Categorization of the amyotrophic lateral sclerosis population via the clinical determinant of post-onset ΔFS for study design and medical practice.

The amyotrophic lateral sclerosis (ALS) functional rating scale-revised (ALSFRS-R) has become the most widely utilized measure of disease severity in patients with ALS, with change in ALSFRS-R from baseline being a trusted primary outcome measure in ALS clinical trials. This is despite the scale having several established limitations, and although alternative scales have been proposed, it is unlikely that these will displace ALSFRS-R in the foreseeable future. Here, we discuss the merits of delta FS (ΔFS), the slope or rate of ALSFRS-R decline over time, as a relevant tool for innovative ALS study design, with an as yet untapped potential for optimization of drug effectiveness and patient management. In our view, categorization of the ALS population via the clinical determinant of post-onset ΔFS is an important study design consideration. It serves not only as a critical stratification factor and basis for patient enrichment but also as a tool to explore differences in treatment response across the overall population; thereby, facilitating identification of responder subgroups. Moreover, because post-onset ΔFS is derived from information routinely collected as part of standard patient care and monitoring, it provides a suitable patient selection tool for treating physicians. Overall, post-onset ΔFS is a very attractive enrichment tool that is, can and should be regularly incorporated into ALS trial design.

Genetic variability in sporadic amyotrophic lateral sclerosis.

With the advent of gene therapies for amyotrophic lateral sclerosis (ALS), there is a surge in gene testing for this disease. Although there is ample experience with gene testing for C9orf72, SOD1, FUS and TARDBP in familial ALS, large studies exploring genetic variation in all ALS-associated genes in sporadic ALS (sALS) are still scarce. Gene testing in a diagnostic setting is challenging, given the complex genetic architecture of sALS, for which there are genetic variants with large and small effect sizes. Guidelines for the interpretation of genetic variants in gene panels and for counselling of patients are lacking. We aimed to provide a thorough characterization of genetic variability in ALS genes by applying the American College of Medical Genetics and Genomics (ACMG) criteria on whole genome sequencing data from a large cohort of 6013 sporadic ALS patients and 2411 matched controls from Project MinE. We studied genetic variation in 90 ALS-associated genes and applied customized ACMG-criteria to identify pathogenic and likely pathogenic variants. Variants of unknown significance were collected as well. In addition, we determined the length of repeat expansions in C9orf72, ATXN1, ATXN2 and NIPA1 using the ExpansionHunter tool. We found C9orf72 repeat expansions in 5.21% of sALS patients. In 50 ALS-associated genes, we did not identify any pathogenic or likely pathogenic variants. In 5.89%, a pathogenic or likely pathogenic variant was found, most commonly in SOD1, TARDBP, FUS, NEK1, OPTN or TBK1. Significantly more cases carried at least one pathogenic or likely pathogenic variant compared to controls (odds ratio 1.75; P-value 1.64 × 10-5). Isolated risk factors in ATXN1, ATXN2, NIPA1 and/or UNC13A were detected in 17.33% of cases. In 71.83%, we did not find any genetic clues. A combination of variants was found in 2.88%. This study provides an inventory of pathogenic and likely pathogenic genetic variation in a large cohort of sALS patients. Overall, we identified pathogenic and likely pathogenic variants in 11.13% of ALS patients in 38 known ALS genes. In line with the oligogenic hypothesis, we found significantly more combinations of variants in cases compared to controls. Many variants of unknown significance may contribute to ALS risk, but diagnostic algorithms to reliably identify and weigh them are lacking. This work can serve as a resource for counselling and for the assembly of gene panels for ALS. Further characterization of the genetic architecture of sALS is necessary given the growing interest in gene testing in ALS.

The effect of social support on the emotional well-being of people with amyotrophic lateral sclerosis: Exploring the mediating role of spirituality.

OBJECTIVES: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that, so far, is considered always fatal. Treatments mainly consist in increasing survival and aim to improve the quality of life of people with ALS (pwALS). Social support and spirituality have been shown to play a key role in pwALS' quality of life. Our study explored it in depth by investigating the underlying mechanisms linking social support, spirituality, and emotional well-being. METHODS: Thirty-six pwALS underwent a battery of tests evaluating emotional well-being (emotional well-being scale of the 40-item Amyotrophic Lateral Sclerosis Assessment Questionnaire), social support (6-item Social Support Questionnaire), and spiritual well-being (12-item Functional Assessment of Chronic Illness Therapy - Spiritual well-being). Our recruitment was web-based through the FILSLAN and the ARSLA websites as well as through Facebook® advertisements (ALS groups). Data were analyzed by Pearson correlation analysis and Process macro was used in an SPSS program to analyze the mediator variable effect. RESULTS: Availability of social support, spiritual well-being, and 2 of its dimensions, i.e., meaning and peace, were positively correlated with emotional well-being. The mediational analyses showed that spiritual well-being, meaning, and peace act as mediators in the association between availability of social support and good emotional well-being. SIGNIFICANCE OF RESULTS: Availability of social support and spirituality are essential for the emotional well-being of pwALS. Spirituality as a mediator between availability of social support and emotional well-being appears as real novel finding which could be explored further. Spiritual well-being, meaning, and peace appear as coping resources for pwALS. We provide practical guidance for professionals working with pwALS.

The contribution of Neanderthal introgression and natural selection to neurodegenerative diseases.

Humans are thought to be more susceptible to neurodegeneration than equivalently-aged primates. It is not known whether this vulnerability is specific to anatomically-modern humans or shared with other hominids. The contribution of introgressed Neanderthal DNA to neurodegenerative disorders remains uncertain. It is also unclear how common variants associated with neurodegenerative disease risk are maintained by natural selection in the population despite their deleterious effects. In this study, we aimed to quantify the genome-wide contribution of Neanderthal introgression and positive selection to the heritability of complex neurodegenerative disorders to address these questions. We used stratified-linkage disequilibrium score regression to investigate the relationship between five SNP-based signatures of natural selection, reflecting different timepoints of evolution, and genome-wide associated variants of the three most prevalent neurodegenerative disorders: Alzheimer's disease, amyotrophic lateral sclerosis and Parkinson's disease. We found no evidence for enrichment of positively-selected SNPs in the heritability of Alzheimer's disease, amyotrophic lateral sclerosis and Parkinson's disease, suggesting that common deleterious disease variants are unlikely to be maintained by positive selection. There was no enrichment of Neanderthal introgression in the SNP-heritability of these disorders, suggesting that Neanderthal admixture is unlikely to have contributed to disease risk. These findings provide insight into the origins of neurodegenerative disorders within the evolution of Homo sapiens and addresses a long-standing debate, showing that Neanderthal admixture is unlikely to have contributed to common genetic risk of neurodegeneration in anatomically-modern humans.

Time for optimism in amyotrophic lateral sclerosis.

BACKGROUND AND PURPOSE: Amyotrophic lateral sclerosis (ALS) is among the most common motor neuron diseases in adults. Nevertheless, ALS remains fatal, despite decades of research and clinical trials, which has led to negative conclusions until recently in regard to four specific treatments. It is well known that we can learn from failures, and we consider that the time has come to present positive insight on this disease. METHODS: We did a literature search using PubMed and Scopus for articles published in English from 1 January 2016, to 30 June 2022 dealing with "amyotrophic lateral sclerosis", diagnosis, treatment, and biomarkers. RESULTS: A comprehensive review of the literature on diagnosis, monitoring, and treatment of this condition showed convincing evidence that we are now able to diagnose earlier as well as to better monitor and treat ALS. CONCLUSIONS: Although ALS is often difficult to diagnose and remains incurable, there are many indications that an optimistic view of ALS management in the coming years is now realistic.

Comparison between PFN1 and SOD1 mutations in amyotrophic lateral sclerosis.

BACKGROUND: The objective of this study was to characterize the prototypical phenotype of patients with amyotrophic lateral sclerosis (ALS) associated with PFN1 mutations in profilin 1 (PFN1) and to determine clinical indications to test for mutations in this gene. MATERIAL AND METHODS: The phenotype of three relatives carrying the M114V PFN1 mutation are detailed here and are compared with those of patients with ALS linked to PFN1 previously reported in the literature. RESULTS: In this pedigree and in the literature, the main clinical findings which best describe familial ALS linked to PFN1 might be the following characteristics: pedigrees over five cases, age of onset around 50 years, site of onset systematically lower limbs and the absence of cognitive impairment. CONCLUSION: First, the infrequent incidence of patients with ALS linked to PFN1 mutation supports the pursuit of a precise characterization of the phenotype linked to PFN1 mutations. Then, the numerous similarities between the phenotype amongst patients linked to SOD1 and PFN1 mutations and between histological features amongst both mice models prompts a review of the current ALS classifications, taking into consideration both phenotype and genotype.

Diagnostic delay in amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease, and the time from symptom onset to diagnosis remains long. With the advent of disease-modifying treatments, the need to identify and diagnose ALS in a timely fashion has never been greater. METHODS: We reviewed the literature to define the severity of ALS diagnostic delay, the various factors that contribute to this delay (including patient and physician factors), and the role that site of symptom onset plays in a patient's diagnostic journey. RESULTS: Diagnostic delay is influenced by general practitioners' lack of recognition of ALS due to disease rarity and heterogenous presentations. As a result, patients are referred to non-neurologists, have unnecessary diagnostic testing, and may ultimately be misdiagnosed. Patient factors include their illness behavior-which impacts diagnostic delay-and their site of symptom onset. Limb-onset patients have the greatest diagnostic delay because they are frequently misdiagnosed with degenerative spine disease or peripheral neuropathy. CONCLUSION: Prompt ALS diagnosis results in more effective clinical management, with earlier access to disease-modifying therapies, multidisciplinary care, and, if desired, clinical trial involvement. Due to lack of commercially available ALS biomarkers, alternative strategies to identify and triage patients who likely have ALS must be employed. Several diagnostic tools have been developed to encourage general practitioners to consider ALS and make an urgent referral to ALS specialists, bypassing unnecessary referrals to non-neurologists and unnecessary diagnostic workup.

Evaluation of arterial blood gas parameters as prognostic markers in amyotrophic lateral sclerosis.

BACKGROUND: Forced vital capacity (FVC) remains difficult to determine for some patients suffering from amyotrophic lateral sclerosis (ALS) due to the rapid progression of the disease. Arterial blood gas (ABG) parameters could represent a valuable alternative. The aim of this study was therefore to evaluate the correlation between ABG parameters and FVC, along with the prognostic ability of ABG parameters, in a large cohort of ALS patients. METHODS: ALS patients (n=302) with FVC and ABG parameters available at diagnosis were included. Correlations between ABG parameters and FVC were evaluated. Cox regression was then carried out to determine the association of each parameter (ABG and clinical data) with survival. Finally, receiver operating characteristic (ROC) curves were built to predict the survival of ALS. RESULTS: Bicarbonates (HCO3 - ), oxygen partial pressure (pO2 ), carbon dioxide partial pressure (pCO2 ), base excess (BE), oxygen saturation and oxyhemoglobin were significantly correlated with FVC both in patients with spinal or bulbar onset. Univariate Cox regression showed that HCO3 - and BE were associated with survival but only in spinal forms. ABG parameters predicted the survival of ALS with a similar performance to FVC, HCO3 - being the parameter with the highest area under the curve. CONCLUSIONS: Our results suggest that there is an interest in conducting a longitudinal evaluation throughout disease progression to confirm the equal performances of FVC and ABG. This study highlights the benefits of performing ABG analysis that could be used as an interesting alternative to FVC when spirometry cannot be performed.

Implication of Central Nervous System Barrier Impairment in Amyotrophic Lateral Sclerosis: Gender-Related Difference in Patients.

Central nervous system (CNS) barrier impairment has been reported in amyotrophic lateral sclerosis (ALS), highlighting its potential significance in the disease. In this context, we aim to shed light on its involvement in the disease, by determining albumin quotient (QAlb) at the time of diagnosis of ALS in a large cohort of patients. Patients from the university hospital of Tours (n = 307) were included in this monocentric, retrospective study. In total, 92 patients (30%) had elevated QAlb levels. This percentage was higher in males (43%) than in females (15%). Interestingly, QAlb was not associated with age of onset, age at sampling or diagnostic delay. However, we found an association with ALS functional rating scale-revised (ALSFRS-r) at diagnosis but this was significant only in males. The QAlb levels were not linked to the presence of a pathogenic mutation. Finally, we performed a multivariate survival analysis and found that QAlb was significantly associated with survival in male patients (HR = 2.3, 95% CI = 1.2-4.3, p = 0.009). A longitudinal evaluation of markers of barrier impairment, in combination with inflammatory biomarkers, could give insight into the involvement of CNS barrier impairment in the pathogenesis of the disease. The gender difference might guide the development of new drugs and help personalise the treatment of ALS.

Study of Ubiquitin Pathway Genes in a French Population with Amyotrophic Lateral Sclerosis: Focus on HECW1 Encoding the E3 Ligase NEDL1.

The ubiquitin pathway, one of the main actors regulating cell signaling processes and cellular protein homeostasis, is directly involved in the pathophysiology of amyotrophic lateral sclerosis (ALS). We first analyzed, by a next-generation sequencing (NGS) strategy, a series of genes of the ubiquitin pathway in two cohorts of familial and sporadic ALS patients comprising 176 ALS patients. We identified several pathogenic variants in different genes of this ubiquitin pathway already described in ALS, such as FUS, CCNF and UBQLN2. Other variants of interest were discovered in new genes studied in this disease, in particular in the HECW1 gene. We have shown that the HECT E3 ligase called NEDL1, encoded by the HECW1 gene, is expressed in neurons, mainly in their somas. Its overexpression is associated with increased cell death in vitro and, very interestingly, with the cytoplasmic mislocalization of TDP-43, a major protein involved in ALS. These results give new support for the role of the ubiquitin pathway in ALS, and suggest further studies of the HECW1 gene and its protein NEDL1 in the pathophysiology of ALS.

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.

The hypometabolic state: a good predictor of a better prognosis in amyotrophic lateral sclerosis.

BACKGROUND: Malnutrition and weight loss are negative prognostic factors for survival in patients with amyotrophic lateral sclerosis (ALS). However, energy expenditure at rest (REE) is still not included in clinical practice, and no data are available concerning hypometabolic state in ALS. OBJECTIVE: To evaluate in a referral cohort of patients with ALS the prevalence of hypometabolic state as compared with normometabolic and hypermetabolic states, and to correlate it with clinical phenotype, rate of progression and survival. DESIGN: We conducted a retrospective study examining REE measured by indirect calorimetry in patients with ALS referred to Milan, Limoges and Tours referral centres between January 2011 and December 2017. Hypometabolism and hypermetabolism states were defined when REE difference between measured and predictive values was ≤-10% and ≥10%, respectively. We evaluated the relationship between these metabolic alterations and measures of body composition, clinical characteristics and survival. RESULTS: Eight hundred forty-seven patients with ALS were recruited. The median age at onset was 63.79 years (IQR 55.00-71.17). The male/female ratio was 1.26 (M/F: 472/375). Ten per cent of patients with ALS were hypometabolic whereas 40% were hypermetabolic. Hypometabolism was significantly associated with later need for gastrostomy, non-invasive ventilation and tracheostomy placement. Furthermore, hypometabolic patients with ALS significantly outlived normometabolic (HR=1.901 (95% CI 1.080 to 3.345), p=0.0259) and hypermetabolic (HR=2.138 (95% CI 1.154 to 3.958), p=0.0157) patients. CONCLUSION: Hypometabolism in ALS is not uncommon and is associated with slower disease progression and better survival than normometabolic and hypermetabolic subjects. Indirect calorimetry should be performed at least at time of diagnosis because alterations in metabolism are correlated with prognosis.

Neurolysis of the distal segment of the long thoracic nerve for the treatment of scapular winging due to serratus anterior palsy: a continuous series of 73 cases.

BACKGROUND: Serratus anterior (SA) palsy following mechanical injury to the long thoracic nerve (LTN) is the most common cause of scapular winging. This study aimed to identify the factors influencing the outcome of neurolysis of the distal segment of the LTN. We hypothesized that poor results are due to duration before surgery and to persistent scapulothoracic dysfunction. METHODS: A retrospective study was conducted. The inclusion criteria were partial or complete isolated noniatrogenic SA paralysis of at least 4-month duration with preoperative electrophysiologic assessment confirming the neurogenic origin without signs of reinnervation. RESULTS: Seventy-three patients were assessed at 45 days, 6 months, and 24 months after neurolysis of the distal segment of the LTN. At the last follow-up, improvement was excellent in 38 (52%), good in 22 cases (30%), moderate in 6 (8%), and poor in 7 (10%). No patient showed deterioration in outcomes since the beginning of follow-up. Scapular winging was no longer present in 46 cases (63%), while it was minimal in 23 (31.5%). In 4 cases (5.5%), winging was similar to the preoperative condition. DISCUSSION: The best outcomes occurred in patients who presented without compensatory muscle pain and who were treated within 12 months of paralysis. Beyond this time frame, neurolysis can still provide useful functional improvement and avoid palliative surgery. CONCLUSION: Neurolysis of the distal segment of the LTN is a safe and reliable procedure. This technique allows treatment of SA muscle palsy and corrects scapular winging with excellent or good outcomes in 82% of cases.

Scapular winging due to rhomboid muscle paralysis: clinical assessment of 4 cases and anatomic study of the dorsal scapular nerve.

BACKGROUND: A rare cause of scapular winging is rhomboid muscle paralysis secondary to dorsal scapular nerve (DSN) neuropathy. This paralysis causes winging of the medial border of the scapula with lateral rotation of its inferior angle. We report a series of 4 clinical cases of isolated DSN compression and the results of a specific rehabilitation protocol. METHODS: A continuous clinical series of 4 patients with isolated rhomboid muscle deficiency was analyzed. Two patients were men and 2 were women, with a mean age of 40 years (range, 33-51 years). Three patients were right-handed and 1 was left-handed. Scapular winging always affected the dominant side. Two patients had occupations involving heavy physical work. The sports practiced involved exertion of the arms (dancing, boxing, gymnastics, muscle strengthening). A specific rehabilitation protocol was offered to the patients. In addition, 6 fresh cadaver dissections were performed to reveal possible DSN compression. Potential areas of compression were identified, in particular when the arm was raised. RESULTS: The 4 patients presented with isolated DSN neuropathy were confirmed by electroneuromyographic testing. Total correction of scapular winging was not obtained in any patient. Three patients experienced residual pain with a neuropathic pain by the questionnaire for a Diagnosis of Neuropathic Pain (DN4) score of 2. The mean Quick-Disabilities of the Arm, Shoulder and Hand (DASH) score after treatment was 31.8 of 100. The mean ASES score was 56.2. Only 1 patient agreed to rehabilitation in a specialized center and underwent follow-up electroneuromyography. Signs of rhomboid muscle denervation were no longer present and distal motor latencies had become normal. In all cadaver dissections, the DSN originated from the C5 nerve root and did not pass through the middle scalene muscle. We identified a site of dynamic compression of the DSN by the upper part of the medial border of the scapula when the arm was raised. DISCUSSION: DSN compression is conventionally attributed to the middle scalene muscle, but it is noteworthy that our study reveals the possibility of dynamic compression of the nerve by the proximal part of the medial border of the scapula, which occurs when the arm elevation is above 90°. CONCLUSION: Our study reveals the possibility of dynamic compression of the DSN by the proximal part of the medial border of the scapula, which occurs when the arm is raised above 90°. In the absence of a surgical solution, conservative treatment is fundamental and requires management in a rehabilitation center with intervention by a multidisciplinary team.

The Roles of NEDD4 Subfamily of HECT E3 Ubiquitin Ligases in Neurodevelopment and Neurodegeneration.

The ubiquitin pathway regulates the function of many proteins and controls cellular protein homeostasis. In recent years, it has attracted great interest in neurodevelopmental and neurodegenerative diseases. Here, we have presented the first review on the roles of the 9 proteins of the HECT E3 ligase NEDD4 subfamily in the development and function of neurons in the central nervous system (CNS). We discussed their regulation and their direct or indirect involvement in neurodevelopmental diseases, such as intellectual disability, and neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease or Amyotrophic Lateral Sclerosis. Further studies on the roles of these proteins, their regulation and their targets in neurons will certainly contribute to a better understanding of neuronal function and dysfunction, and will also provide interesting information for the development of therapeutics targeting them.

Split-hand and split-limb phenomena in amyotrophic lateral sclerosis: pathophysiology, electrophysiology and clinical manifestations.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting the upper and lower motor neurons. A key clinical feature of ALS is the absence of accurate, early-stage diagnostic indicators. 'Split-hand syndrome' was first described in ALS at the end of the last century and a considerable body of literature suggests that the split-hand phenomenon may be an important clinical feature of ALS. Considering the published investigations, it is conceivable that the 'split-hand syndrome' results from the associated upper and lower motor neuron degeneration, whose interaction remains to be fully clarified. Additionally, other split syndromes have been described in ALS involving upper or lower limbs, with a nuanced description of clinical and neurophysiological manifestations that may further aid ALS diagnosis. In this review, we endeavour to systematically present the spectrum of the 'split syndromes' in ALS from a clinical and neurophysiology perspective and discuss their diagnostic and pathogenic utility.

Effect of familial clustering in the genetic screening of 235 French ALS families.

OBJECTIVES: To determine whether the familial clustering of amyotrophic lateral sclerosis (ALS) cases and the phenotype of the disease may help identify the pathogenic genes involved. METHODS: We conducted a targeted next-generation sequencing analysis on 235 French familial ALS (FALS), unrelated probands to identify mutations in 30 genes linked to the disease. The genealogy, that is, number of cases and generations with ALS, gender, age, site of onset and the duration of the disease were analysed. RESULTS: Regarding the number of generations, 49 pedigrees had only one affected generation, 152 had two affected generations and 34 had at least three affected generations. Among the 149 pedigrees (63.4%) for which a deleterious variant was found, an abnormal G4C2 expansion in C9orf72 was found in 98 cases as well as SOD1, TARBP or FUS mutations in 30, 9 and 7 cases, respectively. Considering pedigrees from the number of generations, abnormal G4C2 expansion in C9orf72 was more frequent in pedigrees with pairs of affected ALS cases, which represented 65.2% of our cohort. SOD1 mutation involved all types of pedigrees. No TARDBP nor FUS mutation was present in monogenerational pedigrees. TARDBP mutation predominated in bigenerational pedigrees with at least three cases and FUS mutation in multigenerational pedigrees with more than seven cases, on average, and with an age of onset younger than 45 years. CONCLUSION: Our results suggest that familial clustering, phenotypes and genotypes are interconnected in FALS, and thus it might be possible to target the genetic screening from the familial architecture and the phenotype of ALS cases.

Impact of a frequent nearsplice SOD1 variant in amyotrophic lateral sclerosis: optimising SOD1 genetic screening for gene therapy opportunities.

OBJECTIVE: Mutations in superoxide dismutase 1 gene (SOD1), encoding copper/zinc superoxide dismutase protein, are the second most frequent high penetrant genetic cause for amyotrophic lateral sclerosis (ALS) motor neuron disease in populations of European descent. More than 200 missense variants are reported along the SOD1 protein. To limit the production of these aberrant and deleterious SOD1 species, antisense oligonucleotide approaches have recently emerged and showed promising effects in clinical trials. To offer the possibility to any patient with SOD1-ALS to benefit of such a gene therapy, it is necessary to ascertain whether any variant of unknown significance (VUS), detected for example in SOD1 non-coding sequences, is pathogenic. METHODS: We analysed SOD1 mutation distribution after SOD1 sequencing in a large cohort of 470 French familial ALS (fALS) index cases. RESULTS: We identified a total of 27 SOD1 variants in 38 families including two SOD1 variants located in nearsplice or intronic regions of the gene. The pathogenicity of the c.358-10T>G nearsplice SOD1 variant was corroborated based on its high frequency (as the second most frequent SOD1 variant) in French fALS, the segregation analysis confirmed in eight affected members of a large pedigree, the typical SOD1-related phenotype observed (with lower limb onset and prominent lower motor neuron involvement), and findings on postmortem tissues showing SOD1 misaccumulation. CONCLUSIONS: Our results highlighted nearsplice/intronic mutations in SOD1 are responsible for a significant portion of French fALS and suggested the systematic analysis of the SOD1 mRNA sequence could become the method of choice for SOD1 screening, not to miss these specific cases.

Familial clustering of primary lateral sclerosis and amyotrophic lateral sclerosis: Supplementary evidence for a continuum.

BACKGROUND AND PURPOSE: Primary lateral sclerosis (PLS) is a motor neuron disorder characterized by a pure upper motor neuron degeneration in the bulbar and spinal regions. The key difference with amyotrophic lateral sclerosis (ALS) is the lower motor neuron system integrity. Despite important literature on this disease, the pathophysiology of PLS remains unknown, and the link with ALS still balances between a continuum and a separate entity from ALS. METHODS: We report nine families in which both PLS and ALS cases occurred, in general among first-degree relatives. RESULTS: The patients with PLS and ALS had a typical disease presentation. Genetic studies revealed mutations in SQSMT1, TBK1, and TREM2 genes in two PLS patients and one ALS patient. CONCLUSIONS: These results strongly support a phenotypic continuum between PLS and ALS.