Amyotrophic Lateral Sclerosis Pedigrees Research Articles

A rare genetic variant in APEX1 is associated with familial amyotrophic lateral sclerosis with slow progression.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by loss of motor neurons and progressive muscle weakness. We aimed to identify the pathogenic genetic variants in familial ALS (fALS) pedigrees and to elucidate their impact on the disease phenotype. Through the analysis of whole-genome sequencing data of 34 fALS probands that screened negative for mutations in the most common ALS-causing genes, we identified a rare missense variant in APEX1 (NM_001641.4: c.22G > A, p.Gly8Arg) associated with ALS in one pedigree. Fluorescence microscopy images using green fluorescent protein (GFP)-fusion proteins suggested that this amino acid substitution could cause an impairment in nuclear localization of the protein. We described the clinical characteristics of this cohort analyzed and found that patients carrying this variant exhibit lower motor neuron onset and prolonged survival. The relation between APEX1 and ALS occurrence has been elusive despite evidence of a neuroprotective role for the gene. This study provides evidence linking an APEX1 variant with fALS and information on the distinct clinical manifestation. This study contributes to the understanding of the genetic basis of ALS, as well as a potential mechanism leading to loss of neurons, highlighting possible opportunities of targeted treatment harnessing the DNA repair process or ameliorating the oxidative stress.

C9orf72 Repeat Expansion Discordance in 6 Multigenerational Kindreds.

A hexanucleotide repeat expansion in the noncoding region of the C9orf72 gene is the most common genetically identifiable cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia in populations of European ancestry. Pedigrees associated with this expansion exhibit phenotypic heterogeneity and incomplete disease penetrance, the basis of which is poorly understood. Relatives of those carrying the C9orf72 repeat expansion exhibit a characteristic cognitive endophenotype independent of carrier status. To examine whether additional shared genetic or environmental risks within kindreds could compel this observation, we have conducted a detailed cross-sectional study of the inheritance within multigenerational Irish kindreds carrying the C9orf72 repeat expansion. One hundred thirty-one familial ALS pedigrees, 59 of which carried the C9orf72 repeat expansion (45.0% [95% CI 36.7-53.5]), were identified through the Irish population-based ALS register. C9orf72 genotyping was performed using repeat-primed PCR with amplicon fragment length analysis. Pedigrees were further investigated using SNP, targeted sequencing data, whole-exome sequencing, and whole-genome sequencing. We identified 21 kindreds where at least 1 family member with ALS carried the C9orf72 repeat expansion and from whom DNA was available from multiple affected family members. Of these, 6 kindreds (28.6% [95% CI 11.8-48.3]) exhibited discordant segregation. The C9orf72 haplotype was studied in 2 families and was found to segregate with the C9orf72-positive affected relative but not the C9orf72-negative affected relative. No other ALS pathogenic variants were identified within these discordant kindreds. Family members of kindreds associated with the C9orf72 repeat expansion may carry an increased risk of developing ALS independent of their observed carrier status. This has implications for assessment and counseling of asymptomatic individuals regarding their genetic risk.

Atypical TDP-43 protein expression in an ALS pedigree carrying a p.Y374X truncation mutation in TARDBP.

We describe an autosomal dominant, multi-generational, amyotrophic lateral sclerosis (ALS) pedigree in which disease co-segregates with a heterozygous p.Y374X nonsense mutation within TDP-43. Mislocalization of TDP-43 and formation of insoluble TDP-43-positive neuronal cytoplasmic inclusions is the hallmark pathology in >95% of ALS patients. Neuropathological examination of the single case for which CNS tissue was available indicated typical TDP-43 pathology within lower motor neurons, but classical TDP-43-positive inclusions were absent from motor cortex. The mutated allele is transcribed and translated in patient fibroblasts and motor cortex tissue, but overall TDP-43 protein expression is reduced compared to wild-type controls. Despite absence of TDP-43-positive inclusions we confirmed deficient TDP-43 splicing function within motor cortex tissue. Furthermore, urea fractionation and mass spectrometry of motor cortex tissue carrying the mutation revealed atypical TDP-43 protein species but not typical C-terminal fragments. We conclude that the p.Y374X mutation underpins a monogenic, fully penetrant form of ALS. Reduced expression of TDP-43 combined with atypical TDP-43 protein species and absent C-terminal fragments extends the molecular phenotypes associated with TDP-43 mutations and with ALS more broadly. Future work will need to include the findings from this pedigree in dissecting the mechanisms of TDP-43-mediated toxicity.

Phenotype of VCP Mutations in Chinese Amyotrophic Lateral Sclerosis Patients.

Mutations in the valosin-containing protein (VCP) gene have been linked to amyotrophic lateral sclerosis (ALS) in the Caucasian populations. However, the phenotype of VCP mutations in Chinese patients with (ALS) remains unclear. Targeted next-generation sequencing covered 28 ALS-related genes including the VCP gene was undertaken to screen in a Chinese cohort of 275 sporadic ALS cases and 15 familial ALS pedigrees. An extensive literature review was performed to identify all patients with ALS carrying VCP mutations previously reported. The clinical characteristics and genetic features of ALS patients with VCP mutations were reviewed. One known p.R155C mutation in the VCP gene was detected in two siblings from a familial ALS pedigree and two sporadic individuals. In addition, the same VCP p.R155C mutation was detected in an additional patient with ALS referred in 2021. Three patients with VCP p.R155C mutation presented with muscular weakness starting from proximal extremities to distal extremities. The other patient developed a phenotype of Paget's disease of bone in addition to the progressive muscular atrophy. We reported the first VCP mutation carrier manifesting ALS with Paget's disease of bone in the Chinese population. Our findings expand the phenotypic spectrum of the VCP mutations in Chinese patients with ALS and suggest that ALS patients with VCP p.R155C mutations tend to present with relatively young onset, symmetrical involvement of proximal muscles weakness of arms or legs, and then progressed to distal muscles of limbs.

Application of Hepatocyte Growth Factor for Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disorder characterized by the death of upper and lower motor neurons. About 10% of all ALS cases are familial, and we have identified SOD1 and FUS mutations as the most common causes in a consecutive series of 111 familial ALS pedigrees in Japan (Nishiyama A, 2017). From studies of the TDP43, FUS, and C9orf72 genes, perturbations of RNA processing can be highly adverse in motor neurons. Hepatocyte growth factor (HGF) is one of the most potent survival-promoting factors for motor neurons. We administered human recombinant HGF (hrHGF) by continuous intrathecal delivery to transgenic rats at onset of paralysis for 4 weeks. Intrathecal administration of hrHGF attenuated motor neuron degeneration and prolonged the duration of the disease by 63% (Ishigaki A, 2007). To translate this strategy to human treatment, we induced a contusive cervical spinal cord injury in the common marmoset, a primate, and then administered hrHGF intrathecally. We conducted a first-in-human phase I trial of intrathecal hrHGF in 15 Japanese patients with ALS (Warita H, 2019). Based on the results, we are conducting a phase II trial of intrathecal hrHGF for patients with ALS.

Mutations in the Glycosyltransferase Domain of GLT8D1 Cause Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disorder without effective neuroprotective therapy. Known genetic variants impair pathways including RNA processing, axonal transport and protein homeostasis. Here we report mutations in a new ALS gene encoding the glycosyltransferase GLT8D1; this class of proteins has not previously been associated with neurodegeneration. Exome sequencing in an autosomal dominant ALS pedigree identified p.R92C mutations in GLT8D1 which co-segregate with disease. Sequencing of local and international cohorts demonstrated significant ALS-association in the same exon, including additional rare deleterious mutations in conserved amino acids. Mutations are associated with the substrate binding site and R92C reduces GLT8D1 enzyme activity ~2-fold. Mutated GLT8D1 exhibits in vitro cytotoxicity and induces motor deficits in zebrafish consistent with ALS. Relative toxicity of mutations in model systems mirrors clinical severity. In conclusion, we have discovered a previously uncharacterised pathophysiological pathway for ALS caused by inherited mutations within a glycosyltransferase enzyme.

Comprehensive targeted next-generation sequencing in Japanese familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterized by loss of motor neurons. We have recently identified SOD1 and FUS mutations as the most common causes in a consecutive series of 111 familial ALS pedigrees in Japan. To reveal possible genetic causes for the remaining 51 patients with familial ALS (45 pedigrees), we performed targeted next-generation sequencing of 35 known ALS/motor neuron diseases-related genes. Known variants in ANG, OPTN, SETX, and TARDBP were identified in 6 patients. A novel likely pathogenic homozygous variant in ALS2 was identified in 1 patient. In addition, 18 patients harbored 1–3 novel variants of uncertain significance, whereas hexanucleotide repeat expansions in C9ORF72 were not detected using repeat-primed polymerase chain reaction. Collectively, in our Japanese cohort, the frequencies of SOD1, FUS, SETX, TARDBP, ANG, and OPTN variants were 32%, 11%, 2%, 2%, 1%, and 1%, respectively. These findings indicate considerable differences in the genetic variations associated with familial ALS across populations. Further genetic analyses and functional studies of novel variants are warranted.

A novel 10-base pair insertion mutation in exon 5 of the SOD1 gene in a Chinese family with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult-onset, progressive, fatal neurodegenerative disease. Several genes are associated with ALS. Copper-zinc superoxide dismutase 1 (SOD1) is one of the most commonly mutated genes in ALS, and more than 160 mutations in SOD1 have been reported. We reported a novel heterozygous insertion mutation that led to a frameshift and a premature termination at position 136 in exon 5 of the SOD1 gene (c.392_393insGCAAAGGTGG; p.N132Qfs*5) in a Chinese familial ALS pedigree. This mutation in the pedigree demonstrated an autosomal dominant pattern of inheritance and a phenotype characterized by an early onset (approximately 34 years old) with a relatively rapid course (approximately 2 years) and limb onset with respiratory involvement. The clinical feature of the p.N132Qfs*5 mutation was nearly identical to a previously reported mutation (Gly127insTGGG). Experiments in G127X mice demonstrated that the G127X mutation was pathogenic. SOD1 activity in the p.N132Qfs*5 mutation carriers in the family decreased significantly compared with normal family members. In conclusion, we identified a novel SOD1 mutation in an ALS family, which is an important addition to the catalog of SOD1 mutations in ALS.

Identification of a novel missense (C7W) mutation of SOD1 in a large familial amyotrophic lateral sclerosis pedigree

Mutations of Cu-Zn superoxide dismutase (SOD1) have rarely been identified in Chinese patients with amyotrophic lateral sclerosis (ALS). We recently initiated a program to screen mutations of SOD1, TARDBP, and C9orf72 genes, the most commonly mutated genes in ALS patients in Western countries, in Chinese ALS patients. In this study, we report a novel missense SOD1 mutation with a substitution of tryptophan for cysteine at the seventh amino acid (p.C7W, traditionally named p.C6W) based on HUGO Gene Nomenclature in a familial ALS pedigree. We also found that the activities of SOD1 were significantly decreased in the C7W patient and the carriers of the family, compared with the SOD1 activities of normal family members. Compared with reported C7G and C7S patients, analysis of phenotype revealed relatively mild disease phenotypes in C7W patients, which is correlated with less deteriorated alteration in protein structure. Like those of many other familial ALS families, variable clinical phenotypes in the C7W intrafamily suggest that potential genetic modifiers may contribute to this disease.

Screening of the TARDBP gene in familial and sporadic amyotrophic lateral sclerosis patients of Chinese origin

TAR DNA-binding protein (TARDBP) mutations have been reported in patients with amyotrophic lateral sclerosis (ALS) in different populations. Only a few studies have screened for TARDBP mutations in Chinese populations. Here, we sequenced the coding region of all five TARDBP exons for mutations in 13 familial ALS (FALS) pedigrees and 312 sporadic ALS (SALS) patients of Chinese origin, as well as 245 healthy control subjects. Two heterozygous missense mutations, c.875G>A (p.S292N) and c.1043G>T (p.G348V), were identified in two and one SALS patients, respectively. One synonymous substitution, c.1098C>G (p.A366A), was identified in two SALS patients. None of the substitutions were found in healthy control subjects. In Chinese populations, the estimated frequency of TARDBP mutations in SALS patients (0.73%) is higher than Japanese and lower than White populations, whereas the estimated mutation frequency in superoxide dismutase 1 (SOD1)-negative FALS patients (15.2%) is higher than both Japanese and White populations. Our findings provide an overview of the occurrence of TARDBP mutations in Chinese ALS patients and highlight the importance of TARDBP mutation screening in Chinese ALS patients.

Identification of a novel missense mutation in angiogenin in a Chinese amyotrophic lateral sclerosis cohort

Abstract Angiogenin (ANG) gene mutations have been identified in both familial and sporadic amyotrophic lateral sclerosis (ALS) patients from multiple European and North American populations. However, no ANG mutation has yet been reported in Asian ALS populations. Here, we screened for ANG mutations in a Chinese ALS cohort. The entire coding region of the ANG gene was sequenced in 10 familial ALS pedigrees, 202 sporadic ALS patients, and 151 healthy controls. All patients were negative for SOD1, FUS, and TARDBP mutations. We identified a novel missense mutation, c.379G > A (p.V103I), in one sporadic ALS patient, but not in the controls. No mutations were found in the familial ALS patients. A novel missense variant, c.323A > G (p.H84R), was detected in one healthy individual. We identified the presence of the known single nucleotide polymorphism, rs11701 (T/G), in both ALS cases and controls. However, no significant association of the G allele with ALS susceptibility was demonstrated. In conclusion, ANG mutations accounted for 0.5% of our SOD1-, FUS-, TARDBP- mutation-negative ALS cohort. Our findings highlight that the genetic background of ALS differs between different populations, and suggest that ANG mutation may be involved in the aetiology of ALS in the Han Chinese population.

Whole-genome sequencing reveals a coding non-pathogenic variant tagging a non-coding pathogenic hexanucleotide repeat expansion in C9orf72 as cause of amyotrophic lateral sclerosis

Motor neuron degeneration in amyotrophic lateral sclerosis (ALS) has a familial cause in 10% of patients. Despite significant advances in the genetics of the disease, many families remain unexplained. We performed whole-genome sequencing in five family members from a pedigree with autosomal-dominant classical ALS. A family-based elimination approach was used to identify novel coding variants segregating with the disease. This list of variants was effectively shortened by genotyping these variants in 2 additional unaffected family members and 1500 unrelated population-specific controls. A novel rare coding variant in SPAG8 on chromosome 9p13.3 segregated with the disease and was not observed in controls. Mutations in SPAG8 were not encountered in 34 other unexplained ALS pedigrees, including 1 with linkage to chromosome 9p13.2–23.3. The shared haplotype containing the SPAG8 variant in this small pedigree was 22.7 Mb and overlapped with the core 9p21 linkage locus for ALS and frontotemporal dementia. Based on differences in coverage depth of known variable tandem repeat regions between affected and non-affected family members, the shared haplotype was found to contain an expanded hexanucleotide (GGGGCC)n repeat in C9orf72 in the affected members. Our results demonstrate that rare coding variants identified by whole-genome sequencing can tag a shared haplotype containing a non-coding pathogenic mutation and that changes in coverage depth can be used to reveal tandem repeat expansions. It also confirms (GGGGCC)n repeat expansions in C9orf72 as a cause of familial ALS.

Screening of the FUS gene in familial and sporadic amyotrophic lateral sclerosis patients of Chinese origin

According to studies in European, North American, Australian, and Asian populations, FUS gene mutations occur in 0.6-20.2% of the patients with familial amyotrophic lateral sclerosis (ALS) and 0.4-2.0% of sporadic ALS cases. In China, FUS mutations have been reported in several familial ALS pedigrees but not in sporadic ALS cases. Here, we screened for FUS mutations in Chinese patients with ALS. We sequenced all of the 15 exons of FUS in 10 familial ALS pedigrees, exons 5, 6, 14, and 15 in 210 patients with sporadic ALS and 151 healthy controls. All patients were negative for SOD1, TARDBP, and ANG mutations. A c.1562G>T (p.R521L) missense mutation was identified in one familial ALS proband and her asymptomatic daughter. A c.1562G>A (p.R521H) missense mutation was identified in two patients with sporadic ALS. Three synonymous mutations (c.453C>T, c.648C>T, and c.1464C>T) were detected among four patients with sporadic ALS, and a untranslated region variant (*14C>T) was identified in one familial ALS proband and one patient with sporadic ALS. The frequency of FUS mutations is approximately 1.0% in our SOD1-, ANG-, TARDBP-mutation-negative sporadic ALS cohort and similar to that reported in previous studies from Asia in our familial ALS cohort. [Correction added on 31 May 2012, after first online publication: the gene FUS- was changed to ANG-]. Our findings provide an overview of the occurrence of FUS mutations in Chinese sporadic and familial ALS cases and highlight the importance of screening for FUS mutations in ALS patients of Chinese origin.

Four familial ALS pedigrees discordant for two SOD1 mutations: are all SOD1 mutations pathogenic?

Background153 mutations in the Cu/Zn superoxide dismutase (SOD1) gene have been claimed to be associated with amyotrophic lateral sclerosis (ALS) in familial and sporadic ALS in an autosomal dominant or...

The occurrence of mutations in FUS in a Belgian cohort of patients with familial ALS

Mutations in fused in sarcoma (FUS) were recently identified as a cause of familial amyotrophic lateral sclerosis (ALS). The frequency of occurrence of mutations in FUS in sets of patients with familial ALS remains to be established. We sequenced the FUS gene in a cohort of patients with familial ALS seen at the neuromuscular clinic in Leuven. A total of 28 patients with SOD1-negative ALS from 22 families were analyzed. We identified a R521H mutation in 4 patients, belonging to a kindred of dominantly inherited classical ALS. The mutation segregated with disease. Mutations in FUS were observed in 2.9% of ALS pedigrees in our cohort. These results show that mutations in FUS are also a significant cause of familial ALS in Belgium.

Mutations in CHMP2B in Lower Motor Neuron Predominant Amyotrophic Lateral Sclerosis (ALS)

BackgroundAmyotrophic lateral sclerosis (ALS), a common late-onset neurodegenerative disease, is associated with fronto-temporal dementia (FTD) in 3–10% of patients. A mutation in CHMP2B was recently identified in a Danish pedigree with autosomal dominant FTD. Subsequently, two unrelated patients with familial ALS, one of whom also showed features of FTD, were shown to carry missense mutations in CHMP2B. The initial aim of this study was to determine whether mutations in CHMP2B contribute more broadly to ALS pathogenesis.Methodology/Principal FindingsSequencing of CHMP2B in 433 ALS cases from the North of England identified 4 cases carrying 3 missense mutations, including one novel mutation, p.Thr104Asn, none of which were present in 500 neurologically normal controls. Analysis of clinical and neuropathological data of these 4 cases showed a phenotype consistent with the lower motor neuron predominant (progressive muscular atrophy (PMA)) variant of ALS. Only one had a recognised family history of ALS and none had clinically apparent dementia. Microarray analysis of motor neurons from CHMP2B cases, compared to controls, showed a distinct gene expression signature with significant differential expression predicting disassembly of cell structure; increased calcium concentration in the ER lumen; decrease in the availability of ATP; down-regulation of the classical and p38 MAPK signalling pathways, reduction in autophagy initiation and a global repression of translation. Transfection of mutant CHMP2B into HEK-293 and COS-7 cells resulted in the formation of large cytoplasmic vacuoles, aberrant lysosomal localisation demonstrated by CD63 staining and impairment of autophagy indicated by increased levels of LC3-II protein. These changes were absent in control cells transfected with wild-type CHMP2B.Conclusions/SignificanceWe conclude that in a population drawn from North of England pathogenic CHMP2B mutations are found in approximately 1% of cases of ALS and 10% of those with lower motor neuron predominant ALS.We provide a body of evidence indicating the likely pathogenicity of the reported gene alterations. However, absolute confirmation of pathogenicity requires further evidence, including documentation of familial transmission in ALS pedigrees which might be most fruitfully explored in cases with a LMN predominant phenotype.

Variation in aggregation propensities among ALS-associated variants of SOD1: Correlation to human disease

To date, 146 different mutations in superoxide dismutase 1 (SOD1) have been identified in patients with familial amyotrophic lateral sclerosis (ALS). The mean age of disease onset in patients inheriting mutations in SOD1 is 45–47 years of age. However, although the length of disease duration is highly variable, there are examples of consistent disease durations associated with specific mutations (e. g. A4V, less than 2 years). In the present study, we have used a large set of data from SOD1-associated ALS pedigrees to identify correlations between disease features and biochemical/biophysical properties of more than 30 different variants of mutant SOD1. Using a reliable cell culture assay, we show that all ALS-associated mutations in SOD1 increase the inherent aggregation propensity of the protein. However, the relative propensity to do so varied considerably among mutants. We were not able to explain the variation in aggregation rates by differences in known protein properties such as enzyme activity, protein thermostability, mutation position or degree of change in protein charge. Similarly, we were not able to explain variability in the duration of disease in SOD1-associated ALS pedigrees by these properties. However, we find that the majority of pedigrees in which patients exhibit reproducibly short disease durations are associated with mutations that show a high inherent propensity to induce aggregation of SOD1.

Primary lateral sclerosis may occur within familial amyotrophic lateral sclerosis pedigrees

Primary lateral sclerosis may occur within familial amyotrophic lateral sclerosis pedigrees