1 patient with schizophrenia with TDP-43 pathology. No known TARDBP mutations or other variants were found in any of the subjects studied herein. CONCLUSIONS: The similar findings of TDP-43 pathology in elderly patients with severe mental illness and controls suggest common age-dependent TDP-43 changes in limbic brain areas that may signify that these regions are affected early in the course of a cerebral TDP-43 multisystem proteinopathy. Finally, our data provide an age-related baseline for the development of whole-brain pathological TDP-43 evolution schemata.

Ataxin-2 intermediate-length polyglutamine expansions are associated with increased risk for ALS.

The causes of amyotrophic lateral sclerosis (ALS), a devastating human neurodegenerative disease, are poorly understood, although the protein TDP-43 has been suggested to have a critical role in disease pathogenesis. Here we show that ataxin 2 (ATXN2), a polyglutamine (polyQ) protein mutated in spinocerebellar ataxia type 2, is a potent modifier of TDP-43 toxicity in animal and cellular models. ATXN2 and TDP-43 associate in a complex that depends on RNA. In spinal cord neurons of ALS patients, ATXN2 is abnormally localized; likewise, TDP-43 shows mislocalization in spinocerebellar ataxia type 2. To assess the involvement of ATXN2 in ALS, we analysed the length of the polyQ repeat in the ATXN2 gene in 915 ALS patients. We found that intermediate-length polyQ expansions (27-33 glutamines) in ATXN2 were significantly associated with ALS. These data establish ATXN2 as a relatively common ALS susceptibility gene. Furthermore, these findings indicate that the TDP-43-ATXN2 interaction may be a promising target for therapeutic intervention in ALS and other TDP-43 proteinopathies.

Extensive FUS-immunoreactive pathology in juvenile amyotrophic lateral sclerosis with basophilic inclusions.

Juvenile amyotrophic lateral sclerosis (ALS) with basophilic inclusions is a well-recognized entity. However, the molecular underpinnings of this devastating disease are poorly understood. Here, we present genetic and neuropathological characterizations in two young women with fatal rapidly progressive ALS with basophilic inclusions. In one case, a germline mutation (P525L) was detected in the fused in sarcoma/translocated in liposarcoma (FUS/TLS) gene, whereas no mutation was identified in the other case. Postmortem examination in both cases revealed severe loss of spinal motor neurons with remaining neurons showing basophilic inclusions that contain abnormal aggregates of FUS proteins and disorganized intracellular organelles, including mitochondria and endoplasmic reticulum. In both patients, the FUS-positive inclusions were also detected in neurons in layers IV-V of cerebral cortex and several brainstem nuclei. In contrast, spinal motor neurons in patients with late-onset sporadic ALS showed no evidence of abnormal accumulation of FUS protein. These results underscore the importance of FUS mutations and pathology in rapidly progressive juvenile ALS. Furthermore, our study represents the first detailed characterizations of neuropathological findings in rapidly progressive juvenile ALS patients with a mutation in the FUS/TLS gene.

FUS pathology defines the majority of tau- and TDP-43-negative frontotemporal lobar degeneration.

Through an international consortium, we have collected 37 tau- and TAR DNA-binding protein 43 (TDP-43)-negative frontotemporal lobar degeneration (FTLD) cases, and present here the first comprehensive analysis of these cases in terms of neuropathology, genetics, demographics and clinical data. 92% (34/37) had fused in sarcoma (FUS) protein pathology, indicating that FTLD-FUS is an important FTLD subtype. This FTLD-FUS collection specifically focussed on aFTLD-U cases, one of three recently defined subtypes of FTLD-FUS. The aFTLD-U subtype of FTLD-FUS is characterised clinically by behavioural variant frontotemporal dementia (bvFTD) and has a particularly young age of onset with a mean of 41 years. Further, this subtype had a high prevalence of psychotic symptoms (36% of cases) and low prevalence of motor symptoms (3% of cases). We did not find FUS mutations in any aFTLD-U case. To date, the only subtype of cases reported to have ubiquitin-positive but tau-, TDP-43- and FUS-negative pathology, termed FTLD-UPS, is the result of charged multivesicular body protein 2B gene (CHMP2B) mutation. We identified three FTLD-UPS cases, which are negative for CHMP2B mutation, suggesting that the full complement of FTLD pathologies is yet to be elucidated.

Amyotrophic lateral sclerosis and frontotemporal lobar degeneration: a spectrum of TDP-43 proteinopathies.

It is now established that pathological transactive response DNA-binding protein with a Mr of 43 kD (TDP-43) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis is the major disease protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) with ubiquitin-positive inclusions (now known as FTLD-TDP). In fact, the discovery of pathological TDP-43 solidified the idea that these disorders are multi-system diseases and this led to the concept of a TDP-43 proteinopathy as a spectrum of disorders comprised of different clinical and pathological entities extending from ALS to ALS with cognitive impairment/dementia and FTLD-TDP without or with motor neuron disease (FTLD-MND). These align along a broad disease continuum sharing similar pathogenetic mechanisms linked to pathological TDP-43. We here review salient findings in the development of a concept of TDP-43 proteinopathy as a novel group of neurodegenerative diseases similar in concept to alpha-synucleinopathies and tauopathies.