Ad astra per aspera: treatment challenges and opportunities for children with spinal muscular atrophy and tracheostomy.

To summarize the current knowledge on brain involvement in spinal muscular atrophy (SMA) type 1, focusing on brain pathology, cognition, and speech/language development. A scoping review was performed using the methodology of the Joanna Briggs Institute. Five databases and references from relevant articles were searched up to December 2019. Articles were screened on the basis of titles and abstracts. Full-text papers published in peer-reviewed journals in English were selected. Nineteen articles met eligibility criteria. Eight case series/reports on brain pathology showed abnormalities in few SMA type 0/1 cases, supported by findings in three post-mortem examinations in mice. Four studies (three case-control, one cross-sectional) on cognition reported contradictory results, with impaired cognitive performances in recent, small groups with SMA type 1. Four studies (three cross-sectional, one observational) on speech/language showed that untreated SMA type 1 patients rarely achieve functional and intelligible speech, with data limited to parent reports/non-formal evaluations. Brain involvement is an under-investigated aspect of SMA type 1, requiring further exploration in longitudinal studies. A deeper knowledge of brain involvement would improve the interpretation of clinical phenotypes and the personalization of rehabilitation programmes supporting patients' autonomies and quality of life. Additionally, it may help to define further outcome measures testing the efficacy of current and new developing drugs on this domain. Brain involvement is under-investigated in spinal muscular atrophy (SMA) type 1. Neuropathological data suggest progressive brain involvement in severe forms of SMA. Impaired cognitive performances are reported in small groups with SMA type 1. Data on language in those with SMA type 1 are limited to parent reports and non-formal assessments.

Sleep architecture in children with spinal muscular atrophy type 2

Serum acetylcholinesterase (AChE) and pseudocholinesterase (ChE) activity in infantile and juvenile spinal muscular atrophy (SMA) was determined. The total AChE activity was either normal or decreased in the childhood SMA (Type 1), the other SMA groups and disease controls (ALS, X-linked SMA). In the majority of SMA Type 1 cases (6/7 tested) an absence of the asymmetric A12 form was found. This was accompanied by changes in the other asymmetric and globular forms. The latter was, however, not specific for SMA Type 1 cases. The ChE activity was increased in the majority of SMA cases as well as disease controls. The asymmetric A12 ChE form was increased in all SMA Type 3 cases, the values of this form in SMA Type 1 was variable. A change in the ChE globular forms in SMA Type 1 and SMA Type 2 was a frequent finding. It is suggested that the absence of the asymmetric A12 AChE form in SMA Type 1 arises because of muscle cell immaturity and undeveloped muscle-nerve interactions. The reason of ChE changes is obscure.

Patient and parent oriented tools to assess health-related quality of life, activity of daily living and caregiver burden in SMA. Rome, 13 July 2019

Spinal muscular atrophy (SMA), a leading genetic cause of infant death, is caused by the loss of survival motor neuron 1 (SMN1) gene. SMA is characterized by the degeneration and loss of spinal cord motoneurons (MNs), muscular atrophy, and weakness. SMN2 is the centromeric duplication of the SMN gene, whose numbers of copies determine the intracellular levels of SMN protein and define the disease onset and severity. It has been demonstrated that elevating SMN levels can be an important strategy in treating SMA and can be achieved by several mechanisms, including promotion of protein stability. SMN protein is a direct target of the calcium-dependent protease calpain and induces its proteolytic cleavage in muscle cells. In this study, we examined the involvement of calpain in SMN regulation on MNs. In vitro experiments showed that calpain activation induces SMN cleavage in CD1 and SMA mouse spinal cord MNs. Additionally, calpain 1 knockdown or inhibition increased SMN level and prevent neurite degeneration in these cells. We examined the effects of calpain inhibition on the phenotype of two severe SMA mouse models. Treatment with the calpain inhibitor, calpeptin, significantly improved the lifespan and motor function of these mice. Our observations show that calpain regulates SMN level in MNs and calpeptin administration improves SMA phenotype demonstrating the potential utility of calpain inhibitors in SMA therapy.

Background Spinal muscular atrophy (SMA) is caused by degeneration of anterior horn cells of the spinal cord, which leads to progressive muscle weakness. Children with SMA type I will never be able to sit without support and usually die by the age of two years. There are no known efficacious drug treatments that influence the course of the disease. This is an update of a review first published in 2009. Objectives To evaluate whether drug treatment is able to slow or arrest the disease progression of SMA type I, and to assess if such therapy can be given safely. Drug treatment for SMA types II and III is the topic of a separate updated Cochrane review. Search methods We searched the Cochrane Neuromuscular Disease Group Specialized Register (8 March 2011), CENTRAL (The Cochrane Library 2011, Issue 1), MEDLINE (January 1991 to February 2011), EMBASE (January 1991 to February 2011) and ISI Web of Knowledge (January 1991 to 8 March 2011). We searched the Clinical Trials Registry of the U.S. National Institute of Health (www.ClinicalTrials.gov) (8 March 2011) to identify additional trials that had not yet been published. Selection criteria We sought all randomised or quasi-randomised trials that examined the efficacy of drug treatment for SMA type I. Participants had to fulfil the clinical criteria and have a deletion or mutation of the SMN1 gene (5q11.2-13.2) confirmed by genetic analysis.The primary outcome measure was time from birth until death or full time ventilation. Secondary outcome measures were development of rolling, sitting or standing within one year after the onset of treatment, and adverse events attributable to treatment during the trial period. Data collection and analysis Two authors (RW and AV) independently reviewed and extracted data from all potentially relevant trials. For included studies, pooled relative risks and standardised mean differences were to be calculated to assess treatment efficacy. Main results One small randomised controlled study comparing riluzole treatment to placebo for 10 SMA type 1 children was identified and included in the original review. No further trials were identified for the update in 2011. Regarding the primary outcome measure, three of seven children treated with riluzole were still alive at the ages of 30, 48 and 64 months, whereas all three children in the placebo group died; but the difference was not statistically significant. Regarding the secondary outcome measures, none of the children in the riluzole or placebo group developed the ability to roll, sit or stand, and no adverse effects were observed. For several reasons the overall quality of the study was low, mainly because the study was too small to detect an effect and because of baseline differences. Follow-up of the 10 included children was complete. Authors' conclusions No drug treatment for SMA type I has been proven to have significant efficacy.

In a cross-sectional study, we aimed to determine (1) the effect of spinal muscular atrophy (SMA) type 2 and 3 on mandibular function reflected as masticatory performance, mandibular range of motion, and bite force and (2) the predictors of mandibular dysfunction. Sixty patients with SMA type 2 and 3 (mean age 32.3 years, SD 17.4 years) and 60 age-matched controls filled out questionnaires about impairments of mandibular function. All participants underwent detailed clinical examination to document the mandibular range of motion including maximal mouth opening, bite force, and masticatory function. All mandibular movements, including mouth opening, lateral range of motion, and protrusion of the mandible, were reduced in patients with SMA type 2 and 3 compared to healthy controls (p < 0.001). Maximal bite force was 19% lower in patients than controls, and more in patients with SMA type 2 than type 3. The strongest predictive factor was SMA type for impairment of mandibular range of motion (R(2) = 0.82) and weakness of neck muscles for bite force (R(2) = 0.47). Reduced mandibular mobility and bite force are common complications in SMA. SMA type and neck muscle strength are important correlates of these complications. We provide further evidence for clinically relevant bulbar involvement in patients with SMA.

ObjectiveRecent advances in therapeutics have improved prognosis for severely affected spinal muscular atrophy (SMA) type 1 and 2 patients, while the best method of treatment for SMA type 3 patients with later onset of disease is unknown. To better characterize the SMA type 3 population and provide potential therapeutic targets, we aimed to understand gene expression differences in whole blood of SMA type 3 patients (n = 31) and age‐ and gender‐matched controls (n = 34).MethodsWe performed the first large‐scale whole blood transcriptomic screen with L1000, a rapid, high‐throughput gene expression profiling technology that uses 978 landmark genes to capture a representation of the transcriptome and predict expression of 9196 additional genes.ResultsThe primary downregulated KEGG pathway in adult SMA type 3 patients was "Regulation of Actin Cytoskeleton,” and downregulated expression of key genes in this pathway, including ROCK1, RHOA, and ACTB, was confirmed in the same whole blood samples using RT‐qPCR. SMA type 3 patient‐derived fibroblasts had lower expression of these genes compared to control fibroblasts from unaffected first‐degree relatives. Overexpression of SMN levels using an AAV vector in fibroblasts did not normalize ROCK1, RHOA, and ACTB mRNA expression, indicating the involvement of additional genes in cytoskeleton dynamic regulation.InterpretationOur findings from whole blood and patient‐derived fibroblasts suggest SMA type 3 patients have decreased expression of actin cytoskeleton regulators. These observations provide new insights and potential therapeutic targets for SMA patients with longstanding denervation and secondary musculoskeletal pathophysiology.

BackgroundThe Pediatric Spinal Muscular Atrophy Registry Program of Iran (PSMAIR) was established as part of the global TREAT-NMD network, which collects data from spinal muscular atrophy (SMA) patients under 18 years of age in Iran. The registry employs a web-based data entry system to collect detailed longitudinal demographic, geographic, clinical, genetic, and treatment outcome data of Iranian children who suffer from SMA.ResultsFrom October 2021 to September 2022, 59 SMA patients were enrolled; 52.5% were female, 47.5% were male, and the average age was 4.98 ± 4.08 years. The majority of registered patients were diagnosed with SMA Type I (47%), followed by Type II (29%) and Type III (24%). Overall, about 19% of the registered patients died; all of them were Type I patients. In the registry, 44% of patients had been hospitalized previously. Usage rates for wheelchairs or other mobility assistive devices, occurrence of scoliosis, tube feeding, and mechanical ventilation among these patients were 15%, 15%, 19%, and 20%, respectively. The data reveal a gradient of severity across SMA types, with earlier symptom onset, lower CMAP amplitude, and lower ACTIVLIM scores associated with more severe SMA (type I), and increments observed moving towards milder forms (type III). The data reveal that symptom onset age, CMAP amplitude, and ACTIVLIM scores progressively increase from SMA type I to SMA type III. The CHOP-INTEND questionnaire's average score was notably higher in children with SMA type II compared to those with type I, while the HFMSE questionnaire scores were notably increased in type III compared to type II patients. A significant correlation between the SMN2 copy number and the SMA phenotype was observed in the population. The geographic distribution of the enrolled patients covers 15 and 18 (out of the 31) provinces of Iran for place of birth and current place of residence, respectively. For patients residing outside Tehran city (where the registry’s referral center is located), the average distance to the registry’s referral center was roughly 463 km.ConclusionsThe PSMAIR offers an important step toward understanding the characteristics of Iranian pediatric SMA patients. The outcome of PSMAIR facilitates data-driven planning and decision-making for Iranian pediatric SMA patients and can help in the advancement of SMA care standards, management, and therapies.

Background: Spinal muscular atrophy (SMA) type 1 is a severe condition leading to early respiratory failure. Treatment options have become available, yet respiratory outcome measures in SMA type 1 are limited. The aim of this study was to assess the respiratory pattern in SMA type 1 patients via structured light plethysmography (SLP). SLP measures the thoraco-abdominal movements by projecting a light grid onto the anterior thoraco-abdominal surface. Methods: Cross-sectional study of consecutive children with SMA type 1. All children underwent motor assessment (CHOP-INTEND) and one-minute tidal breathing recording by SLP in supine position while self-ventilating in room air. The Respiratory rate, the abdominal vs. chest contribution to breath (Relative Expired Abdomen%, Relative Expired Chest%) and the severity of thoraco-abdominal paradox (Phase Angle) were acquired. Results: Nineteen patients were included, median (IQR) age 2.3 years (1.4–7.9). Their respiratory pattern captured via SLP showed a raised median (IQR) respiratory rate per age of 33.5 bpm (26.6–41.7), a prevalent abdominal contribution to tidal breathing with median (IQR) Relative Expired Abdomen 77% (68–90) vs. Chest 23% (10–32). Thoracoabdominal paradox was detected (median Phase Angle 48.70°) and its severity correlated negatively with CHOP-INTEND (r −0.8, p < 0.01). Conclusions: SLP captured and quantified the respiratory features of infants and children with SMA type 1.

To describe the natural history of the upper limb motor function in spinal muscular atrophy (SMA) type 2 and analyze the impact of SMA-modifying therapies on Revised Upper Limb Module (RULM) scores. This is a retrospective, multicenter, observational study including individuals with SMA type 2, aged between 30months and 20years at the time of their first RULM assessment, with available follow-up data. We enrolled 149 untreated individuals as part of the natural history cohort, with a mean age of 9.5 years at the first assessment and a mean follow-up duration of 3.98 years (SD 1.97, range 0.3-7.7). An increase in RULM scores was observed in early childhood within this cohort. However, after 4.4 years of age, a gradual decline in RULM scores was noted with increasing age. In contrast, RULM scores were significantly higher in individuals receiving treatment with nusinersen or risdiplam compared to natural history data. Our findings provide a natural history of upper extremity motor function in children and adolescents with SMA type 2. The RULM scores typically improve during the early years of life, peaking around 4.4years of age, after which they progressively decline with age. The data presented herewill facilitate the assessment of treatment response in individuals with SMA type 2, especially in those with already severely limited motor function.

Motor neuron diseases (MNDs) are neurodegenerative disorders characterized by upper and/or lower MN loss. MNDs include amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), and spinal and bulbar muscular atrophy (SBMA). Despite variability in onset, progression, and genetics, they share a common skeletal muscle involvement, suggesting that it could be a primary site for MND pathogenesis. Due to the key role of muscle-specific microRNAs (myomiRs) in skeletal muscle development, by real-time PCR we investigated the expression of miR-206, miR-133a, miR-133b, and miR-1, and their target genes, in G93A-SOD1 ALS, Δ7SMA, and KI-SBMA mouse muscle during disease progression. Further, we analyzed their expression in serum of SOD1-mutated ALS, SMA, and SBMA patients, to demonstrate myomiR role as noninvasive biomarkers. Our data showed a dysregulation of myomiRs and their targets, in ALS, SMA, and SBMA mice, revealing a common pathogenic feature associated with muscle impairment. A similar myomiR signature was observed in patients’ sera. In particular, an up-regulation of miR-206 was identified in both mouse muscle and serum of human patients. Our overall findings highlight the role of myomiRs as promising biomarkers in ALS, SMA, and SBMA. Further investigations are needed to explore the potential of myomiRs as therapeutic targets for MND treatment.

Spinal Muscular Atrophy: Survival Pattern and Functional Status

Bifunctional RNAs Targeting the Intronic Splicing Silencer N1 Increase SMN Levels and Reduce Disease Severity in an Animal Model of Spinal Muscular Atrophy

Spinal Muscular Atrophy: A Deficiency in a Ubiquitous Protein; a Motor Neuron-Specific Disease