Duchenne muscular dystrophy (DMD) is a severe neuromuscular disorder with increasing life expectancy from late teens to over 30 years of age. The aim of this nationwide study was to explore the ...prevalence, life expectancy and leading causes of death in patients with DMD in Sweden. Patients with DMD were identified through the National Quality Registry for Neuromuscular Diseases in Sweden, the Swedish Registry of Respiratory Failure, pathology laboratories, neurology and respiratory clinics, and the national network for neuromuscular diseases. Age and cause of death were retrieved from the Cause of Death Registry and cross-checked with medical records. 373 DMD patients born 1970–2019 were identified, of whom 129 patients deceased during the study period. Point prevalence of adult patients with DMD on December 31st 2019 was 3.2 per 100,000 adult males. Birth prevalence was 19.2 per 100,000 male births. Median survival was 29.9 years, the leading cause of death being cardiopulmonary in 79.9% of patients. Non-cardiopulmonary causes of death (20.1% of patients) mainly pertained to injury-related pulmonary embolism (1.3 per 1000 person-years), gastrointestinal complications (1.0 per 1000 person-years), stroke (0.6 per 1000 person-years) and unnatural deaths (1.6 per 1000 person-years). Death from non-cardiopulmonary causes occurred at younger ages (mean 21.0 years, SD 8.2;
p
= 0.004). Age at loss of independent ambulation did not have significant impact on overall survival (
p
= 0.26). We found that non-cardiopulmonary causes contribute to higher mortality among younger patients with DMD. We present novel epidemiological data on the increasing population of adult patients with DMD.
Abstract
Introduction
Ataluren is a relatively new treatment for male patients with Duchenne muscular dystrophy (DMD) due to a premature stop codon. Long-term longitudinal data as well as efficacy ...data on non-ambulant patients are still lacking. Here we present the results from a long-term follow-up study of all DMD patients treated with ataluren and followed at the Queen Silvia Children’s Hospital in Gothenburg, Sweden, with focus on the evolution of patients’ upper motor and respiratory function over time.
Methods
This is a retrospective longitudinal case-series study of all male DMD patients treated with ataluren and followed at the Queen Silvia Children’s Hospital in Gothenburg, Sweden, since 2008.
Results
Our eleven patients had a median exposure to ataluren of 2312 days which is almost a fourfold higher than previous studies. Loss of ambulation occurred at a median age of 13.2 years. Patients who lost ambulation prior to 13.2 years of age had received ataluren for 5 years, whereas patients who continued to be ambulatory after 13.2 years of age had received ataluren for 6.5 years until loss of ambulation or last follow-up if still ambulatory. Four of six non ambulatory patients had Performance of the Upper Limb scores above the expected mean values over time. All but one patient maintained a pulmonary decline above the expected over time. All ambulatory patients increased in their predicted forced vital capacity (FVC) with 2.8 to 8.2% annually. Following loss of ambulation, 5 of 6 patients declined in predicted FVC (%), with annual rate of decline varying from 1.8 to 21.1%. The treatment was safe and well tolerated throughout the follow-up period.
Conclusions
This is the first study to present long-term cumulative treatment outcomes over a median period of 6.3 years on ataluren treatment. Our results indicate a delay in loss of ambulation, as well as a slower decline in FVC and upper limb motor function even after loss of ambulation. We suggest that treatment with ataluren should be initiated as soon as the diagnosis is confirmed, closely monitored and, in case of sustainable benefit, continued even after loss of ambulation.
Aim
Individuals with spinal muscular atrophy (SMA) are at risk of developing skeletal problems. This study investigated bone mineral density (BMD), bone turnover markers and motor function in ...children and adolescents with SMA type 2 and type 3 over a two‐year period. The effect of nusinersen was studied in a subgroup.
Methods
Single‐centre study, including 20 patients, 2–18 years, of whom ten patients received nusinersen treatment. BMD was measured by dual‐energy X‐ray absorptiometry.
Results
All patients had low BMD levels at baseline; mean Z‐score −2.3 for total body less head (TBLH) and −2.9 for total hip left (THL). Significant correlations were found both at baseline and for the follow‐up change for motor function and Z‐scores (TBLH and THL). For the whole study group, reduced bone formation and unchanged bone resorption, assessed by bone‐specific alkaline phosphatase (BALP) (p = 0.0006, ES = –0.83) and C‐terminal cross‐linking telopeptide of type I collagen (CTX), respectively, were found over the study period. However, BALP decreased less in the nusinersen treatment group, which suggests a positive development on bone mass in these patients.
Conclusion
Bone health evaluation is important in follow‐up programmes for SMA patients. Further investigations are warranted for individuals on survival motor neuron‐targeted treatments.
Local intramuscular administration of the antisense oligonucleotide PRO051 in patients with Duchenne's muscular dystrophy with relevant mutations was previously reported to induce the skipping of ...exon 51 during pre-messenger RNA splicing of the dystrophin gene and to facilitate new dystrophin expression in muscle-fiber membranes. The present phase 1-2a study aimed to assess the safety, pharmacokinetics, and molecular and clinical effects of systemically administered PRO051.
We administered weekly abdominal subcutaneous injections of PRO051 for 5 weeks in 12 patients, with each of four possible doses (0.5, 2.0, 4.0, and 6.0 mg per kilogram of body weight) given to 3 patients. Changes in RNA splicing and protein levels in the tibialis anterior muscle were assessed at two time points. All patients subsequently entered a 12-week open-label extension phase, during which they all received PRO051 at a dose of 6.0 mg per kilogram per week. Safety, pharmacokinetics, serum creatine kinase levels, and muscle strength and function were assessed.
The most common adverse events were irritation at the administration site and, during the extension phase, mild and variable proteinuria and increased urinary α(1)-microglobulin levels; there were no serious adverse events. The mean terminal half-life of PRO051 in the circulation was 29 days. PRO051 induced detectable, specific exon-51 skipping at doses of 2.0 mg or more per kilogram. New dystrophin expression was observed between approximately 60% and 100% of muscle fibers in 10 of the 12 patients, as measured on post-treatment biopsy, which increased in a dose-dependent manner to up to 15.6% of the expression in healthy muscle. After the 12-week extension phase, there was a mean (±SD) improvement of 35.2±28.7 m (from the baseline of 384±121 m) on the 6-minute walk test.
Systemically administered PRO051 showed dose-dependent molecular efficacy in patients with Duchenne's muscular dystrophy, with a modest improvement in the 6-minute walk test after 12 weeks of extended treatment. (Funded by Prosensa Therapeutics; Netherlands National Trial Register number, NTR1241.).
We studied the biomarker patterns related to axonal injury, astrogliosis and amyloid metabolism in cerebrospinal fluid (CSF) of children and adolescents with mitochondrial encephalopathy and ...identified correlations with phenotype and survival outcome. Forty-six pediatric patients with genetically verified mitochondrial encephalopathy and twenty-two controls investigated at the Queen Silvia Children's Hospital, Sweden, were included. CSF lactate and neurofilament light (NF-L) were significantly increased in patients with mitochondrial encephalopathy compared to controls. Elevated CSF NF-L was associated with abnormal brain MRI and poorer survival. We suggest that CSF NF-L may be used in both clinical and research settings for monitoring the neurodegenerative process in mitochondrial disease.
Mitochondrial myopathies are a heterogeneous group of disorders associated with a wide range of clinical phenotypes. We present a 16-year-old girl with a history of exercise intolerance since ...childhood. Acylcarnitine species suggestive of multiple acyl-CoA dehydrogenase deficiency were found in serum, however genetic analysis did not reveal variants in genes associated with this disorder. Biochemical analyses of skeletal muscle mitochondria revealed an isolated and extremely low activity of cytochrome c oxidase (COX). This finding was confirmed by enzyme histochemistry, which demonstrated an almost complete absence of fibers with normal COX activity. Whole-exome sequencing revealed a single base-pair deletion (m.8088delT) in MT-CO2, which encodes subunit 2 of COX, resulting in a premature stop codon. Restriction fragment length polymorphism-analysis confirmed mtDNA heteroplasmy with high mutant load in skeletal muscle, the only clinically affected tissue, but low levels in other investigated tissues. Single muscle fiber analysis showed segregation of the mutant genotype with respiratory chain dysfunction. Immuno-histochemical studies indicated that the truncating variant in COX2 has an inhibitory effect on the assembly of the COX holoenzyme.
Summary Background Muscle biopsy is the gold standard for diagnosis of mitochondrial disorders because of the lack of sensitive biomarkers in serum. Fibroblast growth factor 21 (FGF-21) is a growth ...factor with regulatory roles in lipid metabolism and the starvation response, and concentrations are raised in skeletal muscle and serum in mice with mitochondrial respiratory chain deficiencies. We investigated in a retrospective diagnostic study whether FGF-21 could be a biomarker for human mitochondrial disorders. Methods We assessed samples from adults and children with mitochondrial disorders or non-mitochondrial neurological disorders (disease controls) from seven study centres in Europe and the USA, and recruited healthy volunteers (healthy controls), matched for age where possible, from the same centres. We used ELISA to measure FGF-21 concentrations in serum or plasma samples (abnormal values were defined as >200 pg/mL). We compared these concentrations with values for lactate, pyruvate, lactate-to-pyruvate ratio, and creatine kinase in serum or plasma and calculated sensitivity, specificity, and positive and negative predictive values for all biomarkers. Findings We analysed serum or plasma from 67 patients (41 adults and 26 children) with mitochondrial disorders, 34 disease controls (22 adults and 12 children), and 74 healthy controls. Mean FGF-21 concentrations in serum were 820 (SD 1151) pg/mL in adult and 1983 (1550) pg/mL in child patients with respiratory chain deficiencies and 76 (58) pg/mL in healthy controls. FGF-21 concentrations were high in patients with mitochondrial disorders affecting skeletal muscle but not in disease controls, including those with dystrophies. In patients with abnormal FGF-21 concentrations in serum, the odds ratio of having a muscle-manifesting mitochondrial disease was 132·0 (95% CI 38·7–450·3). For the identification of muscle-manifesting mitochondrial disease, the sensitivity was 92·3% (95% CI 81·5–97·9%) and specificity was 91·7% (84·8–96·1%). The positive and negative predictive values for FGF-21 were 84·2% (95% CI 72·1–92·5%) and 96·1 (90·4–98·9%). The accuracy of FGF-21 to correctly identify muscle-manifesting respiratory chain disorders was better than that for all conventional biomarkers. The area under the receiver-operating-characteristic curve for FGF-21 was 0·95; by comparison, the values for other biomarkers were 0·83 lactate (p=0·037, 0·83 for pyruvate (p=0·015), 0·72 for the lactate-to-pyruvate ratio (p=0·0002), and 0·77 for creatine kinase (p=0·013). Interpretation Measurement of FGF-21 concentrations in serum identified primary muscle-manifesting respiratory chain deficiencies in adults and children and might be feasible as a first-line diagnostic test for these disorders to reduce the need for muscle biopsy. Funding Sigrid Jusélius Foundation, Jane and Aatos Erkko Foundation, Molecular Medicine Institute of Finland, University of Helsinki, Helsinki University Central Hospital, Academy of Finland, Novo Nordisk, Arvo and Lea Ylppö Foundation.
Large-scale mitochondrial DNA deletions (LMD) are a common genetic cause of mitochondrial disease and give rise to a wide range of clinical features. Lack of longitudinal data means the natural ...history remains unclear. This study was undertaken to describe the clinical spectrum in a large cohort of patients with paediatric disease onset.
A retrospective multicentre study was performed in patients with clinical onset <16 years of age, diagnosed and followed in seven European mitochondrial disease centres.
A total of 80 patients were included. The average age at disease onset and at last examination was 10 and 31 years, respectively. The median time from disease onset to death was 11.5 years. Pearson syndrome was present in 21%, Kearns-Sayre syndrome spectrum disorder in 50% and progressive external ophthalmoplegia in 29% of patients. Haematological abnormalities were the hallmark of the disease in preschool children, while the most common presentations in older patients were ptosis and external ophthalmoplegia. Skeletal muscle involvement was found in 65% and exercise intolerance in 25% of the patients. Central nervous system involvement was frequent, with variable presence of ataxia (40%), cognitive involvement (36%) and stroke-like episodes (9%). Other common features were pigmentary retinopathy (46%), short stature (42%), hearing impairment (39%), cardiac disease (39%), diabetes mellitus (25%) and renal disease (19%).
Our study provides new insights into the phenotypic spectrum of childhood-onset, LMD-associated syndromes. We found a wider spectrum of more prevalent multisystem involvement compared with previous studies, most likely related to a longer time of follow-up.
Storage of glycogen is essential for glucose homeostasis and for energy supply during bursts of activity and sustained muscle work. We describe three siblings with profound muscle and heart glycogen ...deficiency caused by a homozygous stop mutation (R462-->ter) in the muscle glycogen synthase gene. The oldest brother died from sudden cardiac arrest at the age of 10.5 years. Two years later, an 11-year-old brother showed muscle fatigability, hypertrophic cardiomyopathy, and an abnormal heart rate and blood pressure while exercising; a 2-year-old sister had no symptoms. In muscle-biopsy specimens obtained from the two younger siblings, there was lack of glycogen, predominance of oxidative fibers, and mitochondrial proliferation. Glucose tolerance was normal.
The differential mechanism of action of vamorolone compared to traditional corticosteroid anti-inflammatory drugs is attributed to the loss of gene transcriptional activities associated with ...glucocorticoid response element binding and activation, potent antagonist activity for the mineralocorticoid receptor, superior membrane stabilization properties, and retention of the distinct NFκB inhibitory (anti-inflammatory) activities 3,5–7). Safety endpoints (linear growth, body mass index) are also compared with data from a 12-month trial of daily prednisone (0.75 mg/kg group) in similar-aged boys with DMD 17. Methods Ethics statement All studies had appropriate approvals by ethics committees or institutional review boards, as required by the 11 participating international academic clinical recruitment sites: (Duke University, Durham, NC, US; Alberta Children’s Hospital, Calgary, AB, Canada; Nemours Children’s Hospital, Orlando, FL, US; John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK; Queen Silvia Children’s Hospital, Gothenburg, Sweden; Schneider Children’s Medical Center, Tel Aviv University, Petah Tikvah, Israel; Royal Children’s Hospital and Murdoch Children’s Research Institute, Melbourne, VIC, Australia; The Children’s Hospital at Westmead, Sydney, NSW, Australia; University of Texas Southwestern Medical Center, Dallas, TX, US; Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, US; University of California Davis, Davis, CA, US). ...the total duration of corticosteroid treatment was longer than 18 months for most participants.
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