A novel P66S mutation in exon 3 of the SOD1 gene with early onset and rapid progression

Clinical and molecular features of patients with amyotrophic lateral sclerosis and SOD1 mutations: a monocentric study

Introduction

SOD1 was the first gene associated with both familial and sporadic forms of amyotrophic lateral sclerosis (ALS) and is the second most mutated gene in Caucasian ALS patients. Given their high clinical and molecular heterogeneity, a detailed characterization of SOD1-ALS patients could improve knowledge about the natural history of this disease. Here, the authors aimed to provide a clinical and molecular description of a monocentric cohort of SOD1-ALS patients.

Methods

Amyotrophic lateral sclerosis (ALS) patients referring to the neurology unit of our center between 2008 and 2021 were clinically assessed and underwent molecular testing for SOD1. Segregation studies in available family members and in silico analysis were performed to sustain the pathogenicity of the identified SOD1 variants.

Results

Among the 576 patients in our cohort, we identified 19 individuals harboring a mutation in SOD1 (3.3%), including 15 (78.9%) with a familial and four (21.1%) with a sporadic form. The spinal onset of the disease was observed in all patients, and survival was extremely variable, ranging from 8 months to over 30 years. Twelve different SOD1 missense variants were identified in our cohort, including one novel mutation (p.Pro67Leu).

Discussion

In the present series, we provided the first description of an Italian monocentric cohort of SOD1-ALS patients, and we expanded the repertoire of SOD1 mutations. Our cohort presents several remarkable features, including variable expressivity in the same family, atypical presentation (ataxia, cognitive impairment, and other extra-motor symptoms), and different modes of inheritance of a given mutation in the same family. Given the recent authorization of SOD1-directed antisense oligonucleotide for use in SOD1-ALS patients, we recommend prompt screening for SOD1 mutations in novel ALS patients with familiar or sporadic presentations.

Compound heterozygous P67S/D91A SOD1 mutations in an ALS family with apparently sporadic case

Objectives: To describe a family with heterozygous P67S and D91A SOD1 mutations. Methods: The ALS profile of the proband was described. SOD1 gene sequencing was performed in the proband and his children. Results: The affected individual presented with progressive left peripheral facial palsy and slow progression with late limb involvement. Unequivocal upper and lower motor neuron signs were present, together with diffuse denervation at myography. The absence of trigeminal involvement excluded a FOSMN syndrome. Pedigree analysis did not show any other ALS case in the family. Genetic analysis of this patient showed P67S and D91A SOD1 mutations. The genetic analysis of the children showed that the mutations were each one carried by a different chromosome. Conclusions: P67S SOD1 mutation has been described in several ALS cases, either with familial or apparently sporadic ALS. The mutation is located in a mutational hotspot and was predicted pathogenic by in silico prediction software. The study of phylogenetic data show that at this codon, the proline is highly conserved throughout species reinforcing causality. Conversely, the D91A variant is known to have a recessive influence. Unilateral motor facial involvement, even after several years, in an ALS patient is unusual. The present case with compound heterozygosity and unusual onset in a patient with apparently sporadic ALS, widens the clinical spectrum of the disease and adds further arguments to support the systematic genetic screening of all ALS cases in referral ALS clinics.

Juvenile Amyotrophic Lateral Sclerosis: A Review

Juvenile amyotrophic lateral sclerosis (JALS) is a rare group of motor neuron disorders with gene association in 40% of cases. JALS is defined as onset before age 25. We conducted a literature review of JALS and gene mutations associated with JALS. Results of the literature review show that the most common gene mutations associated with JALS are FUS, SETX, and ALS2. In familial cases, the gene mutations are mostly inherited in an autosomal recessive pattern and mutations in SETX are inherited in an autosomal dominant fashion. Disease prognosis varies from rapidly progressive to an indolent course. Distinct clinical features may emerge with specific gene mutations in addition to the clinical finding of combined upper and lower motor neuron degeneration. In conclusion, patients presenting with combined upper and lower motor neuron disorders before age 25 should be carefully examined for genetic mutations. Hereditary patterns and coexisting features may be useful in determining prognosis.

Clinical and Molecular Landscape of ALS Patients with SOD1 Mutations: Novel Pathogenic Variants and Novel Phenotypes. A Single ALS Center Study

Mutations in the copper zinc superoxide dismutase 1 (SOD1) gene are the second most frequent cause of familial amyotrophic lateral sclerosis (ALS). Nearly 200 mutations of this gene have been described so far. We report all SOD1 pathogenic variants identified in patients followed in the single ALS center of Lyon, France, between 2010 and 2020. Twelve patients from 11 unrelated families are described, including two families with the not yet described H81Y and D126N mutations. Splice site mutations were detected in two families. We discuss implications concerning genetic screening of SOD1 gene in familial and sporadic ALS.

The Occurrence of FUS Mutations in Pediatric Amyotrophic Lateral Sclerosis: A Case Report and Review of the Literature

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease affecting both upper and lower motor neurons and leading to progressive paralysis. Most cases are sporadic, and the symptoms generally begin in the sixth or seventh decade. Juvenile ALS appears in a rare subgroup of patients with onset before the age of 25 years old. Contrary to the classical adult phenotype where 90% of cases are sporadic, most cases of juvenile ALS are caused by a genetic mutation in either SOD1 (superoxide dismutase one), SETX (senataxin), or FUS (fused in sarcoma). In the pediatric population, ALS is more infrequent and rarely considered in the differential diagnosis. There are few reports of ALS in children. Here, we describe a 14-year-old boy with a very fast progressing classical ALS phenotype and tremor caused by a c.1554_1557delACAG mutation in FUS. Our review of the literature advocates that pediatric ALS is highly suggestive of FUS mutations and that gene should be tested in children presenting with symptoms of ALS. The children with FUS-related ALS may have no family history and present initially with learning disabilities, tremor, and mild motor developmental delay.

A novel p.N66T mutation in exon 3 of the SOD1 gene: report of two families of ALS patients with early cognitive impairment

Introduction: To date more than 180 different mutations in the SOD1 gene have been described in ALS; some of these mutations are associated to peculiar clinical features and have contributed to the understanding of disease heterogeneity. Only 5% of SOD1 mutations involve exon 3. Here we report a novel mutation c.197A > C in the exon 3 of the SOD1 gene in two apparently unrelated ALS families with early respiratory and cognitive impairment.Case report: In the first family two brothers developed ALS in their seventies, with arm weakness followed by bulbar involvement and behavioral breakdown. An unrelated 57-year-old man presented with progressive leg weakness and mild compromised executive functions without known family history for ALS/FTD and underwent invasive ventilation in a few months. A novel missense mutation A to C at codon 197 in exon 3 causing aminoacid substitution of arginine by threonine (N66T) was found for all of them. Harmful consequences of c.197A > C mutation on SOD1 function were suggested by in silico prediction and homology with other known mutations at the same position.Discussion and conclusion: Here, we report two apparently unrelated ALS families carrying a novel SOD1 mutation (N66T), supporting its pathogenic role by primary analysis, and characterized by early bulbar, respiratory, and cognitive involvement. Early cognitive impairment has been rarely described in ALS caused by SOD1 mutations, and mainly in the later phases of the disease. This report provides additional data on the SOD1 mutation spectrum and clinical presentation of ALS, widening phenotypical characterization of SOD1 ALS.

Analysis of SOD1 mutations in a Chinese population with amyotrophic lateral sclerosis: a case-control study and literature review

Although the copper/zinc superoxide dismutase-1 (SOD1) gene has been identified in both familial ALS (FALS) and sporadic ALS (SALS), it has rarely been studied in Chinese patients with ALS, and there are few studies with large samples. This study sought to assess the prevalence of SOD1 mutations in Chinese ALS patients. We screened a cohort of 499 ALS patients (487 SALS and 12 FALS) from the Department of Neurology at the West China Hospital of Sichuan University and analyzed all coding exons of SOD1 by Sanger sequencing. In addition, we reviewed the mutation frequencies of common ALS causative genes in Chinese populations. Eight missense mutations in SOD1 were found in 8 ALS individuals: two novel mutations (p.G73D and p.V120F) and six previously reported mutations. The frequencies of SOD1 mutations were 1.03% (5/487) in SALS and 25% (3/12) in FALS from Southwest China. A literature review indicated that the mutation rates of major ALS causative genes were 53.55% in FALS and 6.29% in SALS. In Chinese SALS and FALS, the highest mutation frequency was in the SOD1 gene. Our results suggest that SOD1 mutation is the most common cause of ALS in Chinese populations and that the mutation spectrum of ALS varies among different ethnic populations.

Mutations in FUS are the most frequent genetic cause in juvenile sporadic ALS patients of Chinese origin

Juvenile onset ALS is a very rare form of motor neuron disease, with the first symptoms of motor neuron degeneration manifested before 25 years of age. Mutations in the alsin (ALS2), senataxin (SETX), and spatacsin (SPG11) genes have been associated with familial ALS with juvenile onset and slow progression, whereas the genetic architecture of sporadic juvenile ALS remains unclear. We screened mutations in C9orf72, SOD1, FUS, TARDBP, ANG, VCP and PFN1 in 16 juvenile sporadic ALS patients. Four cases (25%) carrying FUS mutations and one individual (6%) harbouring a SOD1 mutation were identified. All cases had an aggressive disease course. Our results suggest that FUS mutations are the most frequent genetic cause in early-onset sporadic ALS patients of Chinese origin. Genetic testing of FUS should be performed in early-onset ALS patients especially those with an aggressive disease course.

Mutations in SOD1 and FUS caused juvenile-onset sporadic amyotrophic lateral sclerosis with aggressive progression

Juvenile onset amyotrophic lateral sclerosis (ALS) is a very rare form of motor neuron disease, with the first symptoms of motor neuron degeneration manifested before 25 years of age. Juvenile ALS is more frequently familial in nature than the adult-onset forms. Mutations in the alsin (ALS2), senataxin (SETX), and Spatacsin (SPG11) have been associated with familial ALS with juvenile onset and slowly progression. Here we reported two apparently sporadic ALS with juvenile onset and aggressive progression caused by mutations in the SOD1 and FUS gene. We also reviewed juvenile-onset ALS in publications. Our findings, together with other researches, confirms that both SOD1 and FUS mutations can lead to juvenile-onset malignant form of ALS and should be screened in ALS patients with an earlier age of onset, aggressive progression, even if there is no apparent family history.

De novo FUS gene mutations are associated with juvenile-onset sporadic amyotrophic lateral sclerosis in China

Juvenile amyotrophic lateral sclerosis (ALS) is a rare form of motor neuron disease and occurs before 25 years of age. Only very few sporadic cases of juvenile-onset ALS have been reported. Rare SOD1 mutations and several FUS mutations have been identified in juvenile-onset ALS patients. To define the genetics of juvenile-onset sporadic ALS (SALS) of Chinese origin, we sequenced all 5 exons of SOD1, exons 3-6 and 12-15 of FUS in 11 juvenile-onset SALS patients, 105 adult-onset ALS patients (including 6 familial ALS [FALS] pedigrees), and 245 healthy controls. For the 11 juvenile-onset SALS and 6 FALS cases, the other 7 exons of FUS were also screened. A heterozygous de novo missense mutation c.1574C>T (p.P525L), a heterozygous de novo 2-base pair deletion c.1509_1510delAG (p.G504Wfs*12), and a nonsense mutation c.1483C>T (p.R495X) was each identified in 1 juvenile SALS patient. A heterozygous missense mutation c.1561C>G (p.R521G) was identified in a FALS proband. In the Chinese population, the frequency of FUS mutation in FALS is 11.4% (95% confidence interval [CI], 0.9%-22.0%), higher than the Japanese (10%; 95% CI, 0.7%-19.3%), and Caucasians (4.9%; 95% CI, 3.9%-6.0%). The frequency of FUS mutation in SALS patients is 1.5% (95% CI, 0.2%-2.9%), which is similar to Koreans (1.6%; 95% CI, 0%-3.2%), but higher than in Caucasians (0.6%; 95% CI, 0.4%-0.8%). Our findings suggest that de novo FUS mutations are associated with juvenile-onset SALS of Chinese origin and that this gene should be screened in ALS patients with a young age of onset, aggressive progression, and sporadic occurrence.