Association of a Locus in the CAMTA1 Gene With Survival in Patients With Sporadic Amyotrophic Lateral Sclerosis

Recent advances in the genetics of familial and sporadic ALS

ALS shows complex genetic inheritance patterns. In about 5% to 10% of cases, there is a family history of ALS or a related condition such as frontotemporal dementia in a first or second degree relative, and for about 80% of such people a pathogenic gene variant can be identified. Such variants are also seen in people with no family history because of factor influencing the expression of genes, such as age. Genetic susceptibility factors also contribute to risk, and the heritability of ALS is between 40% and 60%. The genetic variants influencing ALS risk include single base changes, repeat expansions, copy number variants, and others. Here we review what is known of the genetic landscape and architecture of ALS.

Abundant transcriptomic alterations in the human cerebellum of patients with a C9orf72 repeat expansion

The most prominent genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) is a repeat expansion in the gene C9orf72. Importantly, the transcriptomic consequences of the C9orf72 repeat expansion remain largely unclear. Here, we used short-read RNA sequencing (RNAseq) to profile the cerebellar transcriptome, detecting alterations in patients with a C9orf72 repeat expansion. We focused on the cerebellum, since key C9orf72-related pathologies are abundant in this neuroanatomical region, yet TDP-43 pathology and neuronal loss are minimal. Consistent with previous work, we showed a reduction in the expression of the C9orf72 gene and an elevation in homeobox genes, when comparing patients with the expansion to both patients without the C9orf72 repeat expansion and control subjects. Interestingly, we identified more than 1000 alternative splicing events, including 4 in genes previously associated with ALS and/or FTLD. We also found an increase of cryptic splicing in C9orf72 patients compared to patients without the expansion and controls. Furthermore, we demonstrated that the expression level of select RNA-binding proteins is associated with cryptic splice junction inclusion. Overall, this study explores the presence of widespread transcriptomic changes in the cerebellum, a region not confounded by severe neurodegeneration, in post-mortem tissue from C9orf72 patients.

Genetic factors affecting survival in Japanese patients with sporadic amyotrophic lateral sclerosis: a genome-wide association study and verification in iPSC-derived motor neurons from patients

BACKGROUND

Several genetic factors are associated with the pathogenesis of sporadic amyotrophic lateral sclerosis (ALS) and its phenotypes, such as disease progression. Here, in this study, we aimed to identify the genes that affect the survival of patients with sporadic ALS.

METHODS

We enrolled 1076 Japanese patients with sporadic ALS with imputed genotype data of 7 908 526 variants. We used Cox proportional hazards regression analysis with an additive model adjusted for sex, age at onset and the first two principal components calculated from genotyped data to conduct a genome-wide association study. We further analysed messenger RNA (mRNA) and phenotype expression in motor neurons derived from induced pluripotent stem cells (iPSC-MNs) of patients with ALS.

RESULTS

Three novel loci were significantly associated with the survival of patients with sporadic ALS-FGF1 at 5q31.3 (rs11738209, HR=2.36 (95% CI, 1.77 to 3.15), p=4.85×10-9), THSD7A at 7p21.3 (rs2354952, 1.38 (95% CI, 1.24 to 1.55), p=1.61×10-8) and LRP1 at 12q13.3 (rs60565245, 2.18 (95% CI, 1.66 to 2.86), p=2.35×10-8). FGF1 and THSD7A variants were associated with decreased mRNA expression of each gene in iPSC-MNs and reduced in vitro survival of iPSC-MNs obtained from patients with ALS. The iPSC-MN in vitro survival was reduced when the expression of FGF1 and THSD7A was partially disrupted. The rs60565245 was not associated with LRP1 mRNA expression.

CONCLUSIONS

We identified three loci associated with the survival of patients with sporadic ALS, decreased mRNA expression of FGF1 and THSD7A and the viability of iPSC-MNs from patients. The iPSC-MN model reflects the association between patient prognosis and genotype and can contribute to target screening and validation for therapeutic intervention.

Strategies to investigate and mitigate collider bias in genetic and Mendelian randomisation studies of disease progression

Genetic studies of disease progression can be used to identify factors that may influence survival or prognosis, which may differ from factors that influence on disease susceptibility. Studies of disease progression feed directly into therapeutics for disease, whereas studies of incidence inform prevention strategies. However, studies of disease progression are known to be affected by collider (also known as "index event") bias since the disease progression phenotype can only be observed for individuals who have the disease. This applies equally to observational and genetic studies, including genome-wide association studies and Mendelian randomisation (MR) analyses. In this paper, our aim is to review several statistical methods that can be used to detect and adjust for index event bias in studies of disease progression, and how they apply to genetic and MR studies using both individual- and summary-level data. Methods to detect the presence of index event bias include the use of negative controls, a comparison of associations between risk factors for incidence in individuals with and without the disease, and an inspection of Miami plots. Methods to adjust for the bias include inverse probability weighting (with individual-level data), or Slope-Hunter and Dudbridge et al.'s index event bias adjustment (when only summary-level data are available). We also outline two approaches for sensitivity analysis. We then illustrate how three methods to minimise bias can be used in practice with two applied examples. Our first example investigates the effects of blood lipid traits on mortality from coronary heart disease, while our second example investigates genetic associations with breast cancer mortality.

Advances in sequencing technologies for amyotrophic lateral sclerosis research

Amyotrophic lateral sclerosis (ALS) is caused by upper and lower motor neuron loss and has a fairly rapid disease progression, leading to fatality in an average of 2-5 years after symptom onset. Numerous genes have been implicated in this disease; however, many cases remain unexplained. Several technologies are being used to identify regions of interest and investigate candidate genes. Initial approaches to detect ALS genes include, among others, linkage analysis, Sanger sequencing, and genome-wide association studies. More recently, next-generation sequencing methods, such as whole-exome and whole-genome sequencing, have been introduced. While those methods have been particularly useful in discovering new ALS-linked genes, methodological advances are becoming increasingly important, especially given the complex genetics of ALS. Novel sequencing technologies, like long-read sequencing, are beginning to be used to uncover the contribution of repeat expansions and other types of structural variation, which may help explain missing heritability in ALS. In this review, we discuss how popular and/or upcoming methods are being used to discover ALS genes, highlighting emerging long-read sequencing platforms and their role in aiding our understanding of this challenging disease.

Genome-wide association study of brain biochemical phenotypes reveals distinct genetic architecture of Alzheimer's disease related proteins

BACKGROUND

Alzheimer's disease (AD) is neuropathologically characterized by amyloid-beta (Aβ) plaques and neurofibrillary tangles. The main protein components of these hallmarks include Aβ40, Aβ42, tau, phosphor-tau, and APOE. We hypothesize that genetic variants influence the levels and solubility of these AD-related proteins in the brain; identifying these may provide key insights into disease pathogenesis.

METHODS

Genome-wide genotypes were collected from 441 AD cases, imputed to the haplotype reference consortium (HRC) panel, and filtered for quality and frequency. Temporal cortex levels of five AD-related proteins from three fractions, buffer-soluble (TBS), detergent-soluble (Triton-X = TX), and insoluble (Formic acid = FA), were available for these same individuals. Variants were tested for association with each quantitative biochemical measure using linear regression, and GSA-SNP2 was used to identify enriched Gene Ontology (GO) terms. Implicated variants and genes were further assessed for association with other relevant variables.

RESULTS

We identified genome-wide significant associations at seven novel loci and the APOE locus. Genes and variants at these loci also associate with multiple AD-related measures, regulate gene expression, have cell-type specific enrichment, and roles in brain health and other neuropsychiatric diseases. Pathway analysis identified significant enrichment of shared and distinct biological pathways.

CONCLUSIONS

Although all biochemical measures tested reflect proteins core to AD pathology, our results strongly suggest that each have unique genetic architecture and biological pathways that influence their specific biochemical states in the brain. Our novel approach of deep brain biochemical endophenotype GWAS has implications for pathophysiology of proteostasis in AD that can guide therapeutic discovery efforts focused on these proteins.

Genetic Mapping of Behavioral Traits Using the Collaborative Cross Resource

The complicated interactions between genetic background, environment and lifestyle factors make it difficult to study the genetic basis of complex phenotypes, such as cognition and anxiety levels, in humans. However, environmental and other factors can be tightly controlled in mouse studies. The Collaborative Cross (CC) is a mouse genetic reference population whose common genetic and phenotypic diversity is on par with that of humans. Therefore, we leveraged the power of the CC to assess 52 behavioral measures associated with locomotor activity, anxiety level, learning and memory. This is the first application of the CC in novel object recognition tests, Morris water maze tasks, and fear conditioning tests. We found substantial continuous behavioral variations across the CC strains tested, and mapped six quantitative trait loci (QTLs) which influenced these traits, defining candidate genetic variants underlying these QTLs. Overall, our findings highlight the potential of the CC population in behavioral genetic research, while the identified genomic loci and genes driving the variation of relevant behavioral traits provide a foundation for further studies.

The role of Calmodulin Binding Transcription Activator 1 (CAMTA1) gene and its putative genetic partners in the human nervous system

The Calmodulin Binding Transcription Activator 1 (CAMTA1) gene plays a central role in the human nervous system. Here evidence-based perspectives on its clinical value for the screening of CAMTA1 malfunction is provided and argued that in future, patients suffering from brain tumours and/or neurological disorders could benefit from this diagnostic. In neuroblastomas as well as in low-grade gliomas, the influence of reduced expression of CAMTA1 results in opposite prognosis, probably because of different carcinogenic pathways in which CAMTA1 plays different roles, but the exact genetics bases remains unsolved. Rearrangements, mutations and variants of CAMTA1 were associated with human neurodegenerative disorders, while some CAMTA1 single nucleotide polymorphisms were associated with poorer memory in clinical cases and also amyotrophic lateral sclerosis. So far, the follow-up of patients with neurological diseases with alterations in CAMTA1 indicates that defects (expression, mutations, and rearrangements) in CAMTA1 alone are not sufficient to drive carcinogenesis. It is necessary to continue studying CAMTA1 rearrangements and expression in more cases than done by now. To understand the influence of CAMTA1 variants and their role in nervous system tumours and in several psychiatric disorders is currently a challenge.

CAMTA1 gene affects the ischemia-reperfusion injury by regulating CCND1

Epigenetic modulations lead to changes in gene expression, including DNA methylation, histone modifications, and noncoding RNAs. In recent years, epigenetic modifications have been related to the pathogenesis of different types of cancer, cardiovascular disease, and other diseases. Emerging evidence indicates that DNA methylation could be associated with ischemic stroke (IS) and plays a role in pathological progression, but the underlying mechanism has not yet been fully understood. In this study, we used human methylation 850K BeadChip to analyze the differences in gene methylation status in the peripheral blood samples from two groups (3 IS patients vs. 3 healthy controls). According to their bioinformatics profiling, we found 278 genes with significantly different methylation levels. Seven genes with the most significant methylation modifications were validated in two expanded groups (100 IS patients vs. 100 healthy controls). The CAMTA1 gene had significantly different methylation changes in patients compared to the controls. To understand the CAMTA1 function in stroke, we generated CAMTA1 knockout in SH-SY5Y cells. RNA seq results in CAMTA1 knockout cells revealed the pathways and gene set enrichments involved in cellular proliferation and cell cycle. Furthermore, a series of experiments demonstrated that in the oxygen-glucose deprivation/re-oxygenation (OGD/R) model system, the expression of cyclin D1, an essential regulator of cell cycle progression, was increased in SH-SY5Y CAMTA1 KO cells. Increasing evidence demonstrated that ischemic stress could inappropriately raise cyclin D1 levels in mature neurons. However, the molecular signals leading to an increased cyclin D1 level are unclear. Our findings demonstrate for the first time that the CAMTA1 gene could regulate cyclin D1 expression and implicate their role in strokes.

Genetic factors for survival in amyotrophic lateral sclerosis: an integrated approach combining a systematic review, pairwise and network meta-analysis

BACKGROUND

The time of survival in patients with amyotrophic lateral sclerosis (ALS) varies greatly, and the genetic factors that contribute to the survival of ALS are not well studied. There is a lack of a comprehensive study to elucidate the role of genetic factors in the survival of ALS.

METHODS

The published studies were systematically searched and obtained from PubMed, EMBASE, and the Cochrane Library without any language restrictions from inception to Oct 27, 2021. A network meta-analysis for ALS causative/risk genes and a systematic review and pairwise meta-analysis for other genetic modifiers were conducted. The PROSPERO registration number: CRD42022311646.

RESULTS

A total of 29,764 potentially relevant references were identified, and 71 papers were eligible for analysis based on pre-decided criteria, including 35 articles in network meta-analysis for 9 ALS causative/risk genes, 17 articles in pairwise meta-analysis for four genetic modifiers, and 19 articles described in the systematic review. Variants in three genes, including ATXN2 (HR: 3.6), C9orf72 (HR: 1.6), and FUS (HR:1.8), were associated with short survival of ALS, but such association was not identified in SOD1, TARDBP, TBK1, NEK1, UBQLN2, and CCNF. In addition, UNC13A rs12608932 CC genotype and ZNF521B rs2275294 C allele also caused a shorter survival of ALS; however, APOE ε4 allele and KIFAP3 rs1541160 did not be found to have any effect on the survival of ALS.

CONCLUSIONS

Our study summarized and contrasted evidence for prognostic genetic factors in ALS and would help to understand ALS pathogenesis and guide clinical trials and drug development.

The Big Picture of Neurodegeneration: A Meta Study to Extract the Essential Evidence on Neurodegenerative Diseases in a Network-Based Approach

The common features of all neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis (ALS), and Huntington's disease, are the accumulation of aggregated and misfolded proteins and the progressive loss of neurons, leading to cognitive decline and locomotive dysfunction. Still, they differ in their ultimate manifestation, the affected brain region, and the kind of proteinopathy. In the last decades, a vast number of processes have been described as associated with neurodegenerative diseases, making it increasingly harder to keep an overview of the big picture forming from all those data. In this meta-study, we analyzed genomic, transcriptomic, proteomic, and epigenomic data of the aforementioned diseases using the data of 234 studies in a network-based approach to study significant general coherences but also specific processes in individual diseases or omics levels. In the analysis part, we focus on only some of the emerging findings, but trust that the meta-study provided here will be a valuable resource for various other researchers focusing on specific processes or genes contributing to the development of neurodegeneration.

Causal Inference of Genetic Variants and Genes in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal progressive multisystem disorder with limited therapeutic options. Although genome-wide association studies (GWASs) have revealed multiple ALS susceptibility loci, the exact identities of causal variants, genes, cell types, tissues, and their functional roles in the development of ALS remain largely unknown. Here, we reported a comprehensive post-GWAS analysis of the recent large ALS GWAS (n = 80,610), including functional mapping and annotation (FUMA), transcriptome-wide association study (TWAS), colocalization (COLOC), and summary data-based Mendelian randomization analyses (SMR) in extensive multi-omics datasets. Gene property analysis highlighted inhibitory neuron 6, oligodendrocytes, and GABAergic neurons (Gad1/Gad2) as functional cell types of ALS and confirmed cerebellum and cerebellar hemisphere as functional tissues of ALS. Functional annotation detected the presence of multiple deleterious variants at three loci (9p21.2, 12q13.3, and 12q14.2) and highlighted a list of SNPs that are potentially functional. TWAS, COLOC, and SMR identified 43 genes at 24 loci, including 23 novel genes and 10 novel loci, showing significant evidence of causality. Integrating multiple lines of evidence, we further proposed that rs2453555 at 9p21.2 and rs229243 at 14q12 functionally contribute to the development of ALS by regulating the expression of C9orf72 in pituitary and SCFD1 in skeletal muscle, respectively. Together, these results advance our understanding of the biological etiology of ALS, feed into new therapies, and provide a guide for subsequent functional experiments.

Genetic Determinants of Survival in Parkinson's Disease in the Asian Population

BACKGROUND

Patients with Parkinson's disease (PD) have reduced life expectancy compared to the general population. Genetic variation was shown to play a role in the heterogeneity of survival for patients with PD, although the underlying genetic background remains poorly studied.

OBJECTIVE

The aim was to explore the genetic determinants influencing the survival of PD.

METHODS

We performed a genome-wide association analysis using a Cox proportional hazards model in a longitudinal cohort of 1080 Chinese patients with PD. Furthermore, we built a clinical-genetic model to predict the survival of patients using clinical variables combined with polygenic risk score (PRS) of survival of PD.

RESULTS

The cohort was followed up for an average of 7.13 years, with 85 incidents of death. One locus rs12628329 (RPL3) was significantly associated with reduced survival time by ~10.8 months (P = 2.72E-08, β = 1.79, standard error = 0.32). Functional exploration suggested this variant could upregulate the expression of RPL3 and induce apoptosis and cell death. In addition, adding PRS of survival in the prediction model substantially improved survival predictability (concordance index [Cindex]: 0.936) compared with the clinical model (Cindex: 0.860).

CONCLUSIONS

These findings improve the current understanding of the genetic cause of survival of PD and provide a novel target RPL3 for further research on PD pathogenesis and potential therapeutic options. Our results also demonstrate the potential utility of PRS of survival in identifying patients with shorter survival and providing personalized clinical monitoring and treatment. © 2022 International Parkinson and Movement Disorder Society.

The Effect of SMN Gene Dosage on ALS Risk and Disease Severity

OBJECTIVE

The role of the survival of motor neuron (SMN) gene in amyotrophic lateral sclerosis (ALS) is unclear, with several conflicting reports. A decisive result on this topic is needed, given that treatment options are available now for SMN deficiency.

METHODS

In this largest multicenter case control study to evaluate the effect of SMN1 and SMN2 copy numbers in ALS, we used whole genome sequencing data from Project MinE data freeze 2. SMN copy numbers of 6,375 patients with ALS and 2,412 controls were called from whole genome sequencing data, and the reliability of the calls was tested with multiplex ligation-dependent probe amplification data.

RESULTS

The copy number distribution of SMN1 and SMN2 between cases and controls did not show any statistical differences (binomial multivariate logistic regression SMN1 p = 0.54 and SMN2 p = 0.49). In addition, the copy number of SMN did not associate with patient survival (Royston-Parmar; SMN1 p = 0.78 and SMN2 p = 0.23) or age at onset (Royston-Parmar; SMN1 p = 0.75 and SMN2 p = 0.63).

INTERPRETATION

In our well-powered study, there was no association of SMN1 or SMN2 copy numbers with the risk of ALS or ALS disease severity. This suggests that changing SMN protein levels in the physiological range may not modify ALS disease course. This is an important finding in the light of emerging therapies targeted at SMN deficiencies. ANN NEUROL 2021;89:686-697.

Novel STMN2 Variant Linked to Amyotrophic Lateral Sclerosis Risk and Clinical Phenotype

Objective

There is a critical need to establish genetic markers that explain the complex phenotypes and pathogenicity of ALS. This study identified a polymorphism in the Stathmin-2 gene and investigated its association with sporadic ALS (sALS) disease risk, age-of onset and survival duration.

Methods

The candidate CA repeat was systematically analyzed using PCR, Sanger sequencing and high throughput capillary separation for genotyping. Stathmin-2 expression was investigated using RT-PCR in patient olfactory neurosphere-derived (ONS) cells and RNA sequencing in laser-captured spinal motor neurons.

Results

In a case-control analysis of a combined North American sALS cohort (n = 321) and population control group (n = 332), long/long CA genotypes were significantly associated with disease risk (p = 0.042), and most strongly when one allele was a 24 CA repeat (p = 0.0023). In addition, longer CA allele length was associated with earlier age-of-onset (p = 0.039), and shorter survival duration in bulbar-onset cases (p = 0.006). In an Australian longitudinal sALS cohort (n = 67), ALS functional rating scale scores were significantly lower in carriers of the long/long genotype (p = 0.034). Stathmin-2 mRNA expression was reduced in sporadic patient ONS cells. Additionally, sALS patients and controls exhibited variable expression of Stathmin-2 mRNA according to CA genotype in laser-captured spinal motor neurons.

Conclusions

We report a novel non-coding CA repeat in Stathmin-2 which is associated with sALS disease risk and has disease modifying effects. The potential value of this variant as a disease marker and tool for cohort enrichment in clinical trials warrants further investigation.

Different miRNA Profiles in Plasma Derived Small and Large Extracellular Vesicles from Patients with Neurodegenerative Diseases

Identifying biomarkers is essential for early diagnosis of neurodegenerative diseases (NDs). Large (LEVs) and small extracellular vesicles (SEVs) are extracellular vesicles (EVs) of different sizes and biological functions transported in blood and they may be valid biomarkers for NDs. The aim of our study was to investigate common and different miRNA signatures in plasma derived LEVs and SEVs of Alzheimer’s disease (AD), Parkinson’s disease (PD), Amyotrophic Lateral Sclerosis (ALS) and Fronto-Temporal Dementia (FTD) patients. LEVs and SEVs were isolated from plasma of patients and healthy volunteers (CTR) by filtration and differential centrifugation and RNA was extracted. Small RNAs libraries were carried out by Next Generation Sequencing (NGS). MiRNAs discriminate all NDs diseases from CTRs and they can provide a signature for each NDs. Common enriched pathways for SEVs were instead linked to ubiquitin mediated proteolysis and Toll-like receptor signaling pathways and for LEVs to neurotrophin signaling and Glycosphingolipid biosynthesis pathway. LEVs and SEVs are involved in different pathways and this might give a specificity to their role in the spreading of the disease. The study of common and different miRNAs transported by LEVs and SEVs can be of great interest for biomarker discovery and for pathogenesis studies in neurodegeneration.

SCFD1 expression quantitative trait loci in amyotrophic lateral sclerosis are differentially expressed

Evidence indicates that common variants found in genome-wide association studies increase risk of disease through gene regulation via expression Quantitative Trait Loci. Using multiple genome-wide methods, we examined if Single Nucleotide Polymorphisms increase risk of Amyotrophic Lateral Sclerosis through expression Quantitative Trait Loci, and whether expression Quantitative Trait Loci expression is consistent across people who had Amyotrophic Lateral Sclerosis and those who did not. In combining public expression Quantitative Trait Loci data with Amyotrophic Lateral Sclerosis genome-wide association studies, we used Summary-data-based Mendelian Randomization to confirm that SCFD1 was the only gene that was genome-wide significant in mediating Amyotrophic Lateral Sclerosis risk via expression Quantitative Trait Loci (Summary-data-based Mendelian Randomization beta = 0.20, standard error = 0.04, P-value = 4.29 × 10^-6). Using post-mortem motor cortex, we tested whether expression Quantitative Trait Loci showed significant differences in expression between Amyotrophic Lateral Sclerosis (n = 76) and controls (n = 25), genome-wide. Of 20 757 genes analysed, the two most significant expression Quantitative Trait Loci to show differential in expression between Amyotrophic Lateral Sclerosis and controls involve two known Amyotrophic Lateral Sclerosis genes (SCFD1 and VCP). Cis-acting SCFD1 expression Quantitative Trait Loci downstream of the gene showed significant differences in expression between Amyotrophic Lateral Sclerosis and controls (top expression Quantitative Trait Loci beta = 0.34, standard error = 0.063, P-value = 4.54 × 10^-7). These SCFD1 expression Quantitative Trait Loci also significantly modified Amyotrophic Lateral Sclerosis survival (number of samples = 4265, hazard ratio = 1.11, 95% confidence interval = 1.05-1.17, P-value = 2.06 × 10^-4) and act as an Amyotrophic Lateral Sclerosis trans-expression Quantitative Trait Loci hotspot for a wider network of genes enriched for SCFD1 function and Amyotrophic Lateral Sclerosis pathways. Using gene-set analyses, we found the genes that correlate with this trans-expression Quantitative Trait Loci hotspot significantly increase risk of Amyotrophic Lateral Sclerosis (beta = 0.247, standard deviation = 0.017, P = 0.001) and schizophrenia (beta = 0.263, standard deviation = 0.008, P-value = 1.18 × 10^-5), a disease that genetically correlates with Amyotrophic Lateral Sclerosis. In summary, SCFD1 expression Quantitative Trait Loci are a major factor in Amyotrophic Lateral Sclerosis, not only influencing disease risk but are differentially expressed in post-mortem Amyotrophic Lateral Sclerosis. SCFD1 expression Quantitative Trait Loci show distinct expression profiles in Amyotrophic Lateral Sclerosis that correlate with a wider network of genes that also confer risk of the disease and modify the disease's duration.

Neurofilaments in motor neuron disorders: towards promising diagnostic and prognostic biomarkers

Motor neuron diseases (MNDs) are etiologically and biologically heterogeneous diseases. The pathobiology of motor neuron degeneration is still largely unknown, and no effective therapy is available. Heterogeneity and lack of specific disease biomarkers have been appointed as leading reasons for past clinical trial failure, and biomarker discovery is pivotal in today's MND research agenda.In the last decade, neurofilaments (NFs) have emerged as promising biomarkers for the clinical assessment of neurodegeneration. NFs are scaffolding proteins with predominant structural functions contributing to the axonal cytoskeleton of myelinated axons. NFs are released in CSF and peripheral blood as a consequence of axonal degeneration, irrespective of the primary causal event. Due to the current availability of highly-sensitive automated technologies capable of precisely quantify proteins in biofluids in the femtomolar range, it is now possible to reliably measure NFs not only in CSF but also in blood.In this review, we will discuss how NFs are impacting research and clinical management in ALS and other MNDs. Besides contributing to the diagnosis at early stages by differentiating between MNDs with different clinical evolution and severity, NFs may provide a useful tool for the early enrolment of patients in clinical trials. Due to their stability across the disease, NFs convey prognostic information and, on a larger scale, help to stratify patients in homogenous groups. Shortcomings of NFs assessment in biofluids will also be discussed according to the available literature in the attempt to predict the most appropriate use of the biomarker in the MND clinic.

Umbilical Cord Mesenchymal Stem Cells in Amyotrophic Lateral Sclerosis: an Original Study

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is still incurable. Although different therapies can affect the health and survival of patients. Our aim is to evaluate the effect of umbilical mesenchymal stem cells administrated intrathecally to patients with amyotrophic lateral sclerosis on disability development and survival.

METHODS

This case-control study involved 67 patients treated with Wharton's jelly mesenchymal stem cells (WJ-MSC). The treated patients were paired with 67 reference patients from the PRO-ACT database which contains patient records from 23 ALS clinical studies (phase 2/3). Patients in the treatment and reference groups were fully matched in terms of race, sex, onset of symptoms (bulbar/spinal), FT9 disease stage at the beginning of therapy and concomitant amyotrophic lateral sclerosis medications. Progression rates prior to treatment varied within a range of ± 0.5 points. All patients received three intrathecal injections of Wharton's jelly-derived mesenchymal stem cells every two months at a dose of 30 × 106 cells. Patients were assessed using the ALSFRS-R scale. Survival times were followed-up until March 2020.

RESULTS

Median survival time increased two-fold in all groups. In terms of progression, three response types measured in ALSFRS-R were observed: decreased progression rate (n = 21, 31.3%), no change in progression rate (n = 33, 49.3%) and increased progression rate (n = 13, 19.4%). Risk-benefit ratios were favorable in all groups. No serious adverse drug reactions were observed.

INTERPRETATION

Wharton's jelly-derived mesenchymal stem cells therapy is safe and effective in some ALS patients, regardless of the clinical features and demographic factors excluding sex. The female sex and a good therapeutic response to the first administration are significant predictors of efficacy following further administrations. Graphical Abstract Medical therapeutic experiment with retrospective case-control analyses.

Genetic modifiers and phenotypic variability in neuromuscular disorders

Neuromuscular disorders are mostly rare diseases with autosomal dominant, recessive, or X-linked inheritance. Interestingly, among patients carrying the same mutations, a range of phenotypic severity is reported. This phenotypic variability in neuromuscular disorders is still not fully understood. This review will focus on genetic modifiers and will briefly describe metabolic pathways, in which they are involved. Genetic modifiers are variants in the same or other genes that modulate the phenotype. Proteins encoded by genetic modifiers in neuromuscular diseases are taking part in different metabolic processes, most commonly in inflammation, growth and regeneration, endoplasmic reticulum metabolism, and cytoskeletal activities. Recent advances in omics technologies, development of computational algorithms, and establishing large international consortia intensified discovery sped up investigation of genetic modifiers. As more individuals affected by neuromuscular disorders are tested, it is often suggested that classic models of genetic causation cannot explain phenotypic variability. There is a growing interest in their discovery and identifying shared metabolic pathways can contribute to design targeted therapies. We provide an update on variants acting as genetic modifiers in neuromuscular disorders and strategies used for their discovery.

Progression and survival of patients with motor neuron disease relative to their fecal microbiota

Gut microbiota studies have been well-investigated for neurodegenerative diseases such as Alzheimer's and Parkinson's disease, however, fewer studies have comprehensively examined the gut microbiome in Motor Neuron Disease (MND), with none examining its impact on disease prognosis. Here, we investigate MND prognosis and the fecal microbiota, using 16S rRNA case-control data from 100 individuals with extensive medical histories and metabolic measurements. We contrast the composition and diversity of fecal microbiome signatures from 49 MND and 51 healthy controls by combining current gold-standard 16S microbiome pipelines. Using stringent quality control thresholds, we conducted qualitative assessment approaches including; direct comparison of taxa, PICRUSt2 predicted metagenomics, Shannon and Chao1-index and Firmicutes/Bacteroidetes ratio. We show that the fecal microbiome of patients with MND is not significantly different from that of healthy controls that were matched by age, sex, and BMI, however there are distinct differences in Beta-diversity in some patients with MND. Weight, BMI, and metabolic and clinical features of disease in patients with MND were not related to the composition of their fecal microbiome, however, we observe a greater risk for earlier death in patients with MND with increased richness and diversity of the microbiome, and in those with greater Firmicutes to Bacteroidetes ratio. This was independent of anthropometric, metabolic, or clinical features of disease, and warrants support for further gut microbiota studies in MND. Given the disease heterogeneity in MND, and complexity of the gut microbiota, large studies are necessary to determine the detailed role of the gut microbiota and MND prognosis.

What do we know about the variability in survival of patients with amyotrophic lateral sclerosis?

INTRODUCTION

ALS is a fatal neurodegenerative disease. However, patients show variability in the length of survival after symptom onset. Understanding the mechanisms of long survival could lead to possible avenues for therapy.

AREAS COVERED

This review surveys the reported length of survival in ALS, the clinical features that predict survival in individual patients, and possible factors, particularly genetic factors, that could cause short or long survival. The authors also speculate on possible mechanisms.

EXPERT OPINION

a small number of known factors can explain some variability in ALS survival. However, other disease-modifying factors likely exist. Factors that alter motor neurone vulnerability and immune, metabolic, and muscle function could affect survival by modulating the disease process. Knowing these factors could lead to interventions to change the course of the disease. The authors suggest a broad approach is needed to quantify the proportion of variation survival attributable to genetic and non-genetic factors and to identify and estimate the effect size of specific factors. Studies of this nature could not only identify novel avenues for therapeutic research but also play an important role in clinical trial design and personalized medicine.

A Knowledge-Based Machine Learning Approach to Gene Prioritisation in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis is a neurodegenerative disease of the upper and lower motor neurons resulting in death from neuromuscular respiratory failure, typically within two to five years of first symptoms. Several rare disruptive gene variants have been associated with ALS and are responsible for about 15% of all cases. Although our knowledge of the genetic landscape of this disease is improving, it remains limited. Machine learning models trained on the available protein-protein interaction and phenotype-genotype association data can use our current knowledge of the disease genetics for the prediction of novel candidate genes. Here, we describe a knowledge-based machine learning method for this purpose. We trained our model on protein-protein interaction data from IntAct, gene function annotation from Gene Ontology, and known disease-gene associations from DisGeNet. Using several sets of known ALS genes from public databases and a manual review as input, we generated a list of new candidate genes for each input set. We investigated the relevance of the predicted genes in ALS by using the available summary statistics from the largest ALS genome-wide association study and by performing functional and phenotype enrichment analysis. The predicted sets were enriched for genes associated with other neurodegenerative diseases known to overlap with ALS genetically and phenotypically, as well as for biological processes associated with the disease. Moreover, using ALS genes from ClinVar and our manual review as input, the predicted sets were enriched for ALS-associated genes (ClinVar p = 0.038 and manual review p = 0.060) when used for gene prioritisation in a genome-wide association study.

TDP-43 enhances translation of specific mRNAs linked to neurodegenerative disease

The RNA-binding protein TDP-43 is heavily implicated in neurodegenerative disease. Numerous patient mutations in TARDBP, the gene encoding TDP-43, combined with data from animal and cell-based models, imply that altered RNA regulation by TDP-43 causes Amyotrophic Lateral Sclerosis and Frontotemporal Dementia. However, underlying mechanisms remain unresolved. Increased cytoplasmic TDP-43 levels in diseased neurons suggest a possible role in this cellular compartment. Here, we examined the impact on translation of overexpressing human TDP-43 and the TDP-43A315T patient mutant protein in motor neuron-like cells and primary cultures of cortical neurons. In motor-neuron like cells, TDP-43 associates with ribosomes without significantly affecting global translation. However, ribosome profiling and additional assays revealed enhanced translation and direct binding of Camta1, Mig12, and Dennd4a mRNAs. Overexpressing either wild-type TDP-43 or TDP-43A315T stimulated translation of Camta1 and Mig12 mRNAs via their 5'UTRs and increased CAMTA1 and MIG12 protein levels. In contrast, translational enhancement of Dennd4a mRNA required a specific 3'UTR region and was specifically observed with the TDP-43A315T patient mutant allele. Our data reveal that TDP-43 can function as an mRNA-specific translational enhancer. Moreover, since CAMTA1 and DENND4A are linked to neurodegeneration, they suggest that this function could contribute to disease.

High plasma concentrations of organic pollutants negatively impact survival in amyotrophic lateral sclerosis

OBJECTIVE

To determine whether persistent organic pollutants (POP) affect amyotrophic lateral sclerosis (ALS) survival.

METHODS

ALS participants seen at the University of Michigan (Ann Arbor, MI, USA) provided plasma samples for measurement of POPs. ALS disease and clinical features were collected prospectively from the medical records. Survival models used a composite summary measure of exposure due to multiple POPs (environmental risk score or ERS).

RESULTS

167 participants (40.7% female, n=68) with ALS were recruited, of which 119 died during the study period. Median diagnostic age was 60.9 years (IQR 52.7-68.2), median time from symptom onset to diagnosis was 1.01 years (IQR 0.67-1.67), bulbar onset 28.7%, cervical onset 33.5% and lumbar onset 37.7%. Participants in the highest quartile of ERS (representing highest composite exposure), adjusting for age at diagnosis, sex and other covariates had a 2.07 times greater hazards rate of mortality (p=0.018, 95% CI 1.13 to 3.80) compared with those in the lowest quartile. Pollutants with the largest contribution to the ERS were polybrominated diphenyl ethers 154 (HR 1.53, 95% CI 0.90 to 2.61), polychlorinated biphenyls (PCB) 118 (HR 1.50, 95% CI 0.95 to 2.39), PCB 138 (HR 1.69, 95% CI 0.99 to 2.90), PCB 151 (HR 1.46, 95% CI 1.01 to 2.10), PCB 175 (HR 1.53, 95% CI 0.98 to 2.40) and p,p'-DDE (HR 1.39, 95% CI 1.07 to 1.81).

CONCLUSIONS

Higher concentrations of POPs in plasma are associated with reduced ALS survival, independent of age, gender, segment of onset and other covariates. This study helps characterise and quantify the combined effects of POPs on ALS and supports the concept that environmental exposures play a role in disease pathogenesis.

ALSgeneScanner: a pipeline for the analysis and interpretation of DNA sequencing data of ALS patients

Amyotrophic lateral sclerosis (ALS, MND) is a neurodegenerative disease of upper and lower motor neurons resulting in death from neuromuscular respiratory failure, typically within two years of first symptoms. Genetic factors are an important cause of ALS, with variants in more than 25 genes having strong evidence, and weaker evidence available for variants in more than 120 genes. With the increasing availability of next-generation sequencing data, non-specialists, including health care professionals and patients, are obtaining their genomic information without a corresponding ability to analyze and interpret it. Furthermore, the relevance of novel or existing variants in ALS genes is not always apparent. Here we present ALSgeneScanner, a tool that is easy to install and use, able to provide an automatic, detailed, annotated report, on a list of ALS genes from whole-genome sequencing (WGS) data in a few hours and whole exome sequence data in about 1 h on a readily available mid-range computer. This will be of value to non-specialists and aid in the interpretation of the relevance of novel and existing variants identified in DNA sequencing data.

Adjustment for index event bias in genome-wide association studies of subsequent events

Following numerous genome-wide association studies of disease susceptibility, there is increasing interest in genetic associations with prognosis, survival or other subsequent events. Such associations are vulnerable to index event bias, by which selection of subjects according to disease status creates biased associations if common causes of incidence and prognosis are not accounted for. We propose an adjustment for index event bias using the residuals from the regression of genetic effects on prognosis on genetic effects on incidence. Our approach eliminates this bias when direct genetic effects on incidence and prognosis are independent, and otherwise reduces bias in realistic situations. In a study of idiopathic pulmonary fibrosis, we reverse a paradoxical association of the strong susceptibility gene MUC5B with increased survival, suggesting instead a significant association with decreased survival. In re-analysis of a study of Crohn’s disease prognosis, four regions remain associated at genome-wide significance but with increased standard errors.

Different from GWAS for susceptibility to disease, GWAS for prognosis or survival may be vulnerable to selection bias. Here, Dudbridge et al present an approach to reduce index event bias in simulated and realistic situations, and apply it to GWAS of survival with idiopathic pulmonary fibrosis and Crohn’s disease prognosis.

Biomarkers in Motor Neuron Disease: A State of the Art Review

Motor neuron disease can be viewed as an umbrella term describing a heterogeneous group of conditions, all of which are relentlessly progressive and ultimately fatal. The average life expectancy is 2 years, but with a broad range of months to decades. Biomarker research deepens disease understanding through exploration of pathophysiological mechanisms which, in turn, highlights targets for novel therapies. It also allows differentiation of the disease population into sub-groups, which serves two general purposes: (a) provides clinicians with information to better guide their patients in terms of disease progression, and (b) guides clinical trial design so that an intervention may be shown to be effective if population variation is controlled for. Biomarkers also have the potential to provide monitoring during clinical trials to ensure target engagement. This review highlights biomarkers that have emerged from the fields of systemic measurements including biochemistry (blood, cerebrospinal fluid, and urine analysis); imaging and electrophysiology, and gives examples of how a combinatorial approach may yield the best results. We emphasize the importance of systematic sample collection and analysis, and the need to correlate biomarker findings with detailed phenotype and genotype data.

Exploration of attractor modules for sporadic amyotrophic lateral sclerosis via systemic module inference and attract method

Sporadic amyotrophic lateral sclerosis (SALS) is a devastating neurodegenerative disorder. However, the understanding of SALS is still poor. This research aimed to excavate attractor modules for SALS by integrating the systemic module inference and attract method. To achieve this, gene expression data and protein-protein data were recruited and preprocessed. Then, based on the Spearman's correlation coefficient (SCC) of the interactions under these two conditions, two PPI networks separately with 870 nodes (979 interactions) in normal control group and 601 nodes (777 interactions) in SALS group were built. Systemic module inference method was performed to identify the modules, and attract method was used to identify attractor modules. Finally, pathway enrichment analysis was performed to disclose the functional enrichment of these attractor modules. In total 44 and 118 modules were identified for normal control and SALS groups, respectively. Among them, 6 modules were with similar gene composition between the two groups, and all 6 modules were considered as the attractor module via attract method. These attractor modules might be potential biomarkers for early diagnosis and therapy of SALS, which could provide insight into the disease biology and suggest possible directions for drug screening programs.

Stratification of amyotrophic lateral sclerosis patients: a crowdsourcing approach

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease where substantial heterogeneity in clinical presentation urgently requires a better stratification of patients for the development of drug trials and clinical care. In this study we explored stratification through a crowdsourcing approach, the DREAM Prize4Life ALS Stratification Challenge. Using data from >10,000 patients from ALS clinical trials and 1479 patients from community-based patient registers, more than 30 teams developed new approaches for machine learning and clustering, outperforming the best current predictions of disease outcome. We propose a new method to integrate and analyze patient clusters across methods, showing a clear pattern of consistent and clinically relevant sub-groups of patients that also enabled the reliable classification of new patients. Our analyses reveal novel insights in ALS and describe for the first time the potential of a crowdsourcing to uncover hidden patient sub-populations, and to accelerate disease understanding and therapeutic development.

The Genetic Diagnosis of Neurodegenerative Diseases and Therapeutic Perspectives

Genetics has led to a new focus regarding approaches to the most prevalent diseases today. Ascertaining the molecular secrets of neurodegenerative diseases will lead to developing drugs that will change natural history, thereby affecting the quality of life and mortality of patients. The sequencing of candidate genes in patients suffering neurodegenerative pathologies is faster, more accurate, and has a lower cost, thereby enabling algorithms to be proposed regarding the risk of neurodegeneration onset in healthy persons including the year of onset and neurodegeneration severity. Next generation sequencing has resulted in an explosion of articles regarding the diagnosis of neurodegenerative diseases involving exome sequencing or sequencing a whole gene for correlating phenotypical expression with genetic mutations in proteins having key functions. Many of them occur in neuronal glia, which can trigger a proinflammatory effect leading to defective proteins causing sporadic or familial mutations. This article reviews the genetic diagnosis techniques and the importance of bioinformatics in interpreting results from neurodegenerative diseases. Risk scores must be established in the near future regarding diseases with a high incidence in healthy people for defining prevention strategies or an early start for giving drugs in the absence of symptoms.

Pregnancy 5 Years After Onset of Amyotrophic Lateral Sclerosis Symptoms: A Case Report and Review of the Literature

BACKGROUND

Pregnancy in patients with amyotrophic lateral sclerosis (ALS) is extremely rare and often results in delivery of a healthy baby when patients are in the early stages of the disease.

CASE

This report describes the case of a successful pregnancy 5 years after ALS onset. Significant worsening of weakness, unsteady balance, and dysphagia were noticed around the third trimester. A healthy child was delivered at term by planned Caesarean section. After delivery the patient developed remarkable weakness, dysphagia, and dysarthria.

CONCLUSION

A literature search found 22 cases through PubMed and Ovid, with key words "amyotrophic lateral sclerosis" and "pregnancy." Both slow progression and rapid progression of ALS during pregnancy have been reported. Worsening of symptoms seems to be common, but little is still known about the influence of pregnancy on ALS onset and progression.

Epidemiology and diagnostic process of amyotrophic lateral sclerosis as distinct from myelopathy: 5-year cohort study of whole-population in South Korea

OBJECTIVE

To investigate the incidence, prevalence, and demographic factors of all amyotrophic lateral sclerosis (ALS) patients diagnosed in South Korea from 2011 to 2015, and to analyze cases misdiagnosed as myelopathy.

METHODS

The whole population registered under the Korean National Health Insurance Service (KNHIS) was applied. All 4551 patients who were registered as having ALS code from 2011 to 2015 were included. For all ALS patients, the incidence, prevalence, and demographic factors were assessed. Trends of diagnosis for myelopathy, and surgery prior to confirmation of ALS diagnosis were identified.

RESULTS

When the whole 48,135,715 KNHIS population enrolled in 2015, the incidence of ALS in 2015 was estimated to be 1.68 per 100,000 person-years, and the prevalence was 6.49 per 100,000 persons. Life expectancy of ALS can be calculated as 3.9 years after the diagnosis, and the mean age of diagnosis was 59.5 ± 13.1. A total of 1902 patients diagnosed with myelopathy before a diagnosis of ALS accounted for 0.13% of all myelopathy patients, and 41.8% of all ALS patients. It took an average of 471.7 d to confirm a diagnosis of ALS after the myelopathy diagnosis. Among the patients finally diagnosed with ALS, more patients underwent surgery for myelopathy (n = 263, 13.8%) than among patients who were diagnosed with myelopathy alone, and underwent surgery (n = 141,148, 9.8%).

CONCLUSIONS

This whole-population nationwide demographic study confirmed the data from previous studies. Clinicians should consider the possibility of ALS when making a myelopathy diagnosis, especially if the symptoms are sufficiently severe to require surgery.

The multistep hypothesis of ALS revisited: The role of genetic mutations

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) incidence rates are consistent with the hypothesis that ALS is a multistep process. We tested the hypothesis that carrying a large effect mutation might account for ≥1 steps through the effect of the mutation, thus leaving fewer remaining steps before ALS begins.

METHODS

We generated incidence data from an ALS population register in Italy (2007-2015) for which genetic analysis for C9orf72, SOD1, TARDBP, and FUS genes was performed in 82% of incident cases. As confirmation, we used data from ALS cases diagnosed in the Republic of Ireland (2006-2014). We regressed the log of age-specific incidence against the log of age with least-squares regression for the subpopulation carrying disease-associated variation in each separate gene.

RESULTS

Of the 1,077 genetically tested cases, 74 (6.9%) carried C9orf72 mutations, 20 (1.9%) had SOD1 mutations, 15 (1.4%) had TARDBP mutations, and 3 (0.3%) carried FUS mutations. In the whole population, there was a linear relationship between log incidence and log age (r² = 0.98) with a slope estimate of 4.65 (4.37-4.95), consistent with a 6-step process. The analysis for C9orf72-mutated patients confirmed a linear relationship (r² = 0.94) with a slope estimate of 2.22 (1.74-2.29), suggesting a 3-step process. This estimate was confirmed by data from the Irish ALS register. The slope estimate was consistent with a 2-step process for SOD1 and with a 4-step process for TARDBP.

CONCLUSION

The identification of a reduced number of steps in patients with ALS with genetic mutations compared to those without mutations supports the idea of ALS as a multistep process and is an important advance for dissecting the pathogenic process in ALS.

Beyond disease susceptibility-Leveraging genome-wide association studies for new insights into complex disease biology

Genetic studies in complex diseases have been highly successful, but have also been largely one-dimensional: predominantly focusing on the genetic contribution to disease susceptibility. While this is undoubtedly important-indeed it is a pre-requisite for understanding the mechanisms underlying disease development-there are many other important aspects of disease biology that have received comparatively little attention. In this review, I will discuss how existing genetic data can be leveraged to provide new insights into other aspects of disease biology, why such insights could change the way we think about complex disease, and how this could provide opportunities for better therapies and/or facilitate personalised medicine. To do this, I will use the example of Crohn's disease-a chronic form of inflammatory bowel disease that has been one of the main success stories in complex disease genetics. Indeed, thanks to genetic studies, we now have a much more detailed understanding of the processes involved in Crohn's disease development, but still know relatively little about what determines the subsequent disease course (prognosis) and why this differs so considerably between individuals. I will discuss how we came to realise that genetic variation plays an important role in determining disease prognosis and how this has changed the way we think about Crohn's disease genetics. This will illustrate how phenotypic data can be used to leverage new insights from genetic data and will provide a broadly applicable framework that could yield new insights into the biology of multiple diseases.

Revisiting the concept of amyotrophic lateral sclerosis as a multisystems disorder of limited phenotypic expression

PURPOSE OF REVIEW

The current review will examine the contemporary evidence that amyotrophic lateral sclerosis (ALS) is a syndrome in which the unifying feature is a progressive loss of upper and lower motor neuron function.

RECENT FINDINGS

Although ALS is traditionally viewed as a neurodegenerative disorder affecting the motor neurons, there is considerable phenotypic heterogeneity and widespread involvement of the central nervous system. A broad range of both causative and disease modifying genetic variants are associated with both sporadic and familial forms of ALS. A significant proportion of ALS patients have an associated frontotemporal dysfunction which can be a harbinger of a significantly shorter survival and for which there is increasing evidence of a fundamental disruption of tau metabolism in those affected individuals. Although the traditional neuropathology of the degenerating motor neurons in ALS is that of neuronal cytoplasmic inclusions composed neuronal intermediate filaments, the presence of neuronal cytoplasmic inclusions composed of RNA binding proteins suggests a key role for RNA dysmetabolism in the pathogenesis of ALS.

SUMMARY

ALS is a complex multisystem neurodegenerative syndrome with marked heterogeneity at not only the level of clinical expression, but also etiologically.

Long-term effects of edaravone on survival of patients with amyotrophic lateral sclerosis

Background and purpose

Oxidative stress has been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). Edaravone, a free radical scavenger, was approved as a therapeutic drug for ALS in 2015 in Japan. A phase 3 clinical trial demonstrated a smaller decline in ALS functional scale scores compared with placebo. However, the long-term effects of edaravone on ALS patients remain unclear. This study aimed to retrospectively investigate the long-term effects of edaravone on the survival of ALS patients.

Methods

We retrospectively analyzed 27 consecutive patients with ALS who were treated with edaravone and 30 consecutive ALS patients who were not treated with edaravone between 2010 and 2016.

Results

The differences of ALSFRS-R scores from baseline to 6 months was significantly reduced in the edaravone group, compared to the control group. The changes in serum creatinine, as a possible marker of ALS severity, from baseline to 6 and 12 months were significantly improved in the edaravone group, compared to the control group. The survival rate was significantly improved in the edaravone group compared with control patients.

Conclusion

Our retrospective single-center analysis suggests slower progression and better prognosis of ALS patients with edaravone treatment. Further investigation, including prospective multicenter analysis, is warranted to confirm the usefulness of edaravone for a better prognosis of ALS.

•

We retrospectively investigate the effects of edaravone on ALS patients.

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The differences of ALSFRS-R scores were reduced in the edaravone group.

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The changes in serum creatinine were improved in the edaravone group.

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The survival rate was improved in the edaravone group.

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A prospective multicenter analysis is warranted to confirm usefulness of edaravone.

Stage at which riluzole treatment prolongs survival in patients with amyotrophic lateral sclerosis: a retrospective analysis of data from a dose-ranging study

Background

Riluzole is the only drug to prolong survival for amyotrophic lateral sclerosis (ALS) and, at a dose of 100 mg, was associated with a 35% reduction in mortality in a clinical trial. A key question is whether the survival benefit occurs at an early stage of disease, late stage, or is spread throughout the course of the disease. To address this question, we used the King's clinical staging system to do a retrospective analysis of data from the original dose-ranging clinical trial of riluzole.

Methods

In the original dose-ranging trial, patients were enrolled between December, 1992, and November, 1993, in Belgium, France, Germany, Spain, Canada, the USA, and the UK if they had probable or definite ALS as defined by the El Escorial criteria. The censor date for the riluzole survival data was set as the original study end date of Dec 31, 1994. For this analysis, King's clinical ALS stage was estimated from the electronic case record data of the modified Norris scale, UK Medical Research Council score for muscle strength, El Escorial category, vital capacity, and gastrostomy insertion data. The lowest allocated stage was 2 because the original trial only included patients with probable or definite ALS. We used a χ² test to assess the independence of stage at trial enrolment and treatment group, Kaplan-Meier product limit distribution to test the transition from each stage to subsequent stages, and Cox regression to confirm an effect of treatment group on time in stage, controlling for covariates. We did sensitivity analyses by combining treatment groups, using alternative strategies to stage, stratifying by stage at trial enrolment, and using multistate outcome analysis of treatments (MOAT).

Findings

We analysed the case records of all 959 participants from the original dose-ranging trial, 237 assigned to 50 mg/day riluzole, 236 to 100 mg/day, 244 to 200 mg/day, and 242 to daily placebo. Clinical stage at enrolment did not significantly differ between treatment groups (p=0·22). Time in stage 4 was longer for patients receiving 100 mg/day riluzole than for those receiving placebo (hazard ratio [HR] 0·55, 95% CI 0·36–0·83; log-rank p=0·037). Combining treatment groups and stratifying by stage at enrolment showed a similar result (HR 0·638, 95% CI 0·464–0·878; p=0·006), as did analysis with MOAT where the mean number of days spent in stage 4 was numerically higher for patients given riluzole at higher doses compared with patients receiving placebo. Time from stages 2 or 3 to subsequent stages or death did not differ between riluzole treatment groups and placebo (p=0·83 for stage 2 and 0·88 for stage 3).

Interpretation

We showed that riluzole prolongs survival in the last clinical stage of ALS; this finding needs to be confirmed in a prospective study, and treatment effects at stage 1 still need to be analysed. The ALS stage at which benefit occurs is important for counselling of patients before starting treatment. Staging should be used in future ALS clinical trials to assess the stage at which survival benefit occurs, and a similar approach could be used for other neurodegenerative diseases.

Funding

NIHR Maudsley Biomedical Research Centre, The European Union Joint Programme on Neurodegeneration, and the King's Summer Undergraduate Studentship.

Emerging understanding of the genotype-phenotype relationship in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive, noncurable neurodegenerative disorder of the upper and lower motor neurons causing weakness and death within a few years of symptom onset. About 10% of patients with ALS have a family history of the disease; however, ALS-associated genetic mutations are also found in sporadic cases. There are over 100 ALS-associated mutations, and importantly, several genetic mutations, including C9ORF72, SOD1, and TARDBP, have led to mechanistic insight into this complex disease. In the clinical realm, knowledge of ALS genetics can also help explain phenotypic heterogeneity, aid in genetic counseling, and in the future may help direct treatment efforts.

An association study between SCFD1 rs10139154 variant and amyotrophic lateral sclerosis in a Chinese cohort

BACKGROUND

A recent genome-wide association study (GWAS) demonstrated that the Sec1 family domain containing 1 (SCFD1) gene is associated with amyotrophic lateral sclerosis (ALS). The objective of our study was to investigate the association between the single nucleotide polymorphism (SNP) rs10139154 in the SCFD1 gene and ALS in a Chinese cohort.

METHODS

A cohort of 1074 sporadic ALS (SALS) patients from the Department of Neurology at the West China Hospital of Sichuan University were genotyped for rs10139154 using a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. In addition, 927 unrelated healthy controls (HCs) from the same region were included.

RESULTS

After adjusting for age and sex, no significant differences in the genotype distributions and allele frequencies in the allelic, additive, dominant or recessive genetic models were found between SALS and HCs and between patients with spinal onset and bulbar onset. Remarkably, rs10139154 was shown to be associated with the age at onset (AAO) of ALS patients. Consistently, ALS patients with the "CC" genotype have an earlier mean AAO than that of patients with a "CG" and "CG + GG" genotype (p = 0.002 and 0.001, respectively).

CONCLUSION

Our results suggest that there is a lack of association of SCFD1 rs10139154 with the risk for ALS in a large Chinese population, but this variant may modulate the age of onset of ALS. These findings add further evidence to the suspected implication of the SCFD1 gene in the pathogenesis of disease in our ALS population.

Burden of rare variants in ALS genes influences survival in familial and sporadic ALS

Genetic variants are implicated in the development of amyotrophic lateral sclerosis (ALS), but it is unclear whether the burden of rare variants in ALS genes has an effect on survival. We performed whole genome sequencing on 8 familial ALS (FALS) patients with superoxide dismutase 1 (SOD1) mutation and whole exome sequencing on 46 sporadic ALS (SALS) patients living in Hong Kong and found that 67% had at least 1 rare variant in the exons of 40 ALS genes; 22% had 2 or more. Patients with 2 or more rare variants had lower probability of survival than patients with 0 or 1 variant (p = 0.001). After adjusting for other factors, each additional rare variant increased the risk of respiratory failure or death by 60% (p = 0.0098). The presence of the rare variant was associated with the risk of ALS (Odds ratio 1.91, 95% confidence interval 1.03-3.61, p = 0.03), and ALS patients had higher rare variant burden than controls (MB, p = 0.004). Our findings support an oligogenic basis with the burden of rare variants affecting the development and survival of ALS.

Amyotrophic lateral sclerosis: moving towards a new classification system

Amyotrophic lateral sclerosis is a progressive adult-onset neurodegenerative disease that primarily affects upper and lower motor neurons, but also frontotemporal and other regions of the brain. The extent to which each neuronal population is affected varies between individuals. The subsequent patterns of disease progression form the basis of diagnostic criteria and phenotypic classification systems, with considerable overlap in the clinical terms used. This overlap can lead to confusion between diagnosis and phenotype. Formal classification systems such as the El Escorial criteria and the International Classification of Diseases are systematic approaches but they omit features that are important in clinical management, such as rate of progression, genetic basis, or functional effect. Therefore, many neurologists use informal classification approaches that might not be systematic, and could include, for example, anatomical descriptions such as flail-arm syndrome. A new strategy is needed to combine the benefits of a systematic approach to classification with the rich and varied phenotypic descriptions used in clinical practice.

Common polymorphisms of chemokine (C-X3-C motif) receptor 1 gene modify amyotrophic lateral sclerosis outcome: A population-based study

INTRODUCTION

In the brain, the chemokine (C-X3-C motif) receptor 1 (1CX3CR1) gene is expressed only by microglia, where it acts as a key mediator of the neuron-microglia interactions. We assessed whether the 2 common polymorphisms of the CX3CR1 gene (V249I and T280M) modify amyotrophic lateral sclerosis (ALS) phenotype.

METHODS

The study included 755 ALS patients diagnosed in Piemonte between 2007 and 2012 and 369 age-matched and sex-matched controls, all genotyped with the same chips.

RESULTS

Neither of the variants was associated with an increased risk of ALS. Patients with the V249I V/V genotype had a 6-month-shorter survival than those with I/I or V/I genotypes (dominant model, P = 0.018). The T280M genotype showed a significant difference among the 3 genotypes (additive model, P = 0.036). Cox multivariable analysis confirmed these findings.

DISCUSSION

We found that common variants of the CX3CR1 gene influence ALS survival. Our data provide further evidence for the role of neuroinflammation in ALS. Muscle Nerve 57: 212-216, 2018.

What causes amyotrophic lateral sclerosis?

Amyotrophic lateral sclerosis is a neurodegenerative disease predominantly affecting upper and lower motor neurons, resulting in progressive paralysis and death from respiratory failure within 2 to 3 years. The peak age of onset is 55 to 70 years, with a male predominance. The causes of amyotrophic lateral sclerosis are only partly known, but they include some environmental risk factors as well as several genes that have been identified as harbouring disease-associated variation. Here we review the nature, epidemiology, genetic associations, and environmental exposures associated with amyotrophic lateral sclerosis.