Journal of neuromuscular diseases最新文献

We described ambulatory Duchenne muscular dystrophy (DMD) progression, across multiple functional measures, via previously established prognostic groups for loss of ambulation (LoA) and health states. Patients closer to vs. farther from LoA had greater declines in some measures (e.g., 6-min walk distance) and less change in others (e.g., timed rise from floor velocity) due to floor effects. Patients in the late vs. early ambulatory health state were concordantly shifted towards higher LoA risk. Findings further characterize health states and prognostic factors in ambulatory DMD and highlight the importance of multiple measures of function to fully characterize disease progression.

Background: Although genetically-engineered mouse models are revolutionizing our understanding of numerous human diseases, some of them fail to reproduce or to mimic the human condition or even exhibit distinct disease features depending on the mouse genetic background, on the environment conditions, and/or on unknown parameters.

Objective: Experiments aimed at further characterizing the muscle defects associated with the I-T substitution at position 4898 of the human type 1 ryanodine receptor (RyR1) protein sequence, responsible for central core disease in affected patients, to use this model for therapeutic development. RyR1 is a cationic channel in the sarcoplasmic reticulum membrane that is responsible for the Ca²⁺ release flux that triggers muscle contraction. The above I-T change was previously described to alter RyR1 channel permeation so as to produce muscle weakness.

Methods: We used the corresponding I4895T mouse model, previously shown unviable in the homozygous form, and with heterozygous animals suffering from depressed RyR1-mediated Ca²⁺ flux and muscle force production. We performed a full characterization, at the molecular level of the RYR1 gene and transcript, and at the functional level at the isolated fiber or whole animal levels.

Results: We found no significant deficit in the heterozygous animals, from force and activity parameters at the whole organism level, to contraction of isolated muscles and Ca²⁺ release in single isolated muscle fibers.

Conclusions: Our results prompt the need for caution when using this model, and point to its potential limited relevance for preclinical studies.

Introduction: Duchenne muscular dystrophy (DMD) is a progressive disorder. This study evaluates upper limb function in DMD patients using the Performance of Upper Limb 2.0 (PUL 2.0) over 36-months.

Methods: Data were collected between 2011 and 2024. Patients with at least 36 months of follow-up were included. Mixed-effects models accounting for repeated measures evaluated 36-month PUL 2.0 changes by entry item and ambulatory status. The entry item assesses the overall upper limb function of the patient. Ambulant patients were defined as those able to walk 10 meters independently, transitioning patients as those who lost ambulation during the duration of the study and non-ambulant as those who had already lost ambulation at baseline.

Results: A total of 219 patients provided 684 paired 36-month assessments. Ambulatory status significantly affected total, shoulder, elbow, and distal scores at baseline. The largest 36-month decline in total scores was found in the 58 transitioning patients (11.62 points, 95%CI = -12.40, 10.84), followed by non-ambulant and ambulant subgroups (n = 116 and n = 86 respectively). The largest declines were seen in patients with baseline entry score of 4 (-11.97, 95% CI = -13.48, -10.46) and 5 (-11.55, 95% CI = -12.46, -10.63), with smaller declines for other entry scores.ConclusionsThe 36-month analysis confirms a clear trend of functional decline across time points, with the transitioning group exhibiting the greatest changes in upper limb function. These findings provide valuable insights for designing trials and offer a reference for long-term comparison of treatment efficacy in both experimental and real-world setting.

Background: Pediatric neuromuscular diseases (NMDs) do not only affect patients themselves, they also exert an impact on parents. However, the impact that parents experience on their own personal lives remains largely understudied.

Objective: This study introduced the construct of parental illness intrusiveness in a NMD population by addressing two objectives. First, to increase our insight in the levels of parental intrusiveness in the NMD population, these parents were compared to parents of youth with type 1 diabetes (T1D). Second, we aimed to increase our understanding of parental illness intrusiveness within the NMD sample by exploring its associations with parental demographical characteristics, parental depressive symptoms and quality of life, and disease- and child characteristics.

Methods: A total of 56 parents of youth with a NMD (aged 12-25) and a 2:1 matched sample of parents of youth with T1D completed questionnaires on parental illness intrusiveness, parental depressive symptoms, parental quality of life, and perceived patient physical functioning. For Objective 1, ANOVAs were conducted to compare parents in the NMD sample to parents in the T1D sample. For Objective 2, ANOVAs and correlational analyses were used.

Results: First, parents in the NMD sample reported significantly more illness intrusiveness, but not depressive symptoms as compared to parents in the T1D sample. Second, parental illness intrusiveness correlated positively with parental depressive symptoms and perceived patient physical impairment, and negatively with parental quality of life.

Conclusions: Compared to parents of a child with T1D, parents in the NMD population may experience more impact of their child's disease in their personal life. Parents of youth with higher physical impairment may be particularly at risk for experiencing difficulties among a wide array of personal life domains.

Introduction: Spinal Muscular Atrophy (SMA) is a rare neuromuscular disease. With the discovery of disease-modifying therapies, more infantile onset SMA patients will live to adulthood. The purpose of this study was to explore SMA patients' experience with adult care and their transition from pediatric care.

Methods: This was a convergent parallel mixed-methods design including a quantitative cross-sectional survey and qualitative interviews. A purposive sample of 20 participants was recruited. Quantitative data were collected using the Family Experiences with Care Coordination (FECC) survey. Qualitative data were collected using semi-structured interviews. Participants' experiences before, during, and after their transition to adult care were explored. Themes from interviews were identifiedResults:The mean age of participants was 40.5; 10 were male, 15 had SMA type 2, and 5 had SMA type 3. The FECC found that 7 patients had a care coordinator, 0 had a shared care or emergency plan, and 1 had a written transition plan. Three themes emerged from the semi-structured interviews: 1) a disjointed pediatric to adult care transition period 2) physically inaccessible adult healthcare settings and requirements for constant self-advocacy, and 3) suggestions for improving care including: multidisciplinary care teams and increased preparation of pediatric patients for the transition to adult care.

Discussion: The patient experiences captured in this study demonstrate the lack of transition plans and support for SMA patients when graduating to adult care. With more SMA patients anticipated to survive to adulthood, this problem will be exacerbated. Multi-disciplinary SMA pediatric to adult transition programs are necessary.

Biallelic mutations in XPNPEP3 gene, encoding a mitochondrial peptidase, mainly cause nephronophthisis, but associated muscle involvement remains poorly described. We report here a 44-year-old male presenting since childhood with exercise intolerance and recurrent rhabdomyolysis. Electroneuromyography revealed a sensory axonal neuropathy and brain MRI showed white matter lesions in the posterior cranial fossa. Muscle biopsy revealed ragged-red fibers, COX negative fibers and abnormal mitochondria in electron microscopy. Whole genome sequencing identified a homozygous frameshift variant in the XPNPEP3 gene. Our results expand the spectrum associated with XPNPEP3 variants, including metabolic myopathy with subclinical central and peripheral nervous system involvement.

Background and objectivesThe severity of the phenotype of spinal muscular atrophy (SMA) is highly variable, yet little is known about the phenotypic variation among siblings. We systematically investigated the phenotypic variability of therapy-naïve 5q-SMA siblings leveraging a large multicentre cohort from the SMArtCARE registry.ResultsClinical information was available from 132 siblings of 65 families. There were 24 (18.2%) type 1, 38 (28.7%) type 2, 54 (40.9%) type 3 patients, and 16 (12.1%) presymptomatic individuals. In 17 families (32.1%), there was discordance in the type of SMA among symptomatic siblings. We found no influence of gender on discordance in SMA type among siblings (p = 0.528). The median age at disease onset within all sibships varied by 6 months (interquartile range (IQR) = 1-30). There was no correlation in age of onset among siblings (r = 0.405; p = 0.052). Among siblings who lost ambulation, the median interval between the start of wheelchair use was 12 months, but the maximal interval was 18 years. In one pair of siblings, one sibling lost the ability to walk at the age of 13, whereas the other sibling was still ambulatory at the age of 54. In 6 sibling pairs (9.5%), only one of both siblings had a history of scoliosis surgery. Analysing SMN2 copy numbers, in one sibling pair (1.8%) 1 SMN2 gene copy was detected, while 10 (17.5%) had 2 copies, 23 (40.4%) had 3 copies, and 17 (29.8%) had 4 copies. Concordance in SMN2 copy numbers across siblings was observed in 90% of families. With increasing SMN2 copy number, the median differences in age of onset among siblings increased without reaching statistical significance.ConclusionThis study reports considerable phenotypic variability in therapy-naïve SMA sibships that cannot solely be explained by differences in SMN2 copy numbers.

An increasing number of adults with spinal muscular atrophy (SMA) wish to become parents. New disease-modifying therapies (DMT) have improved health outcomes and are expected to reduce disability in adults with SMA, but their current label prevents their use in pregnancy. While there is some information on pregnancy outcomes in the pre-DMT era, little has been published recently, and no ubiquitously accepted guidelines exist. Nonetheless, it is crucial to provide knowledgeable and open counselling, ideally in the context of treatments. Counseling for both adolescent and adult patients should include the subject of 'reproductive choices' when discussing the selection of DMTs for those considering parenthood. A multi-disciplinary team, including gynecologists and neurologists with expertise in neuromuscular disorders must closely monitor pregnant patients with SMA, preferably within disease registries, to detect potential complications early and ensure optimal treatment options are available. Real-world data in so far three patients with SMA showed a beneficial pregnancy outcome with nusinersen. It is anticipated that forthcoming real-world data will finally clarify the safety of administering Nusinersen during pregnancy, particularly in relation to child health and for preserving muscle function and preventing motor deterioration in the affected mother.

Background: Electrical impedance myography (EIM) has been proposed as an efficient, non-invasive biomarker of muscle composition in facioscapulohumeral muscular dystrophy (FSHD).

Objective: We investigate whether EIM parameters are associated with muscle structure measured by magnetic resonance imaging (MRI), muscle histology, and transcriptomic analysis as well as strength at the individual leg muscle level.

Methods: We performed a multi-center cross-sectional study enrolling 33 patients with FSHD. EIM measurements were recorded from bilateral vastus lateralis, tibialis anterior (TA), and medial gastrocnemius muscles and compared to quantitative muscle volume measures by MRI as well as knee extension and ankle dorsiflexion strength by quantitative muscle testing. EIM measurements of the bilateral TA were further compared to histology and transcriptomic analysis (RNAseq) of muscle and fat content.

Results: EIM phase at multiple frequencies was positively associated to the amount of muscle measured by MRI (ρ = 0.48 to 0.70, p $\le$ 0.001) and negatively associated to the amount of fat replacement of muscle (ρ = -0.53 to -0.73, p $\le$ 0.001). EIM phase of the vastus lateralis and TA was positively associated with knee extension and ankle dorsiflexion strength normalized to age and sex (ρ = 0.45 to 0.60, p < 0.0001). The bilateral TA muscles were analyzed at the histopathological and molecular (transcriptomic) levels and showed that EIM phase was positively associated with amount of muscle (ρ = 0.33 to 0.35, p < .01) and negatively associated with amount of fat (ρ = -0.36 to -0.56, p < .001) by transcriptomic analysis.

Conclusions: This study supports the hypothesis that the amount and quality of muscle tissue as assessed by EIM is associated with the amount and quality of muscle tissues as assessed by MRI and muscle biopsy, with all measures ultimately being strongly associated with muscle strength. These data provide further convergent validity for the use of EIM as a potential non-invasive biomarker to assess muscle health in FSHD.

Next-generation sequencing has improved diagnostic outcomes for neuromuscular disorders, but interpreting rare missense variants remains challenging. We evaluated AlphaMissense, a recently developed machine learning tool, for predicting missense variant pathogenicity, using 45 (likely) pathogenic variants and 21 variants of uncertain significance from 58 deeply phenotyped patients. AlphaMissense predicted 69% of pathogenic variants correctly, but also classified 62% of variants of uncertain significance as pathogenic. Median AlphaMissense scores were not significantly different between pathogenic and uncertain variants. Overall, AlphaMissense accurately predicted the pathogenicity of most missense variants, but may be limited in certain functional contexts, highlighting the need for disease-specific interpretation approaches.