Childhood spinal muscular atrophy: controversies and challenges. Lancet Neurol. 2012;11:443-452. [PMID: 22516079 DOI: 10.1016/s1474-4422(12)70061-3]

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.

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.

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

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

Physiological Features of the Neural Stem Cells Obtained from an Animal Model of Spinal Muscular Atrophy and Their Response to Antioxidant Curcumin

The most prevalent rare genetic disease affecting young individuals is spinal muscular atrophy (SMA), which is caused by a loss-of-function mutation in the telomeric gene survival motor neuron (SMN) 1. The high heterogeneity of the SMA pathophysiology is determined by the number of copies of SMN2, a separate centromeric gene that can transcribe for the same protein, although it is expressed at a slower rate. SMA affects motor neurons. However, a variety of different tissues and organs may also be affected depending on the severity of the condition. Novel pharmacological treatments, such as Spinraza, Onasemnogene abeparvovec-xioi, and Evrysdi, are considered to be disease modifiers because their use can change the phenotypes of the patients. Since oxidative stress has been reported in SMA-affected cells, we studied the impact of antioxidant therapy on neural stem cells (NSCs) that have the potential to differentiate into motor neurons. Antioxidants can act through various pathways; for example, some of them exert their function through nuclear factor (erythroid-derived 2)-like 2 (NRF2). We found that curcumin is able to induce positive effects in healthy and SMA-affected NSCs by activating the nuclear translocation of NRF2, which may use a different mechanism than canonical redox regulation through the antioxidant-response elements and the production of antioxidant molecules.

Safety analysis of laboratory parameters in paediatric patients with spinal muscular atrophy treated with nusinersen

BACKGROUND

Spinal muscular atrophy (SMA) is a progressive neurodegenerative disorder that can be treated with intrathecal nusinersen, an antisense oligonucleotide. In addition to efficacy, safety is a determining factor in the success of any therapy. Here, we aim to assess the safety of nusinersen therapy in paediatric patients with SMA.

METHODS

Laboratory data of paediatric patients with SMA who received nusinersen between October 2019 and May 2022 were retrospectively analysed.

RESULTS

During the observation period, 46 infants and children aged 2.9 months to 13.6 years received a total of 213 nusinersen doses without safety concerns. Inflammatory markers were stable throughout the study. International normalized ratio was increased by 0.09 per injection. Urea levels were increased by 0.108 mmol/L, and cystatin C decreased by 0.029 mg/L per injection. There were no significant changes in platelet count, activated partial thrombin time, creatinine levels or liver enzyme levels during treatment. The cerebrospinal fluid (CSF) leukocyte count remained stable, and total protein increased by 24.038 mg/L per injection.

CONCLUSION

Our data showed that nusinersen therapy is generally safe in children with SMA. Laboratory monitoring did not identify any persistent or significantly abnormal findings. CSF protein should be monitored to gain more insights.

A horizontal and perpendicular interlaminar approach for intrathecal nusinersen injection in patients with spinal muscular atrophy and scoliosis: an observational study

BACKGROUND

Lumbar puncture is challenging for patients with scoliosis. Previous ultrasound-assisted techniques for lumbar puncture used the angle of the probe as the needle trajectory; however, reproducing the angle is difficult and increases the number of needle manipulations. In response, we developed a technique that eliminated both the craniocaudal and lateromedial angulation of the needle trajectory to overall improve this technique. We assessed the feasibility and safety of this method in patients with scoliosis and identify factors related to difficult lumbar puncture.

METHODS

Patients with spinal muscular atrophy and scoliosis who were referred to the anesthesia department for intrathecal nusinersen administrations were included. With a novel approach that utilized patient position and geometry, lumbar puncture was performed under ultrasound guidance. Success rates, performance times and adverse events were recorded. Clinical-demographic and spinal radiographic data pertaining to difficult procedures were analyzed.

RESULTS

Success was achieved in all 260 (100%) lumbar punctures for 44 patients, with first pass and first attempt success rates of 70% (183/260) and 87% (226/260), respectively. Adverse events were infrequent and benign. Higher BMI, greater skin dural sac depth and smaller interlaminar size might be associated with greater difficulty in lumbar puncture.

CONCLUSIONS

The novel ultrasound-assisted horizontal and perpendicular interlaminar needle trajectory approach is an effective and safe method for lumbar puncture in patients with spinal deformities. This method can be reliably performed at the bedside and avoids other more typical and complex imaging such as computed tomography guided procedure.

Real-world evidence: Risdiplam in a patient with spinal muscular atrophy type I with a novel splicing mutation and one SMN2 copy

Spinal muscular atrophy (SMA), which results from the deletion or/and mutation in the SMN1 gene, is an autosomal recessive neuromuscular disorder that leads to weakness and muscle atrophy. SMN2 is a paralogous gene of SMN1. SMN2 copy number affects the severity of SMA, but its role in patients treated with disease modifying therapies is unclear. The most appropriate individualized treatment for SMA has not yet been determined. Here, we reported a case of SMA type I with normal breathing and swallowing function. We genetically confirmed that this patient had a compound heterozygous variant: one deleted SMN1 allele and a novel splice mutation c.628-3T>G in the retained allele, with one SMN2 copy. Patient-derived sequencing of 4 SMN1 cDNA clones showed that this intronic single transversion mutation results in an alternative exon (e)5 3' splice site, which leads to an additional 2 nucleotides (AG) at the 5' end of e5, thereby explaining why the patient with only one copy of SMN2 had a mild clinical phenotype. Additionally, a minigene assay of wild type and mutant SMN1 in HEK293T cells also demonstrated that this transversion mutation induced e5 skipping. Considering treatment cost and goals of avoiding pain caused by injections and starting treatment as early as possible, risdiplam was prescribed for this patient. However, the patient showed remarkable clinical improvements after treatment with risdiplam for 7 months despite carrying only one copy of SMN2. This study is the first report on the treatment of risdiplam in a patient with one SMN2 copy in a real-world setting. These findings expand the mutation spectrum of SMA and provide accurate genetic counseling information, as well as clarify the molecular mechanism of careful genotype-phenotype correlation of the patient.

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

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

Dysfunction of proprioceptive sensory synapses is a pathogenic event and therapeutic target in mice and humans with spinal muscular atrophy

Spinal muscular atrophy (SMA) is a neurodegenerative disease characterized by a varying degree of severity that correlates with the reduction of SMN protein levels. Motor neuron degeneration and skeletal muscle atrophy are hallmarks of SMA, but it is unknown whether other mechanisms contribute to the spectrum of clinical phenotypes. Here, through a combination of physiological and morphological studies in mouse models and SMA patients, we identify dysfunction and loss of proprioceptive sensory synapses as key signatures of SMA pathology. We demonstrate that SMA patients exhibit impaired proprioception, and their proprioceptive sensory synapses are dysfunctional as measured by the neurophysiological test of the Hoffmann reflex (H-reflex). We further show that loss of excitatory afferent synapses and altered potassium channel expression in SMA motor neurons are conserved pathogenic events found in both severely affected patients and mouse models. Lastly, we report that improved motor function and fatigability in ambulatory SMA patients and mouse models treated with SMN-inducing drugs correlate with increased function of sensory-motor circuits that can be accurately captured by the H-reflex assay. Thus, sensory synaptic dysfunction is a clinically relevant event in SMA, and the H-reflex is a suitable assay to monitor disease progression and treatment efficacy of motor circuit pathology.

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.

Long-Term Comparative Efficacy and Safety of Risdiplam and Nusinersen in Children with Type 1 Spinal Muscular Atrophy

INTRODUCTION

Spinal muscular atrophy (SMA) is a severe genetic neuromuscular disease characterized by a loss of motor neurons and progressive muscle weakness. Children with untreated type 1 SMA never sit independently and require increasing levels of ventilatory support as the disease progresses. Without intervention, and lacking ventilatory support, death typically occurs before the age of 2 years. There are currently no head-to-head trials comparing available treatments in SMA. Indirect treatment comparisons are therefore needed to provide information on the relative efficacy and safety of SMA treatments for healthcare decision-making.

METHODS

The long-term efficacy and safety of risdiplam versus nusinersen in children with type 1 SMA was evaluated using indirect treatment comparison methodology to adjust for differences between population baseline characteristics, to reduce any potential bias in the comparative analysis. An unanchored matching-adjusted indirect comparison was conducted using risdiplam data from 58 children in FIREFISH (NCT02913482) and published aggregate nusinersen data from 81 children obtained from the ENDEAR (NCT02193074) and SHINE (NCT02594124) clinical trials with at least 36 months of follow-up.

RESULTS

Children with type 1 SMA treated with risdiplam had a 78% reduction in the rate of death, an 81% reduction in the rate of death or permanent ventilation, and a 57% reduction in the rate of serious adverse events compared with children treated with nusinersen. Children treated with risdiplam also had a 45% higher rate of achieving a Hammersmith Infant Neurological Examination, Module 2 motor milestone response and a 186% higher rate of achieving a ≥ 4-point improvement in Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders compared with children treated with nusinersen.

CONCLUSION

Long-term data supported risdiplam as a superior alternative to nusinersen in children with type 1 SMA. Video abstract available for this article. Video abstract (MP4 184542 KB).

General movements in spinal muscular atrophy type 1

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Exploiting urine-derived induced pluripotent stem cells for advancing precision medicine in cell therapy, disease modeling, and drug testing

The field of regenerative medicine has witnessed remarkable advancements with the emergence of induced pluripotent stem cells (iPSCs) derived from a variety of sources. Among these, urine-derived induced pluripotent stem cells (u-iPSCs) have garnered substantial attention due to their non-invasive and patient-friendly acquisition method. This review manuscript delves into the potential and application of u-iPSCs in advancing precision medicine, particularly in the realms of drug testing, disease modeling, and cell therapy. U-iPSCs are generated through the reprogramming of somatic cells found in urine samples, offering a unique and renewable source of patient-specific pluripotent cells. Their utility in drug testing has revolutionized the pharmaceutical industry by providing personalized platforms for drug screening, toxicity assessment, and efficacy evaluation. The availability of u-iPSCs with diverse genetic backgrounds facilitates the development of tailored therapeutic approaches, minimizing adverse effects and optimizing treatment outcomes. Furthermore, u-iPSCs have demonstrated remarkable efficacy in disease modeling, allowing researchers to recapitulate patient-specific pathologies in vitro. This not only enhances our understanding of disease mechanisms but also serves as a valuable tool for drug discovery and development. In addition, u-iPSC-based disease models offer a platform for studying rare and genetically complex diseases, often underserved by traditional research methods. The versatility of u-iPSCs extends to cell therapy applications, where they hold immense promise for regenerative medicine. Their potential to differentiate into various cell types, including neurons, cardiomyocytes, and hepatocytes, enables the development of patient-specific cell replacement therapies. This personalized approach can revolutionize the treatment of degenerative diseases, organ failure, and tissue damage by minimizing immune rejection and optimizing therapeutic outcomes. However, several challenges and considerations, such as standardization of reprogramming protocols, genomic stability, and scalability, must be addressed to fully exploit u-iPSCs' potential in precision medicine. In conclusion, this review underscores the transformative impact of u-iPSCs on advancing precision medicine and highlights the future prospects and challenges in harnessing this innovative technology for improved healthcare outcomes.

Efficacy and safety of onasemnogene abeparvovec for the treatment of patients with spinal muscular atrophy type 1: A systematic review with meta-analysis

BACKGROUND

Onasemnogene abeparvovec has been approved for the treatment of spinal muscular atrophy 5q type 1 in several countries, which calls for an independent assessment of the evidence regarding efficacy and safety.

OBJECTIVE

Conduct a meta-analysis to assess the efficacy and safety of onasemnogene abeparvovec in patients diagnosed with SMA type 1, based on the available evidence.

METHODS

This article results from searches conducted on databases up to November 2022. Outcomes of interest were global survival and event-free survival, improvement in motor function and treatment-related adverse events. Risk of bias assessment and certainty of evidence were performed for each outcome. Proportional meta-analysis models were performed when applicable.

RESULTS

Four reports of three open-label, non-comparative clinical trials covering 67 patients were included. Meta-analyses of data available in a 12-month follow-up estimate a global survival of 97.56% (95%CI: 92.55 to 99.86, I2 = 0%, n = 67), an event-free survival of 96.5% (95%CI: 90.76 to 99.54, I2 = 32%, n = 66) and a CHOP-INTEND score ≥ 40 points proportion of 87.28% (95%CI: 69.81 to 97.83, I2 = 69%, n = 67). Proportion of 52.64% (95%CI: 27.11 to 77.45, I2 = 78%, n = 67) of treatment-related adverse events was estimated.

CONCLUSION

The results indicate a potential change in the natural history of type 1 SMA, but the methodological limitations of the studies make the real extent of the technology's long-term benefits uncertain.

Optimized MLPA workflow for spinal muscular atrophy diagnosis: identification of a novel variant, NC_000005.10:g.(70919941_70927324)del in isolated exon 1 of SMN1 gene through long-range PCR

BACKGROUND

Spinal muscular atrophy (SMA) is a rare autosomal recessive hereditary neuromuscular disease caused by survival motor neuron 1 (SMN1) gene deletion or mutation. Homozygous deletions of exon 7 in SMN1 result in 95% of SMA cases, while the remaining 5% are caused by other pathogenic variants of SMN1.

METHODS

We analyzed two SMA-suspected cases that were collected, with no SMN1 gene deletion and point mutation in whole-exome sequencing. Exon 1 deletion of the SMN gene was detected using Multiplex ligation-dependent probe amplification (MLPA) P021. We used long-range polymerase chain reaction (PCR) to isolate the SMN1 template, optimized-MLPA P021 for copy number variation (CNV) analysis within SMN1 only, and validated the findings via third-generation sequencing.

RESULTS

Two unrelated families shared a genotype with one copy of exon 7 and a novel variant, g.70919941_70927324del, in isolated exon 1 of the SMN1 gene. Case F1-II.1 demonstrated no exon 1 but retained other exons, whereas F2-II.1 had an exon 1 deletion in a single SMN1 gene. The read coverage in the third-generation sequencing results of both F1-II.1 and F2-II.1 revealed a deletion of approximately 7.3 kb in the 5' region of SMN1. The first nucleotide in the sequence data aligned to the 7385 bp of NG_008691.1.

CONCLUSION

Remarkably, two proband families demonstrated identical SMN1 exon 1 breakpoint sites, hinting at a potential novel mutation hotspot in Chinese SMA, expanding the variation spectrum of the SMN1 gene and corroborating the specificity of isolated exon 1 deletion in SMA pathogenesis. The optimized-MLPA P021 determined a novel variant (g.70919941_70927324del) in isolated exon 1 of the SMN1 gene based on long-range PCR, enabling efficient and affordable detection of SMN gene variations in patients with SMA, providing new insight into SMA diagnosis to SMN1 deficiency and an optimized workflow for single exon CNV testing of the SMN gene.

Gray and white matter abnormalities in children with type 2 and 3 SMA: A morphological assessment

This study investigated the changes in brain gray and white matter structure in SMA patients and their correlation with the severity of the disease. A total of 43 SMA patients (including 22 type II and 21 type III SMA patients) and 37 healthy controls were evaluated by MRI. The gray matter volume, gray matter thickness, gray matter surface area, and white matter volume of designated brain regions automatically segmented by FreeSurfer, were compared. We evaluate clinical characteristics of SMA and study the correlation between clinical characteristics and structural changes. SMA showed significant bilateral cortical superficial area loss in the frontal, parietal, and temporal lobes and global white matter volume decreases. Moreover, these patients were also found with an increased mean thickness of entire brain and right gray matter. An increased right postcentral gyrus superficial area, right central sulcus volume, and white matter volume of the right postcentral were associated with higher HFMSE scores.

CONCLUSION

Type 2 and 3 children SMA had extensive, multifocal, symmetrical gray and white matter alterations. Postcentral gyrus degeneration of SMA was associated with the severity of muscular atrophy. The lack of SMN protein possibly interacted with cerebellar structural changes in somatosensory areas.

WHAT IS KNOWN

• MRI has found brain changes in SMA patients, however, there is no unified conclusion and lack of correlation with clinical degree in children SMA with type 2-3.

WHAT IS NEW

• Type II and II children SMA had extensive, multifocal, symmetrical gray and white matter alterations. Postcentral gyrus degeneration of SMA was associated with the severity of muscular atrophy. Cerebellar structural changes in somatosensory areas may attribute to the lack of SMN protein.

Effect of nusinersen after 3 years of treatment in 57 young children with SMA in terms of SMN2 copy number or type

BACKGROUND

Spinal muscular atrophy (SMA) is a rare genetic neuromuscular disorder due to an autosomal recessive mutation in the survival motor neuron 1 gene (SMN1), causing degeneration of the anterior horn cells of the spinal cord and resulting in muscle atrophy. This study aimed to report on the 36-month follow-up of children with SMA treated with nusinersen before the age of 3 years. Changes in motor function, nutritional and ventilatory support, and orthopedic outcomes were evaluated at baseline and 36 months after intrathecal administration of nusinersen and correlated with SMA type and SMN2 copy number.

RESULTS

We found that 93% of the patients gained new motor skills during the 3 years-standing without help for 12 of 37 and walking with help for 11 of 37 patients harboring three SMN2 copies. No patients with two copies of SMN2 can stand alone or walk. Patients bearing three copies of SMN2 are more likely to be spared from respiratory, nutritional, and orthopedic complications than patients with two SMN2 copies.

CONCLUSION

Children with SMA treated with nusinersen continue to make motor acquisitions at 3 years after initiation of treatment. Children with two SMN2 copies had worse motor, respiratory, and orthopedic outcomes after 3 years of treatment than children with three copies.

Onasemnogene Abeparvovec: Post-infusion Efficacy and Safety in Patients With Spinal Muscular Atrophy (SMA)-A Fondazione Policlinico Gemelli IRCCS Experience

Objective: The term Spinal Muscular Atrophy (SMA) identifies a group of genetic disorders affecting spinal motor neurons. It is caused by the loss of the SMN1 gene, resulting in degeneration of spinal alpha motor neurons and muscle atrophy. This study is focused on innovative gene therapies with onasemnogene abeparvovec approved in Italy in March 2021 with full reimbursement by the National Health Service. The objective pursued is verify, by means of the CHOP-INTEND scores obtained, whether therapy with onasemnogene abeparvovec led to an improvement in the clinical picture of the treated subjects and any adverse reactions that occurred. Methods: this study was conducted by evaluating the scores in the different re-evaluations of individual patients treated in our hospital (Fondazione Policlinico Universitario Agostino Gemelli IRCCS - Rome) and comparing them with the results of the CL-303 study described in SPC (Summary of Product Characteristics). The data were extracted from the patients' clinical records on the AIFA (Agenzia Italiana del Farmaco - Italian Medicines Agency) registries, also collecting information on any post-infusion ADRs. Everything was then represented graphically to have a clear comparison with the data from the study registered for drug approval. Results: from the data obtained, 7 out of 8 patients improved their health status post infusion with, in some cases, a significant increase in score. Conclusions: this result allows us to understand how crucial it is to start treatment as soon as possible after the diagnosis of the condition as the greatest improvements were seen in subjects who received treatment within 2 months of birth.

Life-Saving Treatments for Spinal Muscular Atrophy: Global Access and Availability

Background and Objectives

Spinal muscular atrophy (SMA) is a neurodegenerative disorder manifesting with progressive muscle weakness and atrophy. SMA type 1 used to be fatal within the first 2 years of life, but is now treatable with therapies targeting splicing modification and gene replacement. Nusinersen, risdiplam, and onasemnogene abeparvovec-xioi improve survival, motor strength, endurance, and ability to thrive, allowing many patients to potentially attain a normal life; all have been recently approved by major regulatory agencies. Although these therapies have revolutionized the world of SMA, they are associated with a high economic burden, and access to these therapies is limited in some countries. The primary objective of this study was to compare the availability and implementation of treatment of SMA from different regions of the world.

Methods

In this qualitative study, we surveyed health care providers from 21 countries regarding their experiences caring for patients with SMA. The main outcome measures were provider survey responses on newborn screening, drug availability/access, barriers to treatment, and related questions.

Results

Twenty-four providers from 21 countries with decades of experience (mean 26 years) in treating patients with SMA responded to the survey. Nusinersen was the most available therapy for SMA. Our survey showed that while genetic testing is usually available, newborn screening is still unavailable in many countries. The provider-reported treatment cost also varied between countries, and economic burden was a major barrier in treating patients with SMA.

Discussion

Overall, this survey highlights the global inequality in managing patients with SMA. The spread of newborn screening is essential in ensuring improved access to care for patients with SMA. With the advancement of neurotherapeutics, more genetic diseases will soon be treatable, and addressing the global inequality in clinical care will require novel approaches to mitigate such inequality in the future.

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

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

Correlations between clinical motor scores and CMAP in patients with type 2 spinal muscular amyotrophy treated with nusinersen

BACKGROUND

Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by the degeneration of the anterior horn cells of the spinal cord. Nusinersen for the treatment of SMA has been covered by public healthcare in France since May 2017.

OBJECTIVE

Our aim was to investigate whether there is a correlation between clinical and compound motor action potential (CMAP) measurements in SMA patients treated with nusinersen after 3  years' follow-up.

METHOD

Motor skills were evaluated regularly between M0 and M36 using the Motor Function Measure (MFM) score. CMAP measurements were collected regularly between M0 and M22.

RESULTS

Data for 10 patients with SMA type 2 were collected and divided into two age groups (< 5 years and > 5 years). Motor function improved, but not significantly, regarding distal motor skills (D3) in both groups, and in axial and proximal motor function (D2) in the younger group. CMAP measurements improved in all patients. CMAP increased significantly for the median nerve, and this improvement correlated significantly with global MFM and with axial and proximal tone (D2).

CONCLUSION

Our study shows gain in distal motor function with nusinersen, especially in younger patients with SMA type 2. These results encourage the screening of SMA patients and treatment as early as possible. CMAP measurements of the median nerve show clear improvement in patients treated with nusinersen and could be performed as routine follow-up.

Current Advances in Genetic Testing for Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is one of the most common genetic disorders worldwide, and genetic testing plays a key role in its diagnosis and prevention. The last decade has seen a continuous flow of new methods for SMA genetic testing that, along with traditional approaches, have affected clinical practice patterns to some degree. Targeting different application scenarios and selecting the appropriate technique for genetic testing have become priorities for optimizing the clinical pathway for SMA. In this review, we summarize the latest technological innovations in genetic testing for SMA, including MassArray®, digital PCR (dPCR), next-generation sequencing (NGS), and third-generation sequencing (TGS). Implementation recommendations for rationally choosing different technical strategies in the tertiary prevention of SMA are also explored.

Efficacy and safety of salbutamol in treatment of children with later-onset spinal muscular atrophy

OBJECTIVES

To investigate the clinical efficacy and safety of salbutamol in the treatment of children with later-onset spinal muscular atrophy (SMA).

METHODS

This study is a prospective single-arm phase Ⅲ clinical study. Pediatric patients with SMA type Ⅱ and Ⅲ who visited Department of Neurology, Children's Hospital, Zhejiang University School of Medicine from December 2020 to June 2022 were enrolled. All patients were evaluated with motor function scales, pulmonary function test and drug safety before study. Patients were treated with salbutamol tablets orally, with an initial dose of 1 mg (tid). If tolerable, the dose was increased to 1.5 mg (tid) in the second week, then increased to 2 mg (tid) from the third week and maintained for 6 months. Patients were followed up at 1, 3 and 6 months of treatment.

RESULTS

Twenty-six patients were enrolled, including 10 boys and 16 girls. There were 16 cases of SMA type Ⅱ and 10 cases of type Ⅲ with age at treatment initiation of 5.67 (3.13, 7.02) years and disease duration of 2.54 (1.31, 4.71) years. The Hammersmith Functional Motor Scale-Expanded (HFMSE) scores were increased from 14.0 (6.5, 43.0) before treatment to 26.0 (15.0, 46.5) after treatment (Z=－4.144, P<0.01) in 25 cases. The Revised Upper Limb Module Scale scores were increased from 33.0 (25.5, 36.0) before treatment to 35.0 (31.0, 36.5) after treatment (Z=－2.214, P<0.05) in 9 cases. In 7 ambulant children with SMA type Ⅲ, the six minutes walking distance was increased by 30 (15, 52) m after a 6-month treatment (Z=－2.366, P<0.05). Compared with the baseline pulmonary functions the patients showed a significant increase in forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF) in 15 cases after treatment (all P<0.05). According to patients and caregivers subjective reporting, there were various degrees of improvement in coughing, sputum production ability and exercise endurance. No serious adverse events were observed during the study.

CONCLUSIONS

Short-term oral administration of salbutamol may improve motor and pulmonary functions in later-onset SMA children with good safety.

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

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

Structured Light Plethysmography for Non-Invasive Assessment of Respiratory Pattern in Spinal Muscular Atrophy Type 1

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.

Nusinersen for Spinal Muscular Atrophy Type I with Chronic Respiratory Failure: A Retrospective Study in South Korea

PURPOSE

To analyze the efficacy and safety of nusinersen in patients with spinal muscular atrophy (SMA) type I with chronic respiratory failure.

MATERIALS AND METHODS

We retrospectively reviewed seven patients diagnosed with SMA type I and chronic respiratory failure who were on permanent ventilation and treated with nusinersen at Gangnam Severance Hospital between January 2018 and July 2023. Patient demographics and clinical characteristics were recorded, and treatment progress was evaluated according to Hammersmith Infant Neurological Examination (HINE-2) and Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scores.

RESULTS

Patients initially developed hypotonia at a mean age of 3.7 months. Mean age at start of nusinersen was 7.3 years; the mean duration of follow-up after starting nusinersen was 46.2 months. At 6-, 18-, 38-, 58-, and 74-month follow-up, the mean changes in CHOP-INTEND scores were 1.0, 2.9, 1.8, 1.5, and 1.5, respectively, and the proportions of patients who showed disease amelioration were 28.6%, 71.4%, 75.0%, 100%, and 100%, respectively.

CONCLUSION

Nusinersen is safe and effective in patients with SMA type I, even those with chronic respiratory failure and those on permanent ventilation. No significant adverse effects of nusinersen were observed.

Role of circulating biomarkers in spinal muscular atrophy: insights from a new treatment era

Spinal muscular atrophy (SMA) is a lower motor neuron disease due to biallelic mutations in the SMN1 gene on chromosome 5. It is characterized by progressive muscle weakness of limbs, bulbar and respiratory muscles. The disease is usually classified in four different phenotypes (1-4) according to age at symptoms onset and maximal motor milestones achieved. Recently, three disease modifying treatments have received approval from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA), while several other innovative drugs are under study. New therapies have been game changing, improving survival and life quality for SMA patients. However, they have also intensified the need for accurate biomarkers to monitor disease progression and treatment efficacy. While clinical and neurophysiological biomarkers are well established and helpful in describing disease progression, there is a great need to develop more robust and sensitive circulating biomarkers, such as proteins, nucleic acids, and other small molecules. Used alone or in combination with clinical biomarkers, they will play a critical role in enhancing patients' stratification for clinical trials and access to approved treatments, as well as in tracking response to therapy, paving the way to the development of individualized therapeutic approaches. In this comprehensive review, we describe the foremost circulating biomarkers of current significance, analyzing existing literature on non-treated and treated patients with a special focus on neurofilaments and circulating miRNA, aiming to identify and examine their role in the follow-up of patients treated with innovative treatments, including gene therapy.

Cognitive impairment in Chinese adult patients with type III spinal muscular atrophy without disease-modifying treatment

Objective

Spinal muscular atrophy (SMA) is a neurodegenerative disorder characterized by the degeneration of motor neurons in the spinal cord. It remains uncertain whether the cognitive performance of adult patients with SMA is impaired. The objective of this study was to assess the cognitive profile of adult Chinese patients with SMA and the association between clinical features and cognitive ability, particularly executive function.

Methods

This cross-sectional study included 22 untreated adult patients with type III SMA and 20 healthy subjects. The following variables were assessed: general intelligence, memory, attention, language, executive function, depression, anxiety, and other demographic and clinical parameters. In addition, physical function was evaluated using the Hammersmith Functional Motor Scale Expanded (HFMSE), the Revised Upper Limb Module (RULM), and the 6-Minute Walk Test (6MWT).

Results

SMA patients had lower scores than healthy subjects in the Verbal Fluency Test, Stroop effect, Total Errors, Perseverative Responses, Perseverative Errors, and Non-perseverative Errors in the Wisconsin Card Sorting Test, showing impaired abilities of SMA patients in executive function. In the Attention Network Test (ANT), the results indicated that the SMA patients also had selective deficits in their executive control networks. Ambulant patients had better executive function test performance than non-ambulant ones. Compromised executive abilities in patients with SMA were correlated with a younger age at onset, poorer motor function, and higher levels of anxiety and depression.

Conclusion

Our study presented the distribution of cognitive impairment in a Chinese cohort with SMA. Patients with type III SMA showed selective deficits in executive function, which may be associated with disease severity, physical impairment, depression and anxiety. Future cognitive studies, accounting for motor and emotional impairment, are needed to evaluate if executive impairment is driven by specific brain changes or by those confounding factors.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

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

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/46363.

Significant healthcare burden and life cost of spinal muscular atrophy: real-world data

OBJECTIVES

The aim of this study is to quantify the mortality rate, direct healthcare costs, and cumulative life costs of pediatric patients with spinal muscular atrophy (SMA) type 1, type 2, and type 3 born in Hong Kong.

METHODS

Data were collected from genetically confirmed SMA patients born in or after 2000 from the Hospital Authority medical database. Patients were followed up from birth until they died, left Hong Kong, reached 18 years, or initiated disease-modifying treatment. Study outcomes included incidence risks of mortality, cumulative direct medical costs-attendances of special outpatient clinics, emergency department, allied health services, and mean length of stay in hospitals over time. Total direct medical costs were calculated as unit costs multiplied by utilization frequencies of corresponding healthcare services at each age.

RESULTS

Seventy-one patients with SMA were included. Over a median follow-up period of 6 years, the overall incidence rate of death was 5.422/100 person-years (95%CI 3.542-7.945/100 person-years). 67.7% and 11% of deaths occurred in SMA1 and SMA2 groups, respectively. The median age of death was 0.8 years in SMA1 and 10.9 years in SMA2. The mean cumulative direct medical costs in overall SMA, SMA1, SMA2 and SMA3 groups per patient were US$935,570, US$2,393,250, US$413,165, and US$40,735, respectively.

INTERPRETATION

Our results confirmed a significantly raised mortality and extremely high healthcare burden for patients with SMA especially SMA type 1 and 2 without disease-modifying treatment. Study evaluating health and economic impact of newborn screening and early treatment is needed.

Bone Health Status of Children with Spinal Muscular Atrophy

BACKGROUND

Spinal muscular atrophy (SMA) is a group of rare, inherited neuromuscular disorders. Bone health is often a neglected issue in children with SMA. This study aimed to evaluate the bone health status of children with SMA in Hong Kong.

METHODS

This retrospective study included children with SMA who were managed in the Neuromuscular Disorder Clinics of 2 quaternary centers in Hong Kong. Bone health status was assessed by fracture history, bone mineral density (BMD) measured by dual energy X-ray absorptiometry, and serum 25-hydroxy-vitamin D (25[OH]D) level.

RESULTS

Thirty-two children were included (males, 12). The median age was 10.8 years. BMD assessments were performed in 17 patients (SMA type 1=2, type 2=8, type 3=7). Low BMD was observed in 16 out of 17 patients. Four had a history of long bone fractures and were started on bisphosphonates. SMA types, age at last visit, sex, ambulation, and 25(OH)D level were not associated with fracture history or BMD Z-scores. Only one fulfilled the 2019 International Society for Clinical Densitometry (ISCD) pediatric definition of osteoporosis, with both low BMD and a history of clinically significant fracture.

CONCLUSIONS

Children with SMA on disease-modifying treatments commonly had Low BMD and a history of fractures, but osteoporosis was uncommon according to the 2019 ISCD pediatric definition. A special definition of osteoporosis may be needed for this high-risk group.

Electrophysiological and Imaging Biomarkers to Evaluate Exercise Training in Patients with Neuromuscular Disease: A Systematic Review

Exercise therapy as part of the clinical management of patients with neuromuscular diseases (NMDs) is complicated by the limited insights into its efficacy. There is an urgent need for sensitive and non-invasive quantitative muscle biomarkers to monitor the effects of exercise training. Therefore, the objective of this systematic review was to critically appraise and summarize the current evidence for the sensitivity of quantitative, non-invasive biomarkers, based on imaging and electrophysiological techniques, for measuring the effects of physical exercise training. We identified a wide variety of biomarkers, including imaging techniques, i.e., magnetic resonance imaging (MRI) and ultrasound, surface electromyography (sEMG), magnetic resonance spectroscopy (MRS), and near-infrared spectroscopy (NIRS). Imaging biomarkers, such as muscle maximum area and muscle thickness, and EMG biomarkers, such as compound muscle action potential (CMAP) amplitude, detected significant changes in muscle morphology and neural adaptations following resistance training. MRS and NIRS biomarkers, such as initial phosphocreatine recovery rate (V), mitochondrial capacity (Qmax), adenosine phosphate recovery half-time (ADP t1/2), and micromolar changes in deoxygenated hemoglobin and myoglobin concentrations (Δ[deoxy(Hb + Mb)]), detected significant adaptations in oxidative metabolism after endurance training. We also identified biomarkers whose clinical relevance has not yet been assessed due to lack of sufficient study.

Profile of cognitive abilities in spinal muscular atrophy type II and III: what is the role of motor impairment?

There has recently been some concern on possible cognitive impairment in patients with Spinal Muscular Atrophy (SMA). The aim of this study was to assess cognitive profiles in type II and III SMA with a focus on individual indexes and possible correlations with motor function. 57 type II and III individuals, aged 3.5-17 years, were consecutively enrolled in a prospective, multicentric study. Cognitive function was assessed using age-appropriate Weschler Scales. Motor function was concomitantly assessed using disease-specific functional scales. Only 2 individuals (3%) had a intellectual disability of mild degree while the others were within normal range, with no significant difference in relation to SMA type, gender or functional status. While the overall quotients were mostly within normal range, some indexes showed wider variability. A significant positive medium correlation was found between Processing Speed Index and motor functional scores. Working memory had lower scores in type III patients compared to type II. Intellectual disability is uncommon in type II and III SMA. Motor functional abilities may play a role in some of the items contributing to the overall cognitive profile.

Feasibility and tolerability of multimodal peripheral electrophysiological techniques in a cohort of patients with spinal muscular atrophy

OBJECTIVE

Electrophysiological techniques are emerging as an aid in identifying prognostic or therapeutic biomarkers in patients with spinal muscular atrophy (SMA), but electrophysiological assessments may be burdensome for patients. We, therefore, assessed feasibility and tolerability of multimodal peripheral non-invasive electrophysiological techniques in a cohort of patients with SMA.

METHODS

We conducted a single center, longitudinal cohort study investigating the feasibility and tolerability of applying multimodal electrophysiological techniques to the median nerve unilaterally. Techniques consisted of the compound muscle action potential scan, motor nerve excitability tests, repetitive nerve stimulation and sensory nerve action potential. We assessed tolerability using the numeric rating scale (NRS), ranging from 0 (no pain) to 10 (worst possible pain), and defined the protocol to be tolerable if the NRS score ≤ 3. The protocol was considered feasible if it could be performed according to test and quality standards.

RESULTS

We included 71 patients with SMA types 1-4 (median 39 years; range 13-67) and 63 patients at follow-up. The protocol was feasible in 98% of patients and was well-tolerated in up to 90% of patients. Median NRS score was 2 (range 0-6 at baseline and range 0-4 at follow-up (p < 0.01)). None of the patients declined follow-up assessment.

CONCLUSIONS

Multimodal, peripheral, non-invasive, electrophysiological techniques applied to the median nerve are feasible and well-tolerated in adolescents and adults with SMA types 1-4.

SIGNIFICANCE

Our study supports the use of non-invasive multimodal electrophysiological assessments in adolescents and adults with SMA types 1-4.

Decision-making and challenges within the evolving treatment algorithm in spinal muscular atrophy: a clinical perspective

INTRODUCTION

The clinical application of disease modifying therapies has dramatically changed the paradigm of the management of people with spinal muscular atrophy (SMA), from sole reliance on symptomatic care directed toward the downstream consequences of muscle weakness, to proactive intervention and even preventative care.

AREAS COVERED

In this perspective, the authors evaluate the contemporary therapeutic landscape of SMA and discuss the evolution of novel phenotypes and the treatment algorithm, including the key factors that define individual treatment choice and treatment response. The benefits achieved by early diagnosis and treatment through newborn screening are highlighted, alongside an appraisal of emerging prognostic methods and classification frameworks to inform clinicians, patients, and families about disease course, manage expectations, and improve care planning. A future perspective of unmet needs and challenges is provided, emphasizing the key role of research.

EXPERT OPINION

SMN-augmenting therapies have improved health outcomes for people with SMA and powered the practice of personalized medicine. Within this new proactive diagnostic and treatment paradigm, new phenotypes and different disease trajectories are emerging. Ongoing collaborative research efforts to understand the biology of SMA and define optimal response are critical to refining future approaches.

Early Development of Spinal Deformities in Children Severely Affected with Spinal Muscular Atrophy after Gene Therapy with Onasemnogene Abeparvovec-Preliminary Results

Spinal muscular atrophy (SMA) is a rare genetic disorder, with the most common form being 5q SMA. Survival of children with severe SMA is poor, yet major advances have been made in recent years in pharmaceutical treatment, such as gene-therapy, which has improved patient survival. Therefore, clinical problems, such as the development of spinal deformities in these genetically treated SMA children represent an unknown challenge in clinical work. In a retrospective case series, the development of spinal deformities was analyzed in 16 SMA children (9 male, 7 female) treated with onasemnogene abeparvovec in two institutions during the years 2020 to 2022. Ten out of sixteen patients had a significant kyphosis, and nine out of sixteen patients had significant scoliosis, with the mean curvature angles of 24 ± 27° for scoliosis, and 69 ± 15° for kyphosis. Based on these preliminary data, it can be assumed that early-onset kyphosis presents a clinical challenge in gene-therapy-treated SMA children. Larger datasets with longer follow-up times need to be collected in order to verify these preliminary observations.

Measuring Fatigue and Fatigability in Spinal Muscular Atrophy (SMA): Challenges and Opportunities

Fatigue, a common symptom, together with the characteristic of performance fatigability, are well-documented features of SMA that impact quality of life and function. Importantly, establishing associations between multidimensional self-reported fatigue scales and patient performance has proven difficult. This review was conducted to evaluate the various patient-reported fatigue scales applied in SMA, with the objective of considering the limitations and advantages of each measure. Variable use of fatigue-related nomenclature, including conflicting terminology interpretation, has affected assessment of physical fatigue attributes, specifically perceived fatigability. This review encourages the development of original patient-reported scales to enable perceived fatigability assessment, providing a potential complementary method of evaluating treatment response.

Objective measurement of oral function in adults with spinal muscular atrophy

BACKGROUND

Impairment of bulbar function in adult individuals with spinal muscular atrophy (SMA) usually is not assessed by established motor scores. Measurements of oral function including quantitative muscle and endurance tests are able to detect subtle changes. The aim of this study was to systematically evaluate the measurement of maximum bite force and endurance, maximum tongue pressure and endurance, as well as maximum mouth opening in adult individuals with SMA types 2 and 3.

METHODS

Data from oral function tests in 43 individuals were analyzed. Differences in oral function between individuals with different SMA types and numbers of SMN2 copies were tested. Spearman´s rho correlations among oral function measures themselves as well as with established clinical outcome scales were analyzed.

RESULTS

The absolute maximum measures of oral function (maximum bite force, maximum tongue pressure, maximum mouth opening) were able to discriminate between individuals with different SMA types, individuals with a different number of SMN2 copies and with different walking abilities. The pairwise correlations of the absolute maximum measures of oral function were fair to moderate in size; the same was true for their correlations with the established motor scores. All correlations assessing endurance measures of oral function were weaker and statistically insignificant.

CONCLUSIONS

Among the oral function tests maximum tongue pressure and maximum mouth opening are particulary promising as clinical and sensitive outcome measures for clinical trials. Oral function tests may supplement existing motor scores, in particular concerning specific questions about bulbar function or in severely affected non-ambulatory individuals where mild (treatment-related) changes would otherwise remain undetected. Trial registration DRKS, DRKS00015842. Registered 30 July 2019, https://drks.de/search/de/trial/DRKS00015842.

Nusinersen for spinal muscular atrophy types II and III: a retrospective single-center study in South Korea

BACKGROUND

This study investigated the efficacy and safety of nusinersen, an antisense oligonucleotide, in patients with spinal muscular atrophy (SMA) types II (OMIM: 253,550) or III (OMIM: 253,400), including those with severe scoliosis or requiring respiratory support via mechanical ventilation.

METHODS

Data from 40 patients with genetically confirmed SMA who were treated with nusinersen at our institute from March 2019 to April 2022 were retrospectively analyzed. Of these, 30 patients with an age of onset < 3 years and not on permanent ventilation were selected. Clinical and genetic characteristics were investigated, and motor function was evaluated based on the Hammersmith Functional Motor Scale-Expanded (HFMSE) score.

RESULTS

The mean age of symptom onset was 1.2 years. Most patients were diagnosed with SMA type II (27/30, 90%). Nusinersen was administered via computed tomography-guided or direct intrathecal injection in 87% (26/30) and 13% (4/30) of the patients, respectively. At the 6-, 14-, 22-, and 26-month follow-ups, 72%, 71%, 88%, and 86% of patients showed motor improvement, respectively, with mean changes in HFMSE scores of 2.10, 2.88, 4.21, and 5.29, respectively. Multivariable analysis showed that the use of noninvasive ventilation was associated with poorer outcomes of motor function.

CONCLUSIONS

Patients with SMA type II or III who received nusinersen treatment showed significant improvement in motor function. A longer treatment duration led to a higher number of patients with improved motor function. No significant side effects of nusinersen were observed. Patients with SMA, even those with severe scoliosis or on respiratory support, can be safely treated using nusinersen.

Onasemnogene abeparvovec in spinal muscular atrophy: predictors of efficacy and safety in naïve patients with spinal muscular atrophy and following switch from other therapies

Background

Efficacy and safety of onasemnogene abeparvovec (OA) for Spinal Muscular Atrophy infants under 7 months and <8.5 kg has been reported in clinical trials. This study examines efficacy and safety predictors in a wide age (22 days-72 months) and weight (3.2-17 kg) range, also including patients previously treated with other drugs.

Methods

46 patients were treated for 12 months between January 2020 and March 2022. Safety profile was also available for another 21 patients with at least 6 month follow-up after OA infusion. 19/67 were treatment naïve when treated with OA. Motor function was measured with the CHOP-INTEND.

Findings

CHOP-INTEND changes varied among age groups. Baseline score and age at OA treatment best predicted changes. A mixed model post-hoc analysis showed that in patients treated before the age of 24 months the CHOP-INTEND changes were already significant 3 months after OA while in those treated after the age of 24 months the difference was only significant 12 months after OA. Adverse events occurred in 51/67. The risk for elevated transaminases serum levels was higher in older patients. This was also true for weight and for pre-treatment with nusinersen when analysed individually. A binomial negative regression analysis showed that only age at OA treatment had a significant effect on the risk of elevated transaminases.

Interpretation

Our paper describes OA 12-month follow-up showing efficacy across various age and weight groups not targeted by clinical trials. The study identifies prognostic factors for safety and efficacy in treatment selection.

Funding

None.

Longitudinal prospective cohort study to assess peripheral motor function with extensive electrophysiological techniques in patients with Spinal Muscular Atrophy (SMA): the SMA Motor Map protocol

BACKGROUND

Hereditary spinal muscular atrophy (SMA) is a motor neuron disorder with a wide range in severity in children and adults. Two therapies that alter splicing of the Survival Motor Neuron 2 (SMN2) gene, i.e. nusinersen and risdiplam, improve motor function in SMA, but treatment effects vary. Experimental studies indicate that motor unit dysfunction encompasses multiple features, including abnormal function of the motor neuron, axon, neuromuscular junction and muscle fibres. The relative contributions of dysfunction of different parts of the motor unit to the clinical phenotype are unknown. Predictive biomarkers for clinical efficacy are currently lacking. The goals of this project are to study the association of electrophysiological abnormalities of the peripheral motor system in relation to 1) SMA clinical phenotypes and 2) treatment response in patients treated with SMN2-splicing modifiers (nusinersen or risdiplam).

METHODS

We designed an investigator-initiated, monocentre, longitudinal cohort study using electrophysiological techniques ('the SMA Motor Map') in Dutch children (≥ 12 years) and adults with SMA types 1-4. The protocol includes the compound muscle action potential scan, nerve excitability testing and repetitive nerve stimulation test, executed unilaterally at the median nerve. Part one cross-sectionally assesses the association of electrophysiological abnormalities in relation to SMA clinical phenotypes in treatment-naïve patients. Part two investigates the predictive value of electrophysiological changes at two-months treatment for a positive clinical motor response after one-year treatment with SMN2-splicing modifiers. We will include 100 patients in each part of the study.

DISCUSSION

This study will provide important information on the pathophysiology of the peripheral motor system of treatment-naïve patients with SMA through electrophysiological techniques. More importantly, the longitudinal analysis in patients on SMN2-splicing modifying therapies (i.e. nusinersen and risdiplam) intents to develop non-invasive electrophysiological biomarkers for treatment response in order to improve (individualized) treatment decisions.

TRIAL REGISTRATION

NL72562.041.20 (registered at https://www.toetsingonline.nl . 26-03-2020).

Evaluation of sputum cultures in children with spinal Muscular atrophy

BACKGROUND

Spinal Muscular Atrophy (SMA) is a severe neuromuscular disorder. Despite increased survival due to novel therapies, morbidity from respiratory complications still persists. We aim to describe these patients' sputum cultures as an expression of chronic infectious airway disease.

METHODS

Retrospective review of medical records of all children with SMA followed at the multidisciplinary respiratory neuromuscular clinic at Schneider Childrens' Medical Center of Israel over a 16-year period. Sputum cultures were obtained during routine visits or pulmonary exacerbations.

RESULTS

Sixty-one SMA patients, aged 1 month to 21 years, were included in this cohort. Of these, sputum cultures were collected from 41 patients. Overall, 288 sputum cultures were obtained, and 98 (34%) were negative for bacterial growth. For the first culture taken from each patient, 12 out of 41 (29%) were sterile. The most common bacteria were pseudomonas aeruginosa (PSA) (38%) and staphylococcus aureus (19.6%). PSA was found in SMA type I patients more frequently than in type II patients (15/26 = 58% vs 4/13 = 31%, p < 0.001). PSA infection was positively associated with noninvasive ventilation, recurrent atelectasis, recurrent pneumonias, swallowing difficulties, but no significant association was found with cough assist machine usage. The incidence of positive cultures did not differ between those treated with Onasemnogene abeparvovec or Nusinersen compared to those without treatment, but the age of first PSA isolation was slightly older with Nusinersen treatment (p = 0.01).

CONCLUSIONS

Airway bacterial colonization is common in SMA type I patients and is not decreased by Onasemnogene abeparvovec or Nusinersen treatment.

Swallowing Problems in Spinal Muscular Atrophy Types 2 and 3: A Clinical, Videofluoroscopic and Ultrasound Study

Background: Spinal muscular atrophy (SMA) is a hereditary motor neuron disorder, characterized by the degeneration of motor neurons and progressive muscle weakness. There is a large variability of disease severity, reflected by the classification of SMA types 1–4. Objective: The aim of this cross-sectional study was to determine the nature of swallowing problems and underlying mechanisms in patients with SMA types 2 and 3, and the relationship between swallowing and mastication problems. Methods: We enrolled patients (aged 13–67 years) with self-reported swallowing and/or mastication problems. We used a questionnaire, the functional oral intake scale, clinical tests (dysphagia limit, and timed test swallowing, the test of mastication and swallowing solids), a videofluoroscopic swallowing study (VFSS), and muscle ultrasound of the bulbar muscles (i.e. digastric, geniohyoid and tongue muscles). Results: Non-ambulant patients (n = 24) had a reduced dysphagia limit (median 13 ml (3–45), and a swallowing rate at the limit of normal (median 10 ml/sec (range 4–25 ml). VFSS revealed piecemeal deglutition and hypo-pharyngeal residue. We found pharyngo-oral regurgitation in fourteen patients (58%), i.e. they transported the residue from the hypopharynx back into the oral cavity and re-swallowed it. Six patients (25%) demonstrated impaired swallowing safety (i.e. PAS >3). Muscle ultrasound revealed an abnormal muscle structure of the submental and tongue muscles. Ambulant patients (n = 3), had a normal dysphagia limit and swallowing rate, but VFSS showed hypo-pharyngeal residue, and muscle ultrasound demonstrated an abnormal echogenicity of the tongue. Swallowing problems were associated with mastication problems (p = 0.001).

Neurocognitive profile of a cohort of SMA type 1 pediatric patients and emotional aspects, resilience and coping strategies of their caregivers

Spinal muscular atrophy (SMA) type 1 represents the most severe condition of the spectrum of SMA 5q. In the absence of therapeutic interventions, patients do not achieve any motor milestone and their life expectancy does not exceed two years of age. To date, three disease-modifying drugs have been approved for SMA type I. These treatments have radically changed the natural history of the disease, improving motor, respiratory and bulbar functions. In recent years huge amount of data have been collected worldwide related to motor, respiratory and swallowing function outcome in treated patients, whereas the neurocognitive profile of treated patients has been poorly explored. Here we report the neurocognitive development profile of a cohort of SMA type I children treated with a disease modifying therapy. We also describe the burden and resilience as well as the coping strategies of their caregivers. Our finding show a global developmental delay in most patients and defects in gross motor functions contribute most to lower the general development quotient of Griffiths III, whereas the scores obtained on evaluating learning and language abilities scales suggest a positive trend in the developmental trajectory of general neurocognitive abilities. Some parents reported anxiety and stress but overall they were resilient (and had good coping strategies towards the burden of care for their child. These results reinforce the importance of routinely assessing the neurocognitive aspects in SMA type I patients and to offer an early intervention to favor the psychosocial development of these children.

Adherence and Persistence to Nusinersen for Spinal Muscular Atrophy: A US Claims-Based Analysis

INTRODUCTION

Spinal muscular atrophy (SMA) is a genetic, neuromuscular disease caused by deletions and/or mutations in the survival of motor neuron 1 (SMN1) gene leading to reduced SMN protein levels. Nusinersen, an intrathecally administered antisense oligonucleotide therapy that increases SMN protein levels, is approved for use in adult and pediatric patients with SMA. Data to inform real-world patient adherence and persistence to nusinersen are limited, with disparities in the population with SMA, study design, and results. The objective of this study is to characterize real-world nusinersen adherence and persistence in patients with SMA.

METHODS

This retrospective study examined nusinersen adherence and persistence over a 2-year period in patients with SMA in the USA from the IQVIA PharMetrics Plus claims database. Patients were followed from the date of first evidence of nusinersen treatment (occurring after 1 July 2017) until the end of the study period (31 December 2019) or end of continuous pharmacy and medical benefit enrollment, whichever came first. Subgroup analyses for nusinersen adherence and persistence were performed on the basis of age and presence or absence of spinal complications.

RESULTS

The final cohort consisted of 179 patients with SMA treated with nusinersen. Adherence to nusinersen treatment was 41% at 56 weeks and 39% at 104 weeks. In the base-case persistence analysis, there was a decrease in persistence before 6 months (67%) and further decline at 1 (57%) and 2 years (55%). Patients with spinal complication versus without had numerically higher persistence with nusinersen.

CONCLUSIONS

The findings suggest that adherence and persistence to nusinersen treatment appear low. Demographic (age ≥ 18 years) and clinical factors (no spinal complications) may contribute to nusinersen treatment discontinuation. Future research should explore possible reasons for low adherence and persistence to nusinersen treatment, such as clinical or logistical factors, patient preferences, and payer restrictions.

Lung function decline preceding chronic respiratory failure in spinal muscular atrophy: a national prospective cohort study

BACKGROUND

Progressive lung function decline, resulting in respiratory failure, is an important complication of spinal muscular atrophy (SMA). The ability to predict the need for mechanical ventilation is important. We assessed longitudinal patterns of lung function prior to chronic respiratory failure in a national cohort of treatment-naïve children and adults with SMA, hypothesizing an accelerated decline prior to chronic respiratory failure.

METHODS

We included treatment-naïve SMA patients participating in a prospective national cohort study if they required mechanical ventilation because of chronic respiratory failure and if lung function test results were available from the years prior to initiation of ventilation. We analyzed Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 s (FEV₁), Peak Expiratory Flow (PEF) and Maximum Expiratory Pressure (PE_max). We studied the longitudinal course using linear mixed-effects models. We compared patients who electively started mechanical ventilation compared to patients who could not be weaned after acute respiratory failure.

RESULTS

We analyzed 385 lung function tests from 38 patients with SMA types 1c-3a. At initiation of ventilation median age was 18.8 years (IQR: 13.2-30.1) and median standardized FVC, FEV₁ and PEF were 28.8% (95% CI: 23.5; 34.2), 28.8% (95% CI: 24.0; 33.7) and 30.0% (95% CI: 23.4; 36.7), with an average annual decline of 1.75% (95% CI: 0.86; 2.66), 1.72% (95% CI: 1.04; 2.40) and 1.65% (95% CI: 0.71; 2.59), respectively. Our data did not support the hypothesis of an accelerated decline prior to initiation of mechanical ventilation. Median PE_max was 35.3 cmH₂O (95% CI: 29.4; 41.2) at initiation of mechanical ventilation and relatively stable in the years preceding ventilation. Median FVC, FEV_1, PEF and PE_max were lower in patients who electively started mechanical ventilation (p < 0.001).

CONCLUSIONS

Patterns of lung function decline cannot predict impending respiratory failure: SMA is characterized by a gradual decline of lung function. We found no evidence for an accelerated deterioration. In addition, PE_max remains low and stable in the years preceding initiation of ventilation. Patients who electively started mechanical ventilation had more restrictive lung function at initiation of ventilation, compared to patients who could not be weaned after surgery or a respiratory tract infection.

Areas of improvement in the medical care of SMA: evidence from a nationwide patient registry in Germany

BACKGROUND

Management and treatment of spinal muscular atrophy (SMA) has changed in recent years due to the introduction of novel transformative and potentially curative therapies resulting in the emergence of new disease phenotypes. Yet, little is known about the uptake and impact of these therapies in real-world clinical practice. The objective of this study was to describe current motor function, need of assistive devices, and therapeutic and supportive interventions provided by the healthcare system, as well as the socioeconomic situation of children and adults with different SMA phenotypes in Germany. We conducted a cross-sectional, observational study of German patients with genetically confirmed SMA identified and recruited via a nationwide SMA patient registry ( www.sma-register.de ) within the TREAT-NMD network. Study data was recorded directly from patient-caregiver pairs through a study questionnaire administered online via a dedicated study website.

RESULTS

The final study cohort consisted of 107 patients with SMA. Of these, 24 were children and 83 adults. In total, about 78% of all participants were taking medication for SMA (predominantly nusinersen and risdiplam). All children with SMA1 were able to sit and 27% of children with SMA2 were able to stand or walk. Impaired upper limb function, scoliosis and bulbar dysfunction were observed more frequently in patients with reduced lower limb performance. Physiotherapy, occupational therapy, and speech therapy, as well as the use of cough assists were less common than indicated by care guidelines. Family planning and educational and employment status appear to be related to motor skill impairment.

CONCLUSIONS

We show that the natural history of disease has changed in Germany following improvements in SMA care and the introduction of novel therapies. Yet, a non-trivial proportion of patients remain untreated. We also identified considerable limitations in rehabilitation and respiratory care, as well as low labour-market participation among adults with SMA, calling for action to improve the current situation.

Two-year efficacy and safety of risdiplam in patients with type 2 or non-ambulant type 3 spinal muscular atrophy (SMA)

Risdiplam is an oral, survival of motor neuron 2 (SMN2) pre-mRNA splicing modifier approved for the treatment of spinal muscular atrophy (SMA). SUNFISH (NCT02908685) Part 2, a Phase 3, randomized, double-blind, placebo-controlled study, investigated the efficacy and safety of risdiplam in type 2 and non‑ambulant type 3 SMA. The primary endpoint was met: a significantly greater change from baseline in 32-item Motor Function Measure (MFM32) total score was observed with risdiplam compared with placebo at month 12. After 12 months, all participants received risdiplam while preserving initial treatment blinding. We report 24-month efficacy and safety results in this population. Month 24 exploratory endpoints included change from baseline in MFM32 and safety. MFM‑derived results were compared with an external comparator. At month 24 of risdiplam treatment, 32% of patients demonstrated improvement (a change of ≥ 3) from baseline in MFM32 total score; 58% showed stabilization (a change of ≥ 0). Compared with an external comparator, a treatment difference of 3.12 (95% confidence interval [CI] 1.67-4.57) in favor of risdiplam was observed in MFM-derived scores. Overall, gains in motor function at month 12 were maintained or improved upon at month 24. In patients initially receiving placebo, MFM32 remained stable compared with baseline (0.31 [95% CI - 0.65 to 1.28]) after 12 months of risdiplam; 16% of patients improved their score and 59% exhibited stabilization. The safety profile after 24 months was consistent with that observed after 12 months. Risdiplam over 24 months resulted in further improvement or stabilization in motor function, confirming the benefit of longer-term treatment.

Comprehensive SMN1 and SMN2 profiling for spinal muscular atrophy analysis using long-read PacBio HiFi sequencing

Spinal muscular atrophy, a leading cause of early infant death, is caused by bi-allelic mutations of SMN1. Sequence analysis of SMN1 is challenging due to high sequence similarity with its paralog SMN2. Both genes have variable copy numbers across populations. Furthermore, without pedigree information, it is currently not possible to identify silent carriers (2+0) with two copies of SMN1 on one chromosome and zero copies on the other. We developed Paraphase, an informatics method that identifies full-length SMN1 and SMN2 haplotypes, determines the gene copy numbers, and calls phased variants using long-read PacBio HiFi data. The SMN1 and SMN2 copy-number calls by Paraphase are highly concordant with orthogonal methods (99.2% for SMN1 and 100% for SMN2). We applied Paraphase to 438 samples across 5 ethnic populations to conduct a population-wide haplotype analysis of these highly homologous genes. We identified major SMN1 and SMN2 haplogroups and characterized their co-segregation through pedigree-based analyses. We identified two SMN1 haplotypes that form a common two-copy SMN1 allele in African populations. Testing positive for these two haplotypes in an individual with two copies of SMN1 gives a silent carrier risk of 88.5%, which is significantly higher than the currently used marker (1.7%-3.0%). Extending beyond simple copy-number testing, Paraphase can detect pathogenic variants and enable potential haplotype-based screening of silent carriers through statistical phasing of haplotypes into alleles. Future analysis of larger population data will allow identification of more diverse haplotypes and genetic markers for silent carriers.

Safety and efficacy of gene therapy with onasemnogene abeparvovec in the treatment of spinal muscular atrophy: A systematic review and meta-analysis

Spinal muscular atrophy (SMA) is an autosomal recessive hereditary disease which leads to progressive muscle weakness and atrophy. Our systematic review and meta-analysis aims to explore the efficacy and safety of onasemnogene abeparvovec in SMA patients. We searched PubMed, EMBASE, Web of Science and Cochrane through April 2022. Ten reports enrolling 250 SMA patients were included. CHOP INTEND and motor-milestone significant improvements were detected at both short- and long-term follow-up. Common adverse events included pyrexia, vomiting, thrombocytopenia and elevated aminotransferases. Thrombocytopenia (79.3%, 95%CI: 65.8~90.5) and elevated aminotransferases (71.7%, 95%CI: 62.5~80.1) were more common in SMA patients aged older than 8 months. Despite the paucity of randomized control trial data and low quality of evidence to establish the safety and efficacy of onasemnogene abeparvovec in the treatment of SMA, the data suggest that it is a valuable option for patients with this condition.