Assessment of cerebral spinal fluid biomarkers and microRNA-mediated disease mechanisms in spinal muscular atrophy patient samples.

Cerebral spinal fluid (CSF) is a promising biospecimen for the detection of central nervous system biomarkers to monitor therapeutic efficacy at the cellular level in neurological diseases. Spinal muscular atrophy (SMA) patients receiving intrathecal antisense oligonucleotide (nusinersen) therapy tend to show improved motor function, but the treatment effect on cellular health remains unknown. The objective of this study was to assess the potential of extracellular RNAs and microRNAs in SMA patient CSF as indicators of neuron and glial health following nusinersen treatment. Extracellular RNA analysis of CSF samples revealed ongoing cellular stress related to inflammation and glial differentiation, even after treatment administration. Downregulated microRNA expression associated with SMA-specific or general motor neuron dysfunction in animal and cellular models, tended to increase in nusinersen-treated patient CSF samples and correlated with SMA Type 1 and 2 motor functioning improvements. However, miR-146a, known to be upregulated in SMA-induced pluripotent stem cell (iPSC)-derived astrocytes, showed increased expression in nusinersen-treated CSF samples. We then used mRNA sequencing and multi-electrode arrays to assess the transcriptional and functional effects of miR-146a on healthy and SMA iPSC-derived motor neurons. miR-146a treatment on iPSC-derived motor neurons led to a downregulation of extracellular matrix genes associated with synaptic perineuronal net and alterations in spontaneous electrophysiological activity. Altogether, this study suggests that extracellular RNAs and microRNAs may serve as useful biomarkers to monitor cellular health during nusinersen treatment. Moreover, these data highlight the importance of addressing astrocyte health and response to nusinersen in SMA pathogenesis and treatment strategies.

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

INTRODUCTION/AIMS: While prompt identification and treatment of infants with spinal muscular atrophy (SMA) can ameliorate outcomes, variability persists. This study assessed management and outcomes of early-treated infants with SMA. METHODS: We analyzed retrospective data at 12 centers on infants with SMA treated at age ≤6 weeks from August 2018 to December 2023. RESULTS: Sixty-six patients, 35 with two SMN2 copies and 31 with ≥3 SMN2 copies, were included. Twenty-five (38%, 22 with two SMN2 copies), had SMA findings before initial treatment which was onasemnogene abeparvovec in 47 (71%) and nusinersen in 19 (29%). Thirty-two received sequential or combination treatments, including 16 adding nusinersen or risdiplam due to SMA findings following onasemnogene abeparvovec. All sat independently. Compared to children with ≥3 SMN2 copies, those with two SMN2 copies were less likely to walk (23/34 [68%] vs. 31/31 [100%], p < .001) and less likely to walk on time (9/34 [26%] vs. 29/31 [94%], p < .001); one non-ambulatory child was <18 months old and was excluded from this analysis. No patients required permanent ventilation or exclusively enteral nutrition; six required nocturnal non-invasive ventilation and four utilized supplemental enteral nutrition, all with two SMN2 copies. DISCUSSION: Early treatment of infants with SMA can improve outcomes as indicated by our cohort, all of whom sat independently and are without permanent ventilation. However, our study demonstrates ongoing disability in most children with two SMN2 copies despite early monotherapy and emphasizes the need for additional research, including earlier monotherapy, initial combination therapy, prenatal treatment, and non-SMN modifying treatments.

Repeated intravenous cardiosphere-derived cell therapy in late-stage Duchenne muscular dystrophy (HOPE-2): a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial.

BACKGROUND: Cardiosphere-derived cells (CDCs) ameliorate skeletal and cardiac muscle deterioration in experimental models of Duchenne muscular dystrophy. The HOPE-2 trial examined the safety and efficacy of sequential intravenous infusions of human allogeneic CDCs in late-stage Duchenne muscular dystrophy. METHODS: In this multicentre, randomised, double-blind, placebo-controlled, phase 2 trial, patients with Duchenne muscular dystrophy, aged 10 years or older with moderate upper limb impairment, were enrolled at seven centres in the USA. Patients were randomly assigned (1:1) using stratified permuted blocks to receive CAP-1002 (1·5 × 108 CDCs) or placebo intravenously every 3 months for a total of four infusions. Clinicians, caregivers, patients, and clinical operations personnel were fully masked to treatment groups. The primary outcome was the change in mid-level elbow Performance of Upper Limb version 1.2 (PUL 1.2) score at 12 months, assessed in the intention-to-treat population. Safety was assessed in all individuals who received an investigational product. This trial is registered with ClinicalTrials.gov, NCT03406780. FINDINGS: Between March 1, 2018, and March 31, 2020, 26 male patients with Duchenne muscular dystrophy were enrolled, of whom eight were randomly assigned to the CAP-1002 group and 12 to the placebo group (six were not randomised due to screening failure). In patients who had a post-treatment PUL 1.2 assessment (eight in the CAP-1002 group and 11 in the placebo group), the mean 12-month change from baseline in mid-level elbow PUL1.2 favoured CAP-1002 over placebo (percentile difference 36·2, 95% CI 12·7-59·7; difference of 2·6 points; p=0·014). Infusion-related hypersensitivity reactions without long-term sequelae were observed in three patients, with one patient discontinuing therapy due to a severe allergic reaction. No other major adverse reactions were noted, and no deaths occurred. INTERPRETATION: CAP-1002 cell therapy appears to be safe and effective in reducing deterioration of upper limb function in patients with late-stage Duchenne muscular dystrophy. Various measures of cardiac function and structure were also improved in the CAP-1002 group compared with the placebo group. Longer-term extension studies are needed to confirm the therapeutic durability and safety of CAP-1002 beyond 12 months for the treatment of skeletal myopathy and cardiomyopathy in Duchenne muscular dystrophy. FUNDING: Capricor Therapeutics.

Acute flaccid myelitis: cause, diagnosis, and management.

Acute flaccid myelitis (AFM) is a disabling, polio-like illness mainly affecting children. Outbreaks of AFM have occurred across multiple global regions since 2012, and the disease appears to be caused by non-polio enterovirus infection, posing a major public health challenge. The clinical presentation of flaccid and often profound muscle weakness (which can invoke respiratory failure and other critical complications) can mimic several other acute neurological illnesses. There is no single sensitive and specific test for AFM, and the diagnosis relies on identification of several important clinical, neuroimaging, and cerebrospinal fluid characteristics. Following the acute phase of AFM, patients typically have substantial residual disability and unique long-term rehabilitation needs. In this Review we describe the epidemiology, clinical features, course, and outcomes of AFM to help to guide diagnosis, management, and rehabilitation. Future research directions include further studies evaluating host and pathogen factors, including investigations into genetic, viral, and immunological features of affected patients, host-virus interactions, and investigations of targeted therapeutic approaches to improve the long-term outcomes in this population.

Anti-Ku antibody-positive systemic sclerosis-polymyositis overlap syndrome in an adolescent.

Systemic sclerosis-polymyositis overlap syndrome is rare in children. Anti-PM/Scl is the most common autoantibody associated with this syndrome. We present a case of systemic sclerosis-polymyositis overlap syndrome in a child with isolated anti-Ku antibodies, an uncommon antibody associated with this rare syndrome.

Uncommon Causes of Rhabdomyolysis.

Rhabdomyolysis is a relatively common phenomenon, and most cases do not require intensive care unit level of care. Although most common causes can be easily identified, in encephalopathic or critically ill patients, symptoms can be easily missed, as can uncommon etiologies. Given the potential morbidity, it is important that in any patient with concern for rhabdomyolysis, evaluation and management occur expeditiously. As the list of potential causes is large, not every possible cause for rhabdomyolysis will be discussed. This article, however, will provide a general framework to manage any patient with this muscle disease.

Pediatrician Exposure to Neuromuscular Patients.

BACKGROUND: Primary care providers (PCPs) provide general care to patients, including those who are followed by specialists. In the field of rare diseases, there is growing research that the primary care needs of these patients are unique to their individual disease state. The purpose of this study is to determine the prevalence of patients with pediatric neuromuscular diseases among a subset of pediatric practices in Southeastern Wisconsin. METHODS: A retrospective review of all patients with neuromuscular diseases seen at Children's Hospital of Wisconsin (CW) was conducted from January 1, 2016 through September 30, 2018. All patients who were seen by Children's Medical Group (CMG) providers were included, with a division of patients by provider. RESULTS: Eight hundred eleven (811) unique pediatric neuromuscular patients were identified; 188 patients were included in the study cohort. The median number of patients per provider was 2.5, mean number of patients was 2.68, and mode number of patients was 1.74; 51% of pediatricians within CMG did not care for a pediatric neuromuscular patient. DISCUSSION: The prevalence of patients with neuromuscular diseases followed by an individual CMG provider is low, with over half of the CMG providers not caring for any patients with neuromuscular diseases. Given the specific primary care knowledge needed to care for these patients, this suggests the need for a novel method of help support these providers.

Differentiating Congenital Myopathy from Congenital Muscular Dystrophy.

The congenital muscular dystrophies and congenital myopathies are a heterogenous group of diseases with a wide variety of presentations and outcomes. With the growing understanding of genetic involvement, and developing therapies, having a genetically confirmed diagnosis with phenotype correlation is essential. To achieve this, a structured approach is warranted to each child to ensure that mimickers are excluded. By structuring the evaluation appropriately, the clinician can help expedite the evaluation of these infants in a cost-effective manner. Understanding the pitfalls of each step of testing will allow the clinician to better understand variants in presentation and avoid cognitive errors in the process.

Severe Neonatal RYR1 Myopathy With Pathological Features of Congenital Muscular Dystrophy.

The phenotypes associated with pathogenic variants in the ryanodine receptor 1 gene (RYR1, OMIM# 180901) have greatly expanded over the last few decades as genetic testing for RYR1 variants has become more common. Initially described in association with malignant hyperthermia, pathogenic variants in RYR1 are typically associated with core pathology in muscle biopsies (central core disease or multiminicore disease) and symptomatic myopathies with symptoms ranging from mild weakness to perinatal lethality. We describe a 2-week-old male patient with multiple congenital dysmorphisms, severe perinatal weakness, and subsequent demise, whose histopathology on autopsy was consistent with congenital muscular dystrophy. Immunohistochemical analysis of dystrophy-associated proteins was normal. Rapid exome sequencing revealed a novel heterozygous nonsense variant (p.Trp661Ter) in RYR1, as well as a previously described RYR1 pathogenic variant associated with congenital myopathy (p.Phe4976Leu). This highlights the potential for RYR1 pathogenic variants to produce pathological findings most consistent with congenital muscular dystrophy.

Siblings With Mutations in TRAPPC11 Presenting With Limb-Girdle Muscular Dystrophy 2S.

Limb-girdle muscular dystrophy 2S (LGMD2S) is an autosomal recessive condition due to mutations in the TRAPPC11 gene. It is recently described with only 9 prior reported individuals. In addition to the muscular dystrophy, some affected individuals have small head size, global developmental delay, seizures, cataracts, and liver problems. Siblings with an uncharacterized LGMD were assessed; whole-exome screening revealed compound heterozygous mutations in the TRAPPC11 gene. Their presentation helps confirm the emerging phenotype for LGMD2S.

Pediatric Opsoclonus-Myoclonus-Ataxia Syndrome Associated With Anti-N-methyl-D-aspartate Receptor Encephalitis.

BACKGROUND: The full clinical spectrum of anti-N-methyl-D-aspartate receptor encephalitis is unknown in the pediatric population. PATIENT: We describe a previously healthy 4-year-old girl presenting with opsoclonus-myoclonus together with ataxia who had NR1-specific, anti-N-methyl-D-aspartate receptor antibodies in the cerebral spinal fluid. CONCLUSION: The presence of NR1-specific, anti-N-methyl-D-aspartate receptor antibodies in the setting of opsoclonus-myoclonus and ataxia syndrome may represent an expansion of the clinical presentations of anti-N-methyl-D-aspartate receptor encephalitis.