Spinal muscular atrophy

Carrier screening for survival motor neuron variants in 7709 pregnant women from Foshan, Guangdong Province

PURPOSE

Spinal muscular atrophy (SMA), a severe autosomal-recessive disorder, is primarily caused by homozygous deletions of exon 7 survival motor neuron 1 (SMN1) gene. However, data on SMN1 variant carrier rates in the Foshan area of Guangdong Province are limited. This retrospective study aimed to determine SMN1 carrier rate among pregnant women in Foshan, evaluate screening uptake, and analyse regional variations to optimize genetic counselling strategies and public health interventions.

METHODOLOGY

Multiplex real-time quantitative polymerase chain reaction was used to determine the SMN1 variant in pregnant women from February 2023 to March 2025 in the Foshan area. If pregnant women screened positive, carrier testing was recommended for their husbands. Prenatal diagnoses were performed for high-risk couples.

RESULTS

Among the 7709 pregnant women who underwent SMN1 variant carrier screening, 104 SMN1 variant carriers were identified, yielding a carrier rate of 1.35 %. Spousal testing (82.7 % compliance) revealed one high-risk couple, with prenatal diagnosis confirming a heterozygous deletion in the foetus. The carrier rate of Foshan was lower than that in Shenzhen and Maoming but higher than that in Hispanic populations.

CONCLUSIONS

Our study revealed a 1.35 % SMN1 carrier rate among Foshan pregnant women, supporting genetic counselling and prenatal diagnosis implementation. Systematic screening facilitates early detection of at-risk couples, enabling prenatal interventions to reduce SMA births.

Mechanisms of functional improvement behind nusinersen treatment in adult spinal muscular atrophy

Nusinersen treatment not only prevents neurological deterioration in presymptomatic or early symptomatic children with spinal muscular atrophy (SMA) but promotes functional improvement in the later plateau phase in adults with SMA, though the mechanisms for such functional improvement are not fully understood. We evaluated the motor behaviors and electrophysiological performance of 10 consecutive adult patients with SMA before and 2, 6, 10 months after nusinersen treatment. Adult SMA mice (Smn-/-SMN2+/+) were treated with nusinersen intracerebroventricularly for 2 months with analysis of the SMN transcripts and proteins expression, motor function, electrophysiology, and pathology of spinal cord and muscles. SMA patients showed motor function improvement in 10 months after nusinersen treatment with an increase in compound muscle action potential (CMAP) amplitude and motor unit number estimation (MUNE). Nusinersen augmented the expression of full-length SMN transcripts and proteins in SMA mice. SMA mice receiving nusinersen treatment showed a motor behavioral improvement with an increase in MUNE. Although nusinersen treatment partially prevented spinal motor neuron death, there was no obvious elevation in motor neuron density despite an increase in MUNE, indicating the reactivation of quiescent motor neurons. Nusinersen treatment not only eliminated progressive denervation at the neuromuscular junction (NMJ), but also promoted NMJ innervation, implying the existence of reinnervation. The functional improvements observed with nusinersen treatment in adults with SMA during the later plateau phase primarily result from two mechanisms: the revival of live but functionless motor neurons and the reinnervation of NMJs through axonal sprouting and the formation of new motor units.

Growth-friendly Technique or Posterior Spinal Fusion With T-construct Pelvic Fixation in Nonambulatory Spinal Muscular Atrophy With Severe Scoliosis

BACKGROUND

The surgical treatment of scoliosis in type 2 spinal muscular atrophy (SMA2) is challenging and little described in the literature due to its rarity and fragility of the patients. The aim of this study was to review the surgical strategies and outcomes in patients with SMA2 who underwent surgery for scoliosis at a French reference neuromuscular center.

METHODS

All consecutive patients with genetically confirmed SMA2 who underwent spinal surgery between 2009 and 2022 at our French reference center were retrospectively analyzed. They were divided into 2 groups, according to their primary surgery: either magnetically controlled growing rods (MCGR) or posterior spinal fusion (PSF). Demographic, respiratory, and radiologic parameters were collected preoperatively and at the latest follow-up. All complications were reported. Patients and/or caregiver-reported outcome questionnaires were also used to assess the improvement of sitting posture.

RESULTS

Seventeen patients underwent MCGR, and 9 patients underwent PSF during the inclusion period. Mean follow-up was 5.3±1.8 years in the MGCR group, and 8.0±4.5 years in the PSF group. The average age at surgery was 9.7±1.6 years in the MCGR group and 12.6±1.7 years in the PSF group. Pelvic fixation was performed using a Tconstruct (2 sacral and 2 iliac screws). PSF was performed with all levelled pedicle screws. In the MGCR group, upper thoracic fixation was lateral ribs (n=4), vertebral on three levels (n=9), or hybrid costo-vertebral (n=4). No blood transfusion was required. No differences were found between preoperative and postoperative lung function tests for the 2 surgical procedures. The major curve correction rate was 44% in the MCGR group and 55% in the PSF group. The pelvic obliquity at last follow-up was <5 degrees in all patients. Three unplanned surgeries occurred: 1 MGCR change after lengthening and 2 PSF-one for proximal hook migration and one for infection. All patients improved their ability to sit.

CONCLUSION

In this series, PSF and MGCR allowed stable radiographic and respiratory results, with a reduced rate of global complications. Pelvic fixation with T-construct was a reliable and effective technique to correct pelvic obliquity in this population of patients.

Early Treatment in Preterm Twins With Spinal Muscular Atrophy

Early treatment in spinal muscular atrophy is widely recognized as critical for improving neurologic and respiratory outcomes, especially in presymptomatic infants. With the expansion of newborn screening, more infants are now diagnosed presymptomatically. Currently, there are no established treatment guidelines for preterm infants with spinal muscular atrophy, with only anecdotal reports available. Additionally, there is limited knowledge regarding the safety and efficacy of the different treatments in preterm infants. In Israel, although a newborn screening program for spinal muscular atrophy is not yet implemented, a significant portion of the population participates in genetic carrier screening. Here, we present a case of presymptomatic preterm twins, born at gestational age of 32 + 2 weeks, birth weights of 1855 and 1740 g, respectively. They were treated with risdiplam followed by onasemnogene abeparvovec at a gestational age of 35 and 43 weeks, respectively. This case adds to the limited data on treatment options for preterm infants.

Gene therapy: principles, challenges and use in clinical practice

INTRODUCTION

Gene therapy is an emerging topic in medicine. The first products have already been licensed in the European Union for the treatment of immune deficiency, spinal muscular atrophy, hemophilia, retinal dystrophy, a rare neurotransmitter disorder and some hematological cancers, while many more are being assessed in preclinical and clinical trials.

OBJECTIVE

The purpose of this review is to provide an overview of the core principles of gene therapy along with information on challenges and risks. Benefits, adverse effects and potential risks are illustrated based on the examples of hemophilia and spinal muscular atrophy.

RESULTS

At present, in-vitro and in-vivo gene addition or gene augmentation is the most commonly established type of gene therapy. More recently, more sophisticated and precise approaches such as in situ gene editing have moved into focus. However, all types of gene therapy require long-term observation of treated patients to ensure safety, efficacy, predictability and durability. Important safety concerns include immune reactions to the vector, the foreign DNA or the new protein resulting from gene therapy, and a remaining low cancer risk based on insertional mutagenesis. Ethical and regulatory issues need to be addressed, and new reimbursement models are called for to ease the financial burden that this new treatment poses for the health care system.

CONCLUSION

Gene therapy holds great promise for considerable improvement or even cure of genetic diseases with serious clinical consequences. However, a number of questions and issues need to be clarified to ensure broad accessibility of safe and efficacious products.

Exploring sleep quality, depressive symptoms, and quality of life in adults with spinal muscular atrophy

Spinal Muscular Atrophy (SMA) is a genetic neuromuscular disorder caused by the mutation of the survival motor neuron 1 (SMN1) gene. Sleep disturbances and their impact on mental health and quality of life in patients with SMA are being understudied, and most of the evidence comes from pediatric SMA patients. We conducted a cross-sectional survey of adult patients with SMA. The participants underwent questionnaires exploring sleep quality with the Pittsburgh Sleep Quality Index (PSQI), depressive symptoms with the Patient Health Questionnaire-9 (PHQ-9), and quality of life with the Short-Form Health Survey 36 (SF-36). Fifty patients with SMA were enrolled in the study: 66 % were females with a median age of 41 years. Of them, 60 % had poor sleep quality, and 72 % had depressive symptoms. SMA 2 patients showed higher PSQI and PHQ-9 scores than SMA 3 patients (8 ± 3 vs 6 ± 1, p < 0.001 and 13±5 vs 7 ± 5, p < 0.001). PSQI total score correlated with the PHQ-9 (r = 0.32, p = 0.02), which was higher in patients with respiratory symptoms. Poor sleep is associated with depressive symptoms and respiratory dysfunction in adult SMA patients. Clinicians should consider sleep quality in SMA patients for optimal care; future studies are needed to understand this aspect better.

Differential respiratory function response in paediatric spinal muscular atrophy types 2 and 3 treated with nusinersen over 3 years

AIM

To establish whether the initial positive effect of nusinersen (NUS) on respiratory outcomes in the first year of treatment was maintained in children with Spinal Muscular Atrophy (SMA) type 2 and to further define the effect on children with type 3 treated over 3 years.

METHODS

A prospective observational study of children with type 2 and 3 beginning NUS in Queensland, Australia between June 2018-December 2020 was undertaken. Investigations conducted included age-appropriate lung function and polysomnography. Lung function data for two-years preceding NUS initiation was retrospectively collected. Change in lung function/polysomnography was assessed using mixed effects linear regression.

RESULTS

24 of 30 children with type 2 and 3 SMA (14 males; 2.6-15.8) were included (type 2 n = 12; type 3 n = 12). No child had respiratory-related admissions during the period of study. For type 2, annual decline in FVC z-score pre-treatment was -0.75 (95 % CI: 1.14, -0.39, p < 0.001), and for the first 3 years on NUS was -0.20 ([95 % CI: 0.33, -0.06, p = 0.01] difference p = 0.008). For type 3 minimal change was seen: pre-NUS and post FVC z-scores -0.20 (95 % CI: 1.00, 0.61 p = 0.05) and -0.46 (95 % CI: 0.88, -0.04 p = 0.40) respectively (difference p = 0.46). Mean change in total apnoea-hypopnoea indices (total AHI) in type 2 tended to reduce -1.75 (95 % CI: 4.95-0.9, p = 0.24); type 3 appeared to remain stable (-0.39 [95 % CI: 1.1-0.33, p = 0.28). One child with type 2 ceased NIV due to normalisation of total AHI and gas exchange.

CONCLUSION

Nusinersen lung function (FVC-z-scores) stability seen in the first year was maintained over 3 years and the total AHI tended to improve in type 2, but the long-term effects in type 3 are less clear.

Antisense oligonucleotides: A promising advancement in neurodegenerative disease treatment

Antisense oligonucleotides (ASOs) are a class of therapeutics designed to modulate gene expression and have shown promise in the treatment of various neurodegenerative diseases. As of March 2025, four ASO-based therapies have received approval for the treatment of neurodegenerative diseases, including spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), and hereditary transthyretin amyloidosis (ATTR). These approvals underscore the therapeutic potential of ASOs as effective treatments for neurodegenerative diseases by addressing specific genetic abnormalities. This is best demonstrated by clinical studies in more than a dozen ASOs, which could pave the way for the development of new therapeutics soon. Moreover, the ongoing extended clinical studies, which target presymptomatic carriers, have significant potential to cure familial ALS based on the SOD1 gene mutation. This review provides an update on clinical trials, highlighting promising results and the challenges encountered.

Rehabilitation improves the effectiveness of nusinersen in children with type 2 spinal muscular atrophy: pNF-H and muscle MRI as potential biomarkers

Introduction

Rehabilitation therapy is an important approach for spinal muscular atrophy (SMA) management. Currently, rare articles introduce that the combination of nusinersen and rehabilitation yields better results in SMA patients compared to using nusinersen alone. The present study examined whether rehabilitation therapy can improve the effectiveness of nusinersen and phosphorylated neurofilament heavy chain (pNF-H) and muscle magnetic resonance imaging (MRI) can serve as potential biomarkers for evaluating the therapeutic effects in type-2 SMA patients.

Methods

This observational study enrolled 22 pediatric patients with type-2 SMA. Enrolled patients were divided into two groups based on the rehabilitation treatment. Motor function and swallowing function were analyzed at baseline, 6, 10, and 14 months. The level of pNF-H and MRI of the thigh skeletal muscles were analyzed at baseline and 14 months.

Results

Greater improvement in motor function was observed in the rehabilitation group compared with the non-rehabilitation group. The levels of pNF-H in the serum and cerebrospinal fluid significantly decreased at 14 months. One patient from the rehabilitation treatment group showed mild improvement in the degree of fatty infiltration in the quadriceps muscles after 14 months.

Conclusion

This study suggests that rehabilitation therapy improves the effectiveness of nusinersen on type-2 SMA patients, and the levels of pNF-H and skeletal muscle MRI can serve as potential biomarkers for evaluating the effectiveness of SMA treatment.

Research trends on spinal muscular atrophy from 1995 to 2023: A bibliometric analysis

BACKGROUND

Spinal muscular atrophy (SMA) is a neuromuscular disease characterized by progressive muscle weakness due to motor neuron degeneration. The discovery of the survival motor neuron 1 (SMN1) gene in 1995 revolutionized SMA research, leading to significant therapeutic advancements. This bibliometric analysis aimed to explore global trends in SMA research and therapy, with a particular focus on China.

METHODS

A comprehensive database search identified 4506 relevant publications (3812 articles, 694 reviews) published between 1995 and 2023. Bibliometric tools were used to analyze publication trends, collaborations, and research topics.

RESULTS

SMA research has experienced substantial growth, with the United States leading in publications followed by the United Kingdom and Germany. China has shown increasing engagement in this field. Key research areas include genetic and molecular mechanisms, survival motor neuron gene therapy, antisense oligonucleotides, and muscle strength-promoting factors. Chinese researchers have contributed significantly to these areas, with a higher reporting frequency of SMA-related topics compared to other countries.

CONCLUSION

This bibliometric analysis provides a comprehensive overview of global SMA research, highlighting significant advancements, and identifying future directions. The findings offer valuable insights for researchers, clinicians, and policymakers in China to ensure alignment with global medical advancements and improve the lives of individuals affected by SMA.

[Spinal Muscular Atrophy: The Reality of the Adult Patient in Spain]

BACKGROUND

Spinal muscular atrophy (SMA) is a neurodegenerative disease in which there has been an increase in survival over the past decade due to proactive, multidisciplinary management and the emergence of disease-modifying therapies. Despite this, there are still several critical challenges that significantly impact the quality of life of individuals with SMA individuals. Given the need to better understand the reality of this disease, Fundación de Atrofia Muscular Espinal (FundAME) created a patient registry (RegistrAME).

METHODS

RegistrAME is a longitudinal prospective study that collects clinical data and patient-reported outcomes.

RESULTS

The registry included 336 individuals, 51.8% of whom were over 16 years old. Most adult subpopulations were classed as type 2 (49.4%) or type 3 (44.8%). Regarding functional status, 19% walked (39.4% used wheelchairs), 46.6% sat without support (84% needed help to sit), and 34.5% were non-sitters. Furthermore, 24.7% reported having no useful function in their hands or not being able to reach their mouths with their hands. Our study indicates that the adult SMA population is progressively accessing disease-modifier treatments. However, 21.8% of the population is still untreated.

CONCLUSIONS

These results provide evidence of a progressive impairment and increased sensitivity to treatment discontinuations in the SMA adult population, along with delayed or reduced access to commercialised SMA drugs and clinical trials. A more rigorous evaluation of the disease's impact and treatment benefits in the adult SMA population is necessary.

Genome-wide profiling of highly similar paralogous genes using HiFi sequencing

Variant calling is hindered in segmental duplications by sequence homology. We developed Paraphase, a HiFi-based informatics method that resolves highly similar genes by phasing all haplotypes of paralogous genes together. We applied Paraphase to 160 long (>10 kb) segmental duplication regions across the human genome with high (>99%) sequence similarity, encoding 316 genes. Analysis across five ancestral populations revealed highly variable copy numbers of these regions. We identified 23 paralog groups with exceptionally low within-group diversity, where extensive gene conversion and unequal crossing over contribute to highly similar gene copies. Furthermore, our analysis of 36 trios identified 7 de novo SNVs and 4 de novo gene conversion events, 2 of which are non-allelic. Finally, we summarized extensive genetic diversity in 9 medically relevant genes previously considered challenging to genotype. Paraphase provides a framework for resolving gene paralogs, enabling accurate testing in medically relevant genes and population-wide studies of previously inaccessible genes.

Application of Digital Polymerase Chain Reaction (dPCR) in Non-Invasive Prenatal Testing (NIPT)

This article reviews the current applications of the digital polymerase chain reaction (dPCR) in non-invasive prenatal testing (NIPT) and explores its potential to complement or surpass the capabilities of Next-Generation Sequencing (NGS) in prenatal testing. The growing incidence of genetic disorders in maternal-fetal medicine has intensified the demand for precise and accessible NIPT options, which aim to minimize the need for invasive prenatal diagnostic procedures. Cell-free fetal DNA (cffDNA), the core analyte in NIPT, is influenced by numerous factors such as maternal DNA contamination, placental health, and fragment degradation. dPCR, with its inherent precision and ability to detect low-abundance targets, demonstrates robustness against these interferences. Although NGS remains the gold standard due to its comprehensive diagnostic capabilities, its high costs limit widespread use, particularly in resource-limited settings. In contrast, dPCR provides comparable accuracy with lower complexity and expense, making it a promising alternative for prenatal testing.

The Effect of Disease-Modifying Therapies on Lung Function and Respiratory Muscle Strength in Spinal Muscular Atrophy: Systematic Review and Meta-Analysis

Background: Spinal muscular atrophy (SMA) is often complicated by respiratory problems. The disease-modifying therapies (DMTs) (nusinersen, onasemnogene abeparvovec, and risdiplam) have improved survival, motor function, and functional muscle strength in patients with SMA, but their effects on lung function and respiratory muscle strength need further clarification. Therefore, we performed a systematic review of studies that documented the effects of DMTs on lung function and respiratory muscle strength in patients with SMA types I, II, III, and IV. Methods: We searched the electronic databases PubMed/MEDLINE, CINAHL, Embase, and Web of Science up to December 2023. We included pre-post studies that determined the effect of DMTs for SMA on lung function or respiratory muscle strength in patients with SMA. Where possible, we performed a meta-analysis using a random-effects model with generic inverse variance weighing. Results: We included 19 studies of 376 identified records (16 longitudinal cohort studies and 3 case series) with 384 participants. Seventeen studies investigated the effect of nusinersen, and two studies investigated the effect of risdiplam. Seventeen studies had a moderate and two had a high risk of bias. Most of these studies did not report statistically significant improvement in lung function or respiratory muscle strength after treatment with nusinersen or risdiplam. A meta-analysis of 13 studies showed no statistically significant improvement in FVC after 2, 6, 10, and > 12 months of treatment with nusinersen. Conclusions: The findings of this review indicate that there is moderate evidence that nusinersen does not improve FVC, FEV1, peak expiratory flow, or maximum inspiratory pressure in subjects with SMA types I, II, III, or IV. There was no statistically significant decline in lung function and respiratory muscle strength after treatment. This may suggest that nusinersen may have stabilized lung function and respiratory muscle strength.

Disruption of RNA-binding proteins in neurological disorders

RNA-binding proteins (RBPs) are multifunctional proteins essential for the regulation of RNA processing and metabolism, contributing to the maintenance of cell homeostasis by modulating the expression of target genes. Many RBPs have been associated with neuron-specific processes vital for neuronal development and survival. RBP dysfunction may result in aberrations in RNA processing, which subsequently initiate a cascade of effects. Notably, RBPs are involved in the onset and progression of neurological disorders via diverse mechanisms. Disruption of RBPs not only affects RNA processing, but also promotes the abnormal aggregation of proteins into toxic inclusion bodies, and contributes to immune responses that drive the progression of neurological diseases. In this review, we summarize recent discoveries relating to the roles of RBPs in neurological diseases, discuss their contributions to such conditions, and highlight the unique functions of these RBPs within the nervous system.

Analysis of SMN protein in umbilical cord blood and postnatal peripheral blood of neonates with SMA: a rationale for prompt treatment initiation to prevent SMA development

BACKGROUND

Spinal muscular atrophy (SMA) is a severe genetic neuromuscular disease caused by insufficient functional survival motor neuron protein (SMN). The SMN expression level in the spinal cord is highest during the 2nd trimester of the foetal period. We previously reported the SMN spot analysis in peripheral blood using imaging flow cytometry (IFC) as a biomarker of functional SMN protein expression. In this study, we analysed neonatal cord blood, postnatal peripheral blood, and maternal peripheral blood in presymptomatic five infants whose sibling has type 1 SMA to estimate prenatal and postnatal SMN dynamics before the onset of severe SMA.

RESULTS

Data from 37 untreated patients with SMA showed that SMN-spot+ cells were significantly correlated with SMA clinical classification and the copy numbers of the SMN2 gene. The range of values for cord blood, converted from each SMN2 copy number statistics, was - 0.7 to + 2.0 standard deviation (SD) (0.1-24.0%) for SMN-spot+ cells in patients with SMA. Subsequent analyses of the peripheral blood of neonates ranged from - 0.8 to + 0.8 SD (0.4-15.2%). The analysis of each maternal blood, converted from carrier statistics, ranged from - 0.2 to + 2.4 SD (1.4-25.2%). A correlation was observed between the cord blood and maternal peripheral blood.

CONCLUSIONS

This study suggests that the status of the motor neuron pool in the spinal cord can be presumed by cord blood SMN-spot+ cells and that SMN protein depletion determines the timing of disease onset. As the SMN spot analysis values tended to decrease with time after birth, they may eventually lead to the development of SMA. Furthermore, a correlation was found between the SMN spot analysis values of neonatal cord blood and maternal blood, which predicts disease severity after birth. In other words, the SMN protein supplied from the mother to the foetus may suppress the development of SMA in the infant at birth, and depletion of the SMN protein may occur after birth, causing the infant to develop SMA. Our findings demonstrated the effectiveness of newborn screening and the potential of maternally mediated treatment strategies by providing a rationale for prompt treatment initiation in SMA.

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.

Comparative study of third-generation sequencing-based CASMA-trio and STR linkage analysis for identifying SMN1 2 + 0 carriers

Spinal Muscular Atrophy (SMA, MIM#253300) is an autosomal recessive neuromuscular disorder caused by defects in the Survival Motor Neuron (SMN) gene. The SMN1 gene, recognized as the primary pathogenic gene for SMA, exhibits a high degree of sequence homology with SMN2 gene. Individuals with the SMN1 2 + 0 genotype represent a unique type of SMA carrier, characterized by two SMN1 copies on one chromosome and zero copies on the other. Accurate identification of this type of carrier is crucial for genetic counseling in families. This study included 28 samples from five SMA families, each with an affected patient carrying a homozygous deletion of the SMN1 gene and a parent suspected to be a SMN1 2 + 0 carrier. Comprehensive Analysis of SMA (CASMA), based on third-generation sequencing technology, was used to detect the SMN1 and SMN2 copy numbers in the samples, and SMN1 2 + 0 carriers were identified through SMN1 haplotypes in parent-child trios (CASMA-trio). The results were compared with those obtained using Multiplex Ligation-dependent Probe Amplification (MLPA) combined with Short Tandem Repeat (STR) linkage analysis. The SMN1 and SMN2 copy numbers detected by MLPA and CASMA were concordant across 25 peripheral blood samples, whereas CASMA failed to accurately determine the copy numbers in the remaining 3 amniotic fluid samples. CASMA-trio identified 5 members from 4 families as SMN1 2 + 0 carriers, which were consistent with the results from STR linkage analysis. However, the two methods yielded inconsistent results for the proband's father in one family. These findings suggest that CASMA has the potential to detect SMN1 and SMN2 copy numbers. Compared to STR linkage analysis, CASMA-trio only requires a parent-child trio to analyze SMN1 2 + 0 carriers, demonstrating a broader application prospect. Implementing CASMA-trio can facilitate comprehensive screening for SMA carriers.

Healthcare Resource Utilization, Economic Burden, and Multi-Level Medical Security System for Individuals with Spinal Muscular Atrophy in Shaanxi Province, China

Objectives: The objective of this study is to quantify healthcare resource utilization, economic burden, and the multi-level medical security system for Spinal Muscular Atrophy (SMA) patients in Shaanxi Province, China, from a societal perspective using a survey. Methods: This observational study employed an online survey with a retrospective cross-sectional design in Shaanxi Province, China. The survey examined various aspects of SMA, including resource utilization, direct and indirect economic burdens, and co-payment mechanisms within a multi-level medical security system. Results: Following the inclusion of nusinersen in the National Reimbursement Drug List (NRDL) in 2022, the treatment rate for SMA patients increased significantly. After risdiplam was added to the NRDL in 2023, its use also saw a marked increase. Treatment costs varied by SMA type: Type 1 incurred the highest costs (RMB 300,000 or USD 41,000), followed by Type 2 (RMB 270,000 or USD 37,000), Type 3 (RMB 200,000 or USD 27,000), and Type 4 (RMB 80,000 or USD 11,000). The primary sources of costs were productivity losses due to primary caregivers (32.94%), nusinersen usage (29.29%), and risdiplam usage (17.33%). Out-of-pocket costs for SMA patients accounted for 29.29% of the total costs. In 2023, basic medical insurance covered 49% of direct costs and 32% of total costs. Patients still had to pay 25.73% of the total cost for the direct costs. Conclusions: Basic medical insurance is a critical foundation for patient security and plays a pivotal role in reimbursement. In contrast, commercial insurance has a relatively limited impact on covering the costs for SMA patients. These findings highlight the substantial healthcare burden faced by SMA patients under the current healthcare system in China.

Motor pool selectivity of neuromuscular degeneration in type I spinal muscular atrophy is conserved between human and mouse

Spinal muscular atrophy (SMA) is caused by low levels of the survival motor neuron (SMN) protein. Even though SMN is ubiquitously expressed, the disease selectively affects motor neurons, leading to progressive muscle weakness. Even among motor neurons, certain motor units appear more clinically resistant to SMA. To quantitatively survey selective resistance, we studied extensive neuromuscular autopsies of Type I SMA patients and age-matched controls. We found highly divergent degrees of degeneration of neighboring motor units, even within individual cranial nerves or a single anatomical area such as the neck. Examination of a Type I SMA patient maintained on life support for 17 years found that most muscles were atrophied, but the diaphragm was strikingly preserved. Nevertheless, some resistant human muscles with preserved morphology displayed nearly complete conversion to slow Type I myofibers. Remarkably, a similar pattern of selective resistance was observed in the SMNΔ7 mouse model. Overall, differential motor unit vulnerability in human Type I SMA suggests the existence of potent, motor unit-specific disease modifiers. Mechanisms that confer selective resistance to SMA may represent therapeutic targets independent of the SMN protein, particularly in patients with neuromuscular weakness refractory to current treatments.

Healthcare resource utilisation and direct medical cost for individuals with 5q spinal muscular atrophy in Sweden

BACKGROUND

Spinal muscular atrophy (SMA) is a rare, progressive, neuromuscular disorder. Recent advances in treatment require an updated assessment of burden to inform reimbursement decisions.

OBJECTIVES

To quantify healthcare resource utilisation (HCRU) and cost of care for patients with SMA.

METHODS

Cohort study of patients with SMA identified in the Swedish National Patient Registry (2007-2018), matched to a reference cohort grouped into four SMA types (1, 2, 3, unspecified adult onset [UAO]). HCRU included inpatient admissions, outpatient visits, procedures, and dispensed medications. Direct medical costs were estimated by multiplying HCRU by respective unit costs. Average annual HCRU and medical costs were modelled for SMA versus reference cohorts to estimate differences attributable to the disease (i.e., average treatment effect estimand). The trajectory of direct costs over time were assessed using synthetic cohorts.

RESULTS

We identified 290 SMA patients. Annualised HCRU was higher in SMA patients compared with reference cohorts. Highest risk ratios were observed for inpatient overnight stays for type 1 (risk ratio [RR]: 29.2; 95% confidence interval [CI]: 16.0, 53.5) and type 2 (RR: 23.3; 95% CI: 16.4,33.1). Mean annual direct medical costs per patient for each year since first diagnosis were greatest for type 1 (€114,185 and SMA-attributable: €113,380), type 2 (€61,876 and SMA-attributable: €61,237), type 3 (€45,518 and SMA-attributable: €44,556), and UAO (€4046 and SMA-attributable: €2098). Costs were greatest in the 2-3 years after the first diagnosis for all types.

DISCUSSION AND CONCLUSION

The economic burden attributable to SMA is significant. Further research is needed to understand the burden in other European countries and the impact of new treatments.

Motor function and compound muscle action potential amplitude in children with spinal muscular atrophy treated with nusinersen

BACKGROUND

Disease-modifying therapies can improve motor function in patients with spinal muscular atrophy (SMA), but efficacy varies between individuals. The aim was to evaluate the efficacy and safety of nusinersen treatment in children with SMA and to investigate prognostic factors.

METHODS

Motor function, compound muscle action potential (CMAP), and other indicators were prospectively collected before and 14 months after nusinersen treatment.

RESULTS

A total of 55 children were included in our study to assess safety. 41 patients (with at least 6 months of nusinersen treatment) were included in the final efficacy analyses, with a median age at first treatment of 4.2 years. After 14 months of treatment with nusinersen, motor function improved, with increases in CHOP INTEND (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders), HINE-2 (Hammersmith Infant Neurological Exam-Part 2), HFMSE (Hammersmith Functional Motor Scale-Expanded) and RULM (Revised Upper Limb Module) of 5.5 (95 % CI -2.4-13.4), 0.8 (95 % CI -0.2-1.9), 5.0 (95 % CI 2.5-7.4) and 2.4 (95 % CI 0.7-4.1) points, respectively. The CMAP amplitudes of the bilateral tibial, median and ulnar nerves increased, with greatest improvements of 0.87 ± 1.41 mV, 1.08 ± 1.71 mV and 0.59 ± 1.01 mV, respectively. Spearman correlation analysis showed that age at first treatment, disease duration, joint contractures and scoliosis were associated with treatment efficacy (r = -0.4-0.7, P < 0.05). Subgroup analyses showed that the mean HFMSE and RULM scores improved in the Physical therapy group (P < 0.05).

CONCLUSION

Early treatment, mild bone and joint complications, and regular rehabilitation training were associated with better outcomes. The other motor-related functions, such as respiratory and bullar function, and prognostic factors should be studied in the future.

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.

Spinal presentations in children with type 1 spinal muscular atrophy on nusinersen treatment across the SMA-REACH UK network: a retrospective national observational study

BACKGROUND

Prior to the introduction of disease-modifying treatments (DMTs), children with type 1 spinal muscular atrophy (SMA) typically did not survive beyond the age of 2 years; management was mainly palliative. Novel therapies have made this a treatable condition, resulting in increased life expectancy and more time spent upright. Survival and improved function mean spinal asymmetry is a new complication with limited data on its prevalence and severity and no current guidelines on management and treatment. This study aimed to evaluate the spinal presentation and management of type 1 SMA children on nusinersen across the SMA-REACH UK network.

METHODS

Spinal presentation and management of 80 children (age range 4 months-14 years, median 4 years 2 months) with type 1 SMA on nusinersen across the SMA-REACH UK network were reviewed through retrospective data analysis.

RESULTS

There were 60 type 1 children who developed a spinal asymmetry, of which 40 had kyphosis and 50 used a supportive thoraco-lumbar-sacral orthosis (TLSO). TLSOs were predominantly a one-piece jacket with abdominal hole, advised to be worn when upright during the day. Reduced neck range of movement was found in 33, 1 of these had plagiocephaly and 5 had torticollis. Of those with reduced neck range of movement, 26 (79%) had spinal asymmetry. Spinal surgery was performed in 7.

CONCLUSIONS

Our study confirms high prevalence of spinal asymmetry in this cohort, requiring long-term management planning. It provides information on presentation and treatment options, facilitating development of guidelines for these new complications observed in children surviving longer with DMTs.

Cre-Lox miRNA-delivery technology optimized for inducible microRNA and gene-silencing studies in zebrafish

While many genetic tools exist for zebrafish, this animal model still lacks robust gene-silencing and microRNA-delivery technologies enabling spatio-temporal control and traceability. We have recently demonstrated that engineered pri-miR backbones can trigger stable gene knockdown and/or express microRNA(s) of choice in this organism. However, this miRNA-expressing technology presents important limitations. First, to trigger potent knockdown(s), multiple synthetic-miRNAs must be expressed simultaneously, compromising the co-expression of fluorescent marker(s) and knockdown traceability. Second, when gene(s) knockdown triggers significant phenotypes, like homozygous mutants with severe early phenotypes, it is difficult, if not impossible, to maintain transgenic carriers. To solve these problems and provide a mature RNAi and microRNA-delivery technology, we have generated new RNAi reagents and an inducible delivery system based on the Cre/Lox technology. This system allows the creation of asymptomatic/silent carriers, easing the production of embryos with potent knockdowns that can be traced and spatiotemporally controlled. We further demonstrated the utility of this approach by establishing novel inducible and tissue-specific models of spinal muscular atrophy, opening new avenues for studying smn1-gene function and pathogenicity. All in all, these materials and techniques will be invaluable in studying microRNA biology and in modelling or tackling conditions in which gene dosage is key.

Experience of nusinersen treatment in advanced spinal muscular atrophy type 1: Characteristics of late responders with delayed treatment efficacy

OBJECTIVE

Little clinical data is available for advanced cases of spinal muscular atrophy (SMA) type 1, particularly those requiring ventilation support. Therefore, this study aimed to evaluate the effectiveness of nusinersen treatment on motor and respiratory function in advanced cases of SMA type 1.

METHODS

This observational cohort study included seven patients with advanced SMA type 1, requiring permanent ventilator support and tracheostomy, at Hyogo Medical University School of Medicine Hospital between July 2017 and July 2019. The primary outcome was change in motor function, assessed using the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score. Subjective changes, which could not be measured with CHOP-INTEND, were also evaluated. The secondary outcomes included changes in respiratory function, measured by tidal volume (TV) and transcutaneous carbon dioxide (TcCO2) levels.

RESULTS

Two patients showed a meaningful improvement in CHOP-INTEND scores (an increase of 4 points) after 2-3 years of nusinersen treatment. The remaining five showed changes ranging from 0 to 2 points. Subjective changes were observed in all patients. Patient respiratory function outcomes varied; TV increased in two patients and decreased in five, and TcCO2 levels decreased in three patients and increased in four.

CONCLUSIONS

Nusinersen may provide meaningful improvement in motor function in some patients with advanced SMA type 1; however, treatment response may take a while and varies between individuals. Further research is needed to substantiate these findings and identify potential prognostic factors for nusinersen treatment.

Emotions experienced by parents whose children have spinal muscular atrophy: A qualitative research

BACKGROUND

The lifelong and intensive treatment and care process of Spinal Muscular Atrophy may cause a decrease in the life quality of the child and the parents. This study aims to examine the emotions of parents who have a child with Spinal Muscular Atrophy within the framework of a phenomenological design.

METHODS

This study was conducted with a phenomenological design. The study was carried out between August 2022 and April 2024 with the parents of children treated for Spinal Muscular Atrophy in the pediatric ward of a university hospital. Using a purposive sampling method, 11 parents were involved in interviews. A semi-structured questionnaire was employed during the interviews, and all the interviews were audio recorded. The data analysis done by applying the inductive thematic analysis method. The study was carried out according to the COREQ checklist.

FINDINGS

It was found that 54.54 % of the children who participated in the study were diagnosed with Spinal Muscular Atrophy between the ages of 0 and 1 year, 72.72 % between 0 and 6 months, and 54.54 % were Spinal Muscular Atrophy TYPE 1 patients. As a result of thematic analysis method, five main and ten sub-themes had emerged. These are; (1) helplessness (helplessness of having to accept, helplessness of not being able to spare time), (2) being upset (being upset about the symptoms of the disease, feeling misunderstood, sadness about their healthy children), (3) stress (stress due to the intensive and exhausting treatment and care process, stress due to the economic situation), (4) fear (fear of death, fear of future pregnancies), (5) unhappiness (being unhappy with the changing living conditions).

DISCUSSION

It was observed that parents who have a child with Spinal Muscular Atrophy experience emotional challenges.

APPLICATION TO PRACTICE

Gaining insights into the perspectives of parents can enable healthcare professionals to better understand the negative emotional experiences of parents caring for children with Spinal Muscular Atrophy. Such understanding may guide the development of targeted strategies to provide comprehensive psychological support aimed at improving parental mental health outcomes. Increasing awareness among healthcare professionals and the broader society fosters a more informed and empathetic approach to addressing the challenges faced by children with Spinal Muscular Atrophy and their families, enhancing the quality of care and support provided.

Motor Unit Magnetic Resonance Imaging (MUMRI) In Skeletal Muscle

Magnetic resonance imaging (MRI) is routinely used in the musculoskeletal system to measure skeletal muscle structure and pathology in health and disease. Recently, it has been shown that MRI also has promise for detecting the functional changes, which occur in muscles, commonly associated with a range of neuromuscular disorders. This review focuses on novel adaptations of MRI, which can detect the activity of the functional sub-units of skeletal muscle, the motor units, referred to as "motor unit MRI (MUMRI)." MUMRI utilizes pulsed gradient spin echo, pulsed gradient stimulated echo and phase contrast MRI sequences and has, so far, been used to investigate spontaneous motor unit activity (fasciculation) and used in combination with electrical nerve stimulation to study motor unit morphology and muscle twitch dynamics. Through detection of disease driven changes in motor unit activity, MUMRI shows promise as a tool to aid in both earlier diagnosis of neuromuscular disorders and to help in furthering our understanding of the underlying mechanisms, which proceed gross structural and anatomical changes within diseased muscle. Here, we summarize evidence for the use of MUMRI in neuromuscular disorders and discuss what future research is required to translate MUMRI toward clinical practice. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

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.

SMN Deficiency Induces an Early Non-Atrophic Myopathy with Alterations in the Contractile and Excitatory Coupling Machinery of Skeletal Myofibers in the SMN∆7 Mouse Model of Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is caused by a deficiency of the ubiquitously expressed survival motor neuron (SMN) protein. The main pathological hallmark of SMA is the degeneration of lower motor neurons (MNs) with subsequent denervation and atrophy of skeletal muscle. However, increasing evidence indicates that low SMN levels not only are detrimental to the central nervous system (CNS) but also directly affect other peripheral tissues and organs, including skeletal muscle. To better understand the potential primary impact of SMN deficiency in muscle, we explored the cellular, ultrastructural, and molecular basis of SMA myopathy in the SMNΔ7 mouse model of severe SMA at an early postnatal period (P0-7) prior to muscle denervation and MN loss (preneurodegenerative [PND] stage). This period contrasts with the neurodegenerative (ND) stage (P8-14), in which MN loss and muscle atrophy occur. At the PND stage, we found that SMN∆7 mice displayed early signs of motor dysfunction with overt myofiber alterations in the absence of atrophy. We provide essential new ultrastructural data on focal and segmental lesions in the myofibrillar contractile apparatus. These lesions were observed in association with specific myonuclear domains and included abnormal accumulations of actin-thin myofilaments, sarcomere disruption, and the formation of minisarcomeres. The sarcoplasmic reticulum and triads also exhibited ultrastructural alterations, suggesting decoupling during the excitation-contraction process. Finally, changes in intermyofibrillar mitochondrial organization and dynamics, indicative of mitochondrial biogenesis overactivation, were also found. Overall, our results demonstrated that SMN deficiency induces early and MN loss-independent alterations in myofibers that essentially contribute to SMA myopathy. This strongly supports the growing body of evidence indicating the existence of intrinsic alterations in the skeletal muscle in SMA and further reinforces the relevance of this peripheral tissue as a key therapeutic target for the disease.

Identification of Biochemical Determinants for Diagnosis and Prediction of Severity in 5q Spinal Muscular Atrophy Using 1H-Nuclear Magnetic Resonance Metabolic Profiling in Patient-Derived Biofluids

This study explores the potential of 1H-NMR spectroscopy-based metabolic profiling in various biofluids as a diagnostic and predictive modality to assess disease severity in individuals with 5q spinal muscular atrophy. A total of 213 biosamples (urine, plasma, and CSF) from 153 treatment-naïve patients with SMA across five German centers were analyzed using 1H-NMR spectroscopy. Prediction models were developed using machine learning algorithms which enabled the patients with SMA to be grouped according to disease severity. A quantitative enrichment analysis was employed to identify metabolic pathways associated with disease progression. The results demonstrate high sensitivity (84-91%) and specificity (91-94%) in distinguishing treatment-naïve patients with SMA from controls across all biofluids. The urinary and plasma profiles differentiated between early-onset (type I) and later-onset (type II/III) SMA with over 80% accuracy. Key metabolic differences involved alterations in energy and amino acid metabolism. This study suggests that 1H-NMR spectroscopy based metabolic profiling may be a promising, non-invasive tool to identify patients with SMA and for severity stratification, potentially complementing current diagnostic and prognostic strategies in SMA management.

Spinal Muscular Atrophy: Current Medications and Re-purposed Drugs

Spinal muscular atrophy (SMA) is an autosomal recessive genetic neuromuscular disorder that is characterized by gradual muscle weakness and atrophy due to the degeneration of alpha motor neurons that are present on the anterior horn of the spinal cord. Despite the comprehensive investigations conducted by global scientists, effective treatments or interventions remain elusive. The time- and resource-intensive nature of the initial stages of drug research underscores the need for alternate strategies like drug repurposing. This review explores the repurposed drugs that have shown some improvement in treating SMA, including branaplam, riluzole, olesoxime, harmine, and prednisolone. The current strategy for medication repurposing, however, lacks systematicity and frequently depends more on serendipitous discoveries than on organized approaches. To speed up the development of successful therapeutic interventions, it is apparent that a methodical approach targeting the molecular origins of SMA is strictly required.

Nutrition outcomes of disease modifying therapies in spinal muscular atrophy: A systematic review

The nutritional implications of spinal muscular atrophy (SMA) are profound. Disease modifying therapies (DMT) have improved clinical outcomes. This review describes the impact of DMT on nutrition outcomes. A systematic search strategy was applied across seven databases until May 2023. Eligible studies measured nutrition outcomes in individuals with SMA on DMT (nusinersen, risdiplam or onasemnogene abeparvovec [OA]) compared to untreated comparators. Nutrition outcomes included anthropometry, feeding route, swallowing dysfunction, dietary intake, dietetic intervention, nutritional biochemistry, metabolism, gastrointestinal issues and energy expenditure. Articles retrieved were screened in duplicate, data were extracted and appraised systematically. Sixty three articles from 54 studies were included; 41% (n = 22) investigated nusinersen in pediatric participants with SMA type 1. Anthropometry (n = 18), feeding route (n = 39), and swallowing dysfunction (n = 18) were the most commonly reported outcomes. In combined pediatric and adult cohorts, BMI z-score remained stable post nusinersen therapy. The proportion of children with SMA requiring enteral nutrition was stable post nusinersen therapy. Ability to thrive at age 1.5 years was higher in children treated in early infancy with OA compared to historical controls. Significant heterogeneity existed across study population characteristics and outcome measures. Nusinersen may prevent deterioration in some nutrition outcomes; and OA in early infancy may be associated with improved nutrition outcomes. Timing of DMT initiation is an important consideration for future nutrition research. Studies investigating nutrition as a primary outcome of DMT, using consistent outcome measures are required for nutritional management strategies for this cohort to be appropriately tailored.

Ultrasound-assisted and landmark-based nusinersen delivery in spinal muscular atrophy adults: A retrospective analysis

Introduction/Purpose

Nusinersen, the first treatment approved for all spinal muscular atrophy (SMA) types, is administered intrathecally through lumbar puncture. We used ultrasound assistance or a landmark-based technique to access the lumbar intrathecal space in adult SMA patients. This study aimed to evaluate the technical success and adverse events (AEs) in such patients using either technique over a long observation period.

Methods

Fifty-one adult patients received 507 consecutive interlaminar nusinersen administrations. Patients presented with both 'uncomplicated spines' or 'complicated spines'; two patients had previous back surgery. Technical success and AEs were recorded using either technique. A generalised linear mixed model was applied to evaluate predictors of technical success and complications.

Results

An overall success rate of 99.6%, with only two procedures failing to reach the intrathecal space, and an overall optimal procedure rate of 90.3% have been reported. A total of 455 procedures (89.7%) were uneventfully performed. One (0.2%) case of severe AE (puncture of a bulky abdominal annexal cyst) was recorded. Twenty-seven episodes (5.3%) of post-dural puncture headache (PDPH) and 24 episodes (4.7%) of radicular or back pain, both successfully treated with medical therapy, have also been reported. Technical success was significantly associated with 'complicated spines' (P = 0.022) and the use of ultrasound assistance (P = 0.01), and the use of ultrasound was the only independent predictor of uncomplicated procedures (P = 0.007).

Discussion

In adult patients with SMA both landmark-based and ultrasound-assisted techniques are safe and effective even in the long term. The use of assistance is associated with technical success and can predict uncomplicated procedures.

Conclusion

Our results support the use of ultrasonography in order to improve the success and reduce the burden of nusinersen intrathecal administration.

Safety and effectiveness of nusinersen, a treatment for spinal muscular atrophy, in 524 patients: results from an interim analysis of post-marketing surveillance in Japan

PURPOSE

Nusinersen is an antisense oligonucleotide approved for the treatment of spinal muscular atrophy (SMA). A post-marketing surveillance (PMS) has been ongoing (August 2017-August 2025) in all patients in Japan who were administered nusinersen intrathecally in real-world clinical settings. We report the interim analysis results for safety and effectiveness.

METHODS

This interim analysis was conducted using data collected from 524 patients whose case report forms were obtained at least once by May 30, 2022. Collected data included patient demographics and adverse events (AEs) for safety, and motor function assessments and Clinical Global Impressions of Improvement (CGI-I) for effectiveness.

RESULTS

Of the 524 patients in the safety analysis set, 522 patients who were diagnosed with SMA were included in the effectiveness analysis (infantile-onset SMA [n = 153, 29.3%], later-onset SMA [n = 369, 70.7%]). The median duration of treatment was 785.0 (range 1-1549) days. AEs occurred in 35.9% of patients (49.0% in infantile-onset SMA and 30.6% in later-onset SMA). Nusinersen treatment significantly improved Hammersmith Infant Neurological Examination scores in patients with infantile-onset SMA and Hammersmith Functional Motor Scale-Expanded scores in patients with later-onset SMA for up to nearly 3 years. Based on CGI-I assessments, 98.5-100% of patients receiving nusinersen 'improved' or remain 'unchanged'.

CONCLUSIONS

This interim analysis of the large-scale, all-case PMS in patients who were administered nusinersen in Japan supports the safety and effectiveness of nusinersen. The benefit-risk balance of nusinersen treatment remains favorable.

Experiences and the psychosocial situation of parental caregivers of children with spinal muscular atrophy against the background of new treatment options: a qualitative interview study

BACKGROUND

Spinal muscular atrophy is a rare neurodegenerative disorder in children which leads untreated to muscle wasting, respiratory impairments, and a shortened life expectancy. Parents as primary caregivers are often physically and psychologically burdened. In recent years, new and promising treatment options have been approved, but it remains unclear if they have an impact on the psychosocial situation of affected families.

OBJECTIVES

The aim of this study was to explore the views and experiences of parents as informal caregivers of children with SMA in the course of the disease against the background of new treatment options (Spinraza® or Zolgensma®).

METHODS

We conducted qualitative interviews with 27 parents of children with SMA treated with Spinraza® and Zolgensma® from April to September 2020. The analysis was done using thematic analysis and reported according to the COREQ criteria.

RESULTS

The data analysis resulted in three main themes: a) caregiver burden and negative consequences for families, b) resources and protective aspects, c) psychosocial care needs. The results are discussed against the background of new treatment options and previous models of supportive care needs. Parental caregivers of affected children face multiple burdens in different stages of the child's disease progression.

CONCLUSION

Although new treatment options for SMA showed observable effects for most parents, the main caregiver burden and reported symptoms were attributable to the overburdening care tasks. To unburden families, more screening for unmet needs, family-centered help services, professional caregivers, childcare, and sufficient financial support are needed.

Intersession Intra-Rater and Inter-Rater Reliability of Myotonometer for Upper and Lower Extremity Muscles in Children with Spinal Muscular Atrophy

Background/Objectives: This study aimed to examine intra- and inter-rater reliability of a myotonometer (MyotonPRO) in measuring upper and lower extremity mechanical properties in children with spinal muscular atrophy types I and II. Methods: Biceps brachii, triceps brachii, rectus femoris, and gastrocnemius muscle tone and stiffness in children (n = 21) were measured using the MyotonPRO device. Examiner 1 performed two sets of measurements in 60 min to determine intra-rater reliability. Examiner 2 performed measurements between Examiner 1's sets. Intra-interclass correlation coefficient, minimal detectable change, and standard error of measurement values were calculated to assess intra- and inter-rater reliabilities in this cross-sectional study. Results: The results showed excellent intra- and inter-rater reliability analyses for frequency and stiffness values except for the stiffness value of the gastrocnemius muscle, which presented good reliability (ICC = 0.71). Minimal detectable change values ranged from 0.59 to 1.98 Hz for muscle tone and 16.08 to 124.74 N/m for stiffness (for both intra- and inter-rater reliabilities). Conclusions: Our findings indicate that MyotonPRO is a reliable tool for quantifying upper and lower extremity mechanical properties within one session in children with spinal muscular atrophy types I and II. Mechanical properties of the extremity muscle can be determined using this easily applied tool in future studies.

Chest and spinal disease in patients with progressive neuromuscular disease

The chest and spine deformity in neuromuscular disease (NMDz) can impact respiratory mechanics and pulmonary function by changing the orientation of the muscles and joints of the respiratory system and placing them in a mechanically unfavorable position. This increases mechanical load on weak respiratory muscles and eventually can cause respiratory failure. Therefore, chest and spine deformity in NMDz will both lead to increased respiratory "load" and decreased respiratory muscle "pump", an exceptionally bad combination. While the current pharmacotherapies used for progressive neuromuscular disease focus on slowing progression, a similar approach has been used for decades in managing chest and spine deformity in patients with NMDz. There are, however, variable approaches to doing so and a recognition that not all "neuromuscular scoliosis" is the same and that each patient type (i.e. hypotonic vs. hypertonic) requires a different approach. Figuring out what approach to use requires both an understanding of the underlying pathophysiology of a particular neuromuscular condition and considering available options for and timing of surgical interventions. The remaining discussion will focus on hypotonic neuromuscular scoliosis.

Why should a 5q spinal muscular atrophy neonatal screening program be started?

Spinal muscular atrophy (SMA) is a genetic neuromuscular progressive disorder that is currently treatable. The sooner the disease-modifying therapies are started, the better the prognosis. Newborn screening for SMA, which is already performed in many countries, has been scheduled to begin in the near future. The development of a well-organized program is paramount to achieve favorable outcomes for the child who is born with the disease and for the costs involved in health care. We herein present a review paper hoping to point out that SMA neonatal screening is urgent and will not increase the cost of its care.

Analysis of blood concentrations and clinical application of risdiplam in patients with spinal muscular atrophy using ultra-high performance liquid chromatography-tandem mass spectrometry

Risdiplam, the first oral therapy approved for spinal muscular atrophy and made globally available in 2021, necessitates a highly sensitive and straightforward assay for therapeutic drug monitoring. This is crucial to manage potential toxicities linked to drug concentrations and supervise dosing regimens. A cutting-edge ultra-high performance liquid chromatography-tandem mass spectrometry bioassay for risdiplam in human serum has been developed. In this method, analytes were separated on a Phenomenex Kinetex XB C18 column using a 6.5-min gradient elution after a single-step protein precipitation. MS detection was conducted via electrospray ionization in positive mode with selected reaction monitoring. The validated range for risdiplam was determined to be 1.95-125.00 ng/mL. The precision and accuracy of intra- and inter-batch analyses were within ±15%. The novel method met all other established criteria. This assay holds promise for monitoring drug concentrations and guiding clinical decisions in patients with spinal muscular atrophy.

Effectiveness of Nusinersen in Adolescents and Adults with Spinal Muscular Atrophy: Systematic Review and Meta-analysis

INTRODUCTION

Nusinersen clinical trials have limited data on adolescents and adults with 5q-associated spinal muscular atrophy (SMA). We conducted a systematic literature review (SLR) and meta-analysis to assess effectiveness of nusinersen in adolescents and adults with SMA in clinical practice.

METHODS

Our search included papers published 12/23/2016 through 07/01/2022 with ≥ 5 individuals ≥ 13 years of age and with ≥ 6 months' data on ≥ 1 selected motor function outcomes [Hammersmith Functional Motor Scale-Expanded (HFMSE), Revised Upper Limb Module (RULM), and Six-Minute Walk Test (6MWT)]. For meta-analysis, effect sizes were pooled using random-effects models. To understand treatment effects by disease severity, subgroup meta-analysis by SMA type and ambulatory status was conducted.

RESULTS

Fourteen publications including 539 patients followed up to 24 months met inclusion criteria for the SLR. Patients were age 13-72 years and most (99%) had SMA Type II or III. Modest improvement or stability in motor function was consistently observed at the group level. Significant mean increases from baseline were observed in HFMSE [2.3 points (95% CI 1.3-3.3)] with 32.1% (21.7-44.6) of patients demonstrating a clinically meaningful increase (≥ 3 points) at 18 months. Significant increases in RULM were consistently found, with a mean increase of 1.1 points (0.7-1.4) and 38.3% (30.3-47.1) showing a clinically meaningful improvement (≥ 2 points) at 14 months. Among ambulatory patients, there was a significant increase in mean 6MWT distance of 25.0 m (8.9-41.2) with 50.9% (33.4-68.2) demonstrating a clinically meaningful improvement (≥ 30 m) at 14 months. The increases in HFMSE were greater for less severely affected patients, whereas more severely affected patients showed greater improvement in RULM.

CONCLUSIONS

Findings provide consolidated evidence that nusinersen is effective in improving or stabilizing motor function in many adolescents and adults with a broad spectrum of SMA.

An early Transcriptomic Investigation in Adult Patients with Spinal Muscular Atrophy Under Treatment with Nusinersen

Spinal muscular atrophy (SMA) is a rare degenerative disorder with loss of motor neurons caused by mutations in the SMN1 gene. Nusinersen, an antisense oligonucleotide, was approved for SMA treatment to compensate the deficit of the encoded protein SMN by modulating the pre-mRNA splicing of SMN2, the centromeric homologous of SMN1, thus inducing the production of a greater amount of biologically active protein. Here, we reported a 10-month transcriptomics investigation in 10 adult SMA who received nusinersen to search for early genetic markers for clinical monitoring. By comparing their profiles with age-matched healthy controls (HC), we also analyzed the changes in miRNA/mRNAs expression and miRNA-target gene interactions possibly associated with SMA. A multidisciplinary approach of HT-NGS followed by bioinformatics/biostatistics analysis was applied. Within the study interval, those SMA patients who showed some clinical improvements were characterized by having the SMN2/SMN1 ratio slightly increased over the time, while in the stable ones the ratio decreased, suggesting that the estimation of SMN2/SMN1 expression may be an early indicator of nusinersen efficacy. On the other hand, the expression of 38/147 genes/genetic regions DE at T0 between SMA and HC like TRADD and JUND resulted "restored" at T10. We also confirmed the dysregulation of miR-146a(-5p), miR-324-5p and miR-423-5p in SMA subjects. Of interest, miR-146a-5p targeted SMN1, in line with experimental evidence showing the key role of astrocyte-produced miR-146a in SMA motor neuron loss. Molecular pathways such as NOTCH, NF-kappa B, and Toll-like receptor signalings seem to be involved in the SMA pathogenesis.

Glucose and Lipid Metabolism Disorders in Adults with Spinal Muscular Atrophy Type 3

BACKGROUND

Spinal muscular atrophy type 3 (juvenile SMA, Kugelberg-Welander disease) is a genetic disease caused by changes in the survival motor neuron 1 (SMN) gene. However, there is increasing evidence of metabolic abnormalities in SMA patients, such as altered fatty acid metabolism, impaired glucose tolerance, and defects in the functioning of muscle mitochondria. Given that data in the literature are scarce regarding this subject, the purpose of this study was to estimate the prevalence of glucose and lipid metabolism disorders in adult patients with SMA type 3.

METHODS

We conducted a cross-sectional study of 23 adult patients with SMA type 3 who underwent a comprehensive evaluation, including a physical examination, biochemical analysis, and an oral glucose tolerance test during 2020-2023.

RESULTS

At least one lipid abnormality was observed in 60.8% of patients. All four lipid parameters were atypical in 4.3% of patients, three lipid parameters were abnormal in 21.7% of patients, and two lipid parameters were altered in 8.7% patients. A total of 91.3% of SMA3 patients met the HOMA-IR criteria for insulin resistance, with 30.43% having impaired glucose tolerance. None of the patients met the criteria for a diagnosis of overt DM2.

CONCLUSIONS

The prevalence of dyslipidemia and altered glucose metabolism in our study sets apart the adult population with SMA3 from the general population, confirming a significant interplay between muscle, liver, and adipose tissue. Ensuring metabolic care for aging patients with SMA 3 is crucial, as they are vulnerable to metabolic derangements and cardiovascular risks.

Neurodegenerative diseases associated with the disruption of proteostasis and their therapeutic strategies using chemical chaperones

Aberrant proteostasis is thought to be involved in the pathogenesis of neurodegenerative diseases. Some proteostasis abnormalities are ameliorated by chaperones. Chaperones are divided into three groups: molecular, pharmacological and chemical. Chemical chaperones intended to alleviate stress in organelles, such as the endoplasmic reticulum (ER), are now being administered clinically. Of the chemical chaperones, 4-phenylbutyrate (4-PBA) has been used as a research reagent, and its mechanism of action includes chaperone effects and the inhibition of histone deacetylase. Moreover, it also binds to the B-site of SEC24 and regulates COPII-mediated transport from the ER. Although its therapeutic effect may not be strong, elucidating the mechanism of action of 4-PBA may contribute to the identification of novel therapeutic targets for neurodegenerative diseases.

Disproportionality Analysis of Nusinersen in the Food and Drug Administration Adverse Event Reporting System: A Real-World Postmarketing Pharmacovigilance Assessment

BACKGROUND

Nusinersen is the first drug for precise targeted therapy of spinal muscular atrophy, a rare disease that occurs in one of 10,000 to 20,000 live births. Therefore, thorough and comprehensive reports on the safety of nusinersen in large, real-world populations are necessary. This study aimed to mine the adverse event (AE) signals related to nusinersen through the Food and Drug Administration Adverse Event Reporting System (FAERS) database.

METHODS

We extracted reports of AEs with nusinersen as the primary suspect from FAERS between December 2016 and March 2023. Reporting odds ratio (ROR) and Bayesian confidence propagation neural network (BCPNN) were used for AE signal detection.

RESULTS

We extracted a total of 4807 suspected AE cases with nusinersen as the primary suspect from the FAERS database. Among them, 106 positive signals were obtained using the ROR and BCPNN. The highest frequency reported systemic organ class was general disorders and administration site conditions. Common clinical AEs of nusinersen were detected in the FAERS database, such as pneumonia, vomiting, back pain, headache, pyrexia, and post-lumbar puncture syndrome. In addition, we identified potential unexpected serious AEs through disproportionality analysis, including sepsis, seizure, epilepsy, brain injury, cardiorespiratory arrest, and cardiac arrest.

CONCLUSIONS

Analyzing large amounts of real-world data from the FAERS database, we identified potential new AEs of nusinersen by disproportionate analysis. It is advantageous for health care professionals and pharmacists to concentrate on effectively managing high-risk AEs of nusinersen, improve medication levels in clinical settings, and uphold patient medication safety.

A Study on the Incidence and Prevalence of 5q Spinal Muscular Atrophy in Canada Using Multiple Data Sources

OBJECTIVES

Spinal muscular atrophy (SMA) is a leading genetic cause of infant death and represents a significant burden of care. An improved understanding of the epidemiology of SMA in Canada may help inform strategies to improve the standard of care for individuals living with SMA.

METHODS

We employed a multisource approach to estimate the minimal incidence and prevalence of 5q SMA and to gain greater insight into recent clinical practices and treatment trends for the Canadian SMA population. Data sources included the Canadian Paediatric Surveillance Program (CPSP), Canadian Neuromuscular Disease Registry (CNDR), and molecular genetics laboratories in Canada.

RESULTS

The estimated annual minimum incidence of 5q SMA was 4.38, 3.44, and 7.99 cases per 100,000 live births in 2020 and 2021, based on CPSP, CNDR, and molecular genetics laboratories data, respectively, representing approximately 1 in 21,472 births (range 12,516-29,070) in Canada. SMA prevalence was estimated to be 0.85 per 100,000 persons aged 0-79 years. Delay in diagnosis exists across all SMA subtypes. Most common presenting symptoms were delayed milestones, hypotonia, and muscle weakness. Nusinersen was the most common disease-modifying treatment received. Most patients utilized multidisciplinary clinics for management of SMA.

CONCLUSION

This study provides data on the annual minimum incidence of pediatric 5q SMA in Canada. Recent therapeutic advances and newborn screening have the potential to drastically alter the natural history of SMA. Findings underline the importance of ongoing surveillance of the epidemiology and long-term health outcomes of SMA in the Canadian population.

Muscular MRI and magnetic resonance neurography in spinal muscular atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disease caused by the degeneration of the α-motor neurons in the anterior horn of the spinal cord. SMA is clinically characterized by progressive and symmetrical muscle weakness and muscle atrophy and ends up with systemic multisystem abnormalities. Quantitative MRI (qMRI) has the advantages of non-invasiveness, objective sensitivity, and high reproducibility, and has important clinical value in evaluating the severity of neuromuscular diseases and monitoring the efficacy of treatment. This article summarizes the clinical use of muscular MRI and magnetic resonance neurography in assessing the progress of SMA.

Spinal muscular atrophy in an upper-middle-income nation before the advent of reimbursed disease-modifying therapies

OBJECTIVE

To elucidate the clinical characteristics and standard of care (SoC) of spinal muscular atrophy (SMA) patients in Thailand, focusing on primary endpoints: age at death and a composite of death or tracheostomy need.

DESIGN

Retrospective observational study.

SETTING

Seven tertiary centres across Thailand.

PATIENTS

Records of 110 patients with genetically confirmed SMA, spanning 2012-2021.

INTERVENTIONS

Historical data review; no active interventions.

MAIN OUTCOME MEASURES

Age at death and a composite measure of death or tracheostomy necessity.

RESULTS

The cohort included 1 SMA0, 50 SMA1, 40 SMA2 and 19 SMA3 cases. Median ages at the onset and diagnosis of SMA1 were 3 and 6.2 months. Of SMA1 patients, 63% required ventilators, and eight received dimethyltryptamines (DMTs) at a median of 15 months (range 6.4-24.5 months). The median time from onset to DMT was 11 months (range 4.2-20.5 months). Among SMA1 patients, 73% died by the study's end. SMA2 and SMA3 patients' median onset ages were 11 and 24 months, respectively, with diagnosis at 24.8 and 68.7 months. Half of all types received physical therapy.

CONCLUSIONS

Significant delays in diagnosis and SoC access, including DMTs, were observed, underscoring urgent needs for improved diagnostic and care strategies to enhance SMA patient outcomes in Thailand.

Pattern of pareses in 5q-spinal muscular atrophy

Background

This prospective study investigates the pattern of pareses in 5q-associated spinal muscular atrophy (SMA) to identify disease-specific characteristics and potential differences from amyotrophic lateral sclerosis (ALS) and spinobulbar muscular atrophy (SBMA). Detailed knowledge about pareses patterns in SMA facilitates differential diagnosis and supports therapeutic monitoring.

Methods

Between January 2021, and June 2021, 66 SMA patients (59.1% male, aged 33.6 ± 15.2 years) were included in the study. Most patients had SMA type II (n = 28) or SMA type III (n = 28), seven patients had SMA type I, and three patients had SMA type IV. We analyzed the pattern of pareses using the UK Medical Research Council (MRC) scoring system.

Results

In both, upper and lower limbs muscle weakness was less pronounced in distal (upper limbs: MRC median 3.0 (interquartile range 1.5-3.5); lower limbs: 1.5 (0.5-3.0)) compared to proximal muscle groups (upper limbs: 2.0 (1.5-2.6); p < 0.001; lower limbs: 0.5 (0.5-1.5); p < 0.001). Thenar muscles were stronger than other small hand muscles (3.0 (2.0-3.5) vs 3.0 (1.5-3.5); p = 0.004). Muscles had more strength in upper (2.3 (1.5-3.1)) compared to lower limbs (1.1 (0.5-2.3); p < 0.001) and in flexors compared to extensors.

Conclusion

We identified a specific pattern of muscle paresis in SMA which is different from the pattern of paresis in ALS and SBMA. As a rule of thumb, the pattern of pareses is similar, but not identical to ALS in distal, but different in proximal muscle groups.

Effect of E134K pathogenic mutation of SMN protein on SMN-SmD1 interaction, with implication in spinal muscular atrophy: A molecular dynamics study

Spinal muscular atrophy (SMA) is a disease that results from mutations in the Survival of Motor Neuron (SMN) gene 1, leading to muscle atrophy due to motor neurons degeneration. SMN plays a crucial role in the assembly of spliceosomal small nuclear ribonucleoprotein complexes via binding to the arginine-glycine rich C-terminal tails of Sm proteins recognized by SMN Tudor domain. E134K Tudor mutation, cause of the more severe type I SMA, compromises the SMN-Sm interaction without a perturbation of the domain fold. By molecular dynamics simulations, we investigated the mechanism of Tudor-SmD1 interaction, and the effects on it of E134K mutation. It was observed that E134 is crucial to catch the positive dimethylated arginines (DMRs) of the SmD1 tail that, wrapping around the acidic Tudor surface, enters a central DMR into an aromatic cage. The flexible cage residue Y130 must be blocked from the wrapped tail to assure a stable binding. The charge inversion in E134K mutation causes the loss of a critical anchor point, disfavoring the tail wrapping and leaving Y130 free to swing, leading to DMR detachments and exposition of the C-terminal region of the tail. This could suggest new hypotheses regarding a possible autoimmune response by anti-Sm autoantibodies.