Targeted Treatments for Inherited Neuromuscular Diseases of Childhood

2020 ◽  
Vol 40 (03) ◽  
pp. 335-341
Author(s):  
Alex J. Fay ◽  
Renatta Knox ◽  
Erin E. Neil ◽  
Jonathan Strober
Keyword(s):  
Motor Neurons ◽  
Targeted Therapies ◽  
Muscular Atrophy ◽  
Genetic Diseases ◽  
Neuromuscular Diseases ◽  
Gene Therapy Vector ◽  
Enzyme Replacement ◽  
Smn2 Gene ◽  
Targeted Treatments ◽  
Near Future

AbstractIn the past decade, the number of genes linked to neuromuscular diseases of childhood has expanded dramatically, and this genetic information is forming the basis for gene-specific and even mutation-specific therapies. At the forefront of these advances are the two recently approved treatments for spinal muscular atrophy: one, an antisense oligonucleotide that modifies splicing of the SMN2 gene, and, the other, a gene therapy vector that delivers the SMN1 gene to motor neurons, both of which are allowing patients to acquire developmental milestones previously unseen in this fatal disease. This review highlights these advances and emerging targeted therapies for Duchenne muscular dystrophy and centronuclear myopathy, while also covering enzyme replacement therapy and small molecule-based targeted therapies for conditions such as Pompe's disease and congenital myasthenic syndromes. With these and other newer techniques for targeted correction of genetic defects, such as CRISPR/Cas9, there is now hope that treatments for many more genetic diseases of the nervous system will follow in the near future.

scholarly journals Circulating MyomiRs as Potential Biomarkers to Monitor Response to Nusinersen in Pediatric SMA Patients

Biomedicines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 21 ◽  
Author(s):  
Silvia Bonanno ◽  
Stefania Marcuzzo ◽  
Claudia Malacarne ◽  
Eleonora Giagnorio ◽  
Riccardo Masson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Motor Neurons ◽  
Muscular Atrophy ◽  
Neuromuscular Diseases ◽  
Autosomal Recessive Disorder ◽  
Response To Therapy ◽  
Survival Motor Neuron ◽  
Smn2 Gene ◽  
Smn Protein ◽  
Potential Biomarkers

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by mutations in survival motor neuron (SMN) 1 gene, resulting in a truncated SMN protein responsible for degeneration of brain stem and spinal motor neurons. The paralogous SMN2 gene partially compensates full-length SMN protein production, mitigating the phenotype. Antisense oligonucleotide nusinersen (Spinraza®) enhances SMN2 gene expression. SMN is involved in RNA metabolism and biogenesis of microRNA (miRNA), key gene expression modulators, whose dysregulation contributes to neuromuscular diseases. They are stable in body fluids and may reflect distinct pathophysiological states, thus acting as promising biomarkers. Muscle-specific miRNAs (myomiRs) as biomarkers for clinical use in SMA have not been investigated yet. Here, we analyzed the expression of miR-133a, -133b, -206 and -1, in serum of 21 infantile SMA patients at baseline and after 6 months of nusinersen treatment, and correlated molecular data with response to therapy evaluated by the Hammersmith Functional Motor Scale Expanded (HFMSE). Our results demonstrate that myomiR serological levels decrease over disease course upon nusinersen treatment. Notably, miR-133a reduction predicted patients’ response to therapy. Our findings identify myomiRs as potential biomarkers to monitor disease progression and therapeutic response in SMA patients.

scholarly journals Review of respiratory therapies in patients with spinal muscular atrophy

2018 ◽  
Vol 1 (1) ◽  
pp. 10-17
Author(s):  
V. Yu. Artemenko ◽  
E. V. Plotna
Keyword(s):  
Respiratory Failure ◽  
Spinal Muscular Atrophy ◽  
Motor Neurons ◽  
Sleep Disturbances ◽  
Muscular Atrophy ◽  
Neuromuscular Diseases ◽  
Respiratory Muscles ◽  
Autosomal Recessive Inheritance ◽  
Severe Form ◽  
State Of Rest

The purpose of this article was to systematize available literary data and to provide general recommendations for respiratory therapy in patients with spinal muscular atrophy. Spinal muscular atrophy (SMA) is a severe neuromuscular disease with autosomal recessive inheritance with degeneration of alpha motor neurons in the anterior horns of the spinal cord, leading to progressive proximal muscle weakness and paralysis. SMN 1–2 genes potentially encode identical proteins, although most of the transcripts of the SMN1 genes are halfsized, whereas most transcripts of the SMN2 genes do not contain the seventh exon. Therefore, the SMN2 gene is only partially functional, and a low-level SMN protein is produced in SMA patients. Moreover, the number of copies of the SMN2 can not be considered an exact predictive factor for any particular patient. The main causes of mortality and deterioration in the quality of life are the development of secondary respiratory failure. Type 1 (a, b, c) is the heaviest: early onset and lack of motor abilities, usually patients with a disease of this type survive no more than 2 years. Type 2 – an intermediate type characterized by a later onset, the patient may take a sedentary position, survival may reach the adult height. Type 3 is the softest form that manifests itself at the age of 1 year, the patient can walk and stand. The forecast is more favorable. Type 4 “adult form” manifests itself at the age from 10 to 20 or from 20 to 30 years and has a favorable outlook. The main causes of respiratory failure in patients with neuromuscular diseases are weakness of the respiratory muscles, unproductive cough and sleep disturbances. The weakness of the respiratory muscles, defined as the inability of resting respiratory muscles in the state of rest to create a normal level of pressure and air flow velocity when entering and exhaling, is common. Patients with neuromuscular diseases are susceptible to sleep disruption, especially in the REM sleep phase, with the most frequent form of this disorder being hypoventilation. Over time, hypoventilation in a dream can become more prolonged, resulting in the development of a severe form of hypoxia, an increase in the level of carbon dioxide in the blood and the suppression of the activity of the respiratory center. Thus, as a result of the review of literary data, a strategy of respiratory support in patients with CMA was proposed.

scholarly journals CSF Diagnostics: A Potentially Valuable Tool in Neurodegenerative and Inflammatory Disorders Involving Motor Neurons: A Review

Diagnostics ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1522
Author(s):  
Karsten Krause ◽  
Maximilian Wulf ◽  
Paula Sommer ◽  
Katalin Barkovits ◽  
Matthias Vorgerd ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Muscular Atrophy ◽  
Neurological Diseases ◽  
Neuromuscular Disorders ◽  
Disease Onset ◽  
Neuromuscular Diseases ◽  
Promising Alternative ◽  
Alternative Techniques ◽  
Subordinate Role ◽  
Lateral Sclerosis

Cerebrospinal fluid (CSF) diagnostics has emerged as a valid tool for a variety of neurological diseases. However, CSF diagnostics has been playing a subordinate role in the diagnosis of many neurological conditions. Thus, in the multitude of neuromuscular diseases in which motor neurons are affected, a CSF sample is rarely taken routinely. However, CSF diagnostics has the potential to specify the diagnosis and monitor the treatment of neuromuscular disorders. In this review, we therefore focused on a variety of neuromuscular diseases, among them amyotrophic lateral sclerosis (ALS), peripheral neuropathies, and spinal muscular atrophy (SMA), for which CSF diagnostics has emerged as a promising option for determining the disease itself and its progression. We focus on potentially valuable biomarkers among different disorders, such as neurofilaments, cytokines, other proteins, and lipids to determine their suitability, differentiating between different neurological disorders and their potential to determine early disease onset, disease progression, and treatment outcome. We further recommend novel approaches, e.g., the use of mass spectrometry as a promising alternative techniques to standard ELISA assays, potentially enhancing biomarker significance in clinical applications.

Split hand and motor axonal hyperexcitability in spinal and bulbar muscular atrophy

2020 ◽  
Vol 91 (11) ◽  
pp. 1189-1194 ◽  
Author(s):  
Kazumoto Shibuya ◽  
Sonoko Misawa ◽  
Akiyuki Uzawa ◽  
Setsu Sawai ◽  
Atsuko Tsuneyama ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Muscular Atrophy ◽  
Therapeutic Option ◽  
Neuromuscular Diseases ◽  
Cortical Motor ◽  
Peripheral Mechanism ◽  
Compound Muscle Action Potentials ◽  
Axonal Excitability ◽  
Threshold Electrotonus ◽  
Normal Controls

ObjectiveThe ‘split hand’ sign refers to preferential wasting of the thenar and first dorsal interosseous muscles with relatively sparing of the hypothenar muscles in amyotrophic lateral sclerosis (ALS) and both cortical and spinal/peripheral excitotoxic mechanisms have been proposed. We aimed to study split hand and axonal excitability in spinal and bulbar muscular atrophy (SBMA) in which cortical motor neurons are intact.MethodsIn 35 patients with genetically confirmed SBMA, 55 with ALS, 158 with other neuromuscular diseases and 90 normal controls; split hand was strictly determined by amplitudes of compound muscle action potentials. Nerve excitability testing of median motor axons was performed in 35 SBMA and 55 patients with ALS and 45 normal controls.ResultsSplit hand was as frequently found for patients with SBMA (57%) and ALS (62%), compared with disease (20%) and normal (0%) controls. Excitability testing showed that in both SBMA and ALS, strength-duration time constant was longer, and threshold changes in depolarising threshold electrotonus and superexcitability in the recovery cycle were greater than in normal controls (p<0.01).ConclusionsSplit hand is not specific to ALS and can be caused by the peripheral mechanism alone in SBMA, whereas the effect of upper motor neuron lesion cannot be excluded in ALS. Our results also suggest that SBMA and ALS share common axonal excitability changes; increased nodal persistent sodium and reduced potassium currents that may accelerate motor neuronal death and differently affect axons-innervating different muscles. Ion channel modulators could be a therapeutic option for both SBMA and ALS.

scholarly journals SAM68 is a physiological regulator of SMN2 splicing in spinal muscular atrophy

2015 ◽  
Vol 211 (1) ◽  
pp. 77-90 ◽  
Author(s):  
Vittoria Pagliarini ◽  
Laura Pelosi ◽  
Maria Blaire Bustamante ◽  
Annalisa Nobili ◽  
Maria Grazia Berardinelli ◽  
...  
Keyword(s):  
Spinal Muscular Atrophy ◽  
Motor Neurons ◽  
Messenger Rna ◽  
Muscular Atrophy ◽  
Splicing Factors ◽  
Hnrnp A1 ◽  
Smn1 Gene ◽  
Smn2 Gene ◽  
Physiological Regulator

Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by loss of motor neurons in patients with null mutations in the SMN1 gene. The almost identical SMN2 gene is unable to compensate for this deficiency because of the skipping of exon 7 during pre–messenger RNA (mRNA) processing. Although several splicing factors can modulate SMN2 splicing in vitro, the physiological regulators of this disease-causing event are unknown. We found that knockout of the splicing factor SAM68 partially rescued body weight and viability of SMAΔ7 mice. Ablation of SAM68 function promoted SMN2 splicing and expression in SMAΔ7 mice, correlating with amelioration of SMA-related defects in motor neurons and skeletal muscles. Mechanistically, SAM68 binds to SMN2 pre-mRNA, favoring recruitment of the splicing repressor hnRNP A1 and interfering with that of U2AF65 at the 3′ splice site of exon 7. These findings identify SAM68 as the first physiological regulator of SMN2 splicing in an SMA mouse model.

scholarly journals INNOVATIVE THERAPIES IN GENETIC DISEASES: SPINAL MUSCULAR ATROPHY

2021 ◽  
Vol 70 (2) ◽  
pp. 108-113
Author(s):  
Elena-Silvia Shelby ◽  
◽  
Andrada Mirea ◽  
Keyword(s):  
Spinal Muscular Atrophy ◽  
Motor Neurons ◽  
Muscular Atrophy ◽  
Pediatric Population ◽  
Genetic Diseases ◽  
Short Review ◽  
Progressive Muscle Weakness ◽  
Innovative Therapies ◽  
Biallelic Mutations ◽  
Congenital Neuromuscular Disease

Spinal muscular atrophy is a congenital neuromuscular disease characterized by the deterioration of the motor neurons located mainly in the anterior horns of the spinal cord, leading to progressive muscle weakness and atrophy. Globally, SMA is, after cystic fibrosis, the second cause of death due to a a genetic disease in the pediatric population. Over 95% of the total cases of SMA are represented by 5q SMA, caused by biallelic mutations in the SMN1 gene (5q13.2), the rest of the SMA types being called, generically, non-5q SMA. Currently, a few genetic targeted therapies are available for 5q SMA, while other innovative therapies are still in clinical trials. Early diagnosis and treatment of 5q SMA have an essential role in preventing the onset and evolution of symptoms and can save the life of the patient and prevent debilitating sequelae. This article aims to briefly describe the cause and symptomatology of 5q SMA as well as to make a short review of the genetic therapies available for this disease.

scholarly journals A subset of SMN complex members have a specific role in tissue regeneration via ERBB pathway-mediated proliferation

2019 ◽  
Author(s):  
Wuhong Pei ◽  
Lisha Xu ◽  
Zelin Chen ◽  
Claire C Slevin ◽  
Kade P Pettie ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Tissue Regeneration ◽  
Hair Cells ◽  
Muscular Atrophy ◽  
Essential Gene ◽  
Genetic Diseases ◽  
Rna Seq ◽  
Genetic Pathways ◽  
Smn Complex ◽  
Survival Of Motor Neurons

AbstractSpinal Muscular Atrophy (SMA) is the most common genetic disease in childhood. SMA is generally caused by mutations in SMN1. The Survival of Motor Neurons (SMN) complex consists of SMN1, Gemins (2–8) and Strap/Unrip. We previously demonstrated smn1 and gemin5 inhibited tissue regeneration in zebrafish. Here we investigated each individual SMN complex member and identified gemin3 as another regeneration-essential gene. These three genes are likely pan-regenerative since they affect the regeneration of hair cells, liver and caudal fin. RNA-Seq and miRNA-Seq analyses reveal that smn1, gemin3, and gemin5 are linked to a common set of genetic pathways, including the tp53 and ErbB pathways. Additional studies indicated all three genes facilitate regeneration by inhibiting the ErbB pathway, thereby allowing cell proliferation in the injured neuromasts. This study provides a new understanding of the SMN complex and a potential etiology for SMA and potentially other rare unidentified genetic diseases with similar symptoms.

scholarly journals A transgene carrying an A2G missense mutation in the SMN gene modulates phenotypic severity in mice with severe (type I) spinal muscular atrophy

2003 ◽  
Vol 160 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Umrao R. Monani ◽  
Matthew T. Pastore ◽  
Tatiana O. Gavrilina ◽  
Sibylle Jablonka ◽  
Thanh T. Le ◽  
...  
Keyword(s):  
Spinal Muscular Atrophy ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Muscular Atrophy ◽  
Autosomal Recessive Disorder ◽  
Type I ◽  
Missense Mutations ◽  
Smn2 Gene ◽  
Smn Gene

5q spinal muscular atrophy (SMA) is a common autosomal recessive disorder in humans and the leading genetic cause of infantile death. Patients lack a functional survival of motor neurons (SMN1) gene, but carry one or more copies of the highly homologous SMN2 gene. A homozygous knockout of the single murine Smn gene is embryonic lethal. Here we report that in the absence of the SMN2 gene, a mutant SMN A2G transgene is unable to rescue the embryonic lethality. In its presence, the A2G transgene delays the onset of motor neuron loss, resulting in mice with mild SMA. We suggest that only in the presence of low levels of full-length SMN is the A2G transgene able to form partially functional higher order SMN complexes essential for its functions. Mild SMA mice exhibit motor neuron degeneration, muscle atrophy, and abnormal EMGs. Animals homozygous for the mutant transgene are less severely affected than heterozygotes. This demonstrates the importance of SMN levels in SMA even if the protein is expressed from a mutant allele. Our mild SMA mice will be useful in (a) determining the effect of missense mutations in vivo and in motor neurons and (b) testing potential therapies in SMA.

scholarly journals Genetic approaches to the treatment of inherited neuromuscular diseases

2019 ◽  
Vol 28 (R1) ◽  
pp. R55-R64 ◽  
Author(s):  
Bhavya Ravi ◽  
Anthony Antonellis ◽  
Charlotte J Sumner ◽  
Andrew P Lieberman
Keyword(s):  
Motor Neurons ◽  
Viral Vectors ◽  
Age Of Onset ◽  
Muscular Atrophy ◽  
Neuromuscular Disorders ◽  
Neuromuscular Diseases ◽  
Clinical Severity ◽  
Charcot Marie Tooth Disease ◽  
Degenerative Disorders ◽  
Clinical Benefits

Abstract Inherited neuromuscular diseases are a heterogeneous group of developmental and degenerative disorders that affect motor unit function. Major challenges toward developing therapies for these diseases include heterogeneity with respect to clinical severity, age of onset and the primary cell type that is affected (e.g. motor neurons, skeletal muscle and Schwann cells). Here, we review recent progress toward the establishment of genetic therapies to treat inherited neuromuscular disorders that affect both children and adults with a focus on spinal muscular atrophy, Charcot–Marie–Tooth disease and spinal and bulbar muscular atrophy. We discuss clinical features, causative mutations and emerging approaches that are undergoing testing in preclinical models and in patients or that have received recent approval for clinical use. Many of these efforts employ antisense oligonucleotides to alter pre-mRNA splicing or diminish target gene expression and use viral vectors to replace expression of mutant genes. Finally, we discuss remaining challenges for optimizing the delivery and effectiveness of these approaches. In sum, therapeutic strategies for neuromuscular diseases have shown encouraging results, raising hope that recent strides will translate into significant clinical benefits for patients with these disorders.

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