Heterozygous truncating loss-of-function (LoF) variants in NEK1 are a known cause of amyotrophic lateral sclerosis (ALS). NEK1 encodes the pleiotropic serine/threonine kinase NIMA-related kinase 1, and prior in vitro studies have implicated kinase dysfunction as the principal pathogenic mechanism underlying NEK1-associated ALS. However, bona fide pathogenic missense variants causally linked to ALS have not previously been reported, leaving this hypothesis unconfirmed. Here, we identify a rare NEK1 missense variant, p.N598S, that co-segregates with disease in a familial ALS pedigree and is enriched in European ALS cohorts. This variant exhibits normal protein expression levels, indicating a functional rather than quantitative defect. Using isogenic human motor neurons, we directly compared the effects of p.N598S with those of the ALS-associated truncating variant p.R812* to delineate disease mechanisms. The p.N598S variant induced pathological phenotypes consistent with NEK1 haploinsufficiency, including increased susceptibility to DNA damage, increased apoptosis, ciliary dysmorphia, and nucleocytoplasmic translocation of TDP-43. Importantly, p.N598S impaired NEK1 kinase activity, and pharmacological inhibition of NEK1 recapitulated the cellular phenotypes observed in both p.N598S- and p.R812*-mutant motor neurons. Collectively, these findings provide strong genetic and functional evidence for a disease-causing role of NEK1 kinase disruption in NEK1-ALS. Our findings provide immediate diagnostic and therapeutic implications, particularly for the functional interpretation of missense variants of uncertain significance and the development of targeted treatment strategies.

Pathogenic variants in the Cu/Zn superoxide dismutase (SOD1) gene can be detected in approximately 2% of sporadic and 11% of familial amyotrophic lateral sclerosis (ALS) patients in Europe. We analyzed the clinical phenotypes of 83 SOD1-ALS patients focusing on patients carrying the most frequent (likely) pathogenic variants (R116G, D91A, L145F) in Germany. Moreover, we describe the effect of tofersen treatment on ten patients carrying these variants. R116G patients showed the most aggressive course of disease with a median survival of 22.0 months compared to 198.0 months in D91A and 87.0 months in L145F patients (HR 7.71, 95% CI 2.89-20.58 vs. D91A; p < 0.001 and HR 4.25, 95% CI 1.55-11.67 vs. L145F; p = 0.02). Moreover, R116G patients had the fastest median ALSFRS-R progression rate with 0.12 (IQR 0.07-0.20) points lost per month. Median diagnostic delay was 10.0 months (IQR 5.5-11.5) and therefore shorter compared to 57.5 months (IQR 14.0-83.0) in D91A (p < 0.001) and 21.5 months (IQR 5.8-38.8) in L145F (p = 0.21) carriers. As opposed to D91A carriers (50.0%), 96.2% of R116G (p < 0.001) and 100.0% of L145F (p = 0.04) patients reported a positive family history. During tofersen treatment, all patients showed a reduction of neurofilament light chain (NfL) serum levels, independent of the SOD1 variant. Patients with SOD1-ALS carrying R116G, D91A, or L145F variants show commonalities, but also differences in their clinical phenotype, including a faster progression rate with shorter survival in R116G, and a comparatively benign disease course in D91A carriers.

Summary: Background: In April 2023, the antisense oligonucleotide tofersen was approved by the U.S. Food and Drug Administration (FDA) for treatment of SOD1-amyotrophic lateral sclerosis (ALS), after a decrease of neurofilament light chain (NfL) levels had been demonstrated. Methods: Between 03/2022 and 04/2023, 24 patients with SOD1-ALS from ten German ALS reference centers were followed-up until the cut-off date for ALS functional rating scale revised (ALSFRS-R), progression rate (loss of ALSFRS-R/month), NfL, phosphorylated neurofilament heavy chain (pNfH) in cerebrospinal fluid (CSF), and adverse events. Findings: During the observation period, median ALSFRS-R decreased from 38.0 (IQR 32.0–42.0) to 35.0 (IQR 29.0–42.0), corresponding to a median progression rate of 0.11 (IQR −0.09 to 0.32) points of ALSFRS-R lost per month. Median serum NfL declined from 78.0 pg/ml (IQR 37.0–147.0 pg/ml; n = 23) to 36.0 pg/ml (IQR 22.0–65.0 pg/ml; n = 23; p = 0.02), median pNfH in CSF from 2226 pg/ml (IQR 1061–6138 pg/ml; n = 18) to 1151 pg/ml (IQR 521–2360 pg/ml; n = 18; p = 0.02). In the CSF, we detected a pleocytosis in 73% of patients (11 of 15) and an intrathecal immunoglobulin synthesis (IgG, IgM, or IgA) in 9 out of 10 patients. Two drug-related serious adverse events were reported. Interpretation: Consistent with the VALOR study and its Open Label Extension (OLE), our results confirm a reduction of NfL serum levels, and moreover show a reduction of pNfH in CSF. The therapy was safe, as no persistent symptoms were observed. Pleocytosis and Ig synthesis in CSF with clinical symptoms related to myeloradiculitis in two patients, indicate the potential of an autoimmune reaction. Funding: No funding was received towards this study.

Although investigation of the potential role of lysosomal storage disorders in Parkinson's disease (PD) has been ongoing since reports highlighted that Gaucher disease can be accompanied by parkinsonism,1for Fabry disease (FD), an X-linked recessive multisystem disorder caused by Galactosidase gene (GLA) mutations, the potential relationship to PD has not been studied until more recently2 and literature cited therein. Here, we report the frequency of GLA variants in 252 PD patients retrospectively selected from our database (mean age, 68.6 years; range, 33–93 years; 59.9% male). With the systematic sequence strategy applied, we found a mean α-galactosidase-A (GAL)-activity of 3.4 μM/h ± 1.44 μM/h (cutoff, <2,8 μM/h) and mean Lyso-globotriaosylsphingosine (Lyso-Gb3) levels of 3.6 ng/mL ±1.30 ng/mL (cutoff, >3.5 ng/mL). By bidirectional Sanger sequencing of all seven exons and flanking 5´untranslated region with at least 20 base pairs of flanking intronic sequences, we detected a total of 96 GLA variants in 57 individuals. None of these variants were classified as pathogenic/likely pathogenic for FD according to the American College of Medical Genetics and Genomics, inasmuch as most variants were intronic or in non-coding part of the gene.3 Most had similar mean allele frequencies (MAF), as reported in major genetic databases gnomAD.4 Nevertheless, two variants predicted to alter the GLA protein were detected in four patients (p.Asp182Asn and p.Asp313Tyr, both of uncertain significance). Of these, p.Asp313Tyr (MAF, 0.85%; MAF in general world population [GWP], 0.30%; P = 0.094; MAF in European Non-Finnish Population [ENFP], 0.45%; P = 0.209) drew our attention (Table 1). All three patients displayed clinical FD features predominantly involving the central nervous system and heart (Table 1), showing a lower mean GAL-activity of 2.3 μM/h ± 0.19 μM/h than cutoff (P = 0.001) and normal mean Lyso-Gb3 level of 3.0 ng/mL ±0.33 ng/mL (P = 0.197). Because p.Asp313Tyr formerly was considered to result in a “pseudodeficient allele” with a pH-dependent enzyme activity, it failed to be classified as clinically relevant or pathogenetic for FD. In recent literature, however, this opinion has shifted, as p.Asp313Tyr may cause predominantly FD nervous system manifestations associated with a milder phenotype and later disease onset—a hypothesis that our data support.5, 6 We performed a meta-analysis with a similarly-sized previous study,7 which screened 236 PD patients in a multistep approach, including GLA next generation sequencing in females and all males with abnormal GAL levels, thereby identifying four women with a p.Asp313Tyr variant. By merging the data, MAF of the GLA p.Asp313Tyr variant in PD patients clearly reached statistical significance (P = 0.006 compared to MAF of the GWP/alone P = 0.021; and P = 0.038 to ENFP/alone P = 0.068).7 In closing, ours is the first biochemically and genetically systematic study of FD in patients with PD. The limited sample size and the lack of a control group make it challenging to draw firm conclusions; nevertheless, we believe our study is meaningful because it highlights anew the possible link between the GLA p.Asp313Tyr variant and PD. Further studies involving larger cohorts are required because the possible pathogenetic role might influence monitoring of p.Asp313Tyr variant carriers and decisions involving potential enzyme replacement therapy. Open Access funding enabled and organized by Projekt DEAL. (1) Research project: A. Conception: Albert C. Ludolph, Kelly del Tredici, Jan Kassubek, Susanne Müller, B. Organization: Susanne Müller, C. Execution: Susanne Müller, Stephan T. Hold, Kathrin Müller; (2) Statistical Analysis: A. Design: Susanne Müller, Stephan T. Hold, Kathrin Müller, Axel Freischmidt, B. Execution: Susanne Müller, Stephan T. Hold, Kathrin Müller, Axel Freischmidt, C. Review and Critique: Susanne Müller, Stephan T. Hold, David C. Kasper, Kathrin Müller, Axel Freischmidt, Reiner Siebert, Benjamin Mayer; (3) Manuscript: A. Writing of the First Draft: Susanne Müller, Stephan T. Hold, Kathrin Müller, B. Review and Critique: Susanne Müller, Jan Kassubek, Benjamin Mayer, Kelly Del Tredici, Heiko Braak, Reiner Siebert, Albert C. Ludolph. Study design: Albert C. Ludolph, Kelly del Tredici, Jan Kassubek, Susanne Müller; execution: Susanne Müller; statistical analysis: Susanne Müller, Stephan T. Hold, David C. Kasper, Kathrin Müller, Axel Freischmidt, Reiner Siebert, Benjamin Mayer; writing: Susanne Müller, Stephan T. Hold, Kathrin Müller; editing of final manuscript version: Susanne Müller, Jan Kassubek, Benjamin Mayer, Kelly Del Tredici, Heiko Braak, Reiner Siebert, Albert C. Ludolph. S.T.H. is an employee of Archimedlife Science since February 2021. D.C.K. is an employee of ARCHIMED Life Science and is a stockholder in ARCHIMED Life Science. J.K. has received honoraria or consultation fees from AbbVie, Bial, Biogen, Desitin, Esteve, Licher MT, Medtronic, NeuroDerm, Novartis, STADA, UCB Pharma, and Zambon; in addition, he is Specialty Chief Editor in Frontiers in Neurology (section Applied Neuroimaging) and Associate Editor (Neurology) in Therapeutic Advances in Chronic Disease. A.C.L. is a member of Advisory Boards of Roche Pharma AG, Biogen, Alector, and Amylyx. He received compensation for talks from Biologix, the German Society of Neurology, Biogen, Springer Medicine, Amylyx, and the company Streamed Up! He is involved in trials that are sponsored by Amylyx, Ferrer International, Novartis Research and Development, Mitsubishi Tanabe, Apellis Pharmaceuticals, Alexion, Orion Pharma, the European Union, BMBF, Biogen, and Orphazyme. The remaining authors declare no competing interests. Data are available from the corresponding author upon individual request. Data S1. Supporting Information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Background The emergence of potentially effective new therapies for genetic forms of amyotrophic lateral sclerosis (ALS) necessitates the identification of biomarkers to facilitate early treatment, prior to the onset of motor symptoms. Here, we sought to investigate whether metabolic alterations are detectable in presymptomatic ALS gene mutation carriers, and whether such alterations precede neurofilament light chain (NfL) changes in serum.Methods Between 02/2014 and 11/2021, we prospectively studied 60 presymptomatic ALS gene mutation carriers (40% male, age 48.7 +/- 14.9; 28 C9orf72, 22 SOD1, 10 other) compared to 73 individuals from the same families (47% male, age 47.4 +/- 12.9) without pathogenic mutations as controls. Bioimpedance analysis (BIA) and indirect calorimetry were performed, and Body Mass Index (BMI), Fat Mass (FM), Body Fat Percentage, Body Water (BW), Lean Body Mass (LBM), Extracellular Mass (ECM), Body Cell Mass (BCM), ECM/BCM ratio, Cells Percentage, Phase Angle, Resting Metabolic Rate (RMR), Metabolic Ratio (MR), and NfL were measured. Participants and evaluators were blinded regarding gene carrier status.Findings Presymptomatic ALS gene carriers showed reduced LBM (p = 0.02), BCM (p = 0.004), Cells Percentage (p = 0.04), BW (p = 0.02), Phase Angle (p = 0.04), and increased ECM/BCM ratio (p = 0.04), consistently indicating a loss of metabolically active body cells. While in C9orf72 mutation carriers all tissue masses were reduced, only metabolically active tissue was affected in SOD1 mutation carriers. Unexpectedly, RMR (p = 0.009) and MR (p = 0.01) were lower in presymptomatic ALS gene carriers compared to non-carriers. NfL serum levels were similar in mutation carriers and non-carriers (p = 0.60).Interpretation The observed metabolic phenomena might reflect reduced physical activity and/or preemptive, insufficient compensatory mechanisms to prepare for the later hypermetabolic state. As pre-symptomatic biomarkers we propose ECM/BCM ratio and Phase Angle for SOD1, and a 4-compartment affection in BIA for C9orf72 mutation carriers.

Amyotrophic lateral sclerosis (ALS) has substantial heritability, in part shared with fronto-temporal dementia (FTD). We show that ALS heritability is enriched in splicing variants and in binding sites of 6 RNA-binding proteins including TDP-43 and FUS. A transcriptome wide association study (TWAS) identified 6 loci associated with ALS, including in NUP50 encoding for the nucleopore basket protein NUP50. Independently, rare variants in NUP50 were associated with ALS risk ( P = 3.71.10 −03 ; odds ratio = 3.29; 95%CI, 1.37 to 7.87) in a cohort of 9,390 ALS/FTD patients and 4,594 controls. Cells from one patient carrying a NUP50 frameshift mutation displayed a decreased level of NUP50. Loss of NUP50 leads to death of cultured neurons, and motor defects in Drosophila and zebrafish. Thus, our study identifies alterations in splicing in neurons as critical in ALS and provides genetic evidence linking nuclear pore defects to ALS.

An expansion of the GGGGCC hexanucleotide in the non-coding region of C9orf72 represents the most common cause of familial amyotrophic lateral sclerosis. The objective was to describe and analyse the clinical and genetic features of amyotrophic lateral sclerosis patients with C9orf72 mutations in a large population. Between November 2011 and December 2020, clinical and genetic characteristics of n = 248 patients with amyotrophic lateral sclerosis carrying C9orf72 mutations were collected from the clinical and scientific network of German motoneuron disease centres. Clinical parameters included age of onset, diagnostic delay, family history, neuropsychological examination, progression rate, phosphorylated neurofilament heavy chain levels in CSF and survival. The number of repeats was correlated with the clinical phenotype. The clinical phenotype was compared to n = 84 patients with SOD1 mutations and n = 2178 sporadic patients without any known disease-related mutations. Patients with C9orf72 featured an almost balanced sex ratio with 48.4% (n = 120) women and 51.6% (n = 128) men. The rate of 33.9% patients (n = 63) with bulbar onset was significantly higher compared to sporadic (23.4%, P = 0.002) and SOD1 patients (3.1%, P < 0.001). Of note, 56.3% (n = 138) of C9orf72, but only 16.1% of SOD1 patients reported a negative family history (P < 0.001). The GGGGCC hexanucleotide repeat length did not influence the clinical phenotypes. Age of onset (58.0, interquartile range 52.0-63.8) was later compared to SOD1 (50.0, interquartile range 41.0-58.0; P < 0.001), but earlier compared to sporadic patients (61.0, interquartile range 52.0-69.0; P = 0.01). Median survival was shorter (38.0 months) compared to SOD1 (198.0 months, hazard ratio 1.97, 95% confidence interval 1.34-2.88; P < 0.001) and sporadic patients (76.0 months, hazard ratio 2.34, 95% confidence interval 1.64-3.34; P < 0.001). Phosphorylated neurofilament heavy chain levels in CSF (2880, interquartile range 1632-4638 pg/ml) were higher compared to sporadic patients (1382, interquartile range 458-2839 pg/ml; P < 0.001). In neuropsychological screening, C9orf72 patients displayed abnormal results in memory, verbal fluency and executive functions, showing generally worse performances compared to SOD1 and sporadic patients and a higher share with suspected frontotemporal dementia. In summary, clinical features of patients with C9orf72 mutations differ significantly from SOD1 and sporadic patients. Specifically, they feature a more frequent bulbar onset, a higher share of female patients and shorter survival. Interestingly, we found a high proportion of patients with negative family history and no evidence of a relationship between repeat lengths and disease severity. Wiesenfarth et al. report that amyotrophic lateral sclerosis patients with C9orf72 mutations differ significantly from sporadic patients and SOD1 gene carriers, including a higher share of bulbar onset, female patients, more severe neuropsychological deficits and shorter survival. No evidence of a relationship between repeat lengths and disease severity was found.

Amyotrophic lateral sclerosis (ALS) is a fatal motoneuron disease with a monogenic cause in approximately 10% of cases. However, familial clustering of disease without inheritance in a Mendelian manner and the broad range of phenotypes suggest the presence of epigenetic mechanisms. Hence, we performed an epigenome-wide association study on sporadic, symptomatic and presymptomatic familial ALS cases with mutations in C9ORF72 and FUS and healthy controls studying DNA methylation in blood cells. We found differentially methylated DNA positions (DMPs) and regions embedding DMPs associated with either disease status, C9ORF72 or FUS mutation status. One DMP reached methylome-wide significance and is attributed to a region encoding a long non-coding RNA (LOC389247). Furthermore, we could demonstrate co-localization of DMPs with an ALS-associated GWAS region near the SCN7A/SCN9A and XIRP2 genes. Finally, a classifier model that predicts disease status (ALS, healthy) classified all but one presymptomatic mutation carrier as healthy, suggesting that the presence of ALS symptoms rather than the presence of ALS-associated genetic mutations is associated with blood cell DNA methylation.

Males with X-linked recessive spinobulbar muscular atrophy (SBMA) are reported to die suddenly and a Brugada electrocardiography (ECG) pattern may be present. A hallmark of this pattern is the presence of ST segment elevations in right precordial leads associated with an increased risk of sudden cardiac death. We aimed to detect subtle myocardial abnormalities using ECG and cardiovascular magnetic resonance imaging (CMR) in patients with SBMA. 30 SBMA patients (55.7 ± 11.9 years) and 11 healthy male controls underwent 12-lead ECGs were recorded using conventional and modified chest leads. CMR included feature-tracking strain analysis, late gadolinium enhancement and native T1 and T2 mapping. Testosterone levels were increased in 6/29 patients. Abnormal ECGs were recorded in 70%, consisting of a Brugada ECG pattern, early repolarization or fragmented QRS. Despite normal left ventricular ejection fraction (66 ± 5%), SBMA patients exhibited more often left ventricular hypertrophy as compared to controls (34.5% vs 20%). End-diastolic volumes were smaller in SBMA patients (left ventricular volume index 61.7 ± 14.7 ml/m2 vs. 79.1 ± 15.5 ml/m2; right ventricular volume index 64.4 ± 16.4 ml/m2 vs. 75.3 ± 17.5 ml/m2). Tissue characterization with T1-mapping revealed diffuse myocardial fibrosis in SBMA patients (73.9% vs. 9.1%, device-specific threshold for T1: 1030 ms). SBMA patients show abnormal ECGs and structural abnormalities, which may explain an increased risk of sudden death. These findings underline the importance of ECG screening, measurement of testosterone levels and potentially CMR imaging to assess cardiac risk factors.

The dose–effect of various SOD1 mutations on SOD1 enzymatic activity offers valuable insights into ALS pathogenesis with possible therapeutic implications. Homozygous SOD1 mutations, yet scarce, are of special interest. We report a novel homozygous SOD1 mutation with decreased enzymatic activity and severe early onset ALS phenotype. Whole exome sequencing and targeted screening of commonly implicated genes were conducted. Repeat-primed PCR and fragment length analysis were used for C9orf72. Bi-directional Sanger sequencing was used for SOD1 and other genes. SOD1 activity was measured by direct spectrophotometry. Serum neurofilament light chain level was measured by the ELLA immunoassay system. The homozygous patient for a novel SOD1 variant p.Ser69Pro showed poor SOD1 enzymatic activity (16% of controls) and an early onset ALS phenotype predominantly affecting lower motor neurons with rapid involvement of the trunk, upper limbs and bulbar muscles. The asymptomatic heterozygous relatives had at least 68% of normal enzyme activity. Level of serum neurofilament light chain was much higher (148 pg/ml) in the patient than the relatives who had normal levels (6–10 pg/ml). This novel mutation adds knowledge to the ALS genotype–phenotype spectrum and supports the strong dose–effect of SOD1 mutations associated with severely decreased enzymatic activity.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive upper and lower motor neuron (LMN) loss. As ALS and other neurodegenerative diseases share genetic risk factors, we performed whole-exome sequencing in ALS patients focusing our analysis on genes implicated in neurodegeneration. Thus, variants in the DHTKD1 gene encoding dehydrogenase E1 and transketolase domain containing 1 previously linked to 2-aminoadipic and 2-oxoadipic aciduria, Charcot-Marie-Tooth (CMT) disease type 2, and spinal muscular atrophy (SMA) were identified. In two independent European ALS cohorts (n = 643 cases), 10 sporadic cases of 225 (4.4%) predominantly sporadic patients of cohort 1, and 12 familial ALS patients of 418 (2.9%) ALS families of cohort 2 harbored 14 different rare heterozygous DHTKD1 variants predicted to be deleterious. Four DHTKD1 variants were previously described pathogenic variants, seven were recurrent, and eight were located in the E1_dh dehydrogenase domain. Nonsense variants located in the E1_dh domain were significantly more prevalent in ALS patients versus controls. The phenotype of ALS patients carrying DHTKD1 variants partially overlapped with CMT and SMA by presence of sensory impairment and a higher frequency of LMN-predominant cases. Our results argue towards rare heterozygous DHTKD1 variants as potential contributors to ALS phenotype and, possibly, pathogenesis.

ABSTRACTBackgroundCoding and noncoding repeat expansions are an important cause of neurodegenerative diseases.ObjectiveThis study determined the clinical and genetic features of a large German family that has been followed for almost 2 decades with an autosomal dominantly inherited spinocerebellar ataxia (SCA) and independent co‐occurrence of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD).MethodsWe carried out clinical examinations and telephone interviews, reviewed medical records, and performed magnetic resonance imaging and positron emission tomography scans of all available family members. Comprehensive genetic investigations included linkage analysis, short‐read genome sequencing, long‐read sequencing, repeat‐primed polymerase chain reaction, and Southern blotting.ResultsThe family comprises 118 members across seven generations, 30 of whom were definitely and five possibly affected. In this family, two different pathogenic mutations were found, a heterozygous repeat expansion in C9ORF72 in four patients with ALS/FTD and a heterozygous repeat expansion in DAB1 in at least nine patients with SCA, leading to a diagnosis of DAB1‐related ataxia (ATX‐DAB1; SCA37). One patient was affected by ALS and SCA and carried both repeat expansions. The repeat in DAB1 had the same configuration but was larger than those previously described ([ATTTT]≈75[ATTTC]≈40‐100[ATTTT]≈415). Clinical features in patients with SCA included spinocerebellar symptoms, sometimes accompanied by additional ophthalmoplegia, vertical nystagmus, tremor, sensory deficits, and dystonia. After several decades, some of these patients suffered from cognitive decline and one from additional nonprogressive lower motor neuron affection.ConclusionWe demonstrate genetic and clinical findings during an 18‐year period in a unique family carrying two different pathogenic repeat expansions, providing novel insights into their genotypic and phenotypic spectrums. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

OBJECTIVE:The only identified cause of amyotrophic lateral sclerosis (ALS) are mutations in a number of genes found in familial cases but also in sporadic cases. De novo mutations occurring in a parental gonadal cell, in the zygote or postzygotic during embryonal development can result in an apparently sporadic/isolated case of ALS later in life. We searched for de novo mutations in SOD1 as a cause of ALS.METHODS:We analysed peripheral-blood exome, genome and Sanger sequencing to identify deleterious mutations in SOD1 in 4000 ALS patients from Germany, South Korea and Sweden. Parental kinship was confirmed using highly polymorphic microsatellite markers across the genome. Medical genealogical and clinical data were reviewed and compared with the literature.RESULTS:We identified four sporadic ALS cases with de novo mutations in SOD1. They aggregate in hot-spot codons earlier found mutated in familial cases. Their phenotypes match closely what has earlier been reported in familial cases with pathogenic mutations in SOD1. We also encountered familial cases where de novo mutational events in recent generations may have been involved.CONCLUSIONS:De novo mutations are a cause of sporadic ALS and may also be underpinning smaller families with few affected ALS cases. It was not possible to ascertain if the origin of the de novo mutations was parental germline, zygotic or postzygotic during embryonal development. All ALS patients should be offered genetic counselling and genetic screening, the challenges of variant interpretation do not outweigh the potential benefits including earlier confirmed diagnosis and possible bespoken therapy.

Mutations in FUS and TBK1 often cause aggressive early-onset amyotrophic lateral sclerosis (ALS) or a late-onset ALS and/or frontotemporal dementia (FTD) phenotype, respectively. Co-occurrence of mutations in two or more Mendelian ALS/FTD genes has been repeatedly reported. However, little is known how two pathogenic ALS/FTD mutations in the same patient interact to shape the final phenotype. We screened 28 ALS patients with a known FUS mutation by whole-exome sequencing and targeted evaluation for mutations in other known ALS genes followed by genotype–phenotype correlation analysis of FUS/TBK1 double-mutant patients. We report on new and summarize previously published FUS and TBK1 double-mutant ALS/FTD patients and their families. We found that, within a family, mutations in FUS cause ALS while TBK1 single mutations are observed in FTD patients. FUS/TBK1 double mutations manifested as ALS and without a manifest difference regarding age at onset and disease duration when compared to FUS single-mutant individuals. In conclusion, TBK1 and FUS variants do not seem to interact in a simple additive way. Rather, the phenotype of FUS/TBK1 double-mutant patients appears to be dominated by the FUS mutation.

Objective The clinical manifestation of amyotrophic lateral sclerosis (ALS) is characterized by motor neuron degeneration, whereas frontotemporal dementia (FTD) patients show alterations of behavior and cognition. Both share repeat expansions in C9orf72 as the most prevalent genetic cause. Before disease-defining symptoms onset, structural and functional changes at cortical level may emerge in C9orf72 carriers. Here, we characterized oculomotor parameters and their association to neuropsychological domains in apparently asymptomatic individuals with mutations in ALS/FTD genes. Patients and methods Forty-eight carriers of ALS genes, without any clinical symptoms underwent video-oculographic examination, including 22 subjects with C9orf72 mutation, 17 with SOD1, and 9 with other ALS associated gene mutations (n = 3 KIF5A; n = 3 FUS/FUS + TBK1; n = 1 NEK1; n = 1 SETX; n = 1 TDP43). A total of 17 subjects underwent a follow-up measurement. Data were compared to 54 age- and gender-matched healthy controls. Additionally, mutation carriers performed a neuropsychological assessment. Results In comparison to controls, the presymptomatic subjects performed significantly worse in executive oculomotor tasks such as the ability to perform correct anti-saccades. A gene mutation subgroup analysis showed that dysfunctions in C9orf72 carriers were much more pronounced than in SOD1 carriers. The anti-saccade error rate of ALS mutation carriers was associated with cognitive deficits: this correlation was increased in subjects with C9orf72 mutation, whereas SOD1 carriers showed no associations. Conclusion In C9orf72 carriers, executive eye movement dysfunctions, especially the increased anti-saccade error rate, were associated with cognitive impairment and unrelated to time. These oculomotor impairments are in support of developmental deficits in these mutations, especially in prefrontal areas.

Background: The gene coding the Cu/Zn superoxide dismutase ( SOD1 ) was the first-identified causative gene of amyotrophic lateral sclerosis (ALS), and the second most common genetic cause for ALS worldwide. The promising therapeutic approaches targeting SOD1 mutations are on the road. The purpose of the present study was to compare the mutational and clinical features of Chinese and German patients with ALS carrying mutations in SOD1 gene, which will facilitate the strategy and design of SOD1 -targeted trials. Methods: Demographic and clinical characteristics were collected from two longitudinal cohorts in China and Germany. Chinese and German patients carrying SOD1 mutations were compared with regard to mutational distribution, age of onset, site of onset, body mass index (BMI) at diagnosis, diagnostic delay, progression rate, and survival. Results: A total of 66 Chinese and 84 German patients with 69 distinct SOD1 mutations were identified. The most common mutation in both populations was p.His47Arg. It was found in 8 Chinese and 2 German patients and consistently showed a slow progression of disease in both countries. Across all mutations, Chinese patients showed a younger age of onset (43.9 vs 49.9 years, p=0.002), a higher proportion of young-onset cases (62.5% vs 30.7%, p<0.001) and a lower BMI at diagnosis (22.8 vs 26.0, p<0.001) compared to German patients. Although riluzole intake was less frequent in Chinese patients (28.3% vs 81.3%, p<0.001), no difference in survival between populations was observed (p=0.90). Across both cohorts, female patients had a longer diagnostic delay (15.0 vs 11.0 months, p=0.01) and a prolonged survival (248.0 vs 60.0 months, p=0.005) compared to male patients. Conclusions: Our data demonstrate the distinct mutational and clinical spectrums of SOD1 -mutant patients in Asian and European populations. Clinical phenotypes seem to be primarily influenced by mutation-specific, albeit not excluding ethnicity-specific factors. Further large-scale transethnical studies are needed to clarify determinants and modifiers of SOD1 phenotypes.

AbstractThe genetic basis of amyotrophic lateral sclerosis (ALS) is still incompletely understood. Using two independent genetic strategies, we show here that a large part of ALS heritability lies in genes expressed in inhibitory and excitatory neurons, especially at splicing sites regulated by a defined set of RNA binding proteins including TDP-43 and FUS. We conducted a transcriptome wide association study (TWAS) and identified 59 loci associated with ALS, including 14 previously identified genes, some of them not previously reaching significance in genome wide association studies. Among the 45 novel genes, several genes are involved in pathways known to be affected in ALS such as mitochondrial metabolism (including ATP5H, ATP5D, BCS1L), proteostasis (including COPS7A, G2E3, TMEM175, USP35) or gene expression and RNA metabolism (including ARID1B, ATXN3, PTBP2, TAF10). Interestingly, decreased expression of NUP50, a constrained gene encoding a nuclear pore basket protein, was associated with ALS in TWAS (Zscore = −4, FDR = 0.034). 11 potentially pathogenic variants (CADD score > 20) in 23 patients were identified in the NUP50 gene, most of them in the region of the protein mediating interaction with Importin alpha, and including 2 frameshift mutations. In cells from two patients carrying NUP50 variants, we showed decreased levels of NUP50 protein. Importantly, knocking down Nup50 led to increased neuronal death associated with p62 and nucleoporin inclusions in cultured neurons, and motor defects in Drosophila and zebrafish models. In all, our study identifies alterations in splicing in neurons as a critical pathogenic process in ALS, uncovers several new loci potentially contributing to ALS missing heritability, and provides genetic evidence linking nuclear pore defects to ALS.

Several studies reported amyotrophic lateral sclerosis (ALS)-linked mutations in TBK1, OPTN, VCP, UBQLN2, and SQSTM1 genes encoding proteins involved in autophagy. SQSTM1 was originally identified by a candidate gene approach because it encodes p62, a multifunctional protein involved in protein degradation both through proteasomal regulation and autophagy. Both p62 and optineurin (encoded by OPTN) are direct interaction partners and substrates of TBK1, and these 3 proteins form the core of a genetic and functional network that may connect autophagy with ALS. Considering the molecular and conceptual relevance of the TBK1/OPTN/SQSTM1 "triangle," we here performed a targeted screen for SQSTM1 variants in 486 patients with familial ALS from Germany and Sweden by analyzing whole-exome sequencing data. We report 9 novel and 5 previously reported rare variants in SQSTM1 and discuss the current evidence for SQSTM1 as a primary disease gene for ALS. We conclude that the evidence for causality remains vague for SQSTM1 and is weaker than for the other autophagy genes, for example, TBK1 and OPTN.