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Myotonic Dystrophy Type 1 (DM1): Clinical Characteristics and Disease Progression in a Large Cohort.Neurology India Jan 2024DM1 is a multisystem disorder caused by expansion of a CTG triplet repeat in the 3' non-coding region of DMPK. Neuropsychological consequences and sleep abnormalities...
BACKGROUND
DM1 is a multisystem disorder caused by expansion of a CTG triplet repeat in the 3' non-coding region of DMPK. Neuropsychological consequences and sleep abnormalities are important associations in DM1.
OBJECTIVE
To describe the clinical phenotype, disease progression and characterize the sleep alterations and cognitive abnormalities in a sub-set of patients.
MATERIALS AND METHODS
A retrospective study on 120 genetically confirmed DM1 cases. Findings in neuropsychological assessment and multiple sleep questionnaires were compared with 14 age and sex matched healthy individuals. All 120 patients were contacted through letters/telephonic consultation/hospital visits to record their latest physical and functional disabilities.
RESULTS
The mean age at symptom onset was 23.1 ± 11.4 years, M: F = 3.8:1, mean duration of illness = 14.3 ± 9.5 years. Clinically 54.2% had adult onset form, juvenile = 27.5%, infantile = 10.8%, late adult onset = 7.5%. Paternal transmission occurred more frequently. The predominant initial symptoms were myotonia (37.5%), hand weakness (21.7%), lower limb weakness (23.3%) and bulbar (10%). Twenty patients completed sleep questionnaires (SQ). Abnormal scores were noted in Epworth sleepiness scale (55%); Pittsburgh sleep quality index (45%); Berlin SQ (30%); Rapid eye movement sleep Behaviour Disorder SQ (15%); Restless leg syndrome rating scale (10%). Neuropsychological assessment of 20 patients revealed frontal executive dysfunction, attention impairment and visuospatial dysfunction. Frontal lobe was most affected (72%) followed by parietal (16%) and temporal lobe (12%).
CONCLUSIONS
The current study provides a comprehensive account of the clinical characteristics in Indian patients with DM1. Hypersomnolence was most commonly seen. Excessive daytime sleepiness and Sleep disordered breathing were the most common sleep related abnormality. Cognitive impairment comprised predominantly of frontal lobe dysfunction.
Topics: Adult; Humans; Child; Adolescent; Young Adult; Myotonic Dystrophy; Retrospective Studies; Disease Progression; Myotonia; Disorders of Excessive Somnolence
PubMed: 38443007
DOI: 10.4103/neuroindia.NI_1432_20 -
Transcranial brain parenchyma sonographic findings in patients with myotonic dystrophy type 1 and 2.Heliyon Mar 2024Myotonic dystrophy type 1 (DM1) and 2 (DM2) are genetically determined progressive muscular disorders with multisystemic affection, including brain involvement....
INTRODUCTION
Myotonic dystrophy type 1 (DM1) and 2 (DM2) are genetically determined progressive muscular disorders with multisystemic affection, including brain involvement. Transcranial sonography (TCS) is a reliable diagnostic tool for the investigation of deep brain structures. We sought to evaluate TCS findings in genetically confirmed DM1 and DM2 patients, and further correlate these results with patients' clinical features.
METHODS
This cross-sectional study included 163 patients (102 DM1, 61 DM2). Echogenicity of the brainstem raphe (BR) and substantia nigra (SN) as well as the diameter of the third ventricle (DTV) were assessed by TCS. Patients were evaluated using the Hamilton Depression Rating Scale, Fatigue Severity Scale and Daytime Sleepiness Scale.
RESULTS
SN hyperechogenicity was observed in 40% of DM1 and 34% of DM2 patients. SN hypoechogenicity was detected in 17% of DM1 and 7% of DM2 patients. BR hypoechogenicity was found in 36% of DM1 and 47% of DM2 subjects. Enlarged DTV was noted in 19% of DM1 and 15% of DM2 patients. Older, weaker, depressive, and fatigued DM1 patients were more likely to have BR hypoechogenicity (p < 0.05). DTV correlated with age and disease duration in DM1 (p < 0.01). In DM2 patients SN hyperechogenicity correlated with fatigue. Excessive daytime sleepiness was associated with hypoechogenic BR (p < 0.05) and enlarged DVT (p < 0.01) in DM2 patients.
CONCLUSIONS
TCS is an easy applicable and sensitive neuroimaging technique that could offer new information regarding several brainstem structures in DM1 and DM2. This may lead to better understanding of the pathogenesis of the brain involvement in DM with possible clinical implications.
PubMed: 38434309
DOI: 10.1016/j.heliyon.2024.e26856 -
Journal of Neuromuscular Diseases 2024The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1...
BACKGROUND
The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1 gene. Clinically, they are characterized by myotonia, defined as delayed muscle relaxation after voluntary contraction, which leads to symptoms of muscle stiffness, pain, fatigue, and weakness. Diagnosis is based on history and examination findings, the presence of electrical myotonia on electromyography, and genetic confirmation.
METHODS
Next-generation sequencing including the CLCN1 and SCN4A genes was performed in patients with clinical neuromuscular disorders. Electromyography, Short Exercise Test, in vivo and in vitro electrophysiology, site-directed mutagenesis and heterologous expression were collected.
RESULTS
A heterozygous point mutation (c.1775C > T, p.Thr592Ile) of muscle voltage-gated sodium channel α subunit gene (SCN4A) has been identified in five female patients over three generations, in a family with non-dystrophic myotonia. The muscle stiffness and myotonia involve mainly the face and hands, but also affect walking and running, appearing early after birth and presenting a clear cold sensitivity. Very hot temperatures, menstruation and pregnancy also exacerbate the symptoms; muscle pain and a warm-up phenomenon are variable features. Neither paralytic attacks nor post-exercise weakness has been reported. Muscle hypertrophy with cramp-like pain and increased stiffness developed during pregnancy. The symptoms were controlled with both mexiletine and acetazolamide. The Short Exercise Test after muscle cooling revealed two different patterns, with moderate absolute changes of compound muscle action potential amplitude.
CONCLUSIONS
The p.Thr592Ile mutation in the SCN4A gene identified in this Sardinian family was responsible of clinical phenotype of myotonia.
Topics: Adult; Female; Humans; Middle Aged; Electromyography; Italy; Myotonia; Myotonia Congenita; NAV1.4 Voltage-Gated Sodium Channel; Pedigree; Point Mutation
PubMed: 38427496
DOI: 10.3233/JND-230134 -
Journal of Cardiovascular Development... Feb 2024Myotonic dystrophy is a hereditary disorder with systemic involvement. The Italian Neuro-Cardiology Network-"Rete delle Neurocardiologie" (INCN-RNC) is a unique... (Review)
Review
Myotonic dystrophy is a hereditary disorder with systemic involvement. The Italian Neuro-Cardiology Network-"Rete delle Neurocardiologie" (INCN-RNC) is a unique collaborative experience involving neurology units combined with cardio-arrhythmology units. The INCN facilitates the creation of integrated neuro-cardiac teams in Neuromuscular Disease Centers for the management of cardiovascular involvement in the treatment of myotonic dystrophy type 1 (MD1).
PubMed: 38392277
DOI: 10.3390/jcdd11020063 -
Nature Communications Feb 2024Myotonic dystrophy type 2 (DM2) is a tetranucleotide CCTG repeat expansion disease associated with an increased prevalence of autoimmunity. Here, we identified an...
Myotonic dystrophy type 2 (DM2) is a tetranucleotide CCTG repeat expansion disease associated with an increased prevalence of autoimmunity. Here, we identified an elevated type I interferon (IFN) signature in peripheral blood mononuclear cells and primary fibroblasts of DM2 patients as a trigger of chronic immune stimulation. Although RNA-repeat accumulation was prevalent in the cytosol of DM2-patient fibroblasts, type-I IFN release did not depend on innate RNA immune sensors but rather the DNA sensor cGAS and the prevalence of mitochondrial DNA (mtDNA) in the cytoplasm. Sublethal mtDNA release was promoted by a chronic activation of the ATF6 branch of the unfolded protein response (UPR) in reaction to RNA-repeat accumulation and non-AUG translated tetrapeptide expansion proteins. ATF6-dependent mtDNA release and resulting cGAS/STING activation could also be recapitulated in human THP-1 monocytes exposed to chronic endoplasmic reticulum (ER) stress. Altogether, our study demonstrates a novel mechanism by which large repeat expansions cause chronic endoplasmic reticulum stress and associated mtDNA leakage. This mtDNA is, in turn, sensed by the cGAS/STING pathway and induces a type-I IFN response predisposing to autoimmunity. Elucidating this pathway reveals new potential therapeutic targets for autoimmune disorders associated with repeat expansion diseases.
Topics: Humans; Myotonic Dystrophy; DNA, Mitochondrial; Autoimmunity; Leukocytes, Mononuclear; RNA; Nucleotidyltransferases; Interferon Type I; Autoimmune Diseases; Endoplasmic Reticulum Stress
PubMed: 38378748
DOI: 10.1038/s41467-024-45535-1 -
EClinicalMedicine Jan 2024Myotonic dystrophy type 1 (DM1) is a devastating multisystemic disorder caused by a CTG repeat expansion in the gene, which subsequently triggers toxic RNA expression...
BACKGROUND
Myotonic dystrophy type 1 (DM1) is a devastating multisystemic disorder caused by a CTG repeat expansion in the gene, which subsequently triggers toxic RNA expression and dysregulated splicing. In a preclinical study, we demonstrated that erythromycin reduces the toxicity of abnormal RNA and ameliorates the aberrant splicing and motor phenotype in DM1 model mice.
METHODS
This multicentre, randomised, double-blind, placebo-controlled, phase 2 trial was conducted at three centres in Japan to translate preclinical findings into practical applications in patients with DM1 by evaluating the safety and efficacy of erythromycin. Between Nov 29, 2019, and Jan 20, 2022, a total of 30 adult patients with DM1 were enrolled and randomly assigned in a 1:2:2 ratio to receive either placebo or erythromycin at two daily doses (500 mg or 800 mg) for 24 weeks. The primary outcome included the safety and tolerability of erythromycin. The secondary efficacy measures included splicing biomarkers, 6-min walk test results, muscle strength, and serum creatinine kinase (CK) values. This trial is registered with the Japan Registry of Clinical Trials, jRCT2051190069.
FINDINGS
Treatment-related gastrointestinal symptoms occurred more frequently in the erythromycin group, but all adverse events were mild to moderate and resolved spontaneously. No serious safety concerns were identified. The CK levels from baseline to week 24 decreased in the overall erythromycin group compared with the placebo group (mean change of -6.4 U/L [SD 149] vs +182.8 [SD 228]), although this difference was not statistically significant (p = 0.070). Statistically significant improvements in the overall erythromycin treated groups compared to placebo were seen for two of the eleven splicing biomarkers that were each evaluated in half of the trial sample. These were (p = 0.048) and (p = 0.042).
INTERPRETATION
Erythromycin demonstrated favourable safety and tolerability profiles in patients with DM1. A well-powered phase 3 trial is needed to evaluate efficacy, building on the preliminary findings from this study.
FUNDING
Japan Agency for Medical Research and Development.
PubMed: 38314057
DOI: 10.1016/j.eclinm.2023.102390 -
Diagnostic uplift through the implementation of short tandem repeat analysis using exome sequencing.European Journal of Human Genetics :... May 2024To date, approximately 50 short tandem repeat (STR) disorders have been identified; yet, clinical laboratories rarely conduct STR analysis on exomes. To assess its...
To date, approximately 50 short tandem repeat (STR) disorders have been identified; yet, clinical laboratories rarely conduct STR analysis on exomes. To assess its diagnostic value, we analyzed STRs in 6099 exomes from 2510 families with mostly suspected neurogenetic disorders. We employed ExpansionHunter and REViewer to detect pathogenic repeat expansions, confirming them using orthogonal methods. Genotype-phenotype correlations led to the diagnosis of thirteen individuals in seven previously undiagnosed families, identifying three autosomal dominant disorders: dentatorubral-pallidoluysian atrophy (n = 3), spinocerebellar ataxia type 7 (n = 2), and myotonic dystrophy type 1 (n = 2), resulting in a diagnostic gain of 0.28% (7/2510). Additionally, we found expanded ATXN1 alleles (≥39 repeats) with varying patterns of CAT interruptions in twelve individuals, accounting for approximately 0.19% in the Korean population. Our study underscores the importance of integrating STR analysis into exome sequencing pipeline, broadening the application of exome sequencing for STR assessments.
Topics: Humans; Microsatellite Repeats; Exome Sequencing; Female; Male; Myotonic Dystrophy; Genetic Testing; Ataxin-1; Exome; Adult; DNA Repeat Expansion
PubMed: 38308084
DOI: 10.1038/s41431-024-01542-w -
Journal of Neuromuscular Diseases 2024Myotonic disorders, such as non-dystrophic myotonias (NDMs) and myotonic dystrophies (DMs) are characterized by a delay in muscle relaxation after a contraction...
BACKGROUND
Myotonic disorders, such as non-dystrophic myotonias (NDMs) and myotonic dystrophies (DMs) are characterized by a delay in muscle relaxation after a contraction stimulus. There is general consensus that protocols to treat myotonia need to be implemented.
OBJECTIVE
Mexiletine is the only pharmacological agent approved for the symptomatic treatment of myotonia in adult patients with NDM and is considered to be the first-line treatment for DMs; however, its production in Italy was halted in 2022 making its availability to patients problematic.
METHODS
A panel of 8 Italian neurologists took part in a two-round Delphi panel between June and October 2022, analyzing the current use of mexiletine in Italian clinical practice.
RESULTS
The panelists assist 1126 patients (69% DM type1, 18% NDM and 13% DM type2). Adult NDM patients receive, on average, 400-600 mg of mexiletine hydrochloride (HCl) while adult DM patients receive 100-600 mg, per day in the long-term. The severity of symptoms is considered the main reason to start mexiletine treatment for both NDM and DM patients. Mexiletine is reckoned to have a clinical impact for both NDM and DM patients, but currently drug access is problematic.
CONCLUSIONS
Mexiletine treatment is recognized to have a role in the reduction of the symptomatic burden for NDM and DM patients. Patient management could be improved by facilitating access to therapy and developing new drug formulations.
Topics: Adult; Humans; Mexiletine; Myotonia; Neurologists; Myotonic Dystrophy; Italy
PubMed: 38306059
DOI: 10.3233/JND-230115 -
Acta Clinica Croatica Apr 2023With advancement of medicine in the field of diagnostics and treatment of women suffering from certain genetic disorders, more and more women have attained reproductive...
DILEMMAS ABOUT THE SELECTION OF ANESTHESIA FOR ELECTIVE CESAREAN SECTION IN PREGNANT WOMEN WITH MYOTONIC DYSTROPHY TYPE 2 AND SUSPECTED von WILLEBRAND DISEASE: A CASE REPORT.
With advancement of medicine in the field of diagnostics and treatment of women suffering from certain genetic disorders, more and more women have attained reproductive age and desired fertility. Maintaining pregnancy, as well as bringing it to an end poses a real challenge not only for obstetricians, but also for anesthesiologists involved in the procedure. In our case report, we describe anesthetic management of a female patient suffering from myotonic dystrophy type 2 and suspected von Willebrand's disease, and undergoing elective cesarean section. It is acknowledged that both diseases have their own peculiarities and specificities related to anesthesia and require careful consideration when it comes to selecting it. Bearing in mind the advantages and disadvantages of certain types of anesthesia, we believe that in this case, general anesthesia was a better choice compared to the regional techniques of anesthesia.
Topics: Female; Pregnancy; Humans; Cesarean Section; von Willebrand Diseases; Pregnant Women; Myotonic Dystrophy; Anesthesia, General; Anesthesia, Obstetrical
PubMed: 38304361
DOI: 10.20471/acc.2023.62.01.26 -
Journal of Neuromuscular Diseases 2024Dysphagia is common in adults living with neuromuscular disease (NMD). Increased life expectancy, secondary to improvements in standards of care, requires the...
BACKGROUND
Dysphagia is common in adults living with neuromuscular disease (NMD). Increased life expectancy, secondary to improvements in standards of care, requires the recognition and treatment of dysphagia with an increased priority. Evidence to support the establishment of healthcare pathways is, however, lacking. The experiences of people living with NMD (pplwNMD) and their caregivers are valuable to guide targeted, value-based healthcare.
OBJECTIVE
To generate preliminary considerations for neuromuscular dysphagia care and future research in the United Kingdom, based on the experiences of those living with, or caring for, people with NMD.
METHODS
Two surveys (one for adults living with NMD and dysphagia, and a second for caregivers) were co-designed with an advisory group of people living with NMD. Surveys were electronically distributed to adults living with NMD and their caregivers between 18th May and 26th July 2020. Distribution was through UK disease registries, charity websites, newsletters, and social media.
RESULTS
Adults living with NMD receive little information or education that they are likely to develop swallowing difficulties. Most respondents report wanting this information prior to developing these difficulties. Difficulties with swallowing food and medication are common in this group, and instrumental assessment is considered a helpful assessment tool. Both adults living with NMD and caregivers want earlier access to neuromuscular swallowing specialists and training in how best to manage their difficulties.
CONCLUSIONS
Improvement is needed in the dysphagia healthcare pathway for adults living with NMD to help mitigate any profound physical and psychological consequences that may be caused by dysphagia. Education about swallowing difficulties and early referral to a neuromuscular swallowing specialist are important to pplwNMD and their caregivers. Further research is required to better understand the experiences of pplwNMD and their caregivers to inform the development of dysphagia healthcare pathways.
Topics: Adult; Humans; Deglutition Disorders; Caregivers; Neuromuscular Diseases; United Kingdom; Surveys and Questionnaires
PubMed: 38250781
DOI: 10.3233/JND-230002