Spinal muscular atrophy

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.

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.

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.

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.

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 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.

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.

Gene therapy for CNS disorders: modalities, delivery and translational challenges

Gene therapy is emerging as a powerful tool to modulate abnormal gene expression, a hallmark of most CNS disorders. The transformative potentials of recently approved gene therapies for the treatment of spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS) and active cerebral adrenoleukodystrophy are encouraging further development of this approach. However, most attempts to translate gene therapy to the clinic have failed to make it to market. There is an urgent need not only to tailor the genes that are targeted to the pathology of interest but to also address delivery challenges and thereby maximize the utility of genetic tools. In this Review, we provide an overview of gene therapy modalities for CNS diseases, emphasizing the interconnectedness of different delivery strategies and routes of administration. Important gaps in understanding that could accelerate the clinical translatability of CNS genetic interventions are addressed, and we present lessons learned from failed clinical trials that may guide the future development of gene therapies for the treatment and management of CNS disorders.

Five Questions to Help Prompt End-of-Life Planning in Neuromuscular Disease

Patients with neuromuscular disease are living longer lives but continue to have significant and often unpredictable morbidity and mortality. End-of-life planning for these patients is thus an essential part of their medical care. This planning should include the following topics: health care surrogates, swallowing and nutrition, daytime respiratory support, and all aspects of when end of life is near. Adult-onset and early-onset diseases may require different approaches to these topics. All patients with neuromuscular disease will benefit from these discussions to best reach patient-centered goals. We present health care providers these five questions and explanations as a guide.

The various forms of hereditary motor neuron disorders and their historical descriptions

Motor neuron disorders comprise a clinically and pathologically heterogeneous group of neurologic diseases characterized by progressive degeneration of motor neurons (including both sporadic and hereditary diseases), affecting the upper motor neurons, lower motor neurons, or both. Hereditary motor neuron disorders themselves represent a vast and heterogeneous group, with numerous clinical and genetic overlaps that can be a source of error. This narrative review aims at providing an overview of the main types of inherited motor neuron disorders by recounting the stages in their historical descriptions. For practical purposes, this review of the literature sets out their various clinical characteristics and updates the list of all the genes involved in the various forms of inherited motor neuron disorders, including spinal muscular atrophy, familial amyotrophic lateral sclerosis, hereditary spastic paraplegia, distal hereditary motor neuropathies/neuronopathies, Kennedy's disease, riboflavin transporter deficiencies, VCPopathy and the neurogenic scapuloperoneal syndrome.

Health-related quality of life of adults with spinal muscular atrophy: insights from a nationwide patient registry in Germany

PURPOSE

Spinal muscular atrophy (SMA) is a rare, autosomal-recessive disease characterized by progressive muscular atrophy and weakness resulting in substantial disability and short life expectancy. The objective of this cross-sectional study was to assess health-related quality of life (HRQoL) of adults with SMA in Germany in the era of disease-modifying therapy.

METHODS

Adults with SMA were recruited via the German national TREAT-NMD SMA patient registry. HRQoL was measured using the EQ-5D-5L, the Health Utilities Index Mark III (HUI), and the Short Form (36) Health Survey (SF-36). Estimates were stratified by current best motor function of the lower limb and trunk (i.e., non-sitter, sitter, and walker) and SMA type (i.e., type I, II, and III).

RESULTS

A total of 82 adults with SMA (mean age: 42 years, 51% female) self-completed the study questionnaire. The mean EQ-5D-5L utility was estimated at 0.5135 (range across subgroups: 0.31-0.99), mean EQ-VAS at 69.71 (64.67-90.00), mean HUI-derived utility at 0.3171 ( - 0.02-0.96), mean SF-6D utility at 0.6308 (0.58-0.65), and mean SF-36 Physical Component Summary and Mental Health Component Summary scores at 33.78 (9.92-53.10) and 53.49 (21.02-72.25), respectively.

CONCLUSIONS

We show that adults with SMA experience considerable impairment across a wide range of health dimensions, including mobility, dexterity, pain, and emotional well-being. However, our results exhibit non-trivial variability across clinical subgroups and HRQoL measures. These data contribute to our understanding of the subjective impact of living with a severely debilitating neuromuscular disease, such as SMA.

A Post-Marketing Surveillance Study of Nusinersen for Spinal Muscular Atrophy in Routine Medical Practice in China: Interim Results

INTRODUCTION

Spinal muscular atrophy (SMA) is a rare, autosomal recessive, neuromuscular disease that leads to progressive muscular weakness and atrophy. Nusinersen, an antisense oligonucleotide, was approved for SMA in China in February 2019. We report interim results from a post-marketing surveillance phase 4 study, PANDA (NCT04419233), that collects data on the safety, efficacy, and pharmacokinetics of nusinersen in children with SMA in routine clinical practice in China.

METHODS

Participants enrolled in PANDA will be observed for 2 years following nusinersen treatment initiation. The primary endpoint is the incidence of adverse events (AEs)/serious AEs (SAEs) during the treatment period. Efficacy assessments include World Health Organization (WHO) Motor Milestones assessment, the Hammersmith Infant Neurological Examination (HINE), and ventilation support. Plasma and cerebrospinal fluid (CSF) concentrations of nusinersen are measured at each dose visit.

RESULTS

Fifty participants were enrolled as of the January 4, 2023, data cutoff: 10 with infantile-onset (≤ 6 months) and 40 with later-onset (> 6 months) SMA. All 50 participants have received at least one dose of nusinersen; 6 have completed the study. AEs were experienced by 45 (90%) participants and were mostly mild/moderate; no AEs led to nusinersen discontinuation or study withdrawal. Eleven participants experienced SAEs, most commonly pneumonia (n = 9); none were considered related to study treatment. Stability or gain of WHO motor milestone was observed and mean HINE-2 scores improved in both subgroups throughout the study. No serious respiratory events occurred, and no permanent ventilation support was initiated during the study. Pre-dose nusinersen CSF concentrations increased steadily through the loading-dose period, with no accumulation in plasma after multiple doses.

CONCLUSION

Nusinersen was generally well tolerated with an acceptable overall safety profile, consistent with the known safety of nusinersen. Efficacy, safety, and nusinersen exposure are consistent with prior observations. These results support continuing PANDA and evaluation of nusinersen in Chinese participants with SMA.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT04419233.

Improvement in functional motor scores in patients with non-ambulatory spinal muscle atrophy during Nusinersen treatment in South Korea: a single center study

We analyzed the changes in various motor function scores over a four-year period in patients with non-ambulatory spinal muscular atrophy (SMA) during Nusinersen treatment. Patients underwent Hammersmith Infant Neurological Examination (HINE) or Hammersmith Functional Motor Scale Expanded (HFMSE) before treatment, and approximately every 4 months thereafter. Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) or Children's Hospital of Philadelphia - Adult Test of Neuromuscular Disorders (CHOP ATEND), Revised Upper Limb Module (RULM), and Motor Function Measure (MFM) were performed based on baseline functional status. Narrative interviews were conducted to explore post-treatment physical improvement regarding activities of daily living (ADLs) and fatigue after ADLs. Based on HFMSE results, 9 patients achieved minimum clinically important differences. Average rates of change (slopes) with corresponding 95% confidence intervals for all assessment tools were in a positive direction. CHOP-INTEND showed the most prominent improvement in children and adolescents followed by HFMSE. Improvements in CHOP-ATEND were most noticeable in adults. Improvements were accompanied by changes in ADLs as observed in the narrative interviews. It is necessary to consider various functional aspects to determine the effectiveness of Nusinersen therapy. The objective assessment of the therapeutic effect of Nusinersen in non-ambulatory SMA requires consideration of functional aspects and the related ADLs.

Survival analysis and life expectancy of pediatric patients with spinal muscular atrophy in Thailand

Background

Survival data for Thai patients with 5q spinal muscular atrophy (SMA), the leading cause of infant mortality worldwide, are lacking.

Objective

This study aimed to determine the survival rates and life expectancies of pediatric patients with SMA types 1, 2, and 3.

Methods

We conducted a retrospective cohort analysis of genetically confirmed 5q SMA patients aged 0-18 years who were treated between 1999 and 2021 at the pediatric neuromuscular clinic of Siriraj Hospital, Bangkok, Thailand. Mortality data were sourced from the Civil Registration Office.

Results

The study included 113 patients: 37 with SMA type 1, 53 with type 2, and 23 with type 3. Life expectancy varied significantly by SMA type: 2.2 years for type 1, 11 years for type 2, and 16.5 years for type 3. The median survival times for SMA type 1 and 2 were 1.9 and 19 years, respectively. In SMA type 2, early onset (<1 year) correlated with a shorter median survival than later onset (≥1 year) (log-rank test P = 0.009). Early onset SMA type 2 had a median survival time of 15.9 years, while 75 % of those with later onset SMA type 2 survived until the age of 19 years. Cox proportional hazards analysis revealed that each month's delay in disease onset reduced the annual mortality risk by 17 % for type 1 patients and by 20 % for type 2 patients. Compared with female patients, male patients with type 2 disease had a 12-fold increased mortality risk.

Conclusions

Age at onset is a significant predictor of survival and life expectancy in patients with SMA types 1 and 2. These insights are crucial for genetic counseling and prognostic discussions in clinical settings.

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.

Nusinersen therapy changed the natural course of spinal muscular atrophy type 1: What about spine and hip?

Purpose

Spinal muscular atrophy type 1 has a devastating natural course and presents a severe course marked by scoliosis and hip subluxation in nonambulatory patients. Nusinersen, Food and Drug Administration-approved spinal muscular atrophy therapy, extends survival and enhances motor function. However, its influence on spinal and hip deformities remains unclear.

Methods

In a retrospective study, 29 spinal muscular atrophy type 1 patients born between 2017 and 2021, confirmed by genetic testing, treated with intrathecal nusinersen, and had registered to the national electronic health database were included. Demographics, age at the first nusinersen dose, total administrations, and Children's of Philadelphia Infant Test of Neuromuscular Disorders scores were collected. Radiological assessments included parasol rib deformity, scoliosis, pelvic obliquity, and hip subluxation.

Results

Mean age was 3.7 ± 1.1 (range, 2-6), and average number of intrathecal nusinersen administration was 8.9 ± 2.9 (range, 4-19). There was a significant correlation between Children's of Philadelphia Infant Test of Neuromuscular Disorders score and the number of nusinersen administration (r = 0.539, p = 0.05). The correlation between Children's of Philadelphia Infant Test of Neuromuscular Disorders score and patient age (r = 0.361) or the time of first nusinersen dose (r = 0.39) was not significant (p = 0.076 and p = 0.054, respectively). While 93.1% had scoliosis, 69% had pelvic obliquity, and 60.7% had hip subluxation, these conditions showed no significant association with patient age, total nusinersen administrations, age at the first dose, or Children's of Philadelphia Infant Test of Neuromuscular Disorders scores.

Conclusion

Disease-modifying therapy provides significant improvements in overall survival and motor function in spinal muscular atrophy type 1. However, progressive spine deformity and hip subluxation still remain significant problems in the majority of cases which would potentially need to be addressed.

Efficient systemic CNS delivery of a therapeutic antisense oligonucleotide with a blood-brain barrier-penetrating ApoE-derived peptide

Antisense oligonucleotide (ASO) has emerged as a promising therapeutic approach for treating central nervous system (CNS) disorders by modulating gene expression with high selectivity and specificity. However, the poor permeability of ASO across the blood-brain barrier (BBB) diminishes its therapeutic success. Here, we designed and synthesized a series of BBB-penetrating peptides (BPP) derived from either the receptor-binding domain of apolipoprotein E (ApoE) or a transferrin receptor-binding peptide (THR). The BPPs were conjugated to phosphorodiamidate morpholino oligomers (PMO) that are chemically analogous to the 2'-O-(2-methoxyethyl) (MOE)-modified ASO approved by the FDA for treating spinal muscular atrophy (SMA). The BPP-PMO conjugates significantly increased the level of full-length SMN2 in the patient-derived SMA fibroblasts in a concentration-dependent manner with minimal to no toxicity. Furthermore, the systemic administration of the most potent BPP-PMO conjugates significantly increased the expression of full-length SMN2 in the brain and spinal cord of SMN2 transgenic adult mice. Notably, BPP8-PMO conjugate showed a 1.25-fold increase in the expression of full-length functional SMN2 in the brain. Fluorescence imaging studies confirmed that 78% of the fluorescently (Cy7)-labelled BPP8-PMO reached brain parenchyma, with 11% uptake in neuronal cells. Additionally, the BPP-PMO conjugates containing retro-inverso (RI) D-BPPs were found to possess extended half-lives compared to their L-counterparts, indicating increased stability against protease degradation while preserving the bioactivity. This delivery platform based on BPP enhances the CNS bioavailability of PMO targeting the SMN2 gene, paving the way for the development of systemically administered neurotherapeutics for CNS disorders.

Reliability and Validity of the Turkish Translation of the PedsQL™ 3.0 Neuromuscular Module for 2-to 4-Year-Olds in Spinal Muscular Atrophy

BACKGROUND

 The Pediatric Quality of Life Inventory™ (PedsQL™) Neuromuscular Module (PedsQL™ 3.0 NM) evaluates the health-related quality of life in children who are affected by neuromuscular diseases. This study's aim is to assess the adaptation of the PedsQL™ 3.0 NM Turkish version (PedsQL™ 3.0 NM-TR) for 2- to 4-year-olds in spinal muscular atrophy (SMA).

METHODS

 The procedure of translating the PedsQL™ 3.0 NM into Turkish was conducted in accordance with the translation methodology outlined by the PedsQL™ measurement model. The PedsQL™ 3.0 NM-TR was administered to 54 parents of children with SMA aged 2 to 4 years. The test-retest reliability and intraclass correlation coefficient (ICC) were measured for reliability analysis. Cronbach's α coefficient and item score correlations were calculated for internal consistency. Concurrent construct validity was evaluated by Pearson correlations between the outcomes of the PedsQL™ 4.0 Generic Core Scale (PedsQL™ 4.0 GCS) and the PedsQL™ 3.0 NM.

RESULTS

 The PedsQL™ 3.0 NM-TR total score shows excellent reliability. The Cronbach's α values for the PedsQL™ 3.0 NM ranged between 0.871 and 0.906, while those for the PedsQL™ 4.0 GCS ranged between 0.843 and 0.897. Test-retest ICC values for the PedsQL™ 3.0 NM-TR ranged between 0.812 and 0.917, and for the PedsQL™ 4.0 GCS ranged between 0.773 and 0.899. The relationship between the PedsQL™ 3.0 NM-TR and the subscores of the PedsQL™ 4.0 GCS demonstrated a range of correlations from excellent to fair, indicating the interplay between two scales.

CONCLUSION

 This study established the PedsQL™ 3.0 NM-TR as reliable, valid, and feasible for use in children aged 2 to 4 years with SMA.

Therapeutic Role of Nusinersen on Respiratory Progression in Pediatric Patients With Spinal Muscular Atrophy Type 2 and Nonambulant Type 3

Background and Objectives

Nusinersen has shown significant functional motor benefit in the milder types of spinal muscular atrophy (SMA). Less is known on the respiratory outcomes in patients with nusinersen-treated SMA. The aim of this study was to describe changes in respiratory function in pediatric patients with SMA type 2 and 3 on regular treatment with nusinersen within the iSMAc international cohort and to compare their trajectory with the natural history (NH) data published by the consortium in 2020.

Methods

This is a 5-year retrospective observational study of pediatric SMA type 2 and nonambulant type 3 (age ≤18 years) treated with nusinersen. The primary objective was to compare the slopes of decline in forced vital capacity % predicted (FVC% pred.), FVC, and age when FVC dropped below 60% between the treated patients and a control group from the natural history cohort. Data on peak cough flow and the use of noninvasive ventilation (NIV) and cough assist were collected.

Results

Data were available for 69 treated patients, 53 were SMA type 2 and 16 type 3. The mean (SD) age at first injection was 8.5 (3.2) and 9.7 (3.7) years, respectively. The median (interquartile range) treatment duration was 1 (0.7; 1.9) and 1.2 (0.9; 1.9) years, respectively. At the time of the first nusinersen injection, 24 of 52 (46%) patients with SMA type 2 and 2 of 16 (13%) patients with SMA type 3 were on NIV. Forty-three of 53 (81%) and 4 of 16 (25%) patients used cough device. FVC% pred. in treated patients with SMA type 2 declined annually by 2.3% vs 3.9% in NH (p = 0.08) and in treated patients with type 3 by 2.6% vs 3.4% NH (p = 0.59). Patients treated reached FVC <60% later than untreated (12.1 vs 10 years, p = 0.05). A higher percentage of treated vs untreated patients maintained FVC% pred. equal/above their baseline after 12 (65% vs 36%) and 24 (50% vs 24%) months, respectively. NIV use among treated did not significantly change throughout 1-year follow-up.

Discussion

This study included the largest real-world cohort of pediatric patients with milder SMA types. The results suggest a positive role of nusinersen in delaying the respiratory decline in patients treated longer than 1 year when compared with natural history. Larger cohorts and longer observation are planned.

Classification of Evidence

This study provided Class III evidence that nusinersen slows progression for patients with SMA types 2 and 3 compared with a natural history cohort.

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.

Small molecules modulating RNA splicing: a review of targets and future perspectives

In eukaryotic cells, RNA splicing is crucial for gene expression. Dysregulation of this process can result in incorrect mRNA processing, leading to aberrant gene expression patterns. Such abnormalities are implicated in many inherited diseases and cancers. Historically, antisense oligonucleotides, which bind to specific RNA targets, have been used to correct these splicing abnormalities. Despite their high specificity of action, these oligonucleotides have drawbacks, such as lack of oral bioavailability and the need for chemical modifications to enhance cellular uptake and stability. As a result, recent efforts focused on the development of small organic molecules that can correct abnormal RNA splicing event under disease conditions. This review discusses known and potential targets of these molecules, including RNA structures, trans-acting splicing factors, and the spliceosome - the macromolecular complex responsible for RNA splicing. We also rely on recent advances to discuss therapeutic applications of RNA-targeting small molecules in splicing correction. Overall, this review presents an update on strategies for RNA splicing modulation, emphasizing the therapeutic promise of small molecules.

Cargo specificity, regulation, and therapeutic potential of cytoplasmic dynein

Intracellular retrograde transport in eukaryotic cells relies exclusively on the molecular motor cytoplasmic dynein 1. Unlike its counterpart, kinesin, dynein has a single isoform, which raises questions about its cargo specificity and regulatory mechanisms. The precision of dynein-mediated cargo transport is governed by a multitude of factors, including temperature, phosphorylation, the microtubule track, and interactions with a family of activating adaptor proteins. Activating adaptors are of particular importance because they not only activate the unidirectional motility of the motor but also connect a diverse array of cargoes with the dynein motor. Therefore, it is unsurprising that dysregulation of the dynein-activating adaptor transport machinery can lead to diseases such as spinal muscular atrophy, lower extremity, and dominant. Here, we discuss dynein motor motility within cells and in in vitro, and we present several methodologies employed to track the motion of the motor. We highlight several newly identified activating adaptors and their roles in regulating dynein. Finally, we explore the potential therapeutic applications of manipulating dynein transport to address diseases linked to dynein malfunction.

No significant sex differences in incidence or phenotype for the SMNΔ7 mouse model of spinal muscular atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive disease that affects 1 out of every 6,000-10,000 individuals at birth, making it the leading genetic cause of infant mortality. In recent years, reports of sex differences in SMA patients have become noticeable. The SMNΔ7 mouse model is commonly used to investigate pathologies and treatments in SMA. However, studies on sex as a contributing biological variable are few and dated. Here, we rigorously investigated the effect of sex on a series of characteristics in SMA mice of the SMNΔ7 model. Incidence and lifespan of 23 mouse litters were tracked and phenotypic assessments were performed at 2-day intervals starting at postnatal day 6 for every pup until the death of the SMA pup(s) in each litter. Brain weights were also collected post-mortem. We found that male and female SMA incidence does not differ significantly, survival periods are the same across sexes, and there was no phenotypic difference between male and female SMA pups, other than for females exhibiting lesser body weights at early ages. Overall, this study ensures that sex is not a biological variable that contributes to the incidence ratio or disease severity in the SMNΔ7 mouse model.

Improved gene therapy for spinal muscular atrophy in mice using codon-optimized hSMN1 transgene and hSMN1 gene-derived promotor

Physiological regulation of transgene expression is a major challenge in gene therapy. Onasemnogene abeparvovec (Zolgensma®) is an approved adeno-associated virus (AAV) vector gene therapy for infants with spinal muscular atrophy (SMA), however, adverse events have been observed in both animals and patients following treatment. The construct contains a native human survival motor neuron 1 (hSMN1) transgene driven by a strong, cytomegalovirus enhancer/chicken β-actin (CMVen/CB) promoter providing high, ubiquitous tissue expression of SMN. We developed a second-generation AAV9 gene therapy expressing a codon-optimized hSMN1 transgene driven by a promoter derived from the native hSMN1 gene. This vector restored SMN expression close to physiological levels in the central nervous system and major systemic organs of a severe SMA mouse model. In a head-to-head comparison between the second-generation vector and a benchmark vector, identical in design to onasemnogene abeparvovec, the 2nd-generation vector showed better safety and improved efficacy in SMA mouse model.

Neurodegeneration Biomarkers in Adult Spinal Muscular Atrophy (SMA) Patients Treated with Nusinersen

The objective of this study is to evaluate biomarkers for neurodegenerative disorders in adult SMA patients and their potential for monitoring the response to nusinersen. Biomarkers for neurodegenerative disorders were assessed in plasma and CSF samples obtained from a total of 30 healthy older adult controls and 31 patients with adult SMA type 2 and 3. The samples were collected before and during nusinersen treatment at various time points, approximately at 2, 6, 10, and 22 months. Using ELISA technology, the levels of total tau, pNF-H, NF-L, sAPPβ, Aβ40, Aβ42, and YKL-40 were evaluated in CSF samples. Additionally, plasma samples were used to measure NF-L and total tau levels using SIMOA technology. SMA patients showed improvements in clinical outcomes after nusinersen treatment, which were statistically significant only in walkers, in RULM (p = 0.04) and HFMSE (p = 0.05) at 24 months. A reduction in sAPPβ levels was found after nusinersen treatment, but these levels did not correlate with clinical outcomes. Other neurodegeneration biomarkers (NF-L, pNF-H, total tau, YKL-40, Aβ40, and Aβ42) were not found consistently changed with nusinersen treatment. The slow progression rate and mild treatment response of adult SMA types 2 and 3 may not lead to detectable changes in common markers of axonal degradation, inflammation, or neurodegeneration, since it does not involve large pools of damaged neurons as observed in pediatric forms. However, changes in biomarkers associated with the APP processing pathway might be linked to treatment administration. Further studies are warranted to better understand these findings.

RNA-Small-Molecule Interaction: Challenging the "Undruggable" Tag

RNA targeting, specifically with small molecules, is a relatively new and rapidly emerging avenue with the promise to expand the target space in the drug discovery field. From being "disregarded" as an "undruggable" messenger molecule to FDA approval of an RNA-targeting small-molecule drug Risdiplam, a radical change in perspective toward RNA has been observed in the past decade. RNAs serve important regulatory functions beyond canonical protein synthesis, and their dysregulation has been reported in many diseases. A deeper understanding of RNA biology reveals that RNA molecules can adopt a variety of structures, carrying defined binding pockets that can accommodate small-molecule drugs. Due to its functional diversity and structural complexity, RNA can be perceived as a prospective target for therapeutic intervention. This perspective highlights the proof of concept of RNA-small-molecule interactions, exemplified by targeting of various transcripts with functional modulators. The advent of RNA-oriented knowledge would help expedite drug discovery.