Emery-Dreifuss Muscular Dystrophy Research Articles

Net39 protects muscle nuclei from mechanical stress during the pathogenesis of Emery-Dreifuss muscular dystrophy.

Mutations in genes encoding nuclear envelope proteins lead to diseases known as nuclear envelopathies, characterized by skeletal muscle and heart abnormalities, such as Emery-Dreifuss muscular dystrophy (EDMD). The tissue-specific role of the nuclear envelope in the etiology of these diseases has not been extensively explored. We previously showed that global deletion of the muscle-specific nuclear envelope protein NET39 in mice leads to neonatal lethality due to skeletal muscle dysfunction. To study the potential role of the Net39 gene in adulthood, we generated a muscle-specific conditional knockout (cKO) of Net39 in mice. cKO mice recapitulated key skeletal muscle features of EDMD, including muscle wasting, impaired muscle contractility, abnormal myonuclear morphology, and DNA damage. The loss of Net39 rendered myoblasts hypersensitive to mechanical stretch, resulting in stretch-induced DNA damage. Net39 was downregulated in a mouse model of congenital myopathy, and restoration of Net39 expression through AAV gene delivery extended life span and ameliorated muscle abnormalities. These findings establish NET39 as a direct contributor to the pathogenesis of EDMD that acts by protecting against mechanical stress and DNA damage.

LMNA-related muscular dystrophy: Identification of variants in alternative genes and personalized clinical translation.

Background: Laminopathies are caused by rare alterations in LMNA, leading to a wide clinical spectrum. Though muscular dystrophy begins at early ages, disease progression is different in each patient. We investigated variability in laminopathy phenotypes by performing a targeted genetic analysis of patients diagnosed with LMNA-related muscular dystrophy to identify rare variants in alternative genes, thereby explaining phenotypic differences. Methods: We analyzed 105 genes associated with muscular diseases by targeted sequencing in 26 pediatric patients of different countries, diagnosed with any LMNA-related muscular dystrophy. Family members were also clinically assessed and genetically analyzed. Results: All patients carried a pathogenic rare variant in LMNA. Clinical diagnoses included Emery-Dreifuss muscular dystrophy (EDMD, 13 patients), LMNA-related congenital muscular dystrophy (L-CMD, 11 patients), and limb-girdle muscular dystrophy 1B (LGMD1B, 2 patients). In 9 patients, 10 additional rare genetic variants were identified in 8 genes other than LMNA. Genotype-phenotype correlation showed additional deleterious rare variants in five of the nine patients (3 L-CMD and 2 EDMD) with severe phenotypes. Conclusion: Analysis f known genes related to muscular diseases in close correlation with personalized clinical assessments may help identify additional rare variants of LMNA potentially associated with early onset or most severe disease progression.

Anesthesia and rare neuromuscular diseases

Neuromuscular diseases, although rare in the general population, can be present in people who need to undergo surgery and anesthesia. Fortunately, the possibility of early diagnosis, new therapeutic approaches and the application of a multidisciplinary approach have significantly extended the life expectancy of such patients. The presence of such a disorder represents a challenge in anesthesiology practice, both during the preparation for surgery itself, the operative procedure and postoperative recovery in intensive care units. A basic understanding of the main disorders of the disease and their potential interactions with the anesthetic itself and the necessary agents in anesthesiology is necessary in order to reduce the risk of perioperative morbidity and mortality, with the aim of reducing the possibility of complications. Rare muscle diseases are very difficult to classify in a standard way because of the variability of their etiology and pathology. This work focuses on a number of muscle diseases such as Dubowitz syndrome, rhabdomyosarcoma in children, spinal muscular atrophy, Kennedy's disease, Congenital muscular dystrophy of the Ullrich type (UCMD), Sotos syndrome, Polymyositis and Setleis syndrome, Nemaline rod myopathy, Pompe disease, Emery-Dreifuss muscular dystrophy (EDMD). The medical literature on anesthetic techniques and perioperative complications was reviewed. Given that they can have a very unfavorable effect on the course of general anesthesia in particular and that these diseases can cause very serious, even life-threatening complications, an adequate anesthesiological approach is very important to reduce the possibility of the mentioned complications. A multidisciplinary approach is imperative for such patients before and after surgery, whether it is performed under analgosedation, some type of regional or general anesthesia. The operative procedure itself must be performed in institutions that are adequately equipped to treat such patients and by personnel who have experience in treating them.

Characterization of cardiac involvement in children with LMNA-related muscular dystrophy.

Introduction: LMNA-related muscular dystrophy is a rare entity that produce "laminopathies" such as Emery-Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B (LGMD1B), and LMNA-related congenital muscular dystrophy (L-CMD). Heart failure, malignant arrhythmias, and sudden death may occur. No consensus exists on cardiovascular management in pediatric laminopathies. The aim was to perform an exhaustive cardiologic follow-up in pediatric patients diagnosed with LMNA-related muscular dystrophy. Methods: Baseline cardiac work-up consisted of clinical assessment, transthoracic Doppler echocardiography, 12-lead electrocardiogram, electrophysiological study, and implantation of a long-term implantable cardiac loop recorder (ILR). Results: We enrolled twenty-eight pediatric patients diagnosed with EDMD (13 patients), L-CMD (11 patients), LGMD1B (2 patients), and LMNA-related mild weakness (2 patients). Follow-up showed dilated cardiomyopathy (DCM) in six patients and malignant arrhythmias in five (four concomitant with DCM) detected by the ILR that required implantable cardioverter defibrillator (ICD) implantation. Malignant arrhythmias were detected in 20% of our cohort and early-onset EDMD showed worse cardiac prognosis. Discussion: Patients diagnosed with early-onset EDMD are at higher risk of DCM, while potentially life-threatening arrhythmias without DCM appear earlier in L-CMD patients. Early onset neurologic symptoms could be related with worse cardiac prognosis. Specific clinical guidelines for children are needed to prevent sudden death.

Nuclear envelope transmembrane proteins involved in genome organization are misregulated in myotonic dystrophy type 1 muscle.

Myotonic dystrophy type 1 is a multisystemic disorder with predominant muscle and neurological involvement. Despite a well described pathomechanism, which is primarily a global missplicing due to sequestration of RNA-binding proteins, there are still many unsolved questions. One such question is the disease etiology in the different affected tissues. We observed alterations at the nuclear envelope in primary muscle cell cultures before. This led us to reanalyze a published RNA-sequencing dataset of DM1 and control muscle biopsies regarding the misregulation of NE proteins. We could identify several muscle NE protein encoding genes to be misregulated depending on the severity of the muscle phenotype. Among these misregulated genes were NE transmembrane proteins (NETs) involved in nuclear-cytoskeletal coupling as well as genome organization. For selected genes, we could confirm that observed gene-misregulation led to protein expression changes. Furthermore, we investigated if genes known to be under expression-regulation by genome organization NETs were also misregulated in DM1 biopsies, which revealed that misregulation of two NETs alone is likely responsible for differential expression of about 10% of all genes being differentially expressed in DM1. Notably, the majority of NETs identified here to be misregulated in DM1 muscle are mutated in Emery-Dreifuss muscular dystrophy or clinical similar muscular dystrophies, suggesting a broader similarity on the molecular level for muscular dystrophies than anticipated. This shows not only the importance of muscle NETs in muscle health and disease, but also highlights the importance of the NE in DM1 disease progression.

954 DILATED CARDIOMYOPATHY AND ATRIOVENTRICULAR BLOCK RELATED TO THE MUTATION IN THE LMNE GENE: DESCRIPTION OF A FAMILY

Abstract The proband was patient A2, suffering by severe left ventricular dysfunction (EF 20%) and II degree Mobitz type 1 atrioventricular block, requiring dual chamber ICD implantation, and retinitis pigmentosa. He had three brothers A1, A4, A5 suffering also by dilated cardiomyopathy and ICD/CRTD recipients. His sister A3, his daughter B1 and the firstborn brother A1 were also affected by retinitis pigmentosa. Genetic analysis was performed in A2 by NGS of a panel of genes related to heart disease and retinitis pigmentosa. It documented the presence of a missense pathogenetic variant (class 4) of the LMNA gene in heterozygosis (c.949G>A). This variant has been described in several scientific papers as associated with cardiac impairment in patients suffering from atrioventricular block and dilated cardiomyopathy. Laminin A/C is a fundamental protein of the nuclear envelope of the cell. Germline mutations in the LMNA gene, present on chromosome 22 (1q22), encoding the A/C lamina, have been causally linked to four different diseases with 42 reported mutations: Dilated cardiomyopathy (DCM) with disease of the conduction system; Limb girdle muscular dystrophy (LGMD); Autosomal dominant variant of Emery-Dreifuss muscular dystrophy (EDMD); Autosomal dominant partial lipodystrophy. LMNA-related dilated cardiomyopathy (DCM) is characterized by left ventricular enlargement and/or reduced systolic function frequently preceded or accompanied by significant conduction system disease. Family studies suggest that conduction system disease commonly precedes the development of DCM by a few years to a decade or more. Conduction system involvement usually starts with disease of the sinus node and/or atrioventricular node that can manifest as sinus bradycardia, sinus node arrest with junctional rhythms, or heart block (commonly first-degree heart block that progresses to second- and third-degree block). The following are also common: symptomatic bradyarrhythmias requiring cardiac pacemakers, supraventricular arrhythmias including atrial flutter, atrial fibrillation, supraventricular tachycardia, and the sick sinus syndrome (i.e., tachycardia-bradycardia syndrome), ventricular arrhythmias including frequent premature ventricular contractions and ventricular tachycardia Sudden cardiac death may occur with progressive disease. Although more malignant, life-threatening arrhythmias may occur with longstanding and usually previously symptomatic DCM, sudden cardiac death can also be the presenting manifestation of LMNA-related DCM, with minimal or no left ventricular dysfunction. In the cardiological setting, the AVB associated with DCM is a reliable marker for LMNA gene molecular screening. Regarding retinitis pigmentosa, the variant in heterozygosis c538C>G was found in the RHO gene in the proband, classifiable as pathogenetic. This gene encodes a protein necessary for the function of retinal photoreceptors and pathogenic mutations have been found in 30-40% of hereditary forms of retinitis pigmentosa. In conclusion, we believe that the tests carried out confirmed the hypothesis of a hereditary form of cardiomyopathy and retinitis pigmentosa, which seem to segregate independently in the family. Both mutations can be transmitted in 50% of cases, regardless of sex. For this reason we recommended to extend genetic analysis to all the first-degree relatives (siblings and children).

Metabolic, fibrotic and splicing pathways are all altered in Emery-Dreifuss muscular dystrophy spectrum patients to differing degrees.

Emery-Dreifuss muscular dystrophy (EDMD) is a genetically and clinically variable disorder. Previous attempts to use gene expression changes to find its pathomechanism were unavailing, so we engaged a functional pathway analysis. RNA-Seq was performed on cells from 10 patients diagnosed with an EDMD spectrum disease with different mutations in seven genes. Upon comparing to controls, the pathway analysis revealed that multiple genes involved in fibrosis, metabolism, myogenic signaling and splicing were affected in all patients. Splice variant analysis revealed alterations of muscle-specific variants for several important muscle genes. Deeper analysis of metabolic pathways revealed a reduction in glycolytic and oxidative metabolism and reduced numbers of mitochondria across a larger set of 14 EDMD spectrum patients and 7 controls. Intriguingly, the gene expression signatures segregated the patients into three subgroups whose distinctions could potentially relate to differences in clinical presentation. Finally, differential expression analysis of miRNAs changing in the patients similarly highlighted fibrosis, metabolism and myogenic signaling pathways. This pathway approach revealed a transcriptome profile that can both be used as a template for establishing a biomarker panel for EDMD and direct further investigation into its pathomechanism. Furthermore, the segregation of specific gene changes into distinct groups that appear to correlate with clinical presentation may template development of prognostic biomarkers, though this will first require their testing in a wider set of patients with more clinical information.

Inherited myopathies in patients from Sub-Saharan Africa: Results from a retrospective cohort

The clinical epidemiology of inherited myopathies in sub-Saharan Africa (SSA) is unknown but likely underdiagnosed due to problems of scientific research and social issues. We report a case series of patients born in SSA, evacuated to Portugal through an international health protocol and seen at a single neuromuscular disorders centre, between January/2004 and August/2021. We identified 9 patients (5 males), 35.6 ± 19.3 years-old (10–64), from Cape Verde (n = 4), Angola (n = 2), Sao Tome and Principe (n = 2) and Guinea-Bissau (n = 1), with a delay in diagnosis of 19.7 ± 14.3 years. Seven patients (77.8 %) had positive family history. Most patients had significant morbidity, requiring wheelchair (55.6 %), and nocturnal non-invasive ventilation (55.6 %). The diagnosis included Bethlem myopathy (n = 2), Duchenne muscular dystrophy (n = 2), Emery-Dreifuss muscular dystrophy (n = 1), LGMDR1 (n = 2), LGMDR2 (n = 1), and type-1 myotonic dystrophy (n = 1). Genetic testing was remarkable for 3 mutations previously not described. Despite the small sample, the spectrum of hereditary myopathies in our cohort is like western studies. Further studies are needed to better understand the epidemiology of muscle diseases in SSA.

Autosomal dominant Emery-Dreifuss muscular dystrophy caused by a mutation in the lamin A/C gene identified by exome sequencing: a case report

BackgroundEmery-Dreifuss Muscular Dystrophy (EDMD) is an uncommon genetic disease among the group of muscular dystrophies. EDMD is clinically heterogeneous and resembles other muscular dystrophies. Mutation of the lamin A/C (LMNA) gene, which causes EDMD, also causes many other diseases. There is inter and intrafamilial variability in clinical presentations. Precise diagnosis can help in patient surveillance, especially before they present with cardiac problems. Hence, this paper shows how a molecular work-out by next-generation sequencing can help this group of disorders.Case presentationA 2-year-10-month-old Javanese boy presented to our clinic with weakness in lower limbs and difficulty climbing stairs. The clinical features of the boy were Gower's sign, waddling gait and high CK level. His father presented with elbow contractures and heels, toe walking and weakness of limbs, pelvic, and peroneus muscles. Exome sequencing on this patient detected a pathogenic variant in the LMNA gene (NM_170707: c.C1357T: NP_733821: p.Arg453Trp) that has been reported to cause Autosomal Dominant Emery-Dreifuss muscular dystrophy. Further examination showed total atrioventricular block and atrial fibrillation in the father.ConclusionEDMD is a rare disabling muscular disease that poses a diagnostic challenge. Family history work-up and thorough neuromuscular physical examinations are needed. Early diagnosis is essential to recognize orthopaedic and cardiac complications, improving the clinical management and prognosis of the disease. Exome sequencing could successfully determine pathogenic variants to provide a conclusive diagnosis.

Emerin interacts with histone methyltransferases to regulate repressive chromatin at the nuclear periphery.

X-Linked Emery-Dreifuss muscular dystrophy is caused by mutations in the gene encoding emerin. Emerin is an inner nuclear membrane protein important for repressive chromatin organization at the nuclear periphery. Myogenic differentiation is a tightly regulated process characterized by genomic reorganization leading to coordinated temporal expression of key transcription factors, including MyoD, Pax7, and Myf5. Emerin was shown to interact with repressive histone modification machinery, including HDAC3 and EZH2. Using emerin-null myogenic progenitor cells we established several EDMD-causing emerin mutant lines in the effort to understand how the functional interaction of emerin with HDAC3 regulates histone methyltransferase localization or function to organize repressive chromatin at the nuclear periphery. We found that, in addition to its interaction with HDAC3, emerin interacts with the histone methyltransferases EZH2 and G9a in myogenic progenitor cells. Further, we show enhanced binding of emerin HDAC3-binding mutants S54F and Q133H to EZH2 and G9a. Treatment with small molecule inhibitors of EZH2 and G9a reduced H3K9me2 or H3K27me3 throughout differentiation. EZH2 and G9a inhibitors impaired cell cycle withdrawal, differentiation commitment, and myotube formation in wildtype progenitors, while they had no effect on emerin-null progenitors. Interestingly, these inhibitors exacerbated the impaired differentiation of emerin S54F and Q133H mutant progenitors. Collectively, these results suggest the functional interaction between emerin and HDAC3, EZH2, and G9a are important for myogenic differentiation.

P.145 Identification of potential genetic modifiers underlying phenotypic variability in a French family with striated muscle laminopathies

<i>LMNA</i> gene mutations are responsible for a wide spectrum of disorders called laminopathies, the majority of which affecting striated muscles. Among them, Emery-Dreifuss muscular dystrophy (EDMD) and limb-girdle muscular type 1B (LGMD1B) show skeletal muscle involvement of different severity but share the same cardiac involvement, i.e., dilated cardiomyopathy with conduction system disease (DCM-CD) that can also be present in an isolated manner. Clinical heterogeneity is well known among the <i>LMNA</i> mutation carriers. Modifier genes have been suggested to explain such variability. The <i>LMNA</i> mutation (p.Gln6*), identified in a large French family (named here EMD1), is associated with a wide range of age at onset of myopathic symptoms (AOMS). According to this latter, three phenotypic subgroups have been described within the family: AOMS before 20 years (early AOMS), AOMS after 30 years (late AOMS) and isolated cardiac disease without musculo-skeletal symptoms. Our objective was to identify genetic modifiers underlying the intrafamilial phenotypic variability within EMD1 family. Whole genome sequencing (WGS) was performed in 16 <i>LMNA</i>-mutation carriers exhibiting the 3 phenotypic subgroups in EMD1 family. Among the 12 million variants annotated, 2 splice variants with a potential aggravating effect and 1 intronic variant with a potential protective effect have been identified and are currently under functional validation. Moreover, 4 structural variants have been detected only in early AOMS patients. An identity by descent analysis specific to phenotypic subgroups was performed and identified one region shared on chromosome 1, containing the <i>LMNA</i> gene. Our results suggest that a single genetic modifier may not be solely responsible for phenotypic variability in this family, but that a combination of several factors is more likely.

P.147 Deflazacort treatment in LMNA-related congenital muscular dystrophy: an ongoing Italian cohort pilot study

<i>LMNA</i>-related congenital muscular dystrophy (L-CMD) and <i>LMNA</i>-linked Emery-Dreifuss muscular dystrophy (EDMD2) with early onset (<5 years) may be considered a continuum phenotype. There is no cure for patients with these neuromuscular diseases. Literature data and ongoing clinical approaches suggest the use of steroids. Starting from the collaborative approach and the multidisciplinary effort of the Italian network for laminopathies, we are planning an open-label prospective cohort pilot study aimed to: <i>1)</i> evaluate the effect of the treatment with deflazacort in a cohort of 20 L-CMD or EDMD2 patients with infantile onset, aged 3-30 years; <i>2)</i> analyze the secretome profile at basal condition and during steroid treatment, to evaluate variations and establish a correlation between steroid treatment and clinical outcome; <i>3)</i> validate selected cytokines as biomarkers for L-CMD and EDMD2. Study protocol: Patients will be monitored for a period of six months. Then, they will start therapy with Deflazacort for 12 months. After 12 months, the treatment will be stopped and the patients will continue to be clinically followed every 3 months until the end of the study. Overall, we expect to evaluate whether a 12-month-treatment with deflazacort is effective in improving clinical outcome measures in L-CMD patients. We also expect to identify a panel of cytokines altered in L-CMD that can be considered as biomarkers of disease.

Clinical and genetic characteristics of Emery-Dreifuss muscular dystrophy patients from Turkey: 30 years longitudinal follow-up study

Emery-Dreifuss muscular dystrophy (EDMD) is a rare inherited disorder usually presenting in childhood with early contractures, slowly progressive scapulohumeroperoneal weakness/atrophy and potentially fatal dilated cardiomyopathy with conduction defects. We evaluated clinical and genetic findings of 32 patients with EDMD phenotype from 14 unrelated families, diagnosed at the Department of Neurology, Istanbul Faculty of Medicine between 1989 and 2022. Twenty-three patients from 8 unrelated families were diagnosed with EDMD1 (58%), 5 patients from 3 families with EDMD2 (21%), and 2 patients from 1 family with the rare EDMD3 (7%). Genetic diagnosis was achieved in 12 unrelated kinships with classical EDMD phenotype (86%) by applying panel testing, but no mutation could be determined in 2 patients with classical EDMD phenotype from 2 unrelated families (14%). Three novel pathogenic variants (c.19delC, c.416_417delTT, c.123C > G) in EMD, and a novel (c.1441dupT) heterozygous likely pathogenic variant in LMNA gene were found. This is the largest cohort from Turkey, expanding the genetic spectrum of EDMD, and providing clues for genetic testing of EDMD in Turkey.

Effectiveness of Physical Therapy in Rehabilitation of Muscular Dystrophy (MD) Patients

A category of hereditary genetic diseases known as muscular dystrophies (MD) gradually weaken the muscles, resulting in a growing degree of impairment. Since MD is a progressive disorder, it deteriorates over time. Before impacting the muscles more broadly, it frequently starts by affecting a specific group of muscles. Some forms of MD eventually impair the heart or the respiratory muscles, which makes the condition potentially fatal. Although there is no known treatment for MD, many of its symptoms can be managed with it. MD is brought on by modifications (mutations) in the genes in charge of a person's muscles' composition and functionality. The muscle fibres undergo alterations as a result of the mutations, which obstruct the muscles' capacity to work. This results in growing handicap over time. A person's parents frequently pass on the mutations to their offspring. Your doctor may recommend genetic testing and counselling if there is a family history of MD in order to assess your risk of contracting the illness or passing it on to a child and to go over your alternatives.&#x0D; There are numerous varieties of MD, and each has relatively unique symptoms. Many do not have an impact on life expectancy, and not all types result in severe disability. Among the more prevalent forms of MD are: One of the most prevalent and severe kinds is Duchenne MD, which often affects boys in their early years and has a life expectancy of only 20 to 30 years. Myotonic dystrophy is a type of MD that can appear at any age. Although it does not usually limit life expectancy, those with a severe form of the disease may do so. Facioscapulohumeral MD is a slow-progressing, mostly non-life-threatening kind of MD that can occur in both childhood and adults. Closely linked to Duchenne MD, Becker MD develops later in childhood, is less severe, and often has less of an impact on life expectancy. limb-girdle MD is a set of illnesses that typically appear in late adolescence or early adulthood, some varieties can advance swiftly and pose a serious threat to life, while others proceed more slowly. Oculopharyngeal MD is a kind of MD that often does not shorten life expectancy until a person is between the ages of 50 and 60. Emery-Dreifuss MD is a kind of MD that often manifests in childhood or early adulthood, most sufferers will live at least into middle age.&#x0D; The various kinds of MD can be diagnosed using a wide range of techniques. Depending on when symptoms first show, an illness may be diagnosed at a different age. Investigation of any symptoms, discussion of any family history of MD, physical examination, blood tests, electrical tests on the nerves and muscles, and a muscle biopsy (where a small tissue sample is extracted for testing) are all steps in the diagnosis process. Although there is no known cure for MD, there are numerous therapies that can help with any physical issues or limitations that may arise. These can include mobility assistance, physical therapy, and other physical aids, as well as support groups to help with the emotional and practical effects of MD, drugs - such as steroids to boost muscle strength, or ACE inhibitors and beta blockers to manage cardiac problems, or surgery - to correct postural deformities, such as scoliosis. Methods of mending the genetic alterations and harmed muscles linked to MD are the subject of recent research.

CRISPR/Cas9 genome editing for a correction of LMNA p.H222P mutation using human-induced pluripotent stem cells (hiPSCs)

Cardiomyopathy caused by A-type lamins gene ( LMNA ) mutations is associated with an early development of heart failure and a poor prognosis. Gene editing is a promising approach to cure these monogenic disorders. CRISPR/Cas9-based strategies have recently allowed an in vivo correction of mutations leading to Duchenne muscular dystrophy. We aim to develop a CRISPR/Cas9-based gene editing therapy of the LMNA p.H222P mutation, which leads to Emery Dreifuss muscular dystrophy. The development and testing of this therapy are carried out on patient-specific induced pluripotent stem cells (iPSCs). We first compared the efficiency of several guide RNAs for two Cas9 enzymes (NmCas9 and SpCas9) in HEK cells and in iPSCs. For the correction, asymmetric single-stranded donor matrices were designed by taking 36 bp on the PAM-distal side and 91 bp on the PAM-proximal side, either on the targeting or on the non-targeting strand. Silent mutations were added to prevent edited DNA recutting and allow the identification of the edited strand. In HEK cells, SpCas9 generated double-strand breaks with higher efficiencies than NmCas9. Two guide RNAs for SpCas9 were therefore selected to be tested in iPSCs carrying the LMNA p.H222P mutation: one with higher specificity (G1), and another with higher efficiency (G2). IPSCs nucleofection with the donor matrix on the targeting strand and either G1 or G2 resulted in 48 and 9 clones respectively. This may be due to a higher double-strand cut efficiency for G2 associated with a lower homologous direct repair (HDR) efficiency. Only one clone issued from G1 had efficiently integrated the donor matrix. To improve HDR efficiency, the matrix on the non-targeting strand as well as the addition of small molecules are currently being tested. We succeeded to obtain one corrected clone using our gene-editing strategy. This will allow us to assess the impact of the LMNA p.H222P mutation by comparing the characteristics of cardiomyocytes derived from mutated iPSCs to their isogenic control. However, the correction needs optimization to increase HDR efficiency before being translated in vivo.

Lethal ventricular arrhythmia can be prevented by adjusting the dialysate potassium concentration and the use of anti-arrhythmic agents: a case report and literature review

BackgroundHypokalemia is common in patients with malnutrition undergoing hemodialysis and is often involved in the development of lethal arrhythmia. Moreover, hemodialysis therapy decreases the serum potassium concentration due to potassium removal to the dialysate. However, it is difficult to adjust the dialysate potassium concentration owing to the use of the central dialysate delivery system in Japan. Here, we have presented a case undergoing hemodialysis with dialysate potassium concentration adjustment to prevent ventricular arrhythmia.Case presentationA 56-year-old man with Emery-Dreifuss muscular dystrophy and chronic heart failure was admitted to our hospital and needed subsequent hemodialysis therapy due to renal dysfunction. During hemodialysis, the cardiac resynchronization therapy defibrillator was activated to the treatment of his lethal ventricular arrhythmia. Decreases in serum potassium concentration after hemodialysis and changes in serum potassium concentration during HD were considered the causes of lethal ventricular arrythmia. Therefore, along with using anti-arrhythmic agents, the dialysate potassium concentration was increased from 2.0 to 3.5 mEq/L to minimize changes in the serum potassium concentration during hemodialysis. Post-dialysis hypokalemia disappeared and these changes during hemodialysis were minimized, and no lethal ventricular arrhythmia occurred thereafter.ConclusionsIn this case, we prevented lethal arrhythmia by maintaining the serum potassium concentration by increasing the dialysate potassium concentration, in addition to the use of anti-arrhythmic agents. In the acute phase of patients with frequent lethal arrhythmia undergoing hemodialysis, an increase in dialysate potassium concentration may be an effective method for preventing arrhythmogenic complications.

Genetics and muscle pathology in the diagnosis of muscular dystrophies: An update.

Muscular dystrophies are a clinically and genetically heterogeneous group of disorders involving the skeletal muscles. They have a progressive clinical course and are characterized by muscle fiber degeneration. Congenital muscular dystrophies (CMD) include dystroglycanopathies, merosin-deficient CMD, collagen VI-deficient CMD, SELENON-related rigid spine muscular dystrophy, and LMNA-related CMD. Childhood and adult-onset muscular dystrophies include dystrophinopathies, limb-girdle muscular dystrophies, Emery-Dreifuss muscular dystrophy, facioscapulohumeral muscular dystrophy, and myotonic dystrophy. Traditionally, muscle biopsy and histopathology along with special pathology techniques such as immunohistochemistry or immunoblotting were used for the diagnosis of muscular dystrophies. However, recent advances in molecular genetic testing, especially the next-generation sequencing technology, have revolutionized the diagnosis of muscular dystrophies. Identification of the underlying genetic basis helps in appropriate management and prognostication of the affected individual and genetic counseling of the family. In addition, identification of the exact disease-causing mutations is necessary for accurate prenatal genetic testing and carrier testing, to prevent recurrence in the family. Mutation identification is also essential for initiating mutation-specific therapies (which have been developed recently, especially for Duchenne muscular dystrophy) and for enrolment of patients into ongoing therapeutic clinical trials. The 'genetic testing first' approach has now become the norm in most centers. Nonetheless, muscle biopsy-based testing still has an important role to play, especially for cases where genetic testing is negative or inconclusive for the etiology.

HF-566-04 PATHOGENIC VARIANTS IN EMD ARE ASSOCIATED WITH AN ISOLATED CARDIAC EMERINOPATHY

Emerin (EMD) is an inner nuclear envelope protein critical to the integrity of the nucleoskeleton and mechanotransduction. Loss-of-Function (LoF) variants in EMD results in Emery-Dreifuss muscular dystrophy type 1 (EDMD1). This syndrome is characterized by a proximal skeletal myopathy associated with joint contractures and cardiac conduction disease. Several small reports have suggested that pathogenic EMD variants are associated with a cardiac emerinopathy (cardiomyopathy without evidence of skeletal myopathy).

Identification of a mutation in a Vietnamese family with Emery-Dreifuss Muscular Dystrophy using whole exome sequencing

Emery-Dreifuss muscular dystrophy (EDMD) is a degenerative neuromuscular disease associated with at least nine genes, including EMD, LMNA, FHL1, TMEM43, SUN1, SUN2, TTN, SYNE1, and SYNE2. Herein, we identified a heterozygous missense LMNA mutation (NM_170707.4: c.1357C&gt;T,p.R453W) in three members of a Vietnamese family using whole-exome sequencing (WES), in which the proband was an 11-year-old girl presenting humeroperoneal muscle weaknesses and generalized contracture. Her father and one other relative also exhibited multiple signs of muscular atrophy and contracture. Sanger sequencing in the extended family verified the causative nature of this mutation, establishing a confirmed diagnosis of autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD2). The clinical presentations of each patient in this study are different from each other, demonstrating the intrafamilial phenotypic variability of this mutation. Early identification of the underlying genetic course of the disease by sequencing, combined with clinical findings provides solid evidence to diagnosis process, genetic counseling and management strategy.

Clinical Profile, Arrhythmias, and Adverse Cardiac Outcomes in Emery-Dreifuss Muscular Dystrophies: A Systematic Review of the Literature.

Simple SummaryCardiolaminopathies portend an augmented risk of atrial and ventricular arrhythmias, thromboembolic events, ventricular dysfunction, and mortality. A high level of evidence on the clinical management of cardiac involvement in this setting is still lacking, and strong recommendations cannot be formulated. Our systematic review reported the incidence rates for the main cardiovascular outcomes in 1070 LMNA mutation carriers and 40 EMD mutation carriers, with a minimum follow-up of one-year. Our results stressed the importance of a structured follow-up aiming at the early recognition of atrial arrhythmias and the prevention of thromboembolic events. In patients with a need for pacing, cardioverter–defibrillator implantation should be considered due to the high burden of malignant ventricular arrhythmias.Cardiolaminopathies are a heterogeneous group of disorders which are due to mutations in the genes encoding for nuclear lamins or their binding proteins. The whole spectrum of cardiac manifestations encompasses atrial arrhythmias, conduction disturbances, progressive systolic dysfunction, and malignant ventricular arrhythmias. Despite the prognostic significance of cardiac involvement in this setting, the current recommendations lack strong evidence. The aim of our work was to systematically review the current data on the main cardiovascular outcomes in cardiolaminopathies. We searched PubMed/Embase for studies focusing on cardiovascular outcomes in LMNA mutation carriers (atrial arrhythmias, ventricular arrhythmias, sudden cardiac death, conduction disturbances, thromboembolic events, systolic dysfunction, heart transplantation, and all-cause and cardiovascular mortality). In total, 11 studies were included (1070 patients, mean age between 26–45 years, with follow-up periods ranging from 2.5 years up to 45 ± 12). When available, data on the EMD-mutated population were separately reported (40 patients). The incidence rates (IR) were individually assessed for the outcomes of interest. The IR for atrial fibrillation/atrial flutter/atrial tachycardia ranged between 6.1 and 13.9 events/100 pts–year. The IR of atrial standstill ranged between 0 and 2 events/100 pts-year. The IR for malignant ventricular arrhythmias reached 10.2 events/100 pts–year and 15.6 events/100 pts–year for appropriate implantable cardioverter–defibrillator (ICD) interventions. The IR for advanced conduction disturbances ranged between 3.2 and 7.7 events/100 pts–year. The IR of thromboembolic events reached up to 8.9 events/100 pts–year. Our results strengthen the need for periodic cardiological evaluation focusing on the early recognition of atrial arrhythmias, and possibly for the choice of preventive strategies for thromboembolic events. The frequent need for cardiac pacing due to advanced conduction disturbances should be counterbalanced with the high risk of malignant ventricular arrhythmias that would justify ICD over pacemaker implantation.