Spinal muscular atrophy

Gene therapy in pediatrics - Clinical studies and approved drugs (as of 2023)

Gene therapy in pediatrics represents a cutting-edge therapeutic strategy for treating a range of genetic disorders that manifest in childhood. Gene therapy involves the modification or correction of a mutated gene or the introduction of a functional gene into a patient's cells. In general, it is implemented through two main modalities namely ex vivo gene therapy and in vivo gene therapy. Currently, a noteworthy array of gene therapy products has received valid market authorization, with several others in various stages of the approval process. Additionally, a multitude of clinical trials are actively underway, underscoring the dynamic progress within this field. Pediatric genetic disorders in the fields of hematology, oncology, vision and hearing loss, immunodeficiencies, neurological, and metabolic disorders are areas for gene therapy interventions. This review provides a comprehensive overview of the evolution and current progress of gene therapy-based treatments in the clinic for pediatric patients. It navigates the historical milestones of gene therapies, currently approved gene therapy products by the U.S. Food and Drug Administration (FDA) and/or European Medicines Agency (EMA) for children, and the promising future for genetic disorders. By providing a thorough compilation of approved gene therapy drugs and published results of completed or ongoing clinical trials, this review serves as a guide for pediatric clinicians to get a quick overview of the situation of clinical studies and approved gene therapy products as of 2023.

Diagnosing missed cases of spinal muscular atrophy in genome, exome, and panel sequencing datasets

Spinal muscular atrophy (SMA) is a genetic disorder that causes progressive degeneration of lower motor neurons and the subsequent loss of muscle function throughout the body. It is the second most common recessive disorder in individuals of European descent and is present in all populations. Accurate tools exist for diagnosing SMA from genome sequencing data. However, there are no publicly available tools for GRCh38-aligned data from panel or exome sequencing assays which continue to be used as first line tests for neuromuscular disorders. This deficiency creates a critical gap in our ability to diagnose SMA in large existing rare disease cohorts, as well as newly sequenced exome and panel datasets. We therefore developed and extensively validated a new tool - SMA Finder - that can diagnose SMA not only in genome, but also exome and panel sequencing samples aligned to GRCh37, GRCh38, or T2T-CHM13. It works by evaluating aligned reads that overlap the c.840 position of SMN1 and SMN2 in order to detect the most common molecular causes of SMA. We applied SMA Finder to 16,626 exomes and 3,911 genomes from heterogeneous rare disease cohorts sequenced at the Broad Institute Center for Mendelian Genomics as well as 1,157 exomes and 8,762 panel sequencing samples from Tartu University Hospital. SMA Finder correctly identified all 16 known SMA cases and reported nine novel diagnoses which have since been confirmed by clinical testing, with another four novel diagnoses undergoing validation. Notably, out of the 29 total SMA positive cases, 23 had an initial clinical diagnosis of muscular dystrophy, congenital myasthenic syndrome, or myopathy. This underscored the frequency with which SMA can be misdiagnosed as other neuromuscular disorders and confirmed the utility of using SMA Finder to reanalyze phenotypically diverse neuromuscular disease cohorts. Finally, we evaluated SMA Finder on 198,868 individuals that had both exome and genome sequencing data within the UK Biobank (UKBB) and found that SMA Finder's overall false positive rate was less than 1 / 200,000 exome samples, and its positive predictive value (PPV) was 97%. We also observed 100% concordance between UKBB exome and genome calls. This analysis showed that, even though it is located within a segmental duplication, the most common causal variant for SMA can be detected with comparable accuracy to monogenic disease variants in non-repetitive regions. Additionally, the high PPV demonstrated by SMA Finder, the existence of treatment options for SMA in which early diagnosis is imperative for therapeutic benefit, as well as widespread availability of clinical confirmatory testing for SMA, warrants the addition of SMN1 to the ACMG list of genes with reportable secondary findings after genome and exome sequencing.

Measurement properties of the EQ-5D-Y-3L, PedsQL 4.0, and PROMIS-25 Profile v2.0 in pediatric patients with spinal muscular atrophy

OBJECTIVE

The objective of this study was to examine the psychometric properties of the EQ-5D-Y-3 L, Patient Reported Outcomes Measurement System 25-item version profile v2.0 (PROMIS-25), and Pediatric Quality of Life Inventory™ version 4.0 Generic Core Scale (PedsQL 4.0) in Chinese pediatric patients with spinal muscular atrophy (SMA).

METHODS

The data used in this study were obtained via a web-based cross-sectional survey. Parents of pediatric patients with SMA completed the proxy-reported EQ-5D-Y-3 L, PedsQL 4.0, and PROMIS-25 measures. Information about socioeconomic and health status was also obtained. The ceiling and floor effects, factorial structure, convergent validity, and known-group validity of the three measures were assessed.

RESULTS

Three hundred and sixty-three parents of children aged from 5 to 12 completed the questionnaires. Strong floor effects were observed for the physical function components of the PROMIS-25 (41.3%) and PedsQL 4.0 (67.8%). For EQ-5D-Y-3 L, 84.6% of the respondents reported having "a lot of" problems with the dimensions "walking" and "looking after myself." Minimal ceiling or floor effects were observed for the EQ-5D-Y-3 L index value. The confirmatory factor analysis supported a six-factor structure for the PROMIS-25, but did not support a four-factor structure for the PedsQL 4.0. All hypothesized correlations of the dimensions among the three measures were confirmed, with coefficients ranging from 0.28 to 0.68. Analysis of variance showed that EQ-5D-Y-3 L demonstrated better known-group validity than the other two measures in 14 out of 16 comparisons.

CONCLUSIONS

The EQ-5D-Y-3 L showed better discriminant power than the other two measures. The physical health dimensions of all three measures showed the significant floor effects. These findings provide valuable insights into the effectiveness of these measures at capturing and quantifying the impact of SMA on patients' health-related quality of life.

A Systematic Literature Review of the Natural History of Respiratory, Swallowing, Feeding, and Speech Functions in Spinal Muscular Atrophy (SMA)

Background

Respiratory and bulbar dysfunctions (including swallowing, feeding, and speech functions) are key symptoms of spinal muscular atrophy (SMA), especially in its most severe forms. Demonstrating the long-term efficacy of disease-modifying therapies (DMTs) necessitates an understanding of SMA natural history.

Objective

This study summarizes published natural history data on respiratory, swallowing, feeding, and speech functions in patients with SMA not receiving DMTs.

Methods

Electronic databases (Embase, MEDLINE, and Evidence-Based Medicine Reviews) were searched from database inception to June 27, 2022, for studies reporting data on respiratory and/or bulbar function outcomes in Types 1-3 SMA. Data were extracted into a predefined template and a descriptive summary of these data was provided.

Results

Ninety-one publications were included: 43 reported data on respiratory, swallowing, feeding, and/or speech function outcomes. Data highlighted early loss of respiratory function for patients with Type 1 SMA, with ventilatory support typically required by 12 months of age. Patients with Type 2 or 3 SMA were at risk of losing respiratory function over time, with ventilatory support initiated between the first and fifth decades of life. Swallowing and feeding difficulties, including choking, chewing problems, and aspiration, were reported in patients across the SMA spectrum. Swallowing and feeding difficulties, and a need for non-oral nutritional support, were reported before 1 year of age in Type 1 SMA, and before 10 years of age in Type 2 SMA. Limited data relating to other bulbar functions were collated.

Conclusions

Natural history data demonstrate that untreated patients with SMA experience respiratory and bulbar function deterioration, with a more rapid decline associated with greater disease severity. This study provides a comprehensive repository of natural history data on bulbar function in SMA, and it highlights that consistent assessment of outcomes in this area is necessary to benefit understanding and approval of new treatments.

Diving deep: zebrafish models in motor neuron degeneration research

In the dynamic landscape of biomedical science, the pursuit of effective treatments for motor neuron disorders like hereditary spastic paraplegia (HSP), amyotrophic lateral sclerosis (ALS), and spinal muscular atrophy (SMA) remains a key priority. Central to this endeavor is the development of robust animal models, with the zebrafish emerging as a prime candidate. Exhibiting embryonic transparency, a swift life cycle, and significant genetic and neuroanatomical congruencies with humans, zebrafish offer substantial potential for research. Despite the difference in locomotion-zebrafish undulate while humans use limbs, the zebrafish presents relevant phenotypic parallels to human motor control disorders, providing valuable insights into neurodegenerative diseases. This review explores the zebrafish's inherent traits and how they facilitate profound insights into the complex behavioral and cellular phenotypes associated with these disorders. Furthermore, we examine recent advancements in high-throughput drug screening using the zebrafish model, a promising avenue for identifying therapeutically potent compounds.

Spinal muscular atrophy genetic epidemiology and the case for premarital genomic screening in Arab populations

BACKGROUND

Spinal muscular atrophy (SMA) is a fatal autosomal recessive disorder for which several treatment options, including a gene therapy, have become available. SMA incidence has not been well-characterized in most Arab countries where rates of consanguinity are high. Understanding SMA disease epidemiology has important implications for screening, prevention, and treatment in those populations.

METHODS

We perform SMA diagnostic testing in a clinical multi-national patient cohort (N = 171) referred for hypotonia and/or muscle weakness. In addition, we carry out genetic newborn screening for SMA on 1502 healthy Emirati newborns to estimate the carrier frequency and incidence of the disease in the United Arab Emirates.

RESULTS

Patients referred for SMA genetic testing are mostly Arabs (82%) representing 18 countries. The overall diagnostic yield is 33.9%, which is higher (>50%) for certain nationalities. Most patients (71%) has two SMN2 copies and earlier disease onset. For the first time, we estimate SMA carrier frequency (1.3%) and incidence of the disease (1 in 7122 live births) in the United Arab Emirates. Using birth and marriage rates in two Arab populations (United Arab Emirates and Saudi Arabia), as well as disease incidence in both countries, we show that, besides preventing new cases, premarital genetic screening could potentially result in around $8 to $324 million annual cost savings, respectively, relative to postnatal treatment.

CONCLUSIONS

The SMA carrier frequency and incidence we document suggests high potential benefit for universal implementation of premarital genomic screening for a wide range of recessive disorders in Arab populations.

Sleep and sleep-related breathing disorders in patients with spinal muscular atrophy: a changing perspective from novel treatments?

Spinal Muscular Atrophy (SMA) is an inherited neuromuscular disorder characterized by progressive muscle weakness and atrophy, resulting from the degeneration of motor neurons in the spinal cord. A critical aspect of SMA is its impact on respiratory function. As the disease progresses, respiratory muscles, in particular intercostal muscles, become increasingly affected, leading to breathing difficulties and respiratory failure. Without intervention, many children with SMA type 1 die from respiratory failure before their second year of life. While assisted ventilation has improved survival, it often results in ventilator dependence. The development of new SMN-augmenting therapies has renewed optimism, but their long-term impact on respiratory function is uncertain, and non-invasive respiratory support remains an important part of SMA management. Despite the importance of respiratory support in SMA, knowledge regarding sleep disorders in this population is limited. This review aims to synthesize existing literature on sleep and sleep-related breathing disorders in patients with SMA, with a focus on SMA type 1. We summarize evidence of sleep-disordered breathing and respiratory failure in SMA, as well as outcomes and survival benefits associated with non-invasive or invasive ventilation with or without pharmacological therapies. We also discuss current knowledge regarding the effects of novel disease-modifying therapies for SMA on respiratory function and sleep. In conclusion, optimal care for children with SMA requires a multidisciplinary approach that includes neurology and respiratory specialists. This review highlights the importance of monitoring sleep and respiratory function in SMA, as well as the potential benefits and challenges associated with assisted ventilation combined with new therapies.

Nusinersen Treatment for Spinal Muscular Atrophy: Retrospective Multicenter Study of Pediatric and Adult Patients in Kuwait

Spinal muscular atrophy is a neuromuscular genetic condition associated with progressive muscle weakness and atrophy. Nusinersen is an antisense oligonucleotide therapy approved for the treatment of 5q spinal muscular atrophy in pediatric and adult patients. The objective of this clinical case series is to describe the efficacy and safety of nusinersen in treating spinal muscular atrophy in 20 pediatric and 18 adult patients across six treatment centers in Kuwait. Functional motor assessments (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders, Hammersmith Functional Motor Scale Expanded, and Revised Upper Limb Module) were used to assess changes in motor function following nusinersen treatment. The safety assessment involved clinical monitoring of adverse events. The results demonstrate clinically meaningful or considerable improvement in motor performance for nearly all patients, lasting over 4 years in some cases. A total of 70% of patients in the pediatric cohort and 72% of patients in the adult cohort achieved a clinically meaningful improvement in motor function following nusinersen treatment. Additionally, nusinersen was well-tolerated in both cohorts. These findings add to the growing body of evidence relating to the clinical efficacy and safety of nusinersen.

Potential of Cell-Penetrating Peptide-Conjugated Antisense Oligonucleotides for the Treatment of SMA

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder that is caused by mutations in the survival motor neuron 1 (SMN1) gene, hindering the production of functional survival motor neuron (SMN) proteins. Antisense oligonucleotides (ASOs), a versatile DNA-like drug, are adept at binding to target RNA to prevent translation or promote alternative splicing. Nusinersen is an FDA-approved ASO for the treatment of SMA. It effectively promotes alternative splicing in pre-mRNA transcribed from the SMN2 gene, an analog of the SMN1 gene, to produce a greater amount of full-length SMN protein, to compensate for the loss of functional protein translated from SMN1. Despite its efficacy in ameliorating SMA symptoms, the cellular uptake of these ASOs is suboptimal, and their inability to penetrate the CNS necessitates invasive lumbar punctures. Cell-penetrating peptides (CPPs), which can be conjugated to ASOs, represent a promising approach to improve the efficiency of these treatments for SMA and have the potential to transverse the blood-brain barrier to circumvent the need for intrusive intrathecal injections and their associated adverse effects. This review provides a comprehensive analysis of ASO therapies, their application for the treatment of SMA, and the encouraging potential of CPPs as delivery systems to improve ASO uptake and overall efficiency.

Unveiling the genetic tapestry: Rare disease genomics of spinal muscular atrophy and phenylketonuria proteins

Rare diseases, defined by their low prevalence, present significant challenges, including delayed detection, expensive treatments, and limited research. This study delves into the genetic basis of two noteworthy rare diseases in Saudi Arabia: Phenylketonuria (PKU) and Spinal Muscular Atrophy (SMA). PKU, resulting from mutations in the phenylalanine hydroxylase (PAH) gene, exhibits geographical variability and impacts intellectual abilities. SMA, characterized by motor neuron loss, is linked to mutations in the survival of motor neuron 1 (SMN1) gene. Recognizing the importance of unveiling signature genomics in rare diseases, we conducted a quantitative study on PAH and SMN1 proteins of multiple organisms by employing various quantitative techniques to assess genetic variations. The derived signature-genomics contributes to a deeper understanding of these critical genes, paving the way for enhanced diagnostics for disorders associated with PAH and SMN1.

General movements in spinal muscular atrophy type 1

PURPOSE

To investigate the motor repertoire of infants diagnosed with spinal muscular atrophy Type I (SMA Type I) without administration of any disease-modifying agent.

METHODS

Motor Optimality Score-Revised (MOS-R) was calculated from videos recorded between post-term weeks 9-17 for 22 infants with SMA Type I. The MOS-R of infants with SMA Type I was compared with those of 22 infants with cerebral palsy (CP) and 22 infants with typical development.

RESULTS

Of the infants with SMA Type I, 17 had absent fidgety movements (FMs) and 5 had sporadic FMs. Age adequate movement repertoire was absent, and the variety of movements in infants was very low. Movements were symmetrical but movements of four limbs remained on the surface level. Antigravity movements were very rare. Movement characterization was monotonous, slow speed, and small amplitude. The MOS-R of infants with SMA Type I was lower than those of infants with typical development but similar to those of infants with CP.

CONCLUSIONS

Infants with SMA Type I had a motor repertoire similar to infants with CP, while they had a poorer motor repertoire than infants with typical development in the fidgety period as evidenced by MOS-R. Central nervous system involvement in these infants with SMA Type I with absent FMs and reduced MOS-R is unknown. Further studies are needed to determine the role of problems in the afferent and efferent pathways of spinal cord and muscle atrophy in the observation of normal FMs.

Exploring functional strength changes during nusinersen treatment in symptomatic children with SMA types 2 and 3

The Hammersmith Functional Motor Scale-Expanded (HFMSE) is a validated outcome measure for monitoring changes in functional strength in patients with spinal muscular atrophy (SMA). The objective of this study was to explore changes in HFMSE item-scores in children with SMA types 2 and 3a treated with nusinersen over a period of six to twenty months. We stratified patients according to motor ability (sitting and walking), and calculated numbers and percentages for each specific improvement (positive score change) or decrease (negative score change) for the total group and each subgroup and calculated frequency distributions of specific score changes. Ninety-one percent of the children showed improvement in at least 1 item, twenty-eight percent showed a score decrease in 1 or more items. In the first six to twenty months of nusinersen treatment motor function change was characterized by the acquisition of the ability to perform specific tasks with compensation strategies (score changes from 0 to 1). Children with the ability to sit were most likely to improve in items that assess rolling, whilst children with the ability to walk most likely improved in items that assess half-kneeling. The ability most frequently lost was hip flexion in supine position.

Bibrachial amyotrophy as a rare manifestation of intraspinal fluid collection: a case report and systematic review

INTRODUCTION

Intraspinal cerebrospinal fluid (CSF) collection has been reported as a rare cause of lower motor neuron (LMN) disorder. We report a case of bibrachial diplegia associated with intraspinal CSF collection and perform a systematic literature review.

PATIENT AND METHODS

A 52-year-old man developed a bibrachial amyotrophy over 6 years, confirmed by the presence of cervical subacute neurogenic changes at electromyography (EMG). Brain magnetic resonance imaging (MRI) revealed cerebral siderosis, while spine MRI showed a ventral longitudinal intraspinal fluid collection (VLISFC) from C2 to L2. No CSF leakage was localized at myelography; a conservative treatment was chosen. We searched for all published cases until 30th April 2023 and extrapolated data of 44 patients reported in 27 publications.

RESULTS

We observed a male predominance, a younger disease onset compared to amyotrophic lateral sclerosis, and a quite long disease duration, highlighting a slow disease progression. LMN signs were more frequently bilateral, mostly involving C5-C6 myotomes. Around 61% of patients presented additional symptoms, but only three referred to a history of headache. Accordingly, CSF opening pressure was mostly normal. Spinal MRI revealed the presence of VLISFC and in some cases myelomalacia. EMG patterns displayed both chronic and subacute neurogenic change in the cervical region. The disease course mainly depended on the treatment choice, which was mostly represented by a surgical approach when a specific dural defect was detected by imaging.

CONCLUSION

Bibrachial diplegia due to VLISFC can be a treatable cause of focal amyotrophy and presents some clinical and radiological "red flags" which cannot be missed by a clinical neurologist.

Improved therapeutic approach for spinal muscular atrophy via ubiquitination-resistant survival motor neuron variant

BACKGROUND

Zolgensma is a gene-replacement therapy that has led to a promising treatment for spinal muscular atrophy (SMA). However, clinical trials of Zolgensma have raised two major concerns: insufficient therapeutic effects and adverse events. In a recent clinical trial, 30% of patients failed to achieve motor milestones despite pre-symptomatic treatment. In addition, more than 20% of patients showed hepatotoxicity due to excessive virus dosage, even after the administration of an immunosuppressant. Here, we aimed to test whether a ubiquitination-resistant variant of survival motor neuron (SMN), SMNK186R, has improved therapeutic effects for SMA compared with wild-type SMN (SMNWT).

METHODS

A severe SMA mouse model, SMA type 1.5 (Smn-/-; SMN2+/+; SMN∆7+/-) mice, was used to compare the differences in therapeutic efficacy between AAV9-SMNWT and AAV9-SMNK186R. All animals were injected within Postnatal Day (P) 1 through a facial vein or cerebral ventricle.

RESULTS

AAV9-SMNK186R-treated mice showed increased lifespan, body weight, motor neuron number, muscle weight and functional improvement in motor functions as compared with AAV9-SMNWT-treated mice. Lifespan increased by more than 10-fold in AAV9-SMNK186R-treated mice (144.8 ± 26.11 days) as compared with AAV9-SMNWT-treated mice (26.8 ± 1.41 days). AAV9-SMNK186R-treated mice showed an ascending weight pattern, unlike AAV9-SMNWT-treated mice, which only gained weight until P20 up to 5 g on average. Several motor function tests showed the improved therapeutic efficacy of SMNK186R. In the negative geotaxis test, AAV9-SMNK186R-treated mice turned their bodies in an upward direction successfully, unlike AAV9-SMNWT-treated mice, which failed to turn upwards from around P23. Hind limb clasping phenotype was rarely observed in AAV9-SMNK186R-treated mice, unlike AAV9-SMNWT-treated mice that showed clasping phenotype for more than 20 out of 30 s. At this point, the number of motor neurons (1.5-fold) and the size of myofibers (2.1-fold) were significantly increased in AAV9-SMNK186R-treated mice compared with AAV9-SMNWT-treated mice without prominent neurotoxicity. AAV9-SMNK186R had fewer liver defects compared with AAV9-SMNWT, as judged by increased proliferation of hepatocytes (P < 0.0001) and insulin-like growth factor-1 production (P < 0.0001). Especially, low-dose AAV9-SMNK186R (nine-fold) also reduced clasping time compared with SMNWT.

CONCLUSIONS

SMNK186R will provide improved therapeutic efficacy in patients with severe SMA with insufficient therapeutic efficacy. Low-dose treatment of SMA patients with AAV9-SMNK186R can reduce the adverse events of Zolgensma. Collectively, SMNK186R has value as a new treatment for SMA that improves treatment effectiveness and reduces adverse events simultaneously.

CRISPR-Based Gene Editing Techniques in Pediatric Neurological Disorders

The emergence of gene editing technologies offers a unique opportunity to develop mutation-specific treatments for pediatric neurological disorders. Gene editing systems can potentially alter disease trajectory by correcting dysfunctional mutations or therapeutically altering gene expression. Clustered regularly interspaced short palindromic repeats (CRISPR)-based approaches are attractive gene therapy platforms to personalize treatments because of their specificity, ease of design, versatility, and cost. However, many such approaches remain in the early stages of development, with ongoing efforts to optimize editing efficiency, minimize unintended off-target effects, and mitigate pathologic immune responses. Given the rapid evolution of CRISPR-based therapies, it is prudent for the clinically based child neurologist to have a conceptual understanding of what such therapies may entail, including both benefits and risks and how such therapies may be clinically applied. In this review, we describe the fundamentals of CRISPR-based therapies, discuss the opportunities and challenges that have arisen, and highlight preclinical work in several pediatric neurological diseases.

Serum myostatin as a candidate disease severity and progression biomarker of spinal muscular atrophy

The identification of biomarkers for spinal muscular atrophy is crucial for predicting disease progression, severity, and response to new disease-modifying therapies. This study aimed to investigate the role of serum levels of myostatin and follistatin as biomarkers for spinal muscular atrophy, considering muscle atrophy secondary to denervation as the main clinical manifestation of the disease. The study evaluated the differential gene expression of myostatin and follistatin in a lesional model of gastrocnemius denervation in mice, as well as in a meta-analysis of three datasets in transgenic mice models of spinal muscular atrophy, and in two studies involving humans with spinal muscular atrophy. Subsequently, a case-control study involving 27 spinal muscular atrophy patients and 27 controls was conducted, followed by a 12-month cohort study with 25 spinal muscular atrophy cases. Serum levels of myostatin and follistatin were analysed using enzyme-linked immunosorbent assay at a single centre in southern Brazil. Skeletal muscle gene expression of myostatin decreased and of follistatin increased following lesional muscle denervation in mice, consistent with findings in the spinal muscular atrophy transgenic mice meta-analysis and in the iliopsoas muscle of five patients with spinal muscular atrophy type 1. Median serum myostatin levels were significantly lower in spinal muscular atrophy patients (98 pg/mL; 5-157) compared to controls (412 pg/mL; 299-730) (P < 0.001). Lower myostatin levels were associated with greater disease severity based on clinician-rated outcomes (Rho = 0.493-0.812; P < 0.05). After 12 months, there was a further reduction in myostatin levels among spinal muscular atrophy cases (P = 0.021). Follistatin levels did not differ between cases and controls, and no significant changes were observed over time. The follistatin:myostatin ratio was significantly increased in spinal muscular atrophy subjects and inversely correlated with motor severity. Serum myostatin levels show promise as a novel biomarker for evaluating the severity and progression of spinal muscular atrophy. The decrease in myostatin levels and the subsequent favourable environment for muscle growth may be attributed to denervation caused by motor neuron dysfunction.

Non-ionizing measurement and quantification of bell-shaped chests in spinal muscular atrophy: a pilot study

Background

Spinal Muscular Atrophy (SMA) is manifested by deformation of the chest wall, including a bell-shaped chest. We determined the ability of a novel non-ionizing, non-volitional method to measure and quantify bell-shaped chests in SMA.

Methods

A 3D depth camera and a chest x-ray (CXR) were used to capture chest images in 14 SMA patients and 28 controls. Both methods measure the distance between two points, but measurements performed by 3D analysis allow for the consideration of the curve of a surface (geodesic measurements), whereas the CXR allows solely for the determination of the shortest path between two points, with no regard for the surface (Euclidean measurements). The ratio of the upper to lower chest distances was quantified to distinguish chest shape in imaging by both the 3D depth camera and the CXR, and the ratios were compared between healthy and SMA patients.

Results

The mean 3D Euclidean ratio of distances measured by 3D imaging was 1.00 in the control group and 0.92 in the SMA group (p = 0.01), the latter indicative of a bell-shaped chest. This result repeated itself in the ratio of geodesic measurements (0.99 vs. 0.89, respectively, p = 0.03).

Conclusion

The herein-described novel, noninvasive 3D method for measuring the upper and lower chest distances was shown to distinguish the bell-shaped chest configuration in patients with SMA from the chests of controls. This method bears several advantages over CXR and may be readily applicable in clinical settings that manage children with SMA.

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.

Cost-effectiveness of spinal muscular atrophy newborn screening based on real-world data in Belgium

The objective of the study was to assess the cost-effectiveness of real-world spinal muscular atrophy newborn screening followed by treatment. We modeled the lifetime cost-effectiveness of the spinal muscular atrophy newborn screening followed by treatment (screening) compared to treatment without screening (no screening) from the Belgian healthcare perspective. Real-world data, including quality of life, costs, and motor development data, were collected on 12 patients identified by screening and 43 patients identified by their symptoms. "Screening" was associated with slightly higher healthcare costs (€ 6,858,061 vs. € 6,738,120) but more quality-adjusted life years (QALY) (40.95 vs. 20.34) compared to "no screening", leading to an incremental cost-effectiveness ratio of € 5,820 per QALY gained. "Screening" was dominant from a societal perspective (negative incremental costs: € -14,457; incremental QALY = 20.61), when incorporating the burden on caregivers (negative incremental costs = € -74,353; incremental QALY = 27.51), and when the treatment was chosen by the parents (negative incremental costs = € -2,596,748; incremental QALY = 20.61). Spinal muscular atrophy newborn screening coupled with early treatment is thus cost-effective compared with late treatment following clinical diagnosis and is dominant when societal perspective, caregiver burden, and treatment based on parental preference were considered.

A Case of a Newborn With Nemaline Myopathy From Al-Qunfudhah City, Saudi Arabia

Nemaline myopathy is a primary skeletal muscle disorder and one of the congenital myopathies. It can be caused by mutations in at least 12 genes, with the nebulin (NEB) gene being the most common. Here, we present the first case of a neonate with nemaline myopathy from Al-Qunfudhah, Saudi Arabia. A full-term baby boy was delivered via cesarean section due to decreased fetal movement. The baby was covered with a thick meconium stain. He was born with severe distress and underwent an endotracheal tube placement. The baby presented generalized muscle weakness, hypotonia, and areflexia. Examination revealed arthrogryposis, bilateral small chin, undescended testicle, joint deformity, hip dislocation, and clubfoot. Chest examination revealed conducting sound and bilateral equal air entry. Moreover, he experienced bilateral chest wheeze and conducting sound. All laboratory tests were normal, and whole-exome sequencing revealed pathogenic homozygous splice acceptor variant NEB gene c.8889+1G˃A. The patient was first suspected to have spinal muscular atrophy as there was no previous nemaline myopathy case reported from Al-Qunfudhah. However, the typical symptoms and genetic sequencing confirmed his condition. As the society in Al-Qunfudhah is known for consanguinity, as in our case, clinicians should identify other types of myopathy as it is expected to occur in further cases.

Application of a Multiplex Ligation-Dependent Probe Amplification-Based Next-Generation Sequencing Approach for the Detection of Pathogenesis of Duchenne Muscular Dystrophy and Spinal Muscular Atrophy Caused by Copy Number Aberrations

Both Duchenne muscular dystrophy (DMD; OMIM no. 310200) and spinal muscular atrophy (SMA; OMIM no. 253300/253550/253400/271150) are genetic disorders characterized by progressive muscle degeneration and weakness. Genetic copy number aberrations in the pathogenetic genes DMD and SMN1 lead to alterations in functional proteins, resulting in DMD and SMA, respectively. Multiplex ligation-dependent probe amplification (MLPA) has become a standard method for the detection of common copy number aberrations (CNAs), including DMD and SMN1 deletions, both of which are associated with poor clinical outcomes. However, traditional MLPA assays only accommodate a maximum of 60 MLPA probes per test. To increase the number of targeted sequences in one assay, an MLPA-based next-generation sequencing (NGS) assay has been developed that is based on the standard MLPA procedure, allows high-throughput screening for a large number of fragments and samples by integrating additional indices for detection, and can be analyzed on all Illumina NGS platforms.

Multidisciplinary physical rehabilitation program of individuals with spinal muscular atrophy in an inclusive school setting

Spinal muscular atrophy (SMA) is a neuromuscular ailment that leads to the deprivation of motor neurons in the spinal cord, producing denervation and muscle weakness. This case report explains how a patient with type 2 SMA used a therapeutic exercise rehabilitation program in a school environment. Motor functions were assessed by Gross Motor Function Measure-88 (GMFM-88), Manual Muscle Testing (MMT), and Hammersmith Functional Motor Scale (HFMS), which is validated and reliable. This study employed a repeated pre-test post-test measures design. During a year of treatment sessions, the child underwent twice weekly 45-minute physical therapy sessions for 48 weeks. The research was carried out between March 2022 and February 2023. The purpose of the intervention, which comprised a variety of therapeutic workouts, was to enhance physical function and gross motor abilities in an age-appropriate manner. The intervention utilized in this study led to improvements in GMFM-88, HFMS, and MMT total scores. The results of this case study showed that a child with type 2 SMA aged nine had successfully improved their gross motor skills and muscle strength.

Efficacy of risdiplam in spinal muscular atrophy: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to assess the efficacy and safety of risdiplam on motor and respiratory function in spinal muscular atrophy (SMA). We systematically searched Medline, Scopus, Web of Science, and the Cochrane Library from inception to March 2023. We included pre-post studies that determined the effect of risdiplam on the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), the 32-item Motor Function Measure (MFM32), the Revised Upper Limb Module (RULM), the Hammersmith Functional Motor Scale - Expanded (HFMSE), respiratory function, and the proportion of risdiplam-related adverse events in a population with SMA (phenotypes 1 and 2/3). Meta-analyses were also performed where possible. Eleven studies were included. After 12 months of treatment, 57% of participants with SMA1 achieved a CHOP-INTEND score ≥ 40 points, and more than half were able to feed orally and had head control. In SMA2/3, MFM32, RULM, and HFMSE increased by 2.09 (1.17, 3.01), 1.73 (1.25, 2.20), and 1.00 (0.40, 1.59) points, respectively. Efficacy on respiratory function in SMA2/3 was inconsistent. Finally, 16% of participants experienced adverse events, but serious adverse events could not be quantified due to a lack of cases. The limited available evidence suggests that risdiplam is an effective and safe drug for the treatment of SMA. In addition, long-term clinical benefit may be partly determined by the stage of disease at which treatment is initiated.

Nusinersen demonstrates effectiveness in treating spinal muscular atrophy: findings from a three-year nationwide study in Korea

Introduction

Nusinersen is the first drug approved for spinal muscular atrophy (SMA) treatment. In this study, we aimed to evaluate the long-term safety and efficacy of nusinersen, assess the therapeutic effects based on the treatment initiation timing and baseline motor function, and explore the perception of functional improvement from either parents or patients, utilizing 3-year nationwide follow-up data in South Korea.

Methods

We enrolled patients with SMA who were treated with nusinersen under the National Health Insurance coverage, with complete motor score records available and a minimum treatment duration of 6 months. To evaluate the motor function of patients, the Hammersmith Infant Neurological Examination-2 (HINE-2) was used for type 1 and the Expanded Hammersmith Functional Motor Scale (HFMSE) was used for types 2 and 3 patients. A significant improvement was defined as a HINE-2 score gain ≥5 for patients with type 1 and an HFMSE score ≥ 3 for patients with types 2 and 3 SMA. Effects of treatment timing were assessed. Patients with type 2 were further categorized based on baseline motor scores for outcome analysis. We also analyzed a second dataset from five tertiary hospitals with the information on parents/patients-reported impressions of improvement.

Results

The study comprised 137 patients, with 21, 103, and 13 patients representing type 1, 2, and 3 SMA, respectively. At the 3-year follow-up, the analysis encompassed 7 patients with type 1, 12 patients with type 2, and none with type 3. Nearly half of all enrolled patients across SMA types (42.8, 59.2 and 46.2%, respectively) reached the 2-year follow-up for analysis. Patients with type 1 SMA exhibited gradual motor function improvement over 1-, 2-, and 3-year follow-ups (16, 9, and 7 patients, respectively). Patients with type 2 SMA demonstrated improvement over 1-, 2-, and 3-year follow-ups (96, 61 and 12 patients, respectively). Early treatment from symptom onset resulted in better outcomes for patients with type 1 and 2 SMA. In the second dataset, 90.7% of 108 patients reported subjective improvement at the 1-year follow-up.

Conclusion

Nusinersen treatment for types 1-3 SMA is safe and effective in long-term follow-up. Early treatment initiation was a significant factor affecting long-term motor outcome.

Neonatal screening for spinal muscular atrophy: A pilot study in Brazil

Spinal muscular atrophy (SMA) is considered one of the most common autosomal recessive disorders, with an estimated incidence of 1 in 10,000 live births. Testing for SMA has been recommended for inclusion in neonatal screening (NBS) panels since there are several therapies available and there is evidence of greater efficacy when introduced in the pre/early symptomatic phases. In Brazil, the National Neonatal Screening Program tests for six diseases, with a new law issued in 2021 stating that it should incorporate more diseases, including SMA. In the present study, dried blood spot (DBS) samples collected by the Reference Services of Neonatal Screening of RS and SP, to perform the conventional test were also screened for SMA, using real-time PCR, with SALSA MC002 technique. A total of 40,000 samples were analyzed, enabling the identification of four positive cases of SMA, that were confirmed by MLPA. Considering our sampling, Brazil seems to have an incidence comparable to the described in other regions. This work demonstrated that the use of the MC002 technique in samples routinely collected for the conventional NBS program is suitable to screen for SMA in our conditions and can be included in the expansion of the neonatal screening programs.

Evaluation of the therapeutic efficacy and tolerability of current drug treatments on the clinical outcomes of paediatric spinal muscular atrophy type 1: A systematic review

Spinal muscular atrophy (SMA) is a severe hereditary lower motor neuron disorder characterised by degeneration of alpha motor neurons in the spinal cord, resulting in progressive weakness and paralysis of proximal muscles. A systematic literature search was carried out by using PRISMA guidelines and searching through different databases that could provide findings of evidence on the health outcomes of the approved therapies for the management of paediatric SMA type 1 regarding efficacy with follow-up in terms of motor and respiratory functions and the tolerability and incidence of adverse drug reactions (ADRs) post-treatment from real-world publications. Half of the publications (50%) had a prospective observational design. Eight studies (66.7%) assessed nusinersen, and three studies (25%) assessed onasemnogene abeparvovec with a duration of follow-up ranging from 6 months to 3 years to evaluate the motor and respiratory functions using different assessment tools, hospitalisation rates, and the tolerability and incidence of ADRs post-treatment. The three currently approved treatments for SMA type 1 provided good support and health outcomes in terms of motor function, respiratory outcomes, reduction of hospitalisations, and improvement of survival. Nevertheless, uncertainties regarding continued improvement after long-term illness and the generalizability of results are still unknown.

Patient and Caregiver Outcomes After Onasemnogene Abeparvovec Treatment: Findings from the Cure SMA 2021 Membership Survey

INTRODUCTION

Onasemnogene abeparvovec (OA) is the only gene replacement therapy currently approved for spinal muscular atrophy (SMA) treatment. We sought to assess real-world patient and caregiver outcomes after OA treatment for SMA.

METHODS

Patients who received OA were identified from the 2021 Cure SMA Membership Survey. Those treated at 6-23 months of age were matched to non-patients treated with OA on the basis of age at the time of survey and survival motor neuron 2 gene copy number. Patient characteristics, motor milestones, and resource and supportive care use, as well as caregiver proxy-reported health-related quality of life (HRQOL), were described. Caregiver unmet needs and HRQOL were also assessed.

RESULTS

Of the 614 patients in the survey, 64 received OA, and 17 were matched with 28 non-OA-treated patients. In general, a greater percentage of OA-treated patients achieved various motor milestones, including 100% sitting without support and 58.8% walking with assistance. OA-treated patients also had numerically lower rates of hospitalization and surgery. None required tracheostomy with a ventilator. The rate of using oxygen or a breathing machine for more than 16 h was also lower for OA-treated patients. OA-treated patients had less frequent trouble swallowing. HRQOL was reported to be similar to non-OA-treated patients. Caregivers of OA-treated patients reported better patient mobility scores and less work impairment.

CONCLUSIONS

The study suggests that treatment with OA is associated with greater rates of motor milestone achievements and less resource and supportive care use for patients with SMA treated at 6-23 months of age in the real world. For caregivers, it may also potentially reduce unmet needs, improve HRQOL, and reduce work impairment.

MicroRNAs as a Tool for Differential Diagnosis of Neuromuscular Disorders

Neuromuscular disorders (NMD) are a class of progressive disorders that are characterized by wasting of the muscles. Some of the disorders like Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), congenital muscular dystrophies (CMDs), limb-girdle muscular dystrophies (LGMD), and mild spinal muscular atrophy (SMA) type III share several presenting clinical features, and hence, diagnosis is usually a challenging task. In this study, the diagnostic potential of some species of microRNAs (miRNAs) that are known to play roles in normal and pathological contexts of myocytes (myomiRs) were evaluated to assess their potential in differential diagnosis of NMDs. In this study, seventy-four patients with different neuromuscular disorders along with thirty age-matched healthy control subjects were enrolled. Peripheral blood samples were collected from enrolled subjects followed by miRNA extraction and reverse transcription followed by quantification of the circulating levels of the studied miRNAs (miR-499, miR-206, miR-208a, miR-223, miR-191, miR-103a-3p, miR-103a-5p), by real-time PCR and statistical analysis. The data indicated that miR-499 level showed high circulating levels in DMD patients as well as in patients with other related disorders such as BMD. However, the levels of miR-499 were much higher in DMD patients and it can be used to diagnose DMD. In addition, miR-206 can selectively differentiate between DMD and all other disorders. The results also revealed that miR-208a and miR-223 were significantly dysregulated in SMA patients, and miR-103a-3p could distinguish DMD from BMD. The expression levels of some miRNA species can be utilized in the process of differential diagnosis of NMDs and can serve as a diagnostic biomarker, and such findings will pave the way towards generating targeted therapies.

Systematic Literature Review of the Natural History of Spinal Muscular Atrophy: Motor Function, Scoliosis, and Contractures

BACKGROUND AND OBJECTIVES

Spinal muscular atrophy (SMA) is a progressive neuromuscular disorder associated with continuous motor function loss and complications, such as scoliosis and contractures. Understanding the natural history of SMA is key to demonstrating the long-term outcomes of SMA treatments. This study reviews the natural history of motor function, scoliosis, and contractures in patients with SMA.

METHODS

Electronic databases were searched from inception to June 27, 2022 (Embase, MEDLINE, and Evidence-Based Medicine Reviews). Observational studies, case-control studies, cross-sectional studies, and case series reporting on motor function (i.e., sitting, standing, and walking ability), scoliosis, and contracture outcomes in patients with types 1-3 SMA were included. Data on study design, baseline characteristics, and treatment outcomes were extracted. Data sets were generated from studies that reported Kaplan-Meier (KM) curves and pooled to generate overall KM curves.

RESULTS

Ninety-three publications were included, of which 68 reported on motor function. Of these, 10 reported KM curves (3 on the probability of sitting in patients with types 2 and 3 SMA and 8 on the probability of walking/ambulation in patients with type 3 SMA). The median time to loss of sitting (95% CI) was 14.5 years (14.1-31.5) for the type 2 SMA sitter population (their maximum ability was independent sitting). The median time to loss of ambulation (95% CI) was 13.4 years (12.5-14.5) for type 3a SMA (disease onset at age younger than 3 years) and 44.2 years (43.0-49.4) for type 3b SMA (disease onset at age 3 years or older). Studies including scoliosis and contracture outcomes mostly reported non-time-to-event data.

DISCUSSION

The results demonstrate that a high degree of motor function loss is inevitable, affecting patients of all ages. In addition, data suggest that untreated patients with types 2 and 3 SMA remain at risk of losing motor milestones during late adulthood, and patients with types 3a and 3b SMA are at risk of loss of ambulation over time. These findings support the importance of stabilization of motor function development even at older ages. Natural history data are key for the evaluation of SMA treatments as they contextualize the assessment of long-term outcomes.

Twice-Weekly Outpatient Rehabilitation Intervention for Young Children With Spinal Muscular Atrophy Treated With Genetic-Based Therapies: Protocol for a Feasibility Study

BACKGROUND

Spinal muscular atrophy (SMA) is a progressive neuromuscular disorder that causes muscle weakness and is the leading genetic cause of infant mortality worldwide. While no definitive cure exists, the approval of 3 genetic-based therapies in Canada since 2018 has led to significant improvements in muscle function for children with SMA. With that, there are no evidence-based rehabilitation interventions and minimal evidence on the combined effects of genetic-based therapies and rehabilitation.

OBJECTIVE

This protocol describes the methodology to assess the feasibility of a twice-weekly outpatient rehabilitation intervention focusing on gross and fine motor function to inform the methodology and sample size of a definitive clinical trial.

METHODS

We will conduct a single-center nonrandomized pilot and feasibility trial to explore an outpatient rehabilitation intervention for children aged 6 months to 3 years with SMA treated with genetic-based therapies. Participation in the study will occur over a 25-week period, with a baseline assessment visit followed by a 12-week intervention period and a 12-week nonintervention period. The rehabilitation intervention comprises weekly physical and occupational therapy for 11 weeks. Assessments will occur at baseline (week 0), end of intervention or early withdrawal (week 12), and follow-up (week 24). Predetermined feasibility indicators will evaluate study feasibility across process (recruitment rates, eligibility criteria, adherence rates, retention rates, questionnaire suitability, and acceptability), resource (time, implementation, and execution), management (materials and data), and scientific (safety, tolerability, and preliminary efficacy) domains.

RESULTS

This project was funded in March 2022, and data will be collected between March 2023 and December 2023. Data analysis will occur between January 2024 and March 2024, with publication expected in the fall of 2024. The protocol for the feasibility trial will be considered successful if it meets the success criteria set out for the feasibility indicators. Indicators of specific interest include all process indicators, as well as time. Exploratory indicators will be reported. Pragmatically, the results of the feasibility trial will inform changes to the protocol and the start-up of a definitive multisite trial.

CONCLUSIONS

This novel twice-weekly outpatient rehabilitation intervention will be the first step toward filling the need for an evidence-based rehabilitation intervention for children with SMA treated with genetic-based therapies. It is expected that consistent and intensive rehabilitation therapy will augment functional gains being observed in this population. In the future, a definitive trial will measure the efficacy of the intervention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05638750; https://clinicaltrials.gov/study/NCT05638750.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/46363.

Serotonergic dysfunction impairs locomotor coordination in spinal muscular atrophy

Neuromodulation by serotonin regulates the activity of neuronal networks responsible for a wide variety of essential behaviours. Serotonin (or 5-HT) typically activates metabotropic G protein-coupled receptors, which in turn initiate second messenger signalling cascades and induce short and long-lasting behavioural effects. Serotonin is intricately involved in the production of locomotor activity and gait control for different motor behaviours. Although dysfunction of serotonergic neurotransmission has been associated with mood disorders and spasticity after spinal cord injury, whether and to what extent such dysregulation is implicated in movement disorders has not been firmly established. Here, we investigated whether serotonergic neuromodulation is affected in spinal muscular atrophy (SMA), a neurodegenerative disease caused by ubiquitous deficiency of the SMN protein. The hallmarks of SMA are death of spinal motor neurons, muscle atrophy and impaired motor control, both in human patients and mouse models of disease. We used a severe mouse model of SMA, that closely recapitulates the severe symptoms exhibited by type I SMA patients, the most common and most severe form of the disease. Together, with mouse genetics, optogenetics, physiology, morphology and behavioural analysis, we report severe dysfunction of serotonergic neurotransmission in the spinal cord of SMA mice, both at early and late stages of the disease. This dysfunction is followed by reduction of 5-HT synapses on vulnerable motor neurons. We demonstrate that motor neurons innervating axial and trunk musculature are preferentially affected, suggesting a possible cause for the proximo-distal progression of disease, and raising the possibility that it may underlie scoliosis in SMA patients. We also demonstrate that the 5-HT dysfunction is caused by SMN deficiency in serotonergic neurons in the raphe nuclei of the brainstem. The behavioural significance of the dysfunction in serotonergic neuromodulation is underlined by inter-limb discoordination in SMA mice, which is ameliorated when selective restoration of SMN in 5-HT neurons is achieved by genetic means. Our study uncovers an unexpected dysfunction of serotonergic neuromodulation in SMA and indicates that, if normal function is to be restored under disease conditions, 5-HT neuromodulation should be a key target for therapeutic approaches.

Gene therapy in spinal muscular atrophy

Infantile SMA is a neuromuscular disease caused by the motor neuron degeneration, depending on the age of appearance of clinical signs and the evolution of the disease, three types of decreasing severity have been defined. SMA is caused by mutations or deletions of the SMN1 gene and disease. Various therapies aimed at increasing SMN protein levels have been developed. Gene therapy is part of the therapeutic arsenal now available for the treatment of SMA under certain conditions. It uses the scAAV9 vector carrying a functional copy of SMN1 to restore SMN protein expression at the cellular level. Because the adeno-associated virus genome is maintained as it is an episome, a single intravenous administration is sufficient to producing a long-lasting therapeutic effect. The effectiveness of gene replacement therapy in patients with SMA has been demonstrated in various studies. It is now clear that treatment as early as possible provides better clinical results. However, this treatment must be carried out in a suitable medical environment, with close monitoring initially due to potentially serious side effects. In France, this treatment has been available since 2019. A national committee of experts involved in the treatment of pediatric SMA patients has established that pediatric patients with SMA decide on the indications for disease-modifying therapies (DMT) in children. The French Spinal Muscular Atrophy Registry (SMA France Registry) was established in January 2020. The registry includes all patients with genetically confirmed SMN1-related SMA. All patients treated with GT are systematically included in the registry. As of July 21, 2023: 72 patients with SMA have been treated with GT in France since June 2019. The arrival of new treatments reveals new clinical phenotypes of SMA which constitute a new management challenge. Treatment as early as possible is also a very important factor for a favorable outcome and calls for presymptomatic screening. However, the arrival of these new treatments, extremely expensive raises other socio-economic questions. © 2023 Published by Elsevier Masson SAS on behalf of French Society of Pediatrics.

Digital measures of respiratory and upper limb function in spinal muscular atrophy: design, feasibility, reliability, and preliminary validity of a smartphone sensor-based assessment suite

Spinal muscular atrophy (SMA) is characterized by progressive muscle weakness and paralysis. Motor function is monitored in the clinical setting using assessments including the 32-item Motor Function Measure (MFM-32), but changes in disease severity between clinical visits may be missed. Digital health technologies may assist evaluation of disease severity by bridging gaps between clinical visits. We developed a smartphone sensor-based assessment suite, comprising nine tasks, to assess motor and muscle function in people with SMA. We used data from the risdiplam phase 2 JEWELFISH trial to assess the test-retest reliability and convergent validity of each task. In the first 6 weeks, 116 eligible participants completed assessments on a median of 6.3 days per week. Eight of the nine tasks demonstrated good or excellent test-retest reliability (intraclass correlation coefficients >0.75 and >0.9, respectively). Seven tasks showed a significant association (P < 0.05) with related clinical measures of motor function (individual items from the MFM-32 or Revised Upper Limb Module scales) and seven showed significant association (P < 0.05) with disease severity measured using the MFM-32 total score. This cross-sectional study supports the feasibility, reliability, and validity of using smartphone-based digital assessments to measure function in people living with SMA.

Changes in electrophysiological findings of spinal muscular atrophy type I after the administration of nusinersen and onasemnogene abeparvovec: two case reports

BACKGROUND

Recently, there have been significant advances in the treatment of spinal muscular atrophy (SMA). Although clinical improvement in patients with SMA after the treatment has been reported, changes in electrophysiological findings, especially needle electromyography (EMG), have rarely been reported. Herein, we report the posttreatment changes in EMG and nerve conduction study findings over time in two patients with SMA type I.

CASE PRESENTATION

Patient 1: A 2.5-year-old girl was diagnosed with SMA type I at 1 month of age. She received nusinersen four times and onasemnogene abeparvovec (OA) was administered at 6 months of age. The compound muscle action potential (CMAP) amplitudes of the median and tibial nerves increased over time. The needle EMG after the treatment showed high-amplitude motor unit potentials (MUPs) suggestive of reinnervation during voluntary contraction, which were not seen before the treatment. However, fibrillation potentials at rest were still seen after the treatment. Patient 2: A 2-year-old girl was diagnosed with SMA type I at 6 months of age. She had received nusinersen two times and OA was administered at 7 months of age. The CMAP amplitudes and the MUPs presented similar changes as presented in Case 1.

CONCLUSION

This is the first report on the changes in needle EMG findings after treatment in patients with SMA type I. These findings suggested that peripheral nerve reinnervation occurred after the treatment, although active denervation was still present. The accumulation of these findings will be important for evaluating the effectiveness of treatment for SMA in the future.

Budget impact analysis: comparing the costs of nusinersen and risdiplam in the treatment of type 3 spinal muscular atrophy patients

OBJECTIVES

The aim of the budget impact analysis (BIA) was to determine the economic impact of introducing risdiplam in the treatment of type 3 spinal muscular atrophy (SMA) patients in a rare diseases reference centre on a 3-year time horizon, as compared with nusinersen.

METHODS

Public databases were used to estimate the target population. Two market scenarios were assessed over a 3-year time horizon: with nusinersen and with the introduction of risdiplam. Drug acquisition and administration costs were considered. BIA is calculated as the difference between scenarios with nusinersen - scenario with risdiplam.

RESULTS

The introduction of risdiplam would generate a 3-year saving of €3411.50. There could be a saving in the administration of risdiplam in the treatment of patients under the age of 2 with a weight of 5 kg (€26 382.08).

CONCLUSION

The BIA shows the overlapping costs of these therapies, although the oral administration of risdiplam could be a decisive factor for the therapeutical switch from nusinersen.

Spinal Muscular Atrophy: An Evolving Scenario through New Perspectives in Diagnosis and Advances in Therapies

Spinal muscular atrophy (SMA) linked to 5q is a recessive motor neuron disease characterized by progressive and diffuse weakness and muscular atrophy. SMA is the most common neurodegenerative disease in childhood with an incidence of approximately 1 in 6000-10,000 live births, being long considered a leading cause of hereditary mortality in infancy, worldwide. The classification of SMA is based on the natural history of the disease, with a wide clinical spectrum of onset and severity. We are currently in a new therapeutic era, that, thanks to the widespread use of the newly approved disease-modifying therapies and the possibility of an early administration, should lead to a deep change in the clinical scenario and, thus, in the history of SMA. With the aim to achieve a new view of SMA, in this review we consider different aspects of this neuromuscular disease: the historical perspective, the clinical features, the diagnostic process, the psychological outcome, innovation in treatments and therapies, the possibility of an early identification of affected infants in the pre-symptomatic phase through newborn screening programs.

Advanced Structural Magnetic Resonance Imaging of the Spinal Cord: Technical Aspects and Clinical Use

For a long time, technical obstacles have hampered the acquisition of high-resolution images and the development of reliable processing protocols for spinal cord (SC) MRI. Fortunately, this scenario has changed in the past 5-10 years, due to hardware and software improvements. Nowadays, with advanced protocols, SC MRI is considered a useful tool for several inherited and acquired neurologic diseases, not only for diagnosis approach but also for pathophysiological unraveling and as a biomarker for disease monitoring and clinical trials. In this review, we address advanced SC MRI sequences for macrostructural and microstructural evaluation, useful semiautomatic and automatic processing tools and clinical applications on several neurologic conditions such as hereditary cerebellar ataxia, hereditary spastic paraplegia, motor neuron diseases and multiple sclerosis.

Health Care Resource Utilization and Costs for Patients with Spinal Muscular Atrophy: Findings from a Retrospective US Claims Database Analysis

INTRODUCTION

Spinal muscular atrophy (SMA) is a neurogenic disorder associated with progressive loss of muscle function, respiratory failure, and premature mortality. This study aimed to describe and compare real-world health care resource utilization (HCRU) and costs for US patients with SMA treated with disease-modifying treatments, including onasemnogene abeparvovec, nusinersen, and/or risdiplam.

METHODS

This study used claims and structured electronic medical record data from the HealthVerity claims database (January 1, 2017-March 31, 2021). Eligible patients were aged ≤ 2 years at index (treatment initiation or switch), diagnosed with SMA, had ≥ 1 pharmacy/medical claim for onasemnogene abeparvovec, nusinersen, and/or risdiplam, and continuous enrollment ≥ 1 month pre- and ≥ 2 months post-index. SMA-related HCRU and costs during the study period (> 12 months post-index) were compared between treatment groups before and after propensity score weighting. Costs were adjusted to 2021 USD.

RESULTS

Of 74 included patients, 62 (83.8%) received nusinersen and 12 (16.2%) received onasemnogene abeparvovec (monotherapy, n = 9; onasemnogene abeparvovec after nusinersen [switching], n = 3). After weighting, nusinersen-treated patients had greater annual numbers of inpatient (mean 5.3 nusinersen vs. 1.8 onasemnogene abeparvovec) and emergency department (mean 3.0 nusinersen vs. 1.5 onasemnogene abeparvovec; p < 0.05) visits, and greater annual SMA-related medical costs (mean $78,446 nusinersen vs. $29,438 onasemnogene abeparvovec; mean difference $49,007, p < 0.05) than onasemnogene abeparvovec-treated patients. Onasemnogene abeparvovec-treated patients incurred greater SMA-treatment pharmacy costs than nusinersen-treated patients (mean $2,241,875 onasemnogene abeparvovec vs. $693,191 nusinersen; mean difference $1,548,684, p < 0.05).

CONCLUSIONS

SMA is associated with substantial economic burden. Patients treated with onasemnogene abeparvovec had greater SMA treatment-related pharmacy costs but lower SMA-related HCRU and medical costs compared with patients receiving nusinersen monotherapy.

Identifying Clinical and Genetic Characteristics of Spinal Muscular Atrophy Patients and Families in Saudi Arabia

INTRODUCTION

 Spinal muscular atrophy (SMA) is an inherited, neuromuscular disease characterized by the deterioration of spinal motor neurons, causing progressive muscular atrophy and weakening. It is an autosomal recessive disease with the mutation of the survival motor neuron 1 (SMN1) gene as a hallmark. Evidence suggests that the SMN2 gene modulates the severity of the disease. SMA is classified based on the maximum motor function achieved. This study aims to describe the genetic makeup and characteristics of an SMA cohort in the Kingdom of Saudi Arabia (KSA).

METHODS

 Data from families presenting with SMA children was collected between January 2018 and December 2020. Blood samples were collected from patients and family members. Genetic testing for SMA and mutations was performed at a European central lab.

RESULTS AND DISCUSSION

 Seventeen families were enrolled in the study, including 52 children. Among 34 parents, 28 were carriers with heterozygous deletion (82.3%), one (2.9%) had no deletion detected by multiplex ligation-dependent probe amplification (MLPA) but had point mutation by sequencing, one (2.9%) had homozygous deletion and was symptomatic, three (8.8%) had no deletion or point mutation and were presumed to have 2+0, and one (2.9%) was not tested.

CONCLUSION

 This study provides insight into the carrier mutational analysis of families with SMA disease manifestations in KSA. Further studies are needed to understand the burden and impact of SMA among the Saudi population.

Pregnancy experience in women with spinal muscular atrophy: a case series

Many women with spinal muscular atrophy (SMA) types II, III, and IV reach fertile age, and some of them may consider pregnancy. However, limited data are available about the potential effects of pregnancy on the course of SMA and the outcomes of pregnancies in these patients. Furthermore, the use of several disease-modifying therapies for the treatment of all types of SMA is expected to increase the number of female SMA patients considering pregnancy in the coming years. The aim of this report is to provide clinicians with an overview of the patients in our cohort who have experienced pregnancies. We conducted a retrospective analysis on these women, through the administration of a questionnaire, which investigated how they experienced the different stages of the pregnancy. Ten patients (3 SMAII; 7 SMA III) participated in the survey; 40% had pregnancies for a total of nine, six of which were term-pregnancies. The mean age of first pregnancy was 32.5 ± 7.8 years for SMA II patients, and 30.5 ± 2.1 years for SMA III. All pregnancies ended in cesarean sections. Interestingly, the sitters had more frequent complications in pre-term labor and delivery, but the newborns were all healthy. This report shows that a successful pregnancy is possible in female patients with SMA. However, the ideal approach should involve a standardized multidisciplinary team capable of effectively addressing every possible scenario. For this reason, it is critically important that clinicians working with SMA patients gain more in-dept knowledge about this topic.

Neurologic orphan diseases: Emerging innovations and role for genetic treatments

Orphan diseases are rare diseases that affect less than 200000 individuals within the United States. Most orphan diseases are of neurologic and genetic origin. With the current advances in technology, more funding has been devoted to developing therapeutic agents for patients with these conditions. In our review, we highlight emerging options for patients with neurologic orphan diseases, specifically including diseases resulting in muscular deterioration, epilepsy, seizures, neurodegenerative movement disorders, inhibited cognitive development, neuron deterioration, and tumors. After extensive literature review, gene therapy offers a promising route for the treatment of neurologic orphan diseases. The use of clustered regularly interspaced palindromic repeats/Cas9 has demonstrated positive results in experiments investigating its role in several diseases. Additionally, the use of adeno-associated viral vectors has shown improvement in survival, motor function, and developmental milestones, while also demonstrating reversal of sensory ataxia and cardiomyopathy in Friedreich ataxia patients. Antisense oligonucleotides have also been used in some neurologic orphan diseases with positive outcomes. Mammalian target of rapamycin inhibitors are currently being investigated and have reduced abnormal cell growth, proliferation, and angiogenesis. Emerging innovations and the role of genetic treatments open a new window of opportunity for the treatment of neurologic orphan diseases.

Gastrointestinal and nutritional care in pediatric neuromuscular disorders

Neuromuscular diseases (NMDs) affect the development and growth of the neuromuscular system in children. The pathology can occur anywhere along the neuromuscular pathway, from the brain to the nerves to the muscle fibers. These diseases have a profound impact on the quality of life not only of children but also of their families. The predominant manifestation in NMDs is hypotonia, which leads to muscle weakness and fatigue, reduced mobility, and decreased physical performance. However, multiple organ systems can be affected, with resulting orthopedic, cardiac, infectious, respiratory, and nutritional problems. Children with NMD present an increased risk for several dietary and feeding difficulties because of their neuromuscular diagnosis, presentation, and severity. These problems include chronic gastrointestinal issues (constipation, dysphagia, gastroesophageal reflux, and diarrhea), dysphagia, malnutrition, and body composition alterations. As a result, compared to the overall pediatric population, infants and children with NMD are more likely to be malnourished, ranging from failure to thrive to overweight or obesity. Disease-specific guidelines vary in level of detail and recommendations for dietary management. Overall, nutritional data available are sparse, with the exception of Duchenne muscular dystrophy, spinal muscular atrophy, and congenital muscular dystrophy. The purpose of this review is to describe the spectrum of nutritional challenges in children with NMD and to summarize the main dietary and gastrointestinal recommendations for each neuromuscular disorder to provide guidance for daily clinical practice.

Prevalence of morbidities across the lifespan for adults with spinal muscular atrophy: a retrospective cohort study

BACKGROUND

Recently approved treatments for spinal muscular atrophy (SMA) may shift clinical care priorities to secondary complications associated with SMA-related aging. To date, there is little knowledge about the natural history of morbidities across the adult lifespan for SMA. The objective of this study was to identify the prevalence and odds ratio (OR) of various morbidities among adults with vs. without SMA prior to SMA-related treatment.

METHODS

This was a retrospective cohort study that accessed Medicare fee-for-service and commercial claims data from 01/01/2008-12/22/2016. Data from adults ≥ 18 years old with SMA and without SMA matched (1:200 case:control) on demographics, region, and study entry year were included. The prevalence of 30 morbidities across physiologic systems (e.g., cardiovascular, metabolic, musculoskeletal, urinary) and mental health disorders was examined. Age- and sex-adjusted OR was estimated using logistic regression for each morbidity and effect modification by age and sex was tested.

RESULTS

There were 2,427 adults with SMA (mean [SD] age, 59.7 [17.4] years; 49.0% female) and 484,528 matched adults without SMA. Adults with vs. without SMA had a higher prevalence and adjusted OR of all 30 morbidities, ranging from OR = 1.61 (95% CI = 1.45-1.80) for hypothyroidism to OR = 7.80 (95% CI = 7.10-8.57) for fluid/electrolyte disorders. There was effect modification by age for 24 morbidities. The OR was highest for the youngest age group (18-40 years; OR range, 2.38 to 117.7; all P < 0.05) and declined with older age groups, but still remained significantly elevated in the oldest age group (≥ 75 years; OR range, 1.30 to 5.96; all P < 0.05).

CONCLUSIONS

The limitations of this study are that evidence of morbidities were limited to diagnostic claims and information on SMA type and symptoms or onset were not available. In conclusion, adults with SMA had a higher and earlier prevalence of a variety of morbidities across physiological systems and mental health disorders.

The Impact of Limited Previous Motor Experience on Action Possibility Judgments in People with Spinal Muscle Atrophy

Previous studies have shown that people with limited motor capabilities may rely on previous motor experience when making action possibility judgments for others. In the present study, we examined if having limited previous motor experience, as a consequence of spinal muscle atrophy (SMA), alters action possibility judgments. Participants with SMA and neurologically healthy (NH) sex- and age-matched controls performed a perceptual-motor judgment task using the Fitts's law paradigm. Participants observed apparent motion videos of reciprocal aiming movements with varying levels of difficulty. For each movement, participants predicted the shortest movement time (MT) at which a neurologically healthy young adult could accurately perform the task. Participants with SMA predicted significantly longer MTs compared to controls; however, the predicted MTs of both SMA and NH participants exhibited a Fitts's law relationship (i.e., the predicted MTs significantly increased as movement difficulty increased). Overall, these results provide evidence that participants with SMA who have limited, or no motor experience may make more conservative action possibility judgments for others. Critically, our finding that the pattern of action possibility judgments was not different between SMA and NH groups suggests that limited previous motor experience may not completely impair action possibility judgments.

Multi-omics profiling of CSF from spinal muscular atrophy type 3 patients after nusinersen treatment: a 2-year follow-up multicenter retrospective study

Spinal muscular atrophy (SMA) is a neurodegenerative disorder caused by mutations in the SMN1 gene resulting in reduced levels of the SMN protein. Nusinersen, the first antisense oligonucleotide (ASO) approved for SMA treatment, binds to the SMN2 gene, paralogue to SMN1, and mediates the translation of a functional SMN protein. Here, we used longitudinal high-resolution mass spectrometry (MS) to assess both global proteome and metabolome in cerebrospinal fluid (CSF) from ten SMA type 3 patients, with the aim of identifying novel readouts of pharmacodynamic/response to treatment and predictive markers of treatment response. Patients had a median age of 33.5 [29.5; 38.25] years, and 80% of them were ambulant at time of the enrolment, with a median HFMSE score of 37.5 [25.75; 50.75]. Untargeted CSF proteome and metabolome were measured using high-resolution MS (nLC-HRMS) on CSF samples obtained before treatment (T0) and after 2 years of follow-up (T22). A total of 26 proteins were found to be differentially expressed between T0 and T22 upon VSN normalization and LIMMA differential analysis, accounting for paired replica. Notably, key markers of the insulin-growth factor signaling pathway were upregulated after treatment together with selective modulation of key transcription regulators. Using CombiROC multimarker signature analysis, we suggest that detecting a reduction of SEMA6A and an increase of COL1A2 and GRIA4 might reflect therapeutic efficacy of nusinersen. Longitudinal metabolome profiling, analyzed with paired t-Test, showed a significant shift for some aminoacid utilization induced by treatment, whereas other metabolites were largely unchanged. Together, these data suggest perturbation upon nusinersen treatment still sustained after 22 months of follow-up and confirm the utility of CSF multi-omic profiling as pharmacodynamic biomarker for SMA type 3. Nonetheless, validation studies are needed to confirm this evidence in a larger sample size and to further dissect combined markers of response to treatment.

Onasemnogene abeparvovec preserves bulbar function in infants with presymptomatic spinal muscular atrophy: a post-hoc analysis of the SPR1NT trial

Bulbar function in spinal muscular atrophy has been defined as the ability to meet nutritional needs by mouth while maintaining airway protection and communicate verbally. The effects of disease-modifying treatment on bulbar function are not clear. A multidisciplinary team conducted post-hoc analyses of phase 3 SPR1NT trial data to evaluate bulbar function of infants at risk for spinal muscular atrophy who received one-time gene replacement therapy (onasemnogene abeparvovec) before symptom onset. Three endpoints represented adequate bulbar function in SPR1NT: (1) absence of physiologic swallowing impairment, (2) full oral nutrition, and (3) absence of adverse events indicating pulmonary instability. Communication was not assessed in SPR1NT. We descriptively assessed numbers/percentages of children who achieved each endpoint and all three collectively. SPR1NT included infants <6 postnatal weeks with two (n = 14) or three (n = 15) copies of the survival motor neuron 2 gene. At study end (18 [two-copy cohort] or 24 [three-copy cohort] months of age), 100% (29/29) of patients swallowed normally, achieved full oral nutrition, maintained pulmonary stability, and achieved the composite endpoint. When administered to infants before clinical symptom onset, onasemnogene abeparvovec allowed children at risk for spinal muscular atrophy to achieve milestones within published normal ranges of development and preserve bulbar function.

Cost-Effectiveness of Newborn Screening for Spinal Muscular Atrophy in England

INTRODUCTION

We sought to evaluate the cost-effectiveness of newborn screening (NBS) versus no NBS for 5q spinal muscular atrophy (SMA) in England.

METHODS

A cost-utility analysis using a combination of decision tree and Markov model structures was developed to estimate the lifetime health effects and costs of NBS for SMA, compared with no NBS, from the perspective of the National Health Service (NHS) in England. A decision tree was designed to capture NBS outcomes, and Markov modeling was used to project long-term health outcomes and costs for each patient group following diagnosis. Model inputs were based on existing literature, local data, and expert opinion. Sensitivity and scenario analyses were conducted to assess the robustness of the model and the validity of the results.

RESULTS

The introduction of NBS for SMA in England is estimated to identify approximately 56 (96% of cases) infants with SMA per year. Base-case results indicate that NBS is dominant (less costly and more effective) than a scenario without NBS, with a yearly cohort of newborns accruing incremental savings of £62,191,531 and an estimated gain in quality-adjusted life-years of 529 years over their lifetime. Deterministic and probabilistic sensitivity analyses demonstrated the robustness of the base-case results.

CONCLUSIONS

NBS improves health outcomes for patients with SMA and is less costly compared with no screening; therefore, it is a cost-effective use of resources from the perspective of the NHS in England.

The Carrier Frequency of Two SMN1 Genes in Parents of Symptomatic Children with SMA and the Significance of SMN1 Exon 8 in Carriers

BACKGROUND

Current carrier screening methods do not identify a proportion of carriers that may have children affected by spinal muscular atrophy (SMA). Additional genetic data is essential to inform accurate risk assessment and genetic counselling of SMA carriers. This study aims to quantify the various genotypes among parents of children with SMA.

METHOD

A retrospective cohort study was undertaken at Sydney Children's Hospital Network, the major SMA referral centre for New South Wales, Australia. Participants included children with genetically confirmed SMA born between 2005 and 2021. Data was collected on parent genotype inclusive of copy number of SMN1 exons 7 and 8. The number of SMN2 exon 7 copies were recorded for the affected children. Descriptive statistics were used to determine the proportion of carriers of 2+0 genotype classified as silent carriers. Chi-square test was used to correlate the association between parents with a heterozygous SMN1 exon 7 deletion and two copies of exon 8 and ≥3 SMN2 copy number in the proband.

RESULTS

SMA carrier testing was performed in 118/154 (76.6%) parents, incorporating 59 probands with homozygous SMN1 deletions and one proband with compound heterozygote pathogenic variants. Among parents with a child with SMA, 7.6% had two copies of SMN1 exon 7. When only probands with a homozygous SMN1 exon 7 deletion were included, 6.9% of parents had two copies of SMN1 exon 7. An association was observed between heterozygous deletion of SMN1 exon 7 with two copies of exon 8 in a parent and ≥3 SMN2 copy number in the affected proband (p = 0.07).

CONCLUSIONS

This study confirmed a small but substantial proportion of silent carriers not identified by conventional screening within an Australian context. Accordingly, the effectiveness of carrier screening for SMA is linked with genetic counselling to enable health literacy regarding high and low risk results and is complemented by new-born screening and maintaining clinical awareness for SMA. Gene conversion events may underpin the associations between parent carrier status and proband SMN2 copy number.

Pregnancy in a Patient with Spinal Muscular Atrophy and Severe Restrictive Lung Disease

Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disease that is often associated with chronic respiratory failure. Few cases have described the antepartum and postpartum course in patients with severely compromised respiratory status. We present a case of a 24-year-old nullipara with a history of SMA type II complicated by surgically corrected kyphoscoliosis and severe restrictive lung disease. Her pregnancy was complicated by progressively worsening dyspnea resulting in increased use of noninvasive positive pressure ventilation, ultimately leading to indicated premature delivery at 28 weeks' gestation via cesarean section under general anesthesia. Women with SMA and severe restrictive lung disease are at high risk of premature delivery secondary to worsening respiratory status. A multidisciplinary approach is vital in treating these patients.

A preliminary study on self-care telemonitoring of dysarthria in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a rare neuromuscular disease which may cause impairments in oro-facial musculature. Most of the individuals with SMA present bulbar signs such as flaccid dysarthria which mines their abilities to speak and, as consequence, their psychic balance. To support clinicians, recent work has demonstrated the feasibility of video-based techniques for assessing the oro-facial functions in patients with neurological disorders such as amyotrophic lateral sclerosis. However, no work has so far focused on automatic and quantitative monitoring of dysarthria in SMA. To overcome limitations this work's aim is to propose a cloud-based store-and-forward telemonitoring system for automatic and quantitative evaluation of oro-facial muscles in individuals with SMA. The system integrates a convolutional neural network (CNN) aimed at identifying the position of facial landmarks from video recordings acquired via a web application by an SMA patient.Clinical relevance- The proposed work is in the preliminary stage, but it represents the first step towards a better understanding of the bulbar-functions' evolution in patients with SMA.