Correlation between SMA type and SMN2 copy number revisited: An analysis of 625 unrelated Spanish patients and a compilation of 2834 reported cases

Treating neuromuscular diseases: unveiling gene therapy breakthroughs and pioneering future applications

In this review, we highlight recent advancements in adeno-associated virus (AAV)-based gene therapy for genetic neuromuscular diseases (NMDs), focusing on spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD). We discuss the current FDA-approved gene therapies for NMDs and provide updates on preclinical studies that demonstrate the potential of various AAV-based gene therapies to reduce SMA severity and serve as effective treatments for DMD. Additionally, we explore the transformative impact of CRISPR/Cas9 technology on the future of gene therapy for NMDs. Despite these encouraging developments, further research is required to identify robust biomarkers that can guide treatment decisions and predict outcomes. Overall, these pioneering advancements in AAV-based gene therapy lay the groundwork for future efforts aimed at curing genetic NMDs and offer a roadmap for developing gene therapies for other neurodegenerative diseases.

Current Advances and Challenges in Gene Therapies for Neurologic Disorders: A Review for the Clinician

Over 300 million people globally are affected by rare diseases, many of which present predominantly with neurologic symptoms. Rare neurologic disorders pose significant diagnostic and therapeutic challenges including delayed diagnoses, limited treatment options, and a shortage of specialists. However, advancements in diagnostics, particularly next-generation sequencing and expansion of newborn screening, have significantly shortened the time to diagnosis for many of these disorders. Concurrently, the past decade has witnessed exponential development of new treatments for rare neurologic diseases, with several approved gene therapies and more trials under way. A range of targeted therapies now offers hope for not only symptomatic management but also for disease modification. As treatments transition from clinical trials to clinical practice, the responsibility of identifying and monitoring patients may increasingly fall on the general neurologists. This evolving therapeutic landscape highlights the urgent need to enhance our understanding of this new class of medications and the details on clinical eligibility and monitoring of patients with diseases that have approved gene therapies. This article provides a comprehensive overview of gene-targeted therapies currently available for neurologic disorders, with a focus on their mechanisms, challenges, and post-treatment considerations.

Neonatal Screening for Spinal Muscular Atrophy and Severe T- and B-Cell Lymphopenias in Andalusia: A Prospective Study

Spinal muscular atrophy (SMA) and severe T- and/or B-cell lymphopenias (STBCL) in the form of severe combined immunodeficiencies (SCID) or X-linked agammaglobulinemia (XLA) are rare but potentially fatal pathologies. In January 2021, we initiated the first pilot study in Spain to evaluate the efficacy of a very early detection technique for SMA and SCID. RT-PCR was performed on prospectively collected dried blood spots (DBSs) from newborns in Western Andalusia (Spain). Internal and external controls (SCID, XLA and SMA) were included. The determination of SMA was relative (positive/negative) and that of TRECs and KRECs was quantitative (copies/punch). A total of 14.035 prospective samples were analysed. All controls were correctly identified while no cases of SMA or SCID/XLA were prospectively identified. DBS analysis of infants with suspected SMA or STBCL that presented to our centre showed pathological values in two cases each for SMA and SCID and one for XLA, all of them being subsequently confirmed genetically. In this prospective pilot study, no infants with SMA or STBCL were detected; however, the technique applied here was shown to be reliable and fast, further supporting the benefits and need to include SMA and SCID in national newborn screening (NBS) programs, as it will allow early supportive and curative therapy.

Outcomes of a Pilot Newborn Screening Program for Spinal Muscular Atrophy in the Valencian Community

Spinal muscular atrophy (SMA) is a degenerative neuromuscular condition resulting from a homozygous deletion of the survival motor neuron 1 (SMN1) gene in 95% of patients. A timely diagnosis via newborn screening (NBS) and initiating treatment before the onset of symptoms are critical for improving health outcomes in affected individuals. We carried out a screening test by quantitative PCR (qPCR) to amplify the exon seven of SMN1 using dried blood spot (DBS) samples. From October 2021 to August 2024, a total of 31,560 samples were tested in the Valencian Community (Spain) and 4 of them were positive for SMA, indicating an incidence of 1/7890. Genetic confirmation was performed using multiplex ligation-dependent probe amplification (MLPA) and AmplideX PCR/CE SMN1/2 Plus kit, in parallel obtaining concordant results in survival motor neuron 2 (SMN2) gene copy number. Within the first few weeks of their lives, two of the four patients detected by NBS showed signs of severe hypotonia, becoming ineligible for treatment. The other two patients were the first presymptomatic patients with two copies of SMN2 to receive treatment with Risdiplam in Spain. In order to treat positive cases in their early stages, we conclude that the official deployment of SMA newborn screening is necessary.

A Real-World Study of Nusinersen Effects in Adults with Spinal Muscular Atrophy Type 2 and 3

BACKGROUND

Spinal muscular atrophy (SMA) is a progressive genetic disorder characterized by muscle weakness ultimately leading to pulmonary impairments that can be fatal. The recent approval of nusinersen, a disease-modifying therapy, substantially changed the prognosis for patients, particularly in children. However, real-world evidence about its long-term effectiveness in adults remains limited. This study aimed to document longitudinal data on motor function, pulmonary function and patient-reported outcome measures of Canadian adults with SMA type 2 and 3 treated with nusinersen.

METHODS

Outcomes from 17 patients were collected at the Institut de réadaptation en déficience physique de Québec during routine clinical visits over 36 months post nusinersen treatment, using the Hammersmith Functional Motor Scale Expanded for SMA (HFMSE), Revised Upper Limb Module (RULM), 6-Minute Walk Test (6MWT), Children's Hospital of Philadelphia Adult Test of Neuromuscular Disorders (CHOP-ATEND), SMA functional rating scale (SMAFRS), pulmonary function testing and subjective changes reported by patients.

RESULTS

After 36 months, 9 patients showed motor function improvement. Changes beyond the minimal clinically important difference were seen for four patients on the HFMSE, four patients on the RULM and five patients on the 6MWT. Pulmonary function remained stable for most subjects. Subjective positive changes were reported in 88% of patients and five patients showed improvement in the SMAFRS.

CONCLUSION

This real-world study demonstrates the positive effects of nusinersen in adults with SMA types 2 and 3. Although stabilizing the patient's condition is considered therapeutic success, this study shows an improvement in motor function and subjective gains in several patients.

Safety and Efficacy of Nusinersen Focusing on Renal and Hematological Parameters in Spinal Muscular Atrophy

BACKGROUND

Spinal muscular atrophy (SMA) is a motor neuron disease caused by mutations in the SMN1 gene. Nusinersen, an antisense oligonucleotide, has been shown to improve motor function in SMA patients. However, concerns regarding its renal safety remain as previous studies have linked similar treatments to renal toxicity.

OBJECTIVE

The aim of this study was to evaluate the effects of the nusinersen treatment on platelet counts and renal functions, specifically urine protein excretion, in SMA patients and to estimate safe urinary protein levels before administration of each intrathecal injection.

METHODS

This retrospective study examined data from 33 patients with SMA to assess the effects of nusinersen on motor functions and laboratory parameters including platelet count, serum creatinine, urine protein, and urine creatinine. Measurements were taken at baseline andprior to each maintenance dose, after the completion of four initial loading doses. The baseline values were compared between SMA Type 1 and Type 2 patients, while the changes in these values over time were analyzed within each group.

RESULTS

No significant adverse effects on platelet counts or renal functions were observed. Urine creatinine and protein levels were significantly higher in SMA Type 2 patients compared to SMA Type 1 at baseline; these parameters remained stable in SMA Type 2 but increased significantly after the loading doses in SMA Type 1. Motor function improvements were observed in both groups, with the most significant gains in SMA Type 1 after the loading doses. Thus, improvement in motor functions was associated with increase in urine creatinine.

CONCLUSION

Nusinersen treatment did not cause significant renal toxicity or affect platelet counts. Urine creatinine levels may serve as a potential biomarker for assessing treatment response in SMA Type 1.

The influence of genotype on the natural history of types 1 - 3 spinal muscular atrophy

The severity of spinal muscular atrophy (SMA) is inversely correlated with the number of survival of motor neuron 2 (SMN2) copies an individual has. This observational, retrospective analysis of natural history data included untreated individuals with a genetic diagnosis of types 1-3 SMA and stratified disease-related characteristics by SMN2 copy number. The outcomes investigated were time to: death, permanent ventilation, respiratory support, feeding support, scoliosis surgery, and achievement and loss of motor milestones. Of 134 individuals; 33 had two SMN2 copies and 101 had 3 or more copies. Survival was linked to increasing SMN2 copy number: mean age at death for individuals with two SMN2 copies was 8 months (standard deviation [SD]: 4 months) and 10 years (SD: 5 months) for individuals with three copies, and no deaths were reported in individuals with ≥4 SMN2 copies. Increasing SMN2 copy number was linked to a longer time to permanent ventilation, respiratory support, feeding support, and scoliosis, as well as loss of motor milestones. SMA disease-related endpoints showed distinct patterns between groups with differing SMN2 copy numbers. Prediction and assessment of disease progression may be stratified by SMN2 copy number, which will be important for evaluating the impact of treatment.

Analysis of spinal muscular atrophy patients from the spinal muscular atrophy and muscular dystrophy registry of Pakistan

BACKGROUND

Spinal Muscular Atrophy (SMA) leads to motor neuron loss, with progressive muscle weakness and wasting. Nationwide registries for neuromuscular diseases are pivotal for assessing epidemiology, preparing for clinical trials, and for adopting standardized management guidelines.

OBJECTIVES

This paper aims to present data gathered during the establishment of Pakistan's inaugural registry for genetically confirmed SMA cases.

METHODS

In this retrospective study, 215 participants with genetically confirmed SMA were recruited. Telephonic interviews were conducted to collect data for the Muscular Disease Registry of Pakistan that was analyzed using STATA version 17.0.

RESULTS

SMA type 1 was the most common type (71.2%, n = 153). Amongst patients who were tested for survival motor neuron (SMN2) copies, the majority (84.4%, n = 168) had two SMN2 copies. SMA types were significantly associated with the ability to sit (p < 0.001) and walk (p < 0.001), and usage of a wheelchair (p = 0.0054). SMN2 copy numbers were significantly associated with the ability to sit (p = 0.020) and walk (p = 0.031).

CONCLUSIONS

This study highlights the high prevalence of SMA genotypes and phenotypes associated with severe disease in our population. Our findings reiterate the challenging prognosis for Pakistani children with SMA and underscore the necessity of the development of nationwide newborn screening programs and making treatments available.

Systematic literature review of the impact of spinal muscular atrophy therapies on bulbar function

BACKGROUND

Improvement and maintenance of bulbar function are important goals of disease-modifying treatments (DMTs) for spinal muscular atrophy (SMA), but standardized and validated measures for assessing bulbar function do not exist, nor does a widely accepted definition of bulbar function in SMA. As such, the impact of DMTs on bulbar function has not yet been comprehensively evaluated.

OBJECTIVE

We conducted a systematic literature review (SLR) to identify evidence about the impact of DMTs for SMA on bulbar function.

METHODS

We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines to conduct this review. Embase® and MEDLINE® databases were searched through August 10, 2023. Eligible studies included patients with SMA who were treated with any DMT and reported bulbar function outcomes. Non-English studies were excluded.

RESULTS

We identified 51 studies (across 83 publications) that evaluated SMA DMTs and bulbar function for more than 1600 patients. The ability to feed orally, the ability to tolerate liquids, and the need for nutrition support were commonly reported. Most infants treated with any DMT before SMA symptom onset preserved bulbar function. Infants, children, and adults treated after SMA symptom onset experienced variable results in terms of bulbar function outcomes.

CONCLUSIONS

The definition and assessment of bulbar function are not standardized. Therefore, the tools, scales, methods, and timing used for bulbar function assessments varied among studies. Larger prospective studies using standardized and age-based assessments with longer follow-up periods are needed to assess the clinical stability of bulbar function for patients with SMA who receive DMTs.

Efficacy and safety of Nusinersen among children with spinal muscular atrophy from North India: A prospective cohort study (NICE-SMA study)

BACKGROUND

Intra-thecal Nusinersen has been approved for the treatment of Spinal muscular atrophy (SMA). Limited data is available regarding the efficacy and safety of Nusinersen in children with SMA type 2 and 3 from North India.

OBJECTIVE

To study the efficacy and safety of Nusinersen among children with SMA type 2 and 3 from North India compared to standard of care (SOC) over 12 months.

METHODS

Children with a genetically confirmed diagnosis of SMA and ≥2 copies of the SMN2 gene were screened for enrolment in prospective study design. Revised Hammersmith score (RHS) and revised upper limb module (RULM) were assessed every three months. Compound muscle action potentials (CMAPs) at median and ulnar nerves and quality of life (QOL) were performed at baseline and 12 months. Intra-thecal procedure-related and treatment-emergent side effects in children receiving Nusinersen therapy were recorded. Outcome measures at 6 and 12 months were compared between the Nusinersen and SOC groups.

RESULTS

Forty-two children with SMA, mean age of 85 ± 6 months, including 16 in the Nusinersen group and 26 in the SOC group, were enrolled. The mean RHS score in the Nusinersen group increased from the baseline of 35 ± 18 to 38.9 ± 19, and 39.9 ± 17 at 6 and 12 months (p value-0.001), in the SOC group increased from the baseline of 28.8 ± 15, to 29.6 ± 16, and 29.9 ± 17 at 6 and 12 months respectively (p value-0.35). The mean gain in the RHS score over 12 months in the Nusinersen group was significantly higher compared to the SOC group (p-value 0.02). RULM showed significant gain in the Nusinersen group compared to the SOC group over 12 months (p value 0.03). The median and ulnar nerve CMAPs, and QOL were similar in both the groups. A total of 119 intrathecal injections of Nusinersen were given. Most adverse events were mild and related to the intra-thecal procedure.

CONCLUSION

Intra-thecal Nusinersen therapy among children with late-onset SMA from North India over 12-month duration was associated with improvement in motor abilities as measured by RHS compared to SOC. Intra-thecal Nusinersen was safe and tolerated well.

Patient-specific responses to SMN2 splice-modifying treatments in spinal muscular atrophy fibroblasts

The availability of three therapies for the neuromuscular disease spinal muscular atrophy (SMA) highlights the need to match patients to the optimal treatment. Two of these treatments (nusinersen and risdiplam) target splicing of SMN2, but treatment outcomes vary from patient to patient. An incomplete understanding of the complex interactions among SMA genetics, SMN protein and mRNA levels, and gene-targeting treatments, limits our ability to explain this variability and identify optimal treatment strategies for individual patients. To address this, we analyzed responses to nusinersen and risdiplam in 45 primary fibroblast cell lines. Pre-treatment SMN2-FL, SMN2Δ7 mRNA, and SMN protein levels were influenced by SMN2 copy number, age, and sex. After treatment, SMN and mRNA levels were more heterogeneous. In 43% of patients, response to both therapies was similar, but in 57% one treatment led to a significantly higher SMN increase than the other treatment. Younger age, higher SMN2 copy number, and higher SMN levels before treatment predicted better in vitro efficacy. These findings showcase patient-derived fibroblasts as a tool for identifying molecular predictors for personalized treatment.

Comprehensive copy number analysis of spinal muscular atrophy among the Iranian population

Copy number variations in the SMN1 gene on chromosome 5 are the primary cause of Spinal Muscular Atrophy (SMA) disease, characterized by muscle weakness and degeneration due to impaired alpha motor neurons in the spinal cord. To obtain a comprehensive molecular understanding of the SMA, including carriers, silent carriers, and patients in the Iranian population, we analyzed data from 5224 individuals referred to Kariminejad - Najmabadi Pathology & Genetics Center, Tehran, Iran, between 2006 and 2023 using MLPA and quantitative RT-PCR methods. The carrier frequency of SMA was estimated to be 5.55%. Furthermore, 3.06% of SMA parents (n = 24) had two copies of the SMN1 gene. Among 725 patients, those with an earlier onset of SMA were more likely to have two copies of the SMN2 gene (46.45%) and no copies of the NAIP gene (49.36%). Among the 654 fetal samples screened for SMA, 22.33% were found to be affected, while 3.46% of their parents tested normal. These findings are valuable for genetic counseling, carrier screening, and prenatal diagnosis of SMA in Iran. Furthermore, they underscore the importance of CNV analysis of SMN1, SMN2, and NAIP genes for accurate diagnosis and prognosis of SMA.

Efficacy and safety of gene therapy with onasemnogene abeparvovec in children with spinal muscular atrophy in the D-A-CH-region: a population-based observational study

Background

Real-world data on gene addition therapy (GAT) with onasemnogene abeparvovec (OA), including all age groups and with or without symptoms of the disease before treatment are needed to provide families with evidence-based advice and realistic therapeutic goals. Aim of this study is therefore a population-based analysis of all patients with SMA treated with OA across Germany, Austria and Switzerland (D-A-CH).

Methods

This observational study included individuals with Spinal Muscular Atrophy (SMA) treated with OA in 29 specialized neuromuscular centers in the D-A-CH-region. A standardized data set including WHO gross motor milestones, SMA validated motor assessments, need for nutritional and respiratory support, and adverse events was collected using the SMArtCARE registry and the Swiss-Reg-NMD. Outcome data were analyzed using a prespecified statistical analysis plan including potential predictors such as age at GAT, SMN2 copy number, past treatment, and symptom status.

Findings

343 individuals with SMA (46% male, 54% female) with a mean age at OA of 14.0 months (range 0-90, IQR 20.0 months) were included in the analysis. 79 (23%) patients were clinically presymptomatic at the time of treatment. 172 (50%) patients received SMN2 splice-modifying drugs prior to GAT (risdiplam: n = 16, nusinersen: n = 154, both: n = 2). Functional motor improvement correlated with lower age at GAT, with the best motor outcome in those younger than 6 weeks, carrying 3 SMN2 copies, and being clinically presymptomatic at time of treatment. The likelihood of requiring ventilation or nutritional support showed a significantly increase with older age at the time of GAT and remained stable thereafter. Pre-treatment had no effect on disease trajectories. Liver-related adverse events occurred significantly less frequently up to 8 months of age. All other adverse events showed an even distribution across all age and weight groups.

Interpretation

Overall, motor, respiratory, and nutritional outcome were dependent on timing of GAT and initial symptom status. It was best in presymptomatic children treated within the first six weeks of life, but functional motor scores also increased significantly after treatment in all age groups up to 24 months. Additionally, OA was best tolerated when administered at a young age. Our study therefore highlights the need for SMA newborn screening and immediate treatment to achieve the best possible benefit-risk ratio.

Funding

The SMArtCARE and Swiss-Reg-NMD registries are funded by different sources (see acknowledgements).

Outcomes of early-treated infants with spinal muscular atrophy: A multicenter, retrospective cohort study

INTRODUCTION/AIMS

While prompt identification and treatment of infants with spinal muscular atrophy (SMA) can ameliorate outcomes, variability persists. This study assessed management and outcomes of early-treated infants with SMA.

METHODS

We analyzed retrospective data at 12 centers on infants with SMA treated at age ≤6 weeks from August 2018 to December 2023.

RESULTS

Sixty-six patients, 35 with two SMN2 copies and 31 with ≥3 SMN2 copies, were included. Twenty-five (38%, 22 with two SMN2 copies), had SMA findings before initial treatment which was onasemnogene abeparvovec in 47 (71%) and nusinersen in 19 (29%). Thirty-two received sequential or combination treatments, including 16 adding nusinersen or risdiplam due to SMA findings following onasemnogene abeparvovec. All sat independently. Compared to children with ≥3 SMN2 copies, those with two SMN2 copies were less likely to walk (23/34 [68%] vs. 31/31 [100%], p < .001) and less likely to walk on time (9/34 [26%] vs. 29/31 [94%], p < .001); one non-ambulatory child was <18 months old and was excluded from this analysis. No patients required permanent ventilation or exclusively enteral nutrition; six required nocturnal non-invasive ventilation and four utilized supplemental enteral nutrition, all with two SMN2 copies.

DISCUSSION

Early treatment of infants with SMA can improve outcomes as indicated by our cohort, all of whom sat independently and are without permanent ventilation. However, our study demonstrates ongoing disability in most children with two SMN2 copies despite early monotherapy and emphasizes the need for additional research, including earlier monotherapy, initial combination therapy, prenatal treatment, and non-SMN modifying treatments.

A contemporary analysis of the Australian clinical and genetic landscape of spinal muscular atrophy: a registry based study

Background

New paradigms of diagnosis and treatment have changed the neurodegenerative trajectory for individuals with spinal muscular atrophy (SMA). Registries are a critical tool to provide real-world data on treatment patterns, their effects and health care provision within this evolving paradigm of care. This study aimed to evaluate the phenotypic and genotypic landscape, treatment patterns and health impact of SMA in Australia through the national registry.

Methods

This cross-sectional study investigated demographic, clinical and genetic information, sequelae of weakness, treatment patterns and patient-reported outcomes amongst individuals with SMA enrolled in the Australian Neuromuscular Disease Registry (ANMDR) from 1st January 2020 to 30th April 2023. Descriptive statistics were used for analysis and Chi-Squared or Fisher's exact tests for associations.

Findings

195 individuals with SMA enrolled into the ANMDR. 5/195 (2.6%) were deceased by censor date. Of (n = 190) individuals living with SMA, 104/190 (54.7%) were children. Minimum Australian prevalence was 0.73/100,000. SMN2 copies were inversely associated with phenotype in those with homozygous SMN1 deletions (p < 0.0001)). Treatment was utilised in 154/190 (81%) of the population, with 65/137 (47.6%) of individuals perceiving improvements with therapeutic intervention on Patient/Parent Global Impression of Improvement scale (p < 0.0001). Engagement with multidisciplinary care practitioners was significantly higher among children with SMA than adults (93% versus 12%, p < 0.0001).

Interpretation

Despite diagnostic and therapeutic advances, mortality and the multi-systemic health impact of SMA continue to be experienced within the Australian population. Healthcare provision must align with patient-centred outcomes, adapting to meeting their changing but ongoing care requirements. The study identified the considerable unmet need for multidisciplinary care, not only for adults with SMA but also for the emerging cohort of treated children, emphasising the imperative for comprehensive healthcare provision to address their evolving needs.

Funding

No funding was received for this study.

Analytical validation of the amplification refractory mutation system polymerase chain reaction-capillary electrophoresis assay to diagnose spinal muscular atrophy

OBJECTIVES

Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by homozygous deletion and compound heterozygous mutations in survival motor neuron 1 (SMN1), with severity tied to the copy number of survival motor neuron 2 (SMN2). This study aimed to develop a rapid and comprehensive method for the diagnosis of SMA.

METHODS

A total of 292 children with clinically suspected SMA and 394 family members were detected by the amplification refractory mutation system polymerase chain reaction-capillary electrophoresis (ARMS-PCR-CE) method, which targeted 19 reported mutations, and the results were compared with those in multiplex ligation-dependent probe amplification (MLPA). Individuals with identified point mutations were further confirmed by SMN1 long-range PCR and Sanger sequencing.

RESULTS

A total of 202 children with SMA, 272 carriers, and 212 normal individuals were identified in this study. No difference was found in the R-value distribution of exons 7 and 8 in SMN1 and SMN2 among these cohorts, with coefficients of variation consistently below 0.08. To detect exon 7 and 8 copy numbers in SMN1 and SMN2, the ARMS-PCR-CE results were concordant with those of MLPA. Approximately 4.95 % (10/202) of the study patients had compound heterozygous mutations.

CONCLUSIONS

The ARMS-PCR-CE assay is a comprehensive, rapid, and accurate diagnostic method for SMA that simultaneously detects copy numbers of exons 7 and 8 in SMN1/SMN2, as well as 19 point mutations in SMN1 and 2 enhancers in SMN2. This approach can effectively reduce the time frame for diagnosis, facilitating early intervention and preventing birth defects.

Type-1 spinal muscular atrophy cohort before and after disease-modifying therapies

BACKGROUND

 Spinal muscular atrophy (SMA-5q) is a neurodegenerative disease characterized by progressive muscle atrophy, hypotonia, and weakness, with SMA 1 presenting symptoms within the first 6 months of life. Disease-modifying therapies have been approved, with better outcomes with earlier treatment.

OBJECTIVE

 To describe the safety and clinical efficacy of disease-modifying therapies based on SMN1 and SMN2 gene strategies concerning motor, respiratory, and bulbar function. Patients with SMA 1 were divided into 2 groups: those exclusively on nusinersen (group 1) and those transitioning to onasemnogene abeparvovec (OA) (group 2).

METHODS

 Over 18 months, patients were assessed using the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scale, developmental milestones, ventilation needs and duration, nutritional support needs, consistency of food, and signs of dysphagia. There were ten patients, divided between the groups; in group 1, the average age for starting nusinersen was 53.6 (12-115) months, and, in group 2, the age was 7 (1-12) months for nusinersen and 15.2 (10-19) months for OA.

RESULTS

 Our results indicate that 70% of patients reached some motor milestones, with group 1 increasing by 10.2 points on the CHOP-INTEND scale, while group 2 increased by 33 points. Additionally, 90% of the patients experienced no respiratory decline, and 30% maintained oral feeding. No serious adverse effects or deaths were recorded.

CONCLUSION

 Both groups showed improvement in motor function and stabilization of respiratory and bulbar function, with the difference between the groups possibly being related to the earlier treatment initiation. Thus, the present study provides valuable insights into the real-world safety and clinical efficacy of disease-modifying therapies for SMA 1 patients.

Outcomes for patients in the RESTORE registry with spinal muscular atrophy and four or more SMN2 gene copies treated with onasemnogene abeparvovec

OBJECTIVE

We describe outcomes following onasemnogene abeparvovec monotherapy for patients with ≥four survival motor neuron 2 (SMN2) gene copies in RESTORE, a noninterventional spinal muscular atrophy patient registry.

METHODS

We evaluated baseline characteristics, motor milestone achievement, post-treatment motor function, use of ventilatory/nutritional support, and adverse events as of December 22, 2022.

RESULTS

At data cutoff, 19 patients in RESTORE had ≥four SMN2 copies and were treated with onasemnogene abeparvovec monotherapy (n=12 [63.2%] four copies; n=7 [36.8%] >four copies). All patients were identified by newborn screening and were reported as asymptomatic at diagnosis. Median age at onasemnogene abeparvovec administration was 3.0 months. Median time from treatment to last recorded visit was 15.4 months, with a range of post-treatment follow-up of 0.03-39.4 months. All 12 children who were assessed for motor development achieved new milestones, including standing alone (n=2) and walking alone (n=5). Five children reported one or more treatment-emergent adverse events (one Grade 3 or greater). No deaths or use of ventilatory/nutritional support were reported.

CONCLUSIONS

Real-world findings from the RESTORE registry indicate that patients with ≥four SMN2 gene copies treated with onasemnogene abeparvovec monotherapy demonstrated improvements in motor function. Adverse events experienced by these patients were consistent with previously reported findings.

The Relevance of Spinal Muscular Atrophy Biomarkers in the Treatment Era

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder that currently has an approved treatment for all forms of the disease. Previously, biomarkers were primarily used for diagnostic purposes, such as detecting the presence of the disease or determining a specific clinical type of SMA. Currently, with the availability of therapy, biomarkers have become more valuable due to their potential for prognostic, predictive, and pharmacodynamic applications. This review describes the most promising physiological, functional, imaging and molecular biomarkers for SMA, derived from different patients' tissues. The review summarizes information about classical biomarkers that are already used in clinical practice as well as fresh findings on promising biomarkers that have been recently disclosed. It highlights the usefulness, limitations, and strengths of each potential biomarker, indicating the purposes for which each is best suited and when combining them may be most beneficial.

Efficacy of Nusinersen Treatment in Type 1, 2, and 3 Spinal Muscular Atrophy: Real-World Data from a Single-Center Study

BACKGROUND

Spinal muscular atrophy (SMA) is an inherited neuromuscular disease characterized by progressive muscle weakness and atrophy due to the absence of the survival motor neuron 1 (SMN1) gene. SMA is classified into types 0 through 4 based on the age of symptom onset and the severity of motor function decline. Recent advances in SMA treatment, including nusinersen, onasemnogene abeparvovec, and risdiplam, have significantly improved the prognosis of SMA patients. This study evaluated the safety and efficacy of nusinersen in pediatric patients with SMA types 1, 2, and 3 in a real-world clinical setting.

METHODS

This prospective observational single-center study assessed the treatment effects of nusinersen in 23 pediatric patients with genetically confirmed SMA over a 22-month observation period. All the participants received intrathecal loading doses of 12 mg of nusinersen on days 1, 14, 28, and 63, followed by maintenance doses every four months. Functional assessments were conducted using the CHOP-INTEND scale. Data were collected during routine patient visits, including clinical laboratory tests and vital sign parameters, and adverse events were recorded. The inclusion criteria were defined by the national reimbursement program for nusinersen treatment in Poland.

RESULTS

Initially, 37 patients ranging from 1 month old to 18 years old were included, but 23 were ultimately observed due to changes in treatment regimens or assessment scales. The patients showed significantly improved CHOP-INTEND scores over the 22-month period. At 6 months, the average increase was 4.2 points, continuing to 17.8 points at 22 months. By the end of the study, 100% of patients showed either stabilization or improvement, with significant clinical improvements observed in several patients. Nusinersen was generally well-tolerated, with post-lumbar puncture headache and lower back pain being the most common adverse events.

CONCLUSIONS

Nusinersen treatment significantly enhances motor function in pediatric patients with SMA types 1, 2, and 3. This study demonstrates the importance of early and sustained treatment, with most patients showing the continuous improvement or stabilization of motor function. These findings support the use of nusinersen as an effective therapy for SMA; however, further research is needed to understand the long-term outcomes and optimize treatment strategies.

SMN2 Copy Number Association with Spinal Muscular Atrophy Severity: Insights from Colombian Patients

Background: Spinal muscular atrophy (SMA) is a genetic neurodegenerative disease primarily affecting paediatric patients, often leading to significant morbidity and mortality. Our principal objective is to describe the sociodemographic characteristics and evaluate the association between the number of SMN2 copies and SMA type in patients from the Colombian Foundation for Spinal Muscular Atrophy (FAMECOL) database. Methodology: An analytical cross-sectional study was conducted on 201 patients with a genetic diagnosis of SMA. Data were identified, extracted, and collected from patient records provided by FAMECOL as patients registered with the association, including 201 patients from April 2013 to April 2024, when the database was delivered. Qualitative variables were described using relative and absolute frequencies, while quantitative variables were described using central tendency and dispersion measures according to their distribution. The association between the SMA type and the SMN2 number of copies was assessed by Fisher's exact test (1 to 5 copies). Results: Of the 201 patients studied, 42% were female (n = 85), and 58% were male (n = 116). The median age was 9 years (IQR 4-16 years). The median age at diagnosis was 9 years (IQR 4-16), varying by subgroup: 2, 7, 14, and 41.5 years for each type, respectively. A total of 25% patients were from Antioquia (n = 51). Eighty-nine per cent had gastrostomy (n = 18). The association between the two variables was statistically significant (p < 0.05). Conclusion: This study highlights SMA clinical variability and its association with the number of SMN2 copies, underscoring the importance of a personalised approach to diagnosing and managing this disease. The findings may guide more effective therapeutic strategies to improve patients' quality of life.

Acceptability, validity and responsiveness of inertial measurement units for assessing motor recovery after gene therapy in infants with early onset spinal muscular atrophy: a prospective cohort study

BACKGROUND

Onasemnogene abeparvovec gene replacement therapy (GT) has changed the prognosis of patients with spinal muscular atrophy (SMA) with variable outcome regarding motor development in symptomatic patients. This pilot study evaluates acceptability, validity and clinical relevance of Inertial Measurement Units (IMU) to monitor spontaneous movement recovery in early onset SMA patients after GT.

METHODS

Clinical assessments including CHOPINTEND score (the gold standard motor score for infants with SMA) and IMU measurements were performed before (M0) and repeatedly after GT. Inertial data was recorded during a 25-min spontaneous movement task, the child lying on the back, without (10 min) and with a playset (15 min) wearing IMUs. Two commonly used parameters, norm acceleration 95th centile (||A||_95) and counts per minute (||A||_CPM) were computed for each wrist, elbow and foot sensors.

RESULTS

23 SMA-patients were included (mean age at diagnosis 8 months [min 2, max 20], 19 SMA type 1, three type 2 and one presymptomatic) and 104 IMU-measurements were performed, all well accepted by families and 84/104 with a good child participation (evaluated with Brazelton scale). ||A||_95 and ||A||_CPM showed high internal consistency (without versus with a playset) with interclass correlation coefficient for the wrist sensors of 0.88 and 0.85 respectively and for the foot sensors of 0.93 and 0.91 respectively. ||A||_95 and ||A||_CPM were strongly correlated with CHOPINTEND (r for wrist sensors 0.74 and 0.67 respectively and for foot sensors 0.61 and 0.68 respectively, p-values < 0.001). ||A||_95 for the foot, the wrist, the elbow sensors and ||A||_CPM for the foot, the wrist, the elbow sensors increased significantly between baseline and the 12 months follow-up visit (respective p-values: 0.004, < 0.001, < 0.001, 0.006, < 0.001, < 0.001).

CONCLUSION

IMUs were well accepted, consistent, concurrently valid, responsive and associated with unaided sitting acquisition especially for the elbow sensors. This study is the first reporting a large set of inertial sensor derived data after GT in SMA patients and paves the way for IMU-based follow-up of SMA patients after treatment.

Oral functions in adult persons with spinal muscular atrophy compared to a healthy control group: a prospective cross-sectional study with a multimodal approach

BACKGROUND

Oral function tests have been shown to reliably detect impaired bulbar function in adults with spinal muscular atrophy (SMA). Although not routinely recorded, it is known that persons with SMA are affected to varying degrees. Detecting differences in bite and tongue force, endurance, and maximum mouth opening has become particularly promising since the introduction of causal therapy for SMA. This study aimed to compare oral function among adult persons with SMA with different SMA types, walking abilities, and treatment status to a healthy control group.

METHODS

Data from oral function tests conducted on 58 persons with SMA and 45 healthy individuals were analyzed. Differences in oral function between SMA subgroups were pairwise tested and compared to the healthy control group using Wilcoxon rank sum tests.

RESULTS

In an overall comparison, three out of five oral function tests revealed lower values for the SMA group compared to the control group. Subgroup analyses indicated lower scores for most oral function tests in non-ambulatory, untreated patients with SMA type 2 compared to controls. Ambulatory, treated patients with SMA type 3 achieved strength and endurance values comparable to those of healthy individuals.

CONCLUSIONS

The impairment of oral function varies across persons with SMA. Routine measurement of oral function is warranted to determine individual bulbar involvement stages. Further evaluation should be scheduled if indicators such as restricted maximum mouth opening arise. Trial registration DRKS, DRKS00015842. Registered 30 July 2019, https://drks.de/register/de/trial/DRKS00015842/preview .

Diagnostic Journey of Korean Patients with Spinal Muscular Atrophy

PURPOSE

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disease characterized by the loss of motor neurons in the spinal cord and brainstem, leading to muscle atrophy and weakness. To understand the diagnostic process of Korean patients with SMA, we analyzed their clinical characteristics and challenges.

MATERIALS AND METHODS

We conducted a retrospective study of 38 patients with SMA (9 type II and 29 type III) between January 2000 and September 2023. Clinical, laboratory, and genetic data were reviewed.

RESULTS

The median ages at symptom onset and diagnosis were 3.0 years [interquartile range (IQR): 1.0-7.3 years] and 25.0 years (IQR: 10.5-37.3 years), respectively. The median diagnostic delay was 19.6 years (IQR: 6.4-31.0 years). A significantly longer delay was observed in SMA type III patients (median: 21.0 years, IQR: 11.0-31.0 years) compared to SMA type II patients (median: 3.0 years, IQR: 0.9-21.0 years) (p=0.021). No significant difference was observed in the number of clinic visits before diagnosis between patients with SMA type II (median: 2.0, IQR: 1.0-4.5) and those with type III (median: 2.0, IQR: 2.0-6.0, p=0.282). The number of clinic visits before diagnosis showed no significant association with the age at symptom onset and diagnosis (p=0.998 and 0.291, respectively).

CONCLUSION

Our investigation is the first examination of the diagnostic journey of Korean patients with SMA. As treatments for SMA progress, the significance of an accurate diagnosis has increased, highlighting the importance of reviewing the diagnostic advancements made thus far.

A reassessment of spinal cord pathology in severe infantile spinal muscular atrophy: Reassessment of spinal cord pathology

AIMS

Spinal muscular atrophy (SMA) is a life-limiting paediatric motor neuron disease characterised by lower motor neuron loss, skeletal muscle atrophy and respiratory failure, if untreated. Revolutionary treatments now extend patient survival. However, a limited understanding of the foundational neuropathology challenges the evaluation of therapeutic success. As opportunities to study treatment-naïve tissue decrease, we have characterised spinal cord pathology in severe infantile SMA using gold-standard techniques, providing a baseline to measure treatment success and therapeutic limitations.

METHODS

Detailed histological analysis, stereology and transmission electron microscopy were applied to post-mortem spinal cord from severe infantile SMA patients to estimate neuron number at the end of life; characterise the morphology of ventral horn, lateral horn and Clarke's column neuron populations; assess cross-sectional spinal cord area; and observe myelinated white matter tracts in the clinically relevant thoracic spinal cord.

RESULTS

Ventral horn neuron loss was substantial in all patients, even the youngest cases. The remaining ventral horn neurons were small with abnormal, occasionally chromatolytic morphology, indicating cellular damage. In addition to ventral horn pathology, Clarke's column sensory-associated neurons displayed morphological features of cellular injury, in contrast to the preserved sympathetic lateral horn neurons. Cellular changes were associated with aberrant development of grey and white matter structures that affected the overall dimensions of the spinal cord.

CONCLUSIONS

We provide robust quantification of the neuronal deficit found at the end of life in SMA spinal cord. We question long-accepted dogmas of SMA pathogenesis and shed new light on SMA neuropathology out with the ventral horn, which must be considered in future therapeutic design.

Cognitive impairment in children with 5q-associated spinal muscular atrophy type 1: two case reports and the review of the literature

Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by mutations in the survival motor neuron 1 (SMN1) gene on chromosome 5, leading to the degeneration of lower motor neurons. There are few studies on cognitive impairment comorbid with SMA. Here, we report two cases of severe cognitive impairment in Chinese children with SMA type 1, marking the first such reports in this demographic. We propose that severe cognitive dysfunction may be a comorbidity of SMA. Clinicians should consider SMA in patients presenting with severe muscle weakness and atrophy accompanied by cognitive impairments, to avoid misdiagnosis and oversight.

Molecular analysis of SMN2, NAIP, and GTF2H2 gene deletions and relationships with clinical subtypes of spinal muscular atrophy

SMA (spinal muscular atrophy) is an autosomal recessive neuromuscular disease that causes muscle atrophy and weakness. SMA is diagnosed by a homozygous deletion in exon 7 of the SMN1 gene. However, mutations in genes located in the SMA region, such as SMN2, NAIP, SERF1, and GTF2H2, may also contribute to the severity of the disease. Within our study's scope, 58 SMA patients who applied in 2018-2021 and 40 healthy controls were analyzed. The study retrospectively included the SMN1 and SMN2 copy numbers previously determined by the MLPA method. Then, NAIP gene analyses with the multiplex PCR method and GTF2H2 gene analyses with the RFLP method were performed. There was a significant correlation (p = 0.00001) between SMN2 copy numbers and SMA subtypes. Also, the NAIP gene (p = 0.01) and the GTF2H2 gene (p = 0.0049) revealed a significant difference between healthy and SMA subjects, whereas the SMA subtypes indicated no significant differences. We detected a significant correlation between clinical subtypes and HFMSE scores in 32 pediatric SMA patients compared (p = 0.01). While pediatric patients with GTF2H2 deletions demonstrated higher motor functions, and those with NAIP deletions demonstrated lower motor functions. In this study, we examined the relationship between NAIP and GTF2H2, called SMN region modifier genes, and the clinical severity of the disease in Turkish SMA patients. Despite its small scale, this research will benefit future investigations into the pathogenesis of SMA disease.

Taldefgrobep Alfa and the Phase 3 RESILIENT Trial in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a rare, genetic neurodegenerative disorder caused by insufficient production of survival motor neuron (SMN) protein. Diminished SMN protein levels lead to motor neuron loss, causing muscle atrophy and weakness that impairs daily functioning and reduces quality of life. SMN upregulators offer clinical improvements and increased survival in SMA patients, although significant unmet needs remain. Myostatin, a TGF-β superfamily signaling molecule that binds to the activin II receptor, negatively regulates muscle growth; myostatin inhibition is a promising therapeutic strategy for enhancing muscle. Combining myostatin inhibition with SMN upregulation, a comprehensive therapeutic strategy targeting the whole motor unit, offers promise in SMA. Taldefgrobep alfa is a novel, fully human recombinant protein that selectively binds to myostatin and competitively inhibits other ligands that signal through the activin II receptor. Given a robust scientific and clinical rationale and the favorable safety profile of taldefgrobep in patients with neuromuscular disease, the RESILIENT phase 3, randomized, placebo-controlled trial is investigating taldefgrobep as an adjunct to SMN upregulators in SMA (NCT05337553). This manuscript reviews the role of myostatin in muscle, explores the preclinical and clinical development of taldefgrobep and introduces the phase 3 RESILIENT trial of taldefgrobep in SMA.

Understanding the Role of the SMN Complex Component GEMIN5 and Its Functional Relationship with Demethylase KDM6B in the Flunarizine-Mediated Neuroprotection of Motor Neuron Disease Spinal Muscular Atrophy

Dysregulated RNA metabolism caused by SMN deficiency leads to motor neuron disease spinal muscular atrophy (SMA). Current therapies improve patient outcomes but achieve no definite cure, prompting renewed efforts to better understand disease mechanisms. The calcium channel blocker flunarizine improves motor function in Smn-deficient mice and can help uncover neuroprotective pathways. Murine motor neuron-like NSC34 cells were used to study the molecular cell-autonomous mechanism. Following RNA and protein extraction, RT-qPCR and immunodetection experiments were performed. The relationship between flunarizine mRNA targets and RNA-binding protein GEMIN5 was explored by RNA-immunoprecipitation. Flunarizine increases demethylase Kdm6b transcripts across cell cultures and mouse models. It causes, in NSC34 cells, a temporal expression of GEMIN5 and KDM6B. GEMIN5 binds to flunarizine-modulated mRNAs, including Kdm6b transcripts. Gemin5 depletion reduces Kdm6b mRNA and protein levels and hampers responses to flunarizine, including neurite extension in NSC34 cells. Moreover, flunarizine increases the axonal extension of motor neurons derived from SMA patient-induced pluripotent stem cells. Finally, immunofluorescence studies of spinal cord motor neurons in Smn-deficient mice reveal that flunarizine modulates the expression of KDM6B and its target, the motor neuron-specific transcription factor HB9, driving motor neuron maturation. Our study reveals GEMIN5 regulates Kdm6b expression with implications for motor neuron diseases and therapy.

Proteomic analysis of the SMN complex reveals conserved and etiologic connections to the proteostasis network

Introduction

Molecular chaperones and co-chaperones are highly conserved cellular components that perform a variety of duties related to the proper three-dimensional folding of the proteome. The web of factors that carries out this essential task is called the proteostasis network (PN). Ribonucleoproteins (RNPs) represent an underexplored area in terms of the connections they make with the PN. The Survival Motor Neuron (SMN) complex is an assembly chaperone and serves as a paradigm for studying how specific RNAs are identified and paired with their client substrate proteins to form RNPs. SMN is the eponymous component of a large complex, required for the biogenesis of uridine-rich small nuclear ribonucleoproteins (U-snRNPs), that localizes to distinct membraneless organelles in both the nucleus and cytoplasm of animal cells. SMN protein forms the oligomeric core of this complex, and missense mutations in the human SMN1 gene are known to cause Spinal Muscular Atrophy (SMA). The basic framework for understanding how snRNAs are assembled into U-snRNPs is known. However, the pathways and mechanisms used by cells to regulate their biogenesis are poorly understood.

Methods

Given the importance of these processes to normal development as well as neurodegenerative disease, we set out to identify and characterize novel SMN binding partners. We carried out affinity purification mass spectrometry (AP-MS) of Drosophila SMN complexes using fly lines exclusively expressing either wildtype or SMA-causing missense alleles.

Results

Bioinformatic analyses of the pulldown data, along with comparisons to proximity labeling studies carried out in human cells, revealed conserved connections to at least two other major chaperone systems including heat shock folding chaperones (HSPs) and histone/nucleosome assembly chaperones. Notably, we found that heat shock cognate protein Hsc70-4 and other HspA family members preferentially associated with SMA-causing alleles of SMN.

Discussion

Hsc70-4 is particularly interesting because its mRNA is aberrantly sequestered by a mutant form of TDP-43 in mouse and Drosophila ALS (Amyotrophic Lateral Sclerosis) disease models. Most important, a missense allele of Hsc70-4 (HspA8 in mammals) was recently identified as a bypass suppressor of the SMA phenotype in mice. Collectively, these findings suggest that chaperone-related dysfunction lies at the etiological root of both ALS and SMA.

Real-world multidisciplinary outcomes of onasemnogene abeparvovec monotherapy in patients with spinal muscular atrophy type 1: experience of the French cohort in the first three years of treatment

BACKGROUND

Spinal muscular atrophy type 1 (SMA1) is the most severe and early form of SMA, a genetic disease with motor neuron degeneration. Onasemnogene abeparvovec gene transfer therapy (GT) has changed the natural history of SMA1, but real-world data are scarce.

METHODS

A French national expert committee identified 95 newly diagnosed treatment-naive SMA1 patients between June 2019 and June 2022. We prospectively report on children treated with GT as the first and only therapy who had more than one-year of follow-up.

RESULTS

Forty-six SMA1 patients received GT. Twelve patients received other treatments. Patients with respiratory insufficiency were oriented toward palliative care after discussion with families. Twenty-nine of the treated patients with more than 12 months of follow-up were included in the follow-up analysis. Among them, 17 had 24 months of follow-up. The mean age at treatment was 7.5 (2.1-12.5) months. Twenty-two patients had two SMN2 copies, and seven had three copies. One infant died in the month following GT due to severe thrombotic microangiopathy, and another died due to respiratory distress. Among the 17 patients with 24 months of follow-up, 90% required spinal bracing (15/17), three patients required nocturnal noninvasive ventilation, and two needed gastrostomy. Concerning motor milestones at the 24-month follow-up, all patients held their head, 15/17 sat for 30 s unassisted, and 12/17 stood with aid. Motor scores (CHOPINTEND and HINE-2) and thoracic circumference significantly improved in all patients.

CONCLUSIONS

Our study shows favorable motor outcomes and preserved respiratory and feeding functions in treatment-naive SMA1 infants treated by GT as the first and only therapy before respiratory and bulbar dysfunctions occurred. Nevertheless, almost all patients developed spinal deformities.

Proteomics profiling and machine learning in nusinersen-treated patients with spinal muscular atrophy

AIM

The availability of disease-modifying therapies and newborn screening programs for spinal muscular atrophy (SMA) has generated an urgent need for reliable prognostic biomarkers to classify patients according to disease severity. We aim to identify cerebrospinal fluid (CSF) prognostic protein biomarkers in CSF samples of SMA patients collected at baseline (T0), and to describe proteomic profile changes and biological pathways influenced by nusinersen before the sixth nusinersen infusion (T302).

METHODS

In this multicenter retrospective longitudinal study, we employed an untargeted liquid chromatography mass spectrometry (LC-MS)-based proteomic approach on CSF samples collected from 61 SMA patients treated with nusinersen (SMA1 n=19, SMA2 n=19, SMA3 n=23) at T0 at T302. The Random Forest (RF) machine learning algorithm and pathway enrichment analysis were applied for analysis.

RESULTS

The RF algorithm, applied to the protein expression profile of naïve patients, revealed several proteins that could classify the different types of SMA according to their differential abundance at T0. Analysis of changes in proteomic profiles identified a total of 147 differentially expressed proteins after nusinersen treatment in SMA1, 135 in SMA2, and 289 in SMA3. Overall, nusinersen-induced changes on proteomic profile were consistent with i) common effects observed in allSMA types (i.e. regulation of axonogenesis), and ii) disease severity-specific changes, namely regulation of glucose metabolism in SMA1, of coagulation processes in SMA2, and of complement cascade in SMA3.

CONCLUSIONS

This untargeted LC-MS proteomic profiling in the CSF of SMA patients revealed differences in protein expression in naïve patients and showed nusinersen-related modulation in several biological processes after 10 months of treatment. Further confirmatory studies are needed to validate these results in larger number of patients and over abroader timeframe.

Association among biomarkers, phenotypes, and motor milestones in Chinese patients with 5q spinal muscular atrophy types 1-3

Background

Biomarkers can be used to assess the severity of spinal muscular atrophy (5q SMA; SMA). Despite their potential, the relationship between biomarkers and clinical outcomes in SMA remains underexplored. This study aimed to assess the association among biomarkers, phenotypes, and motor milestones in Chinese patients diagnosed with SMA.

Methods

We collected retrospective clinical and follow-up data of disease-modifying therapy (DMT)-naïve patients with SMA at our center from 2019 to 2021. Four biomarkers were included: survival motor neuron 2 (SMN2) copies, neuronal apoptosis inhibitory protein (NAIP) copies, full-length SMN2 (fl-SMN2), and F-actin bundling protein plastin 3 (PLS3) transcript levels. Data were analyzed and stratified according to SMA subtype.

Results

Of the 123 patients, 30 were diagnosed with Type 1 (24.3%), 56 with Type 2 (45.5%), and 37 with Type 3 (30.1%). The mortality rate for Type 1 was 50%, with median survival times of 2 and 8 months for types 1a and 1b, respectively. All four biomarkers were correlated with disease severity. Notably, fl-SMN2 transcript levels increased with SMN2 copies and were higher in Type 2b than those in Type 2a (p = 0.028). Motor milestone deterioration was correlated with SMN2 copies, NAIP copies, and fl-SMN2 levels, while PLS3 levels were correlated with standing and walking function.

Discussion

Our findings suggest that SMN2 copies contribute to survival and that fl-SMN2 may serve as a valuable biomarker for phenotypic variability in SMA Type 2 subtypes. These insights can guide future research and clinical management of SMA.

Sleep quality and daytime sleepiness amongst family caregivers of children with Spinal Muscular Atrophy

BACKGROUND

While there are limited studies focusing on sleep quality of family caregivers of children with Spinal Muscular Atrophy (SMA), there are no studies on daytime sleepiness in SMA.

AIMS

This study aimed a) to compare the sleep quality and daytime sleepiness between caregivers of children with SMA and those of healthy peers and b) to investigate the sleep quality and daytime sleepiness of family caregivers of children with different types of SMA.

METHODS AND PROCEDURES

This study included 30 family caregivers of children with SMA (SMA Type 1:12, SMA Type 2:10, and SMA Type 3:8) and 31 family caregivers of healthy peers. Sleep quality and daytime sleepiness of family caregivers were evaluated using the Pittsburg Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (EPS), consecutively.

OUTCOMES AND RESULTS

Demographic characteristics of children with SMA and healthy peers were similar (p > 0.05). The mean ages of family caregivers of children with SMA and healthy peers were 36.07 ± 5.84 and 35.26 ± 5.02 years, respectively (p = 0.6). The PSQI scores of family caregivers of children with SMA (7.50 ± 3.90 points) were lower than those of healthy peers (4.09 ± 1.97 points) (p < 0.001). There was no difference in PSQI scores between SMA types (p = 0.8). Also, no difference was found between SMA types and between SMA and healthy peers in terms of EPS (p > 0.05).

CONCLUSIONS AND IMPLICATIONS

Family caregivers of children with SMA had poor sleep quality but similar daytime sleepiness compared with those of healthy peers. Among SMA types, family caregivers had similar sleep quality and daytime sleepiness. It was demonstrated that the sleep quality of family caregivers should be taken into consideration in the disease management of SMA.

Long-term impact of nusinersen on motor and electrophysiological outcomes in adolescent and adult spinal muscular atrophy: insights from a multicenter retrospective study

BACKGROUND

5q spinal muscular atrophy (SMA) is a progressive autosomal recessive motor neuron disease.

OBJECTIVE

We aimed to assess the effects of nusinersen on motor function and electrophysiological parameters in adolescent and adult patients with 5q SMA.

METHODS

Patients with genetically confirmed 5q SMA were eligible for inclusion, and clinical data were collected at baseline (V1), 63 days (V4), 180 days (V5), and 300 days (V6). The efficacy of nusinersen was monitored by encompassing clinical assessments, including the Revised Upper Limb Module (RULM), Hammersmith Functional Motor Scale Expanded (HFMSE), 6-Minute Walk Test (6MWT), and percent-predicted Forced Vital Capacity in sitting position (FVC%) and Compound Muscle Action Potential (CMAP) amplitude. The patients were divided into "sitter" and "walker" subgroups according to motor function status.

RESULTS

54 patients were screened, divided into "sitter" (N = 22) and "walker" (N = 32), with the mean age at baseline of 27.03 years (range 13-53 years). The HFMSE in the walker subgroup increased significantly from baseline to V4 (mean change +2.32-point, P = 0.004), V5 (+3.09, P = 0.004) and V6 (+4.21, P = 0.005). The patients in both the sitter and walker subgroup had no significant changes in mean RULM between V1 and the following time points. Significant increases in CMAP amplitudes were observed in both upper and lower limbs after treatment. Also, patients with RULM ≥ 36 points showed significant CMAP improvements. Our analysis predicted that patients with CMAP amplitudes of trapezius ≥ 1.76 mV were more likely to achieve significant motor function improvements.

CONCLUSIONS

Nusinersen effectively improves motor function and electrophysiological data in adolescent and adult patients with SMA. This is the first report on the CMAP amplitude changes in the trapezius after treatment in patients with SMA. The CMAP values effectively compensate for the ceiling effect observed in the RULM, suggesting that CMAP could serve as an additional biomarker for evaluating treatment efficacy.

Cost-Effectiveness Analysis of Newborn Screening for Spinal Muscular Atrophy in Italy

BACKGROUND AND OBJECTIVE: Untreated spinal muscular atrophy (SMA) is the leading genetic cause of death in children younger than 2 years of age. Early detection through newborn screening allows for presymptomatic diagnosis and treatment of SMA. With effective treatments available and reimbursed by the National Health Service, many regions in Italy are implementing newborn screening for SMA. We evaluated the cost effectiveness of universal newborn screening for SMA in Italy.

METHODS

A decision-analytic model assessed the cost effectiveness of newborn screening from the National Health Service perspective in 400,000 newborns. Newborn screening enabling early identification and presymptomatic treatment of SMA was compared with no newborn screening, symptomatic diagnosis, and treatment. Transition probabilities between health states were estimated from clinical trial data. Higher-functioning health states were associated with increased survival, higher utility values, and lower costs. Long-term survival and utilities were extrapolated from scientific literature. Health care costs were collected from official Italian sources. A lifetime time horizon was applied, and costs and outcomes were discounted at an annual rate of 3%. Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS

Newborn screening followed by presymptomatic treatment yielded 324 incremental life-years, 390 incremental quality-adjusted life-years, and reduced costs by €1,513,375 over a lifetime time horizon compared with no newborn screening. Thus, newborn screening was less costly and more effective than no newborn screening. Newborn screening has a 100% probability of being cost effective, assuming a willingness-to-pay threshold of > €40,000.

CONCLUSIONS

Newborn screening followed by presymptomatic SMA treatment is cost effective from the Italian National Health Service perspective.

Real-World Data in Children with Spinal Muscular Atrophy Type 1 on Long-Term Ventilation Receiving Gene Therapy: A Prospective Cohort Study

Patients with spinal muscular atrophy type 1 (SMA-1) requiring invasive ventilation can be eligible for gene therapy if they tolerate at least 8 h off ventilation per day. We aimed to assess the short-term safety and efficacy of gene therapy (onasemnogene abeparvovec; Zolgensma) on respiratory function in SMA-1 patients ventilated via tracheostomy pre-gene therapy. A prospective cohort study included 22 patients. Patients were weaned off ventilation for at least 8 h daily by optimizing ventilator settings and duration, using cough augmentation, managing excessive airway secretions, enhancing nutrition, screening for respiratory bacterial colonization, and treating infections. Gene therapy was administered at a median age of 26 (Q1: 18, Q3: 43) months with a mean follow-up period of 7.64 (SD: 6.50) months. Gene therapy was safe and effective in resolving paradoxical breathing, improving cough ability, reducing airway secretions, and enhancing CHOP-INTEND scores. The clinical assessment and management implemented pre-gene therapy were effective in safely weaning patients for at least 8 h off ventilation daily. Gene therapy at a late age was safe and effective over the short-term period; however, long-term follow-up is recommended. In conjunction with gene therapy, high-quality clinical care is beneficial and should be paired with gene therapy.

Clinical perspectives: Treating spinal muscular atrophy

Spinal muscular atrophy is a rare and progressive neuromuscular disease that, without treatment, leads to progressive weakness and often death. A plethora of studies have led to the approval of three high-cost and effective treatments since 2016. These treatments, nusinersen, onasemnogene abeparvovec, and risdiplam, have not been directly compared and have varying challenges in administration. In this review, we discuss the evidence supporting the use of these medications, the process of treatment selection, monitoring after treatment, the limited data comparing treatments, as well as future directions for investigation and therapy.

Rehabilitation Strategies for Patients With Spinal Muscular Atrophy in the Era of Disease-Modifying Therapy

The impact of disease-modifying therapy ranges from cure to no impact with a wide range of intermediates. In cases where the intermediate group reaches a plateau after the acquisition of some muscle strength, it is necessary to set a functional level appropriate for increased motor power and establish a long-term exercise plan to maintain it. As the disease status stabilizes and the life span increases, early nonsurgical interventions are required, such as using a standing frame to prevent joint contracture, applying a spinal brace at the early stage of scoliosis, and maintaining sitting postures that exaggerate lumbar lordosis. In cases where scoliosis and hip displacement occur and progress even after conservative managements are implemented, early referral to surgery should be considered. Oromotor activity and swallowing function are influenced not only by the effects of disease-modifying drugs, but also by post-birth experience and training. Therefore, although the feeding tube cannot be removed, it is necessary to make efforts to simulate the infant feeding development while maintaining partial oral feeding. Since the application period of non-invasive ventilators has increased, it has become more important to prevent long-term complications such as facial abrasion, skin allergy, orthodontic deformities, and maxillary flattening caused by the interface. Dual ventilator mode or interface can also be utilized.

Complex SMN Hybrids Detected in a Cohort of 31 Patients With Spinal Muscular Atrophy

Background and Objectives

Spinal muscular atrophy (SMA) is a recessive neuromuscular disorder caused by the loss or presence of point pathogenic variants in the SMN1 gene. The main positive modifier of the SMA phenotype is the number of copies of the SMN2 gene, a paralog of SMN1, which only produces around 10%-15% of functional SMN protein. The SMN2 copy number is inversely correlated with phenotype severity; however, discrepancies between the SMA type and the SMN2 copy number have been reported. The presence of SMN2-SMN1 hybrids has been proposed as a possible modifier of SMA disease.

Methods

We studied 31 patients with SMA, followed at a single center and molecularly diagnosed by Multiplex Ligand-Dependent Probe Amplification (MLPA), with a specific next-generation sequencing protocol to investigate their SMN2 genes in depth. Hybrid characterization also included bioinformatics haplotype phasing and specific PCRs to resolve each SMN2-SMN1 hybrid structure.

Results

We detected SMN2-SMN1 hybrid genes in 45.2% of the patients (14/31), the highest rate reported to date. This represents a total of 25 hybrid alleles, with 9 different structures, of which only 4 are detectable by MLPA. Of particular interest were 2 patients who presented 4 SMN2-SMN1 hybrid copies each and no pure SMN2 copies, an event reported here for the first time. No clear trend between the presence of hybrids and a milder phenotype was observed, although 5 of the patients with hybrid copies showed a better-than-expected phenotype. The higher hybrid detection rate in our cohort may be due to both the methodology applied, which allows an in-depth characterization of the SMN genes and the ethnicity of the patients, mainly of African origin.

Discussion

Although hybrid genes have been proposed to be beneficial for patients with SMA, our work revealed great complexity and variability between hybrid structures; therefore, each hybrid structure should be studied independently to determine its contribution to the SMA phenotype. Large-scale studies are needed to gain a better understanding of the function and implications of SMN2-SMN1 hybrid copies, improving genotype-phenotype correlations and prediction of the evolution of patients with SMA.

Metabolic syndrome is common in adults with 5q-spinal muscular atrophy and impacts quality of life and fatigue

INTRODUCTION/AIMS

Spinal muscular atrophy (SMA) is a multisystem disorder. We assessed metabolic syndrome (MetS) prevalence in adults with SMA and its association with motor function, quality of life (QoL), fatigue, and depression.

METHODS

MetS was diagnosed using 2009 consensus criteria. Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM), Fatigue Severity Scale (FSS), Beck Depression Inventory (BDI), and 36-Item Short Form Health Survey (SF-36) were recorded and correlations between muscle function, depression, fatigue, QoL, and MetS were analyzed.

RESULTS

We included 36 individuals (18 males; mean age: 38.7 ± 14.6 years). MetS was present in 25.0%. The most common component of MetS was central obesity (69.7%). Nearly half of the SMA individuals exhibited at least one abnormal lipid level result. Individuals with MetS more frequently were SMA type 3 (77.8% vs. 37.0%, p = .02) and had higher levels of fatigue (48.4 ± 6.7 vs. 39.5 ± 11.6, p = .03) than those without MetS. No associations of the presence of MetS with ambulatory status or HFMSE/RULM scores were observed. SMA individuals with MetS scored significantly lower in mental and social domains of QoL and total SF-36 score (p = .04). We observed weak to moderate correlations between the presence of MetS and SMA type, presence of comorbidities, QoL, and fatigue.

DISCUSSION

The frequency of MetS was modestly higher among adults with SMA than in the general population, particularly in SMA type 3. MetS was associated with reduced QoL and increased fatigue. Larger studies are needed to fully understand the significance of MetS in adults with SMA.

Splice-switching antisense oligonucleotides for pediatric neurological disorders

Pediatric neurological disorders are frequently devastating and present unmet needs for effective medicine. The successful treatment of spinal muscular atrophy with splice-switching antisense oligonucleotides (SSO) indicates a feasible path to targeting neurological disorders by redirecting pre-mRNA splicing. One direct outcome is the development of SSOs to treat haploinsufficient disorders by targeting naturally occurring non-productive splice isoforms. The development of personalized SSO treatment further inspired the therapeutic exploration of rare diseases. This review will discuss the recent advances that utilize SSOs to treat pediatric neurological disorders.

A Five-Year Review of Newborn Screening for Spinal Muscular Atrophy in the State of Utah: Lessons Learned

Spinal muscular atrophy (SMA) is an autosomal recessive condition characterized by alpha motor neuron degeneration in the spinal cord anterior horn. Clinical symptoms manifest in the first weeks to months of life in the most severe cases, resulting in progressive symmetrical weakness and atrophy of the proximal voluntary muscles. Approximately 95% of SMA patients present with homozygous deletion of the SMN1 gene. With multiple available therapies preventing symptom development and slowing disease progression, newborn screening for SMA is essential to identify at-risk individuals. From 2018 to 2023, a total of 239,844 infants were screened. 13 positive screens were confirmed to have SMA. An additional case was determined to be a false positive. We are not aware of any false-negative cases. All patients were seen promptly, with diagnosis confirmed within 1 week of the initial clinical visit. Patients were treated with nusinersen or onasemnogene abeparvovec. Treated patients with two copies of SMN2 are meeting important developmental milestones inconsistent with the natural history of type 1 SMA. Patients with 3-4 copies of SMN2 follow normal developmental timelines. Newborn screening is an effective tool for the early identification and treatment of patients with SMA. Presymptomatic treatment dramatically shifts the natural history of SMA, with most patients meeting appropriate developmental milestones. Patients with two copies of SMN2 identified through newborn screening constitute a neurogenetic emergency. Due to the complexities of follow-up, a multidisciplinary team, including close communication with the newborn screening program, is required to facilitate timely diagnosis and treatment.

From data to discovery: AI-guided analysis of disease-relevant molecules in spinal muscular atrophy (SMA)

Spinal Muscular Atrophy is caused by partial loss of survival of motoneuron (SMN) protein expression. The numerous interaction partners and mechanisms influenced by SMN loss result in a complex disease. Current treatments restore SMN protein levels to a certain extent, but do not cure all symptoms. The prolonged survival of patients creates an increasing need for a better understanding of SMA. Although many SMN-protein interactions, dysregulated pathways, and organ phenotypes are known, the connections among them remain largely unexplored. Monogenic diseases are ideal examples for the exploration of cause-and-effect relationships to create a network describing the disease-context. Machine learning tools can utilize such knowledge to analyze similarities between disease-relevant molecules and molecules not described in the disease so far. We used an artificial intelligence-based algorithm to predict new genes of interest. The transcriptional regulation of 8 out of 13 molecules selected from the predicted set were successfully validated in an SMA mouse model. This bioinformatic approach, using the given experimental knowledge for relevance predictions, enhances efficient targeted research in SMA and potentially in other disease settings.

Effects of nusinersen on motor function in children with spinal muscular atrophy: a retrospective study

Background

Spinal muscular atrophy (SMA) is a genetic progressive neuromuscular disease. Nusinersen is the first disease modifying drug approved to treat patients with SMA. Our study aimed to evaluate the efficacy of nusinersen treatment on motor function in children with SMA.

Methods

A retrospective analysis was conducted on the data of 52 genetically confirmed SMA patients from November 2020 to September 2023. Motor function was assessed based on standardized scales from baseline to 14 months of follow-up.

Results

Of patients in this study, the majority had SMA type 2 (40/52, 76.9%), 5 (9.6%) and 7 (13.5%) patients had SMA types 1 and 3, respectively. The median disease duration was 11 months (range 0-52), and the median age at initiation of treatment was 44.5 months (range 5-192). Motor function of all the patients with SMA improved from baseline to 14 months of follow-up. Mean increases of 4.6-point (p = 0.173), 4.7-point (p = 0.021) and 2.7-point (p = 0.013) were observed from baseline to 14 months of follow-up for the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores, the Hammersmith Functional Motor Scale Expanded (HFMSE) and the Revised Upper Limb Module (RULM), respectively. Increased disease duration and age of treatment initiation were negatively correlated with the changes in HFMSE scores (r = -0.567, p = 0.043; r = -0.771 and p = 0.002, respectively). Similar results were observed for the RULM scores (r = -0.714, p = 0.014; r = -0.638 and p = 0.035, respectively).

Conclusion

Our study suggested that 14 months of treatment with nusinersen was effective and improved the motor function of children with SMA types 1, 2, or 3. In addition, disease duration and age at treatment initiation were negatively correlated with treatment outcome in the patients.

Treatment Options in Spinal Muscular Atrophy: A Pragmatic Approach for Clinicians

Spinal muscular atrophy (SMA) is a rare neurodegenerative neuromuscular disorder with a wide phenotypic spectrum of severity. SMA was previously life limiting for patients with the most severe phenotype and resulted in progressive disability for those with less severe phenotypes. This has changed dramatically in the past few years with the approvals of three disease-modifying treatments. We review the evidence supporting the use of currently approved SMA treatments (nusinersen, onasemnogene abeparvovec, and risdiplam), focusing on mechanisms of action, side effect profiles, published clinical trial data, health economics, and pending questions. Whilst there is robust data from clinical trials of efficacy and side effect profile for individual drugs in select SMA populations, there are no comparative head-to-head clinical trials. This presents a challenge for clinicians who need to make recommendations on the best treatment option for an individual patient and we hope to provide a pragmatic approach for clinicians across each SMA profile based on current evidence.

2024 update: European consensus statement on gene therapy for spinal muscular atrophy

Spinal muscular atrophy (SMA) is one of the most common genetic diseases and was, until recently, a leading genetic cause of infant mortality. Three disease-modifying treatments have dramatically changed the disease trajectories and outcome for severely affected infants (SMA type 1), especially when initiated in the presymptomatic phase. One of these treatments is the adeno-associated viral vector 9 (AAV9) based gene therapy onasemnogene abeparvovec (Zolgensma®), which is delivered systemically and has been approved by the European Medicine Agency for SMA patients with up to three copies of the SMN2 gene or with the clinical presentation of SMA type 1. While this broad indication provides flexibility in patient selection, it also raises concerns about the risk-benefit ratio for patients with limited or no evidence supporting treatment. In 2020, we convened a European neuromuscular expert working group to support the rational use of onasemnogene abeparvovec, employing a modified Delphi methodology. After three years, we have assembled a similar yet larger group of European experts who assessed the emerging evidence of onasemnogene abeparvovec's role in treating older and heavier SMA patients, integrating insights from recent clinical trials and real-world evidence. This effort resulted in 12 consensus statements, with strong consensus achieved on 9 and consensus on the remaining 3, reflecting the evolving role of onasemnogene abeparvovec in treating SMA.

Analysis of the efficacy and adverse effects of nusinersen in the treatment of children with spinal muscular atrophy in China

OBJECTIVE

This study was based on a retrospective clinical observational cohort study of a two-center application of nusinersen in China to evaluate the clinical efficacy and adverse effects of nusinersen in the treatment of SMA (spinal muscular atrophy) Types 1-3.

METHODS

Clinical data from children with clinically and genetically confirmed 5qSMA from a double center in western China (the Second Affiliated Hospital of Xi'an Jiaotong University and the Second Hospital of West China of Sichuan University). All children were younger than 18 years of age. Patients were assessed for motor function and underwent blood and fluid tests before each nusinersen injection.

RESULTS

At 14-month follow-up, 100% of children had improved their HFMSE (Hammersmith Functional Motor Scale Expanded) score, 83.6% had improved their CHOP INTEND (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders) score, and 66.6% had improved their RULM (Revised Upper Limb Module) score by ≥3 points from baseline, and their 6MWT (6-min walk test) was 216.00 ± 52.08 m longer than at baseline. The age of the child at the start of treatment was negatively correlated with the clinical efficacy of nusinersen; the younger the child, the better the response to treatment. No significant adverse effects affecting the treatment and quality of life of the child were observed during the treatment of SMA with nusinersen.

CONCLUSION

This study concluded that nusinersen is clinically beneficial for children with SMA in western China, with mild adverse effects.

Clinical decision making around commercial use of gene and genetic therapies for spinal muscular atrophy

Spinal muscular atrophy is no longer a leading cause of inherited infant death in the United States. Since 2016, three genetic therapies have been approved for the treatment of spinal muscular atrophy. Each therapy has been well studied with robust data for both safety and efficacy. However, there are no head-to-head comparator studies to inform clinical decision making. Thus, treatment selection, timing, and combination therapy is largely up to clinician preference and insurance policies. As the natural history of spinal muscular atrophy continues to change, more data is needed to assist in evidence-based and cost-effective clinical decision making.