Subtypes Of Amyotrophic Lateral Sclerosis Research Articles

Inflammatory profiles relate to survival in subtypes of amyotrophic lateral sclerosis.

ObjectiveTo investigate inflammatory cytokines in patients with motor neuron disease (MND) evaluating the putative contribution of amyotrophic lateral sclerosis (ALS)-causing gene variants.MethodsThis study is a retrospective case series with prospective follow-up (1994–2016) of 248 patients with MND, of whom 164 had ALS who were screened for mutations in the genes for SOD1 and C9orf72. Paired CSF and plasma were collected at the diagnostic evaluation before treatment. A panel of cytokines were measured blindly via digital ELISA on the Simoa platform.ResultsTime from disease onset to death was longer for patients with ALS-causing SOD1 mutations (mSOD1, n = 24) than those with C9orf72 hexanucleotide repeat expansion (C9orf72HRE) ALS (n = 19; q = 0.001) and other ALS (OALS) (n = 119; q = 0.0008). Patients with OALS had higher CSF tumor necrosis factor alpha (TNF-α) compared with those with C9orf72HRE ALS (q = 0.014). Patients with C9orf72HRE ALS had higher CSF interferon alpha compared with those with OALS and mSOD1 ALS (q = 0.042 and q = 0.042). In patients with ALS, the survival was negatively correlated with plasma interleukin (IL) 10 (hazard ratio [HR] 1.17, 95% CI 1.05–1.30). Plasma TNF-α, IL-10, and TNF-related apoptosis-inducing ligand (TRAIL) (HR 1.01 [1.00–1.02], 1.15 [1.02–1.30], and 1.01 [1.00–1.01], respectively) of patients with OALS, plasma IL-1β (HR 5.90 [1.27–27.5]) of patients with C9orf72HRE ALS, and CSF TRAIL (10.5 [1.12–98.6]) of patients with mSOD1 ALS all correlated negatively with survival.ConclusionsDifferences in survival times in ALS subtypes were correlated with cytokine levels, suggesting specific immune responses related to ALS genetic variants.

Amyotrophic Lateral Sclerosis with Pallidonigroluysian Degeneration: A Clinicopathological Study.

The pallidonigroluysian (PNL) system, the primary component of corticosubcortical circuits, is generally spared in amyotrophic lateral sclerosis (ALS). We evaluated the clinicopathological features of an unusual form of ALS with PNL degeneration (PNLD) and assessed whether ALS with PNLD represents a distinct ALS subtype. From a cohort of 97 autopsied cases of sporadic ALS with phosphorylated 43kDa TAR DNA-binding protein (TDP-43) inclusions, we selected those with PNLD and analyzed their clinicopathological features. Eleven cases (11%) that showed PNLD were divided into 2 subtypes depending on the lesion distribution: (1) extensive type (n = 6), showing widespread TDP-43 pathology and multisystem degeneration, both involving the PNL system; and (2) limited type (n = 5), showing selective PNL and motor system involvement, thus being unclassifiable in terms of Brettschneider's staging or Nishihira's typing of ALS. The limited type showed a younger age at onset and predominant PNLD that accounted for the early development of extrapyramidal signs. The limited type exhibited the heaviest pathology in the subthalamus and external globus pallidus, suggesting that TDP-43 inclusions propagated via indirect or hyperdirect pathways, unlike ALS without PNLD, where the direct pathway is considered to convey TDP-43 aggregates from the cerebral cortex to the substantia nigra. The PNL system can be involved in the disease process of ALS, either nonselectively as part of multisystem degeneration, or selectively. ALS with selective involvement of the PNL and motor systems exhibits unique clinicopathological features and TDP-43 propagation routes, thus representing a distinct subtype of ALS. ANN NEUROL 2020;87:302-312.

Unbiased MRI Analyses Identify Micropathologic Differences Between Upper Motor Neuron-Predominant ALS Phenotypes

Amyotrophic lateral sclerosis (ALS) is an incurable and progressively fatal neurodegenerative disease that manifests with distinct clinical phenotypes, which are seen in neuroimaging, and clinical studies. T2- and proton density (PD)-weighted magnetic resonance imaging (MRI) displays hyperintense signal along the corticospinal tract (CST) in some ALS patients with upper motor neuron (UMN)-predominant signs. These patients tend to be younger and have significantly faster disease progression. We hypothesize that such ALS patients with CST hyperintensity (ALS-CST+) comprise a clinical subtype distinct from other ALS subtypes, namely patients with UMN-predominant ALS without CST hyperintensity, classic ALS, and ALS with frontotemporal dementia (FTD). Novel approaches such as fractal dimension analysis on conventional MRI (cMRI) and advanced MR techniques such as diffusion tensor imaging (DTI) reveal significant differences between ALS-CST+ and the aforementioned ALS subtypes. Our unbiased neuroimaging studies demonstrate that the ALS-CST+ group, which can be initially identified by T2-, PD-, and FLAIR-weighted cMRI, is distinctive and distinguishable from other ALS subtypes with possible differences in disease pathogenesis.

Integrative multi-omic analysis identifies new drivers and pathways in molecularly distinct subtypes of ALS

Amyotrophic lateral sclerosis (ALS) is an incurable and fatal neurodegenerative disease. Increasing the chances of success for future clinical strategies requires more in-depth knowledge of the molecular basis underlying disease heterogeneity. We recently laid the foundation for a molecular taxonomy of ALS by whole-genome expression profiling of motor cortex from sporadic ALS (SALS) patients. Here, we analyzed copy number variants (CNVs) occurring in the same patients, by using a customized exon-centered comparative genomic hybridization array (aCGH) covering a large panel of ALS-related genes. A large number of novel and known disease-associated CNVs were detected in SALS samples, including several subgroup-specific loci, suggestive of a great divergence of two subgroups at the molecular level. Integrative analysis of copy number profiles with their associated transcriptomic data revealed subtype-specific genomic perturbations and candidate driver genes positively correlated with transcriptional signatures, suggesting a strong interaction between genomic and transcriptomic events in ALS pathogenesis. The functional analysis confirmed our previous pathway-based characterization of SALS subtypes and identified 24 potential candidates for genomic-based patient stratification. To our knowledge, this is the first comprehensive “omics” analysis of molecular events characterizing SALS pathology, providing a road map to facilitate genome-guided personalized diagnosis and treatments for this devastating disease.

Toward in vivo determination of peripheral nervous system immune activity in amyotrophic lateral sclerosis.

We sought to identify patients with amyotrophic lateral sclerosis (ALS) who displayed suspected peripheral nervous system (PNS) inflammation to compare them to those with suspected PNS degeneration. We measured sonographic median and ulnar nerve cross-sectional area (CSA) and cerebrospinal fluid albumin/serum albumin ratio (Qalb ) in patients with ALS to classify them as having suspected PNS degeneration (small CSA/low Qalb ) or inflammation (larger CSA/high Qalb ). Fifty-seven percent of patients had suspected PNS degeneration, 21% had suspected PNS inflammation, and 21% displayed suspected "normal PNS state." Suspected PNS degeneration was related to classic ALS, shorter disease duration, and a smaller hypoechoic nerve area. Suspected PNS inflammation was associated with men, longer disease duration, and a larger hypoechoic nerve area and was the dominant finding in superoxide dismutase 1 mutation carriers. Our simple approach might aid in the in vivo differentiation of supposed ALS subtypes, those with suspected PNS degeneration vs. inflammation, for stratification in clinical trials. Muscle Nerve 59:567-567, 2019.

Motor neuron disease-associated loss of nuclear TDP-43 is linked to DNA double-strand break repair defects

Genome damage and their defective repair have been etiologically linked to degenerating neurons in many subtypes of amyotrophic lateral sclerosis (ALS) patients; however, the specific mechanisms remain enigmatic. The majority of sporadic ALS patients feature abnormalities in the transactivation response DNA-binding protein of 43 kDa (TDP-43), whose nucleo-cytoplasmic mislocalization is characteristically observed in spinal motor neurons. While emerging evidence suggests involvement of other RNA/DNA binding proteins, like FUS in DNA damage response (DDR), the role of TDP-43 in DDR has not been investigated. Here, we report that TDP-43 is a critical component of the nonhomologous end joining (NHEJ)-mediated DNA double-strand break (DSB) repair pathway. TDP-43 is rapidly recruited at DSB sites to stably interact with DDR and NHEJ factors, specifically acting as a scaffold for the recruitment of break-sealing XRCC4-DNA ligase 4 complex at DSB sites in induced pluripotent stem cell-derived motor neurons. shRNA or CRISPR/Cas9-mediated conditional depletion of TDP-43 markedly increases accumulation of genomic DSBs by impairing NHEJ repair, and thereby, sensitizing neurons to DSB stress. Finally, TDP-43 pathology strongly correlates with DSB repair defects, and damage accumulation in the neuronal genomes of sporadic ALS patients and in Caenorhabditis elegans mutant with TDP-1 loss-of-function. Our findings thus link TDP-43 pathology to impaired DSB repair and persistent DDR signaling in motor neuron disease, and suggest that DSB repair-targeted therapies may ameliorate TDP-43 toxicity-induced genome instability in motor neuron disease.

Reaction to Endoplasmic Reticulum Stress via ATF6 in Amyotrophic Lateral Sclerosis Deteriorates With Aging.

Amyotrophic lateral sclerosis (ALS) is a multisystemic neurodegenerative disorder. Given that peripheral blood mononuclear cells (PBMCs) serve as a “window to the central nervous system” we aimed to answer whether endoplasmic reticulum (ER) stress in ALS-PBMCs is related to disease aggressiveness. We studied ER stress in the PBMCs of 49 patients with ALS and 31 age- and sex-matched healthy controls. The expression of a main ER stress marker, activating transcription factor 6 (ATF6), was significantly higher in ALS compared to controls, but did not correlate with age, disease severity, disease duration and disease progression rate. When ATF6 expression levels were plotted against relative D50 (rD50)-derived disease phases derived from the D50 ALS model, two distinct clusters of patients were observed: cluster 1, with progressively increasing ATF6 expression levels and cluster 2, which demonstrated stable ATF6 expression over the disease course. Individuals in the two clusters did not significantly differ in terms of ALS Functional Rating Scale-Revised (ALSFRS-R), disease aggressiveness, disease duration and subtype. However, patients with the increasing ATF6 level were significantly younger, indicating that aging processes might be related to ER stress in ALS. Our data suggest that the reaction to ER stress during disease course may be compromised in older patients with ALS.

Molecular Mechanisms of Neurodegeneration Related to C9orf72 Hexanucleotide Repeat Expansion.

Two clinically distinct diseases, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), have recently been classified as two extremes of the FTD/ALS spectrum. The neuropathological correlate of FTD is frontotemporal lobar degeneration (FTLD), characterized by tau-, TDP-43-, and FUS-immunoreactive neuronal inclusions. An earlier discovery that a hexanucleotide repeat expansion mutation in chromosome 9 open reading frame 72 (C9orf72) gene causes ALS and FTD established a special subtype of ALS and FTLD with TDP-43 pathology (C9FTD/ALS). Normal individuals carry 2–10 hexanucleotide GGGGCC repeats in the C9orf72 gene, while more than a few hundred repeats represent a risk for ALS and FTD. The proposed molecular mechanisms by which C9orf72 repeat expansions induce neurodegenerative changes are C9orf72 loss-of-function through haploinsufficiency, RNA toxic gain-of-function, and gain-of-function through the accumulation of toxic dipeptide repeat proteins. However, many more cellular processes are affected by pathological processes in C9FTD/ALS, including nucleocytoplasmic transport, RNA processing, normal function of nucleolus, formation of membraneless organelles, translation, ubiquitin proteasome system, Notch signalling pathway, granule transport, and normal function of TAR DNA-binding protein 43 (TDP-43). Although the exact molecular mechanisms through which C9orf72 repeat expansions account for neurodegeneration have not been elucidated, some potential therapeutics, such as antisense oligonucleotides targeting hexanucleotide GGGGCC repeats in mRNA, were successful in preclinical trials and are awaiting phase 1 clinical trials. In this review, we critically discuss each proposed mechanism and provide insight into the most recent studies aiming to elucidate the molecular underpinnings of C9FTD/ALS.

ALS-Associated E478G Mutation in Human OPTN (Optineurin) Promotes Inflammation and Induces Neuronal Cell Death.

Amyotrophic Lateral Sclerosis (ALS) is a group of neurodegenerative disorders that featured with the death of motor neurons, which leads to loss of voluntary control on muscles. The etiologies vary among different subtypes of ALS, and no effective management or medication could be provided to the patients, with the underlying mechanisms incompletely understood yet. Mutations in human Optn (Optineurin), particularly E478G, have been found in many ALS patients. In this work, we report that NF-κB activity was increased in Optn knockout (Optn−/−) MEF (mouse embryonic fibroblast) cells expressing OPTN of different ALS-associated mutants especially E478G. Inflammation was significantly activated in mice infected with lenti-virus that allowed overexpression of OPTNE478G mutation in the motor cortex, with marked increase in the secretion of pro-inflammatory cytokines as well as neuronal cell death. Our work with both cell and animal models strongly suggested that anti-inflammation treatment could represent a powerful strategy to intervene into disease progression in ALS patients who possess the distinctive mutations in OPTN gene.

The impact of percutaneous endoscopic gastrostomy on the survival of patients with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing degenerative motor neuron disease that leads to significant muscle weakness. Patients can present with severe dysphagia and require nutritional support. While percutaneous endoscopic gastrostomy (PEG) is a standard procedure for these patients, its effect on survival is not yet clear. Therefore, we aimed to evaluate the impact of PEG placement on ALS patients survival. We retrospectively reviewed health records of ALS patients followed at a Neurological Department in the northeast region of Portugal for the 2005–2016 period. Potentially relevant clinical information was collected for survival analysis using Kaplan–Meier estimator and Mantel–Cox regression. In the studied period, 75 incident ALS cases were identified. Information regarding symptom onset was available for 62 (83%) patients, and PEG was placed after informed consent in 27 (36%) patients. The overall median survival from symptom onset was 1142 (95% CI: 866–1418) days and did not differ between PEG and non-PEG groups (Fig. 1). In the PEG group ( n = 27), 19 (70%) died by the end of the follow-up period. Overall median survival post-PEG placement was 320 (95% CI: 135–505) days. Bulbar ALS cases ( n = 18) had a median survival of 249 days while the remaining 9 Spinal cases had a median survival of 709 days (Fig. 2). Both LogRank test and Mantel–Cox regression using ALS subtype as covariate did not yield significant results regarding post-PEG survival ( P = 0.312; HR = 0.566 [95% CI: 0.185–1.730], P = 0.566; respectively). In conclusion, PEG did not impact ALS survival in our study. Post-PEG survival was also similar in both bulbar- and spinal-onset groups. However, our analysis is limited by the small sample size. Studies with more participants are required to more effectively estimate the impact of PEG in overall and subgroups ALS survival.

The prionlike domain of FUS is multiphosphorylated following DNA damage without altering nuclear localization.

FUS (fused in sarcoma) is an abundant, predominantly nuclear protein involved in RNA processing. Under various conditions, FUS functionally associates with RNA and other macromolecules to form distinct, reversible phase-separated liquid structures. Persistence of the phase-separated state and increased cytoplasmic localization are both hypothesized to predispose FUS to irreversible aggregation, which is a pathological hallmark of subtypes of amyotrophic lateral sclerosis and frontotemporal dementia. We previously showed that phosphorylation of FUS’s prionlike domain suppressed phase separation and toxic aggregation, proportionally to the number of added phosphates. However, phosphorylation of FUS’s prionlike domain was previously reported to promote its cytoplasmic localization, potentially favoring pathological behavior. Here we used mass spectrometry and human cell models to further identify phosphorylation sites within FUS’s prionlike domain, specifically following DNA-damaging stress. In total, 28 putative sites have been identified, about half of which are DNA-dependent protein kinase (DNA-PK) consensus sites. Custom antibodies were developed to confirm the phosphorylation of two of these sites (Ser-26 and Ser-30). Both sites were usually phosphorylated in a subpopulation of cellular FUS following a variety of DNA-damaging stresses but not necessarily equally or simultaneously. Importantly, we found DNA-PK–dependent multiphosphorylation of FUS’s prionlike domain does not cause cytoplasmic localization.

F46. Rostral to caudal spreading patterns of clinical and electrophysiological features in amyotrophic lateral sclerosis with bulbar-onset

Introduction The region of onset and speed of progression in amyotrophic lateral sclerosis (ALS) are subtype-related and highly variable. The present study was to explore the spreading pattern of clinical and electrophysiological features in amyotrophic lateral sclerosis with bulbar-onset (BO-ALS), a special subtype of ALS with more rapid progression and poorer prognosis than ALS with initial limb-onset. Methods We retrospectively reviewed the clinical and electrophysiological data of 42 consecutive in-patients with BO-ALS from 2009 to 2016, and then diagnostic latency (within 6 months or not) was used to group the patients for comparison of data. Results The distribution of weakness, fasciculation, and amyotrophy was significantly different in muscles innervated by bulbar and spinal segments, with the highest involvement in bulbar segment, followed by that in cervical and then in lumbosacral segment. Likewise, the distribution of abnormal muscle spontaneous activity and neurogenic MUPs detected in electromyography was also found in similar gradients from bulbar, cervical, and thoracic to lumbosacral segment. Meanwhile, significantly lower incidence of electrophysiological involvement in lumbosacral segment was observed in patients with shorter diagnostic latency (within 6 months from the onset). In addition, with more frequent finding of widespread neurogenic abnormalities in electromyography, younger patients were easier to receive a definite diagnosis. Conclusion Our study revealed a rostral-caudal spreading pattern of lower motor unit involvement in BO-ALS, which would help guide the early diagnosis of BO-ALS and make detailed care plans for the patients.

The Role of Post-Translational Modifications on Prion-Like Aggregation and Liquid-Phase Separation of FUS.

Subcellular mislocalization and aggregation of the human FUS protein occurs in neurons of patients with subtypes of amyotrophic lateral sclerosis and frontotemporal dementia. FUS is one of several RNA-binding proteins that can functionally self-associate into distinct liquid-phase droplet structures. It is postulated that aberrant interactions within the dense phase-separated state can potentiate FUS’s transition into solid prion-like aggregates that cause disease. FUS is post-translationally modified at numerous positions, which affect both its localization and aggregation propensity. These modifications may influence FUS-linked pathology and serve as therapeutic targets.

Cortical Thinning Pattern of Bulbar- and Spinal-onset Amyotrophic Lateral Sclerosis: a Surface-based Morphometry Study.

Objective The precise cortical thinning pattern has not been elucidated for onset subtypes of amyotrophic lateral sclerosis (ALS). The current study aimed to investigate the altered cortical thickness signatures of the bulbar-onset and spinal-onset ALS using surface-based morphometry, and the correlation between the cortical thickness of positive brain regions and clinical variables of the patients.Methods MR structural images were obtained from 65 ALS patients (15 bulbar-onset, 50 spinal-onset) and 65 normal controls (NCs) on a 3.0T MRI system. The structural images were segmented into gray matter and white matter based on DARTEL method and the central cortical surfaces were reconstructed using projection-based thickness method. The surface-based morphometry was performed to identify the alteration of cortical thickness in overall ALS patients, bulbar-onset ALS patients and spinal-onset ALS patients comparing to the NCs. The correlation analysis was applied between the clinical variables and the mean cortical thickness of the abnormal brain regions with age and sex as covariates.Results The cortex thinning of ALS patients was located in the left precentral gyrus, left postcentral gyrus, right gyrus rectus and right medial precentral gyrus. The bulbar-onset ALS (ALS-bulbar) presented motor cortex thinning of left precentral gyrus and right supplementary motor cortex, and the spinal-onset ALS (ALS-spinal) suffered from extra-motor cortex thinning of left posterior insula and right gyrus rectus. In ALS patients, the thickness of right gyrus rectus was negatively correlated to disease duration (r=-0.311, P=0.013), the thickness of right precentral gyrus was positively correlated to the score of ALS functional rating score-revise (ALSFRS-R) (r=0.271, P=0.032). The thickness of motor cortices in ALS-bulbar were not correlated to disease duration and ALSFRS-R score; the thickness of extra-motor cortices in ALS-spinal were negatively correlated to the disease duration (left insula, r=-0.409, P=0.004; right gyrus rectus, r=-0.351, P=0.014).Conclusion The findings suggested that bilateral motor cortex thinning presented in bulbar-onset ALS and extra-motor cortex thinning presented in spinal-onset ALS. The motor cortex thinning may be the intrinsic pathophysiological change that associated to the disease disability, and extra-motor cortex thinning may be secondary pathophysiological change that associated to disease duration.

Multi-Omics for Biomarker Discovery and Target Validation in Biofluids for Amyotrophic Lateral Sclerosis Diagnosis.

Amyotrophic lateral sclerosis (ALS) is a rare but usually fatal neurodegenerative disease characterized by motor neuron degeneration in the brain and the spinal cord. Two forms are recognized, the familial that accounts for 5-10% and the sporadic that accounts for the rest. New studies suggest that ALS is a highly heterogeneous disease, and this diversity is a major reason for the lack of successful therapeutic treatments. Indeed, only two drugs (riluzole and edaravone) have been approved that provide a limited improvement in the quality of life. Presently, the diagnosis of ALS is based on clinical examination and lag period from the onset of symptoms to the final diagnosis is ∼12 months. Therefore, the discovery of robust molecular biomarkers that can assist in the diagnosis is of major importance. DNA sequencing to identify pathogenic gene variants can be applied in the cases of familial ALS. However, it is not a routinely used diagnostic procedure and most importantly, it cannot be applied in the diagnosis of sporadic ALS. In this expert review, the current approaches in identification of new ALS biomarkers are discussed. The advent of various multi-omics biotechnology platforms, including miRNomics, proteomics, metabolomics, metallomics, volatolomics, and viromics, has assisted in the identification of new biomarkers. The biofluids are the most preferable material for the analysis of potential biomarkers (such as proteins and cell-free miRNAs), since they are easily obtained. In the near future, the biofluid-based biomarkers will be indispensable to classify different ALS subtypes and understand the molecular heterogeneity of the disease.

P 28 Voxel-based Morphometry (VBM) subcortical white matter changes correlate with disease progression in amyotrophic lateral sclerosis

Introduction Amyotrophic lateral sclerosis (ALS) is a progressive, multisystemic disorder.Signs of lower motor neurone involvement are readily detectable but the involvement of the upper motor neurone is elusive.Hence, we must identify the extent and development of ALS related changes in the brain in different subtypes of ALS to facilitate an early diagnosis and stratification for clinical trials.Previous studies applying Voxel-based morphometry (VBM) provided inconsistent results. Objective The aim of this study is to describe the heterogeneity of ALS with regard to the site of onset (bulbar vs.limb), disease duration (long vs.short), degree of disability (high vs.low) and disease progression rate (rapid vs.slow) in a large cohort of well characterized ALS patients.ALS related MRI changes should correlate with clinical parameters, such as ALSFRS-R score and D50 (50% disease progression in a model of sigmoidal decay of the ALSFRS-R). The long-term aim of this study is to evaluate VBM as a predictive marker for ALS in a representative number of subjects ( n > 100 ). Methods High resolution T1-weighted FLASH 3D scans (fl3d) in 92 ALS patients and 62 healthy controls were analyzed using VBM8 in SPM8 on matlab 2009b.Clinical parameters were collected regularly: disease duration, date and location of the first symptom, rate of disease progression and degree of disability (ALSFRS-R). Based on these clinical parameters, patients were classified into the subgroups and analyzed to determine changes in the gray and white matter. Results The mean age of 62 controls was 53.97y and of the 92 patients 60.24y.The patient group included 24 bulbar and 68 limb onsets.Average disease duration was 25 mo, wherein 26 patients had a long ( ⩾ 24mo) and 35 had a short ( ⩽ 12mo) disease duration.Mean ALSFRS-R was 37.8.46 patients had a “low” degree of disability (ALSFRS-R ⩾ 40), whereas 17 patients were “highly” impaired ( ⩽ 30).Mean progression rate was 0.66.A subgroup with a rapid form of ALS included 16 patients, with a slow form 46.Using VBM, more rapid progression, longer disease duration and more severely affected patients had a more pronounced reduction in GMV in the central, and frontal brain regions, whereas subcortical WM was more severely altered. Conclusion Using VBM in high resolution T1 in a large cohort of ALS patients, we were able to identify the key regions of ALS pathology which correlated well with three clinical progression parameters.It is likely that previous studies were underpowered and ALS related heterogeneity obscured the relevant pathology in computerized voxel-based analyses. Acknowledgement This research is supported by BMBF (Bundesministerium fur Bildung and Forschung) in the framework of the E-RARE programme (PYRAMID) and JPND (OnWebDUALS and SOPHIA) of the European Union in collaboration with the Neuroimaging Society in ALS (NiSALS) MRI repository Jena.

Nuclear trafficking in amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

Amyotrophic lateral sclerosis and frontotemporal lobar degeneration are two ends of a phenotypic spectrum of disabling, relentlessly progressive and ultimately fatal diseases. A key characteristic of both conditions is the presence of TDP-43 (encoded by TARDBP) or FUS immunoreactive cytoplasmic inclusions in neuronal and glial cells. This cytoplasmic mislocalization of otherwise predominantly nuclear RNA binding proteins implies a perturbation of the nucleocytoplasmic shuttling as a possible event in the pathogenesis. Compromised nucleocytoplasmic shuttling has recently also been associated with a hexanucleotide repeat expansion mutation in C9orf72, which is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal lobar degeneration, and leads to accumulation of cytoplasmic TDP-43 inclusions. Mutation in C9orf72 may disrupt nucleocytoplasmic shuttling on the level of C9ORF72 protein, the transcribed hexanucleotide repeat RNA, and/or dipeptide repeat proteins translated form the hexanucleotide repeat RNA. These defects of nucleocytoplasmic shuttling may therefore, constitute the common ground of the underlying disease mechanisms in different molecular subtypes of amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

Sonographic evaluation of cervical nerve roots in ALS and its clinical subtypes.

Morphological assessment of peripheral nerves in amyotrophic lateral sclerosis (ALS) has been available by sonography. Detection of possible axonal atrophy could be important in predicting progression. Research on correlation between sonographic findings and clinical presentation has been sparse. The aim of the study was to assess possible motor axon loss in patients with ALS by sonography and to correlate the imaging features with clinical subtypes. Patients with either definite or probable ALS and control subjects had sonographic evaluation of the cervical nerve roots (C5, C6, and C7). Each diameter and their sums were measured. The ALS patients were classified by their clinical onset and progression (arm-onset, leg-onset, bulbar, and flail-arm variant) and the sonographic features were compared. Overall, the cervical nerve roots were thinner in ALS than in the controls, but the diagnostic sensitivity was low. The patients with arm dysfunctions tended to show thinner nerve roots than those with normal or relatively preserved arm functions. The four ALS subtypes showed similar diameters of the nerve roots. There was no correlation between the disease duration and the diameters of the nerve roots. Sonography of the cervical nerve roots showed axonal atrophy in ALS and potentially reflects subtle arm dysfunctions.

Invited review: decoding the pathophysiological mechanisms that underlie RNA dysregulation in neurodegenerative disorders: a review of the current state of the art.

Altered RNA metabolism is a key pathophysiological component causing several neurodegenerative diseases. Genetic mutations causing neurodegeneration occur in coding and noncoding regions of seemingly unrelated genes whose products do not always contribute to the gene expression process. Several pathogenic mechanisms may coexist within a single neuronal cell, including RNA/protein toxic gain-of-function and/or protein loss-of-function. Genetic mutations that cause neurodegenerative disorders disrupt healthy gene expression at diverse levels, from chromatin remodelling, transcription, splicing, through to axonal transport and repeat-associated non-ATG (RAN) translation. We address neurodegeneration in repeat expansion disorders [Huntington's disease, spinocerebellar ataxias, C9ORF72-related amyotrophic lateral sclerosis (ALS)] and in diseases caused by deletions or point mutations (spinal muscular atrophy, most subtypes of familial ALS). Some neurodegenerative disorders exhibit broad dysregulation of gene expression with the synthesis of hundreds to thousands of abnormal messenger RNA (mRNA) molecules. However, the number and identity of aberrant mRNAs that are translated into proteins – and how these lead to neurodegeneration – remain unknown. The field of RNA biology research faces the challenge of identifying pathophysiological events of dysregulated gene expression. In conclusion, we discuss current research limitations and future directions to improve our characterization of pathological mechanisms that trigger disease onset and progression.

AMYOTROPHIC LATERAL SCLEROSIS ASSOCIATED WITH AN INTERMEDIATE LENGTH GGGGCC REPEAT EXPANSION HAS DISTINCT NEUROPATHOLOGY COMPARED TO PATIENTS WITH LARGER EXPANSIONS

<h3>Background</h3> An intronic GGGGCC hexanucleotide repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Thirty repeats is the suggested pathogenic cut-off. However, the 9p21 risk haplotype has been associated with C9orf72 expansions &gt;7 repeats, leading to the description of 7–24 repeats as intermediate. The pathogenicity of intermediate repeat lengths is unknown. Studies have suggested phenotypic similarities between patients with intermediate length expansions and those with larger repeat lengths, although given the broad phenotypic spectrum of ALS this is not conclusive. Previously, there has been no pathological characterisation of an intermediate expansion patient. <h3>Materials and Methods</h3> Pathological material was obtained from the Sheffield Brain Tissue Bank. Genomic DNA was extracted from cerebellar material and reverse primed PCR and Southern hybridisation was conducted to size the expansion. Immunohistochemistry and RNA fluorescence in-situ hybridisation (FISH) was used to screen for pathology typical of C9orf72-ALS. <h3>Results</h3> Repeat-primed PCR and Southern hybridisation revealed a repeat expansion size of 16 repeats in a sporadic ALS (SALS) patient. Neuropathological analysis demonstrated loss of motor neurons and immunohistochemistry revealed coarse neuronal skein-like inclusions identified by ubiquitin and P62 immunostaining. Pathology characteristic of C9orf72-disease, including extramotor neuronal inclusions, RNA foci and neuronal inclusions containing poly-(Gly-Ala)- dipeptide repeat protein, were absent in this patient. <h3>Conclusion</h3> A patient with an intermediate C9orf72 expansion of 16 repeats did not show the characteristic C9orf72 pathology suggesting that, in this case, the disease process was distinct from C9orf72-ALS, and the intermediate expansion is an incidental finding. This is consistent with current toxic gain-of-function theories of C9orf72-ALS. The 9p21 risk haplotype may predispose to expansion of the GGGGCC repeat locus, but we suggest that this must occur to some length larger than 16 repeats to cause the pathology characteristic of the C9orf72 subtype of ALS.