Amyotrophic Lateral Sclerosis Cases Research Articles

Epigenetic age acceleration is associated with occupational exposures, sex, and survival in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is linked to ageing and genetic and environmental risk factors, yet underlying mechanisms are incompletely understood. We aimed to evaluate epigenetic age acceleration (EAA), i.e., DNA methylation (DNAm) age acceleration, and its association with ALS case status and survival. In this study, we included 428 ALS and 288 control samples collected between 2011 and 2021. We calculated EAA using the GrimAge residual method from ALS and control blood samples and grouped participants with ALS into three ageing groups (fast, normal, slow). We associated EAA with ALS case status and survival, stratified by sex, and correlated it with environmental and biological factors through occupational exposure assessments, immune cell proportions, and transcriptome changes. Participants with ALS had higher average EAA by 1.80±0.30 years (p<0.0001) versus controls. Participants with ALS in the fast ageing group had a hazard ratio of 1.52 (95% confidence interval 1.16-2.00, p=0.0028) referenced to the normal ageing group. In males, this hazard ratio was 1.55 (95% confidence interval 1.11-2.17, p=0.010), and EAA was positively correlated with high-risk occupational exposures including particulate matter (adj.p<0.0001) and metals (adj.p=0.0087). Also, in male participants with ALS, EAA was positively correlated with neutrophil proportions and was negatively correlated with CD4+ T cell proportions. Pathways dysregulated in participants with ALS with fast ageing included spliceosome, nucleocytoplasmic transport, axon guidance, and interferons. EAA was associated with ALS case status and, at least in males, with shorter survival after diagnosis. The effect of EAA on ALS was partially explained by occupational exposures and immune cell proportions in a sex-dependent manner. These findings highlight the complex interactions of ageing and exposures in ALS. NIH, CDC/National ALS Registry, ALS Association, Dr. Randall Whitcomb Fund for ALS Genetics, Peter Clark Fund for ALS Research, Sinai Medical Staff Foundation, Scott L. Pranger ALS Clinic Fund, NeuroNetwork Therapeutic Discovery Fund, NeuroNetwork for Emerging Therapies.

Evaluation of Split Hand Syndrome in Early Diagnosis of Amyotrophic Lateral Sclerosis by Nerve Conduction Study as a Diagnostic Tool

Background: Amyotrophic lateral sclerosis (ALS), a degenerative disease of the motor neurons that can present diversly. Needle electromyography (EMG) is the gold standard investigation for the diagnosis of ALS. Split hand syndrome (SHS) demonstrated by nerve conduction study (NCS); a noninvasive tool could be useful in diagnosing ALS. This study aimed to assess SHS by NCS in ALS. Methods: This diagnostic accuracy case-control study included 37 cases of ALS and 37 age and gender-matched controls. Compound muscle action potential (CMAP) and distal motor latency (DML) of median and ulnar nerves and the ratio of median and ulnar CMAP and DML were compared between study groups. The diagnostic validity testing of electrophysiological SHS was also done. Results: The mean age of the ALS and control groups were similar, 39.8±2.7 and 39.3±2.6 years, respectively. Sixteen (43.2%) ALS patients were in 30-59 years age group. Male-female ratio was 5.2. In the ALS group, median-ulnar CMAP ratio was lower and median-ulnar DML ratio was prolonged than the control. The diagnostic efficacy of median-ulnar CMAP ratio and DML ratio were calculated. A median-ulnar CMAP ratio cut-off value ≤1 showed 70% sensitivity, 97% specificity, 96% positive predictive value and 77% negative predictive value. A median-ulnar DML ratio cut-off value ≥1.5 showed 48% sensitivity, 89% specificity, 82% positive predictive value and 65% negative predictive value. Conclusion: NCS demonstrating SHS can be an important tool in the early diagnosis of ALS. J Bangladesh Coll Phys Surg 2024; 42: 350-354

Recent Progress of Antisense Oligonucleotide Therapy for Superoxide-Dismutase-1-Mutated Amyotrophic Lateral Sclerosis: Focus on Tofersen.

Amyotrophic lateral sclerosis (ALS) is a refractory neurodegenerative disease characterized by the degeneration and loss of motor neurons, typically resulting in death within five years of onset. There have been few effective treatments, making the development of robust therapies an urgent challenge. Genetic mutations have been identified as contributors to ALS, with mutations in superoxide dismutase 1 (SOD1), which neutralizes the harmful reactive oxygen species superoxide, accounting for approximately 2% of all ALS cases. To counteract the toxic gain of function caused by SOD1 mutations, therapeutic strategies aimed at suppressing SOD1 gene expression have shown promise. Antisense oligonucleotide (ASO) is an artificially synthesized, short, single-stranded DNA/RNA molecule that binds to target RNA to alter gene expression, representing a next-generation therapeutic approach. In 2023, tofersen became the first ASO drug approved by the FDA for ALS. Administered intrathecally, tofersen specifically binds to SOD1 mRNA, inhibiting the production of toxic SOD1 protein, thereby improving biomarkers of ALS. The long-term efficacy and safety of tofersen require further validation, and the development of more optimized treatment protocols is essential. A series of studies and therapeutic developments related to SOD1 mutations have advanced the understanding of ALS pathophysiology and significantly contributed to treatment strategies for central nervous system disorders. This review focuses on an overview of SOD1 mutations and the development process of tofersen, aiming to deepen the understanding of advancements in ALS research and discuss future challenges and directions for ASO therapy.

Fighting Amyotrophic Lateral Sclerosis by Protecting the Liver? A Prospective Cohort Study.

Previous studies have observed liver abnormalities in amyotrophic lateral sclerosis (ALS) patients. This study aimed to investigate whether early signs of liver disease, measured by magnetic resonance imaging-derived iron-corrected T1-mapping (cT1), are risk factors for developing ALS. cT1 and proton density fat fraction were measured and automatically analyzed using LiverMultiScan® software. The Fibrosis-4 index was calculated using an established formula based on age and blood markers. Cox proportional hazard models were used to examine the relationship between liver disease, liver biomarkers, and incident ALS. In a cohort of 533,707 individuals from UK Biobank, 24 ALS cases were identified among 28,328 participants with liver disease during the follow-up period. Among a total of 33,959 individuals with complete liver imaging data, 15 incident ALS cases were observed during a median follow-up period of 5.6 years. Individuals with liver disease had a higher risk of developing ALS, with an adjusted hazard ratio of 7.35 (95% CI 4.47-12.09; p < 0.001). An increase in cT1 was also associated with a higher risk of ALS. After adjusting for age, sex, Townsend deprivation index, smoking status, alcohol intake frequency, body mass index, proton density fat fraction, Fibrosis-4, and metabolic syndrome, an increase in cT1 remained significantly associated with a higher risk of ALS, with an adjusted hazard ratio of 3.15 (95% CI 1.79-5.55) per 1-SD increase. Sensitivity analyses confirmed these robust results. Liver disease activity, indicated by cT1, increases the risk of developing ALS, independent of metabolic syndrome, liver fat, or fibrosis. ANN NEUROL 2024.

Genome-Wide and Transcriptome-Wide Association Studies on Northern New England and Ohio Amyotrophic Lateral Sclerosis Cohorts.

Amyotrophic lateral sclerosis (ALS) is an age-associated, fatal neurodegenerative disorder causing progressive paralysis and respiratory failure. The genetic architecture of ALS is still largely unknown. We performed a genome-wide association study (GWAS) and transcriptome-wide association study (TWAS) to understand genetic risk factors for ALS using a population-based case-control study of 435 ALS cases and 279 controls from Northern New England and Ohio. Single nucleotide polymorphism (SNP) genotyping was conducted using the Illumina NeuroChip array. Odds ratios were estimated using covariate-adjusted logistic regression. We also performed a genome-wide SNP-smoking interaction screening. TWAS analyses used PrediXcan to estimate associations between predicted gene expression levels across 15 tissues (13 brain tissues, skeletal muscle, and whole blood) and ALS risk. GWAS analyses identified the p.A382T missense variant (rs367543041, p = 3.95E-6) in the TARDBP gene, which has previously been reported in association with increased ALS risk and was found to share a close affinity with the Sardinian haplotype. Both GWAS and TWAS analyses suggested that ZNF235 is associated with decreased ALS risk. Our results support the need for future evaluation to clarify the role of these potential genetic risk factors for ALS and to understand genetic susceptibility to environmental risk factors.

Amyotrophic lateral sclerosis caused by the C9orf72 expansion in Norway – prevalence, ancestry, clinical characteristics and sociodemographic status

Objective The most common genetic cause of amyotrophic lateral sclerosis (ALS) is the C9orf72 expansion. A high incidence of this expansion has been detected in Sweden and Finland. This Norwegian population-based study aimed to identify the prevalence, geographic distribution, ancestry, and relatedness of ALS patients with a C9orf72 expansion (C9pos). Further, we compared C9pos and C9neg patients’ clinical presentation, family history of ALS and other neurodegenerative disorders, and sociodemographic status. Methods We recruited ALS patients from all 17 Departments of neurology in Norway. Blood samples and questionnaires regarding clinical characteristics, sociodemographic status and family history of ALS, and other neurodegenerative disorders were collected. The C9orf72 expansion was examined for all patients. Results The study enrolled 500 ALS patients, 8.8% of whom were C9pos, with half being sporadic ALS cases. The proportion of C9pos cases differed between regions, ranging from 17.9% in the Northern region to 1.9% in the Western region. The majority of C9pos patients had non-Finnish European descent and were not closely related. C9pos patients exhibited a significantly shorter mean survival time, had a higher frequency of relatives with ALS or dementia, and were more often unmarried/single and childless than C9neg patients. Conclusion C9pos patients constitute a large portion of the Norwegian ALS population. Ancestry and relatedness do not adequately explain regional differences. Relying on clinical information to identify C9pos patients has proven to be challenging. Half of C9pos patients were reported as having sporadic ALS, underlining the importance of carefully assessing family history and the need for genetic testing.

Pharmacological and non-pharmacological treatments in amyotrophic lateral sclerosis: an Italian real-world data study.

The purpose was to describe the use patterns of pharmacological and non-pharmacological therapies and investigate potential determinants of riluzole use in patients newly diagnosed with amyotrophic lateral sclerosis (ALS) in three Italian regions. Amyotrophic lateral sclerosis patients were selected from administrative healthcare databases of Latium, Tuscany and Umbria from 1 January 2014 to 31 December 2019 based on hospital- and disease-specific co-payment exemption data. The first trace of ALS was considered the index date. Incident ALS cases were those without a trace of ALS during the 3-year look back. Patients were described in terms of demographics, clinical characteristics and drug use at baseline, and were classified into four categories based on riluzole use in the 2 years before and 1 year after the index date: prevalent, incident, former users and non-users. Use of symptomatic pharmacological and non-pharmacological therapies was described across these categories during 12 months after the index date. Determinants of riluzole use were also investigated. A total of 1636 ALS incident subjects were detected in the three regions, mainly aged 65-74 years. Patients were generally fragile with a high prevalence of comorbidities at baseline. Riluzole was used by 27.4% of the overall study cohort at baseline and steeply increased in the first year after the index date differently between regions (Latium 61.2%, Tuscany 85.0%, Umbria 76.5%), with about half of the subjects being incident users. In the 12 months after the index date, also symptomatic therapies increased, in riluzole users and non-users. Determinants analysis showed that higher patient severity and complexity were associated with a lower likelihood of being treated with riluzole.

Improving prediction models of amyotrophic lateral sclerosis (ALS) using polygenic, pre-existing conditions, and survey-based risk scores in the UK Biobank.

Amyotrophic lateral sclerosis (ALS) causes profound impairments in neurological function, and a cure for this devastating disease remains elusive. This study aimed to identify pre-disposing genetic, phenotypic, and exposure-related factors for amyotrophic lateral sclerosis using multi-modal data and assess their joint predictive potential. Utilizing data from the UK (United Kingdom) Biobank, we analyzed an unrelated set of 292 ALS cases and 408,831 controls of European descent. Two polygenic risk scores (PRS) are constructed: "GWAS Hits PRS" and "PRS-CS," reflecting oligogenic and polygenic ALS risk profiles, respectively. Time-restricted phenome-wide association studies (PheWAS) were performed to identify pre-existing conditions increasing ALS risk, integrated into phenotypic risk scores (PheRS). A poly-exposure score ("PXS") captures the influence of environmental exposures measured through survey questionnaires. We evaluate the performance of these scores for predicting ALS incidence and stratifying risk, adjusting for baseline demographic covariates. Both PRSs modestly predicted ALS diagnosis but with increased predictive power when combined (covariate-adjusted receiver operating characteristic [AAUC] = 0.584 [0.525, 0.639]). PheRS incorporated diagnoses 1year before ALS onset (PheRS1) modestly discriminated cases from controls (AAUC = 0.515 [0.472, 0.564]). The "PXS" did not significantly predict ALS. However, a model incorporating PRSs and PheRS1 improved the prediction of ALS (AAUC = 0.604 [0.547, 0.667]), outperforming a model combining all risk scores. This combined risk score identified the top 10% of risk score distribution with a fourfold higher ALS risk (95% CI [2.04, 7.73]) versus those in the 40%-60% range. By leveraging UK Biobank data, our study uncovers pre-disposing ALS factors, highlighting the improved effectiveness of multi-factorial prediction models to identify individuals at highest risk for ALS.

Investigating the prevalence of MFN2 mutations in amyotrophic lateral sclerosis: insights from an Italian cohort.

The MFN2 gene encodes mitofusin 2, a key protein for mitochondrial fusion, transport, maintenance and cell communication. MFN2 mutations are primarily linked to Charcot-Marie-Tooth disease type 2A. However, a few cases of amyotrophic lateral sclerosis and amyotrophic lateral sclerosis/frontotemporal dementia phenotypes with concomitant MFN2 mutations have been previously reported. This study examines the clinical and genetic characteristics of an Italian cohort of amyotrophic lateral sclerosis patients with rare, non-synonymous MFN2 mutations. A group of patients (n = 385) diagnosed with amyotrophic lateral sclerosis at our Neurology Units between 2008 and 2023 underwent comprehensive molecular testing, including MFN2. After excluding pathogenic mutations in the main amyotrophic lateral sclerosis-related genes (i.e. C9orf72, SOD1, FUS and TARDBP), MFN2 variants were classified based on the American College of Medical Genetics and Genomics guidelines, and demographic and clinical data of MFN2-mutated patients were retrieved. We identified 12 rare, heterozygous, non-synonymous MFN2 variants in 19 individuals (4.9%). Eight of these variants, carried by nine patients (2.3%), were either pathogenic, likely pathogenic or variants of unknown significance according to the American College of Medical Genetics and Genomics guidelines. Among these patients, four exhibited a familial pattern of inheritance. The observed phenotypes included classic and bulbar amyotrophic lateral sclerosis, amyotrophic lateral sclerosis/frontotemporal dementia, flail arm, flail leg and progressive muscular atrophy. Median survival after disease onset was extremely variable, ranging from less than 1 to 13 years. This study investigates the prevalence of rare, non-synonymous MFN2 variants within an Italian cohort of amyotrophic lateral sclerosis patients, who have been extensively investigated, enhancing our knowledge of the underlying phenotypic spectrum. Further research is needed to understand whether MFN2 mutations contribute to motor neuron disease and to what extent. Improving our knowledge regarding the genetic basis of amyotrophic lateral sclerosis is crucial both in a diagnostic and therapeutic perspective.

C9orf72 repeat expansions in Wakayama: One potential cause of amyotrophic lateral sclerosis in the Kii Peninsula, Japan

A cluster of cases of amyotrophic lateral sclerosis (ALS) exists in the southern part of the Kii Peninsula in Japan. Although both genetic and environmental factors are thought to be causative, the critical cause of this cluster has not been identified. C9orf72 is the most common genetic factor in both familial and sporadic C9orf72-related ALS in people of European ancestry, but it is rare among Japanese populations. However, a previous report revealed that the frequency of C9orf72-related ALS was significantly higher in the cluster area. We evaluated the proportion of C9orf72 hexanucleotide repeat expansions in 99 cases of ALS diagnosed in Wakayama Prefecture, including the cluster area, by using repeat-primed polymerase chain reaction and fluorescence fragment length analysis. We found that 2 of the 99 patients (0 % of those with familial ALS and 2.4 % of those with sporadic ALS) had hexanucleotide repeat expansions in C9orf72, and long-read sequencing revealed that these expansions were causative. No expansions were observed among 90 patients with Parkinson's disease or among 90 healthy controls. Haplotype analysis with long-read sequencing data revealed that the two patients with repeat expansions shared the common haplotype with that previously reported in Finnish patients with C9orf72-related ALS, which suggests a founder effect. C9orf72 was thought to be a rare causative gene in Japan, but this study revealed that it may be relatively common in Wakayama Prefecture.

Боковой амиотрофический склероз и его маски, коморбидная патология с быстрым летальным исходом: клинический случай

INTRODUCTION. Despite the fact that more than 150 years have passed since the first mention of amyotrophic lateral sclerosis (ALS), the issues of etiology, pathogenesis, diagnosis and treatment of this disease are still not fully resolved. However, the results of recent research in the field of genetics with the identification of genes associated with ALS, understanding the mechanisms of disease development and, as a result, the creation of effective drugs give hope that in the near future the disease will cease to be fatal. AIM. To analyze domestic and foreign publications on the etiology, pathogenesis, diagnosis and treatment of amyotrophic lateral sclerosis. To present a clinical case of a patient with amyotrophic lateral sclerosis. MATERIAL AND METHODS. The analysis of domestic and foreign publications for the period 1997-2024 is carried out. The sources of the Russian scientific electronic library eLibrary, RSCI databases, PubMed were used. CASE PRESENTATION. A patient is presented who, at the age of 56, developed mixed paresis of the right hand, followed by the development of mixed tetraparesis and simultaneously bulbar syndrome within 3 months. Differential diagnosis was performed between spondylogenic cervical myelopathy, endocrinopathy and ALS. Based on anamnestic data, clinical picture, rate of progression of symptoms, results of electroneuromyography, lack of improvement against the background of therapy, the main diagnosis was made: amyotrophic lateral sclerosis, a primary generalized form with mixed tetraparesis, bulbar syndrome. 2 weeks after discharge from the hospital in a stable condition, the patient was diagnosed with COVID-19 coronavirus infection, with a rapid fatal outcome from respiratory failure (7 months after the debut of ALS). CONCLUSION. A feature of the described ALS case is a rather rare primary generalized form of the disease (having such unfavorable prognosis factors as the development of bulbar syndrome at the beginning of the disease, a short time period from the appearance of the first symptoms to diagnosis), the presence of masking pathology in the form of spondylogenic myelopathy and the addition of COVID-19 with a rapid fatal outcome. With all the severity of ALS and an unfavorable prognosis, the presence of comorbid pathology can make the course of the disease even more dramatic. KEYWORDS: amyotrophic lateral sclerosis, comorbid pathology, coronavirus infection (COVID-19)

Nuclear Localization of Human SOD1 in Motor Neurons in Mouse Model and Patient Amyotrophic Lateral Sclerosis: Possible Links to Cholinergic Phenotype, NADPH Oxidase, Oxidative Stress, and DNA Damage.

Amyotrophic lateral sclerosis (ALS) is a fatal disease that causes degeneration of motor neurons (MNs) and paralysis. ALS can be caused by mutations in the gene that encodes copper/zinc superoxide dismutase (SOD1). SOD1 is known mostly as a cytosolic antioxidant protein, but SOD1 is also in the nucleus of non-transgenic (tg) and human SOD1 (hSOD1) tg mouse MNs. SOD1's nuclear presence in different cell types and subnuclear compartmentations are unknown, as are the nuclear functions of SOD1. We examined hSOD1 nuclear localization and DNA damage in tg mice expressing mutated and wildtype variants of hSOD1 (hSOD1-G93A and hSOD1-wildtype). We also studied ALS patient-derived induced pluripotent stem (iPS) cells to determine the nuclear presence of SOD1 in undifferentiated and differentiated MNs. In hSOD1-G93A and hSOD1-wildtype tg mice, choline acetyltransferase (ChAT)-positive MNs had nuclear hSOD1, but while hSOD1-wildtype mouse MNs also had nuclear ChAT, hSOD1-G93A mouse MNs showed symptom-related loss of nuclear ChAT. The interneurons had preserved parvalbumin nuclear positivity in hSOD1-G93A mice. hSOD1-G93A was seen less commonly in spinal cord astrocytes and, notably, oligodendrocytes, but as the disease emerged, the oligodendrocytes had increased mutant hSOD1 nuclear presence. Brain and spinal cord subcellular fractionation identified mutant hSOD1 in soluble nuclear extracts of the brain and spinal cord, but mutant hSOD1 was concentrated in the chromatin nuclear extract only in the spinal cord. Nuclear extracts from mutant hSOD1 tg mouse spinal cords had altered protein nitration, footprinting peroxynitrite presence, and the intact nuclear extracts had strongly increased superoxide production as well as the active NADPH oxidase marker, p47phox. The comet assay showed that MNs from hSOD1-G93A mice progressively (6-14 weeks of age) accumulated DNA single-strand breaks. Ablation of the NCF1 gene, encoding p47phox, and pharmacological inhibition of NADPH oxidase with systemic treatment of apocynin (10 mg/kg, ip) extended the mean lifespan of hSOD1-G93A mice by about 25% and mitigated genomic DNA damage progression. In human postmortem CNS, SOD1 was found in the nucleus of neurons and glia; nuclear SOD1 was increased in degenerating neurons in ALS cases and formed inclusions. Human iPS cells had nuclear SOD1 during directed differentiation to MNs, but mutant SOD1-expressing cells failed to establish wildtype MN nuclear SOD1 levels. We conclude that SOD1 has a prominent nuclear presence in the central nervous system, perhaps adopting aberrant contexts to participate in ALS pathobiology.

Induced pluripotent stem cell production (CSSi019-A)(14432) from an asymptomatic subject carrying a expansion of C9orf72 gene

One of the genetic mutations most associated with the onset of amyotrophic lateral sclerosis, both in sporadic and familial cases, is the expansion of the C9orf72 gene. The presence of more than 30 repeats (GGGGCC) correlates with uncertain ALS symptomatology. Here we collected a dermal biopsy from a subject carrying 36 hexanucleotide repeats and reprogrammed it into an induced pluripotent stem cell line. Despite the number of repeat elements, the subject had no symptoms at the age of the biopsy (76 years), thus resulting in a healthy carrier of the mutation.

Amyotrophic Lateral Sclerosis (ALS): An Overview of Genetic and Metabolic Signaling Mechanisms.

Amyotrophic Lateral Sclerosis (ALS) is a rare, progressive, and incurable disease. Sporadic (sALS) accounts for ninety percent of ALS cases, while familial ALS (fALS) accounts for around fifteen percent. Reports have identified over 30 different forms of familial ALS. Multiple types of fALS exhibit comparable symptoms with mutations in different genes and possibly with different predominant metabolic signals. Clinical diagnosis takes into account patient history but not genetic mutations, misfolded proteins, or metabolic signaling. As research on genetics and metabolic pathways advances, it is expected that the intricate complexity of ALS will compound further. Clinicians discuss whether a gene's presence is a cause of the disease or just an association or consequence. They believe that a mutant gene alone is insufficient to diagnose ALS. ALS, often perceived as a single disease, appears to be a complex collection of diseases with similar symptoms. This review highlights gene mutations, metabolic pathways, and muscle-neuron interactions.

Phase Separation of SARS-CoV-2 Nucleocapsid Protein with TDP-43 Is Dependent on C-Terminus Domains.

The SARS-CoV-2 nucleocapsid protein (N protein) is critical in viral replication by undergoing liquid-liquid phase separation to seed the formation of a ribonucleoprotein (RNP) complex to drive viral genomic RNA (gRNA) translation and in suppressing both stress granules and processing bodies, which is postulated to increase uncoated gRNA availability. The N protein can also form biomolecular condensates with a broad range of host endogenous proteins including RNA binding proteins (RBPs). Amongst these RBPs are proteins that are associated with pathological, neuronal, and glial cytoplasmic inclusions across several adult-onset neurodegenerative disorders, including TAR DNA binding protein 43 kDa (TDP-43) which forms pathological inclusions in over 95% of amyotrophic lateral sclerosis cases. In this study, we demonstrate that the N protein can form biomolecular condensates with TDP-43 and that this is dependent on the N protein C-terminus domain (N-CTD) and the intrinsically disordered C-terminus domain of TDP-43. This process is markedly accelerated in the presence of RNA. In silico modeling suggests that the biomolecular condensate that forms in the presence of RNA is composed of an N protein quadriplex in which the intrinsically disordered TDP-43 C terminus domain is incorporated.

ALS-FUS mutations cause abnormal PARylation and histone H1.2 interaction, leading to pathological changes

The majority of severe early-onset and juvenile cases of amyotrophic lateral sclerosis (ALS) are caused by mutations in the FUS gene, resulting in rapid disease progression. Mutant FUS accumulates within stress granules (SGs), thereby affecting the dynamics of these ribonucleoprotein complexes. Here, we define the interactome of the severe mutant FUSP525L variant in human induced pluripotent stem cell (iPSC)-derived motor neurons. We find increased interaction of FUSP525L with the PARP1 enzyme, promoting poly-ADP-ribosylation (PARylation) and binding of FUS to histone H1.2. Inhibiting PARylation or reducing H1.2 levels alleviates mutant FUS aggregation, SG alterations, and apoptosis in human motor neurons. Conversely, elevated H1.2 levels exacerbate FUS-ALS phenotypes, driven by the internally disordered terminal domains of H1.2. In C.elegans models, knockdown of H1.2 and PARP1 orthologs also decreases FUSP525L aggregation and neurodegeneration, whereas H1.2 overexpression worsens ALS-related changes. Our findings indicate a link between PARylation, H1.2, and FUS with potential therapeutic implications.

Increased copy-number variant load of associated risk genes in sporadic cases of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an age-related neurodegenerative disease characterized by selective loss of motor neurons in the brainstem and spinal cord. Several genetic factors have been associated to ALS, ranging from causal genes and potential risk factors to disease modifiers. The search for pathogenic variants in these genes has mostly focused on single nucleotide variants (SNVs) while relatively understudied and not fully elucidated is the contribution of structural variants, such as copy number variations (CNVs). Here, we applied an exon-centric aCGH method to investigate, in sporadic ALS patients, the load of CNVs in 131 genes previously associated to ALS. Our approach revealed that CNV load, defined as the total number of CNVs or their size, was significantly higher in ALS cases than controls. About 87% of patients harbored multiple CNVs in ALS-related genes, and 75% structural variants compromised genes directly implicated in ALS pathogenesis (C9orf72, CHCHD10, EPHA4, FUS, HNRNPA1, KIF5A, NEK1, OPTN, PFN1, SOD1, TARDBP, TBK1, UBQLN2, UNC13A, VAPB, VCP). CNV load was also associated to higher onset age and disease progression rate. Although the contribution of individual CNVs in ALS is still unknown, their extensive load in disease-related genes may have relevant implications for the diagnostic, prognostic and therapeutical management of this devastating disorder.

Ferritin is closely associated with microglia in amyotrophic lateral sclerosis.

Iron deposition is a hallmark of amyotrophic lateral sclerosis (ALS) and has been strongly implicated in its pathogenesis. As a byproduct of cellular oxidative stress, iron dysregulation modifies basal levels of the regulatory iron-binding protein ferritin. Examination of thoracic and lumbar spinal cord tissues found increased ferritin immunostaining in white matter axons that corresponded to areas of increased microgliosis in 8 ALS patients versus 8 normal subjects. Gray matter areas containing the motor neurons also demonstrated increased ferritin and microglia in ALS compared to controls but at lower levels than in the white matter. Motor neurons with or without TDP-43 inclusions did not demonstrate either increased ferritin or associated microglial activation. We also observed an association of ferritin with microglia in cerebral cortical tissue samples of ALS cases and in the spinal cord tissues of transgenic mice expressing the SOD1G93A mutation. Elevated ferritin levels were detected in the insoluble fraction from spinal cord tissues of individuals with ALS. These findings suggest that activated microglia and increased ferritin may play significant roles in ALS progression since they are found closely associated in areas of axonal and cortical degeneration.

Clinicopathological analysis of NEK1 variants in amyotrophic lateral sclerosis.

Many genes have been linked to amyotrophic lateral sclerosis (ALS), including never in mitosis A (NIMA)-related kinase 1 (NEK1), a serine/threonine kinase that plays a key role in several cellular functions, such as DNA damage response and cell cycle regulation. Whole-exome sequencing studies have shown that NEK1 mutations are associated with an increased risk for ALS, where a significant enrichment of NEK1 loss-of-function (LOF) variants were found in individuals with ALS compared to controls. In particular, the p.Arg261His missense variant was associated with significantly increased disease susceptibility. This case series aims to understand the neuropathological phenotypes resulting from NEK1 mutations in ALS. We examined a cohort of three Scottish patients with a mutation in the NEK1 gene and evaluated the distribution and cellular expression of NEK1, as well as the abundance of phosphorylated TDP-43 (pTDP-43) aggregates, in the motor cortex compared to age- and sex-matched control tissue. We show pathological, cytoplasmic TDP-43 aggregates in all three NEK1-ALS cases. NEK1 protein staining revealed no immunoreactivity in two of the NEK1-ALS cases, indicating a LOF and corresponding to a reduction in NEK1 mRNA as detected by in situ hybridisation. However, the p.Arg261His missense mutation resulted in an increase in NEK1 mRNA molecules and abundant NEK1-positive cytoplasmic aggregates, with the same morphologic appearance, and within the same cells as co-occurring TDP-43 aggregates. Here we show the first neuropathological assessment of a series of ALS cases carrying mutations in the NEK1 gene. Specifically, we show that TDP-43 pathology is present in these cases and that potential NEK1 LOF can either be mediated through loss of NEK1 translation or through aggregation of NEK1 protein as in the case with p.Arg261His mutation, a potential novel pathological feature of NEK1-ALS.

Identification of a pathogenic mutation in ARPP21 in patients with amyotrophic lateral sclerosis

Background and objectiveBetween 5% and 10% of amyotrophic lateral sclerosis (ALS) cases have a family history of the disease, 30% of which do not have an identifiable underlying genetic cause...