Lamin A/C Missense Mutation R216C Pinpoints Overlapping Features Between Brugada Syndrome and Laminopathies

A 31-year-old man experienced at-rest cardiac arrest. After successful resuscitation, the baseline ECG demonstrated sinus rhythm with concave ST segment elevation in right precordial leads (V1–V3) followed by a negative and symmetrical T-wave. Neither coronary artery disease nor electrolytes’ imbalances were detected. In the following days, ECG showed a spontaneous type 1 Brugada ECG pattern (Figure [A1]), more evident with right precordial leads in II and III intercostal spaces. Transthoracic echocardiography (Figure [A2]) failed to show any cardiomyopathy. Cardiac MRI showed normal chambers dimension, wall thickness, volume, and function (left ventricular end diastolic volume, 67.7 mL/m2; IVS, 1 cm; left ventricular end fraction, 59.7%). Late gadolinium enhancement sequences were negative; adipose and fibrous tissue infiltration were excluded. The patient was implanted with a transvenous single chamber cardioverter defibrillator (Medtronic). Several appropriate ICD interventions on VT and ventricular fibrillation were recorded in the following years. Family history (Figure [B]) was positive for sudden cardiac death: the maternal grandfather died at age 45 years, aII degree maternal cousin died during sleep at age 40 years. The proband’s mother showed a first degree atrioventricular block (PR interval=280 ms) and right bundle branch block (Figure [A3]). A neurological examination in the index case and his mother was negative and creatine phosphokinase levels were normal in both. Informed written consent was obtained from all family members. Study was approved by the Local Ethics Committee (152/2013/O/Oss, June 1, 2013). Molecular genetic analysis was performed by next generation sequencing using PED MASTR Plus assay comprising 52 cardiac electrical disorders related genes, SCN5A included (www.agilent.com)

Cyclosporine A in Ullrich Congenital Muscular Dystrophy: Long-Term Results

Six individuals with Ullrich congenital muscular dystrophy (UCMD) and mutations in the genes-encoding collagen VI, aging 5–9, received 3–5 mg/kg of cyclosporine A (CsA) daily for 1 to 3.2 years. The primary outcome measure was the muscle strength evaluated with a myometer and expressed as megalimbs. The megalimbs score showed significant improvement (P = 0.01) in 5 of the 6 patients. Motor function did not change. Respiratory function deteriorated in all. CsA treatment corrected mitochondrial dysfunction, increased muscle regeneration, and decreased the number of apoptotic nuclei. Results from this study demonstrate that long-term treatment with CsA ameliorates performance in the limbs, but not in the respiratory muscles of UCMD patients, and that it is well tolerated. These results suggest considering a trial of CsA or nonimmunosuppressive cyclosporins, that retains the PTP-desensitizing properties of CsA, as early as possible in UCMD patients when diaphragm is less compromised

Biochemical characterization of patients with in-frame or out-of-frame DMD deletions pertinent to Exon 44 or 45 skipping

Importance: In Duchenne muscular dystrophy (DMD), the reading frame of an out-of-frame DMD deletion can be repaired by antisense oligonucleotide (AO)–mediated exon skipping. This creates a shorter dystrophin protein, similar to those expressed in the milder Becker muscular dystrophy (BMD). The skipping of some exons may be more efficacious than others. Patients with exon 44 or 45 skippable deletions (AOs in clinical development) have a less predictable phenotype than those skippable for exon 51, a group in advanced clinical trials. A way to predict the potential of AOs is the study of patients with BMD who have deletions that naturally mimic those that would be achieved by exon skipping. Objective: To quantify dystrophin messenger RNA (mRNA) and protein expression in patients with DMD deletions treatable by, or mimicking, exon 44 or 45 skipping. Design, Setting, and Participants: Retrospective study of nondystrophic controls (n = 2), patients with DMD (n = 5), patients with intermediate muscular dystrophy (n = 3), and patients with BMD (n = 13) at 4 university-based academic centers and pediatric hospitals. Biochemical analysis of existing muscle biopsies was correlated with the severity of the skeletal muscle phenotype. Main Outcomes and Measures: Dystrophin mRNA and protein expression. Results: Patients with DMD who have out-of-frame deletions skippable for exon 44 or 45 had an elevated number of revertant and trace dystrophin expression (approximately 19% of control, using quantitative immunohistochemistry) with 4 of 9 patients presenting with an intermediate muscular dystrophy phenotype (3 patients) or a BMD-like phenotype (1 patient). Corresponding in-frame deletions presented with predominantly mild BMD phenotypes and lower dystrophin levels (approximately 42% of control) than patients with BMD modeling exon 51 skipping (approximately 80% of control). All 12 patients with in-frame deletions had a stable transcript compared with 2 of 9 patients with out-of-frame deletions (who had intermediate muscular dystrophy and BMD phenotypes). Conclusions and Relevance: Exon 44 or 45 skipping will likely yield lower levels of dystrophin than exon 51 skipping, although the resulting protein is functional enough to often maintain a mild BMD phenotype. Dystrophin transcript stability is an important indicator of dystrophin expression, and transcript instability in DMD compared with BMD should be explored as a potential biomarker of response to AOs. This study is beneficial for the planning, execution, and analysis of clinical trials for exon

Recessive mutations in MSTO1 cause mitochondrial dynamics impairment, leading to myopathy and ataxia.

We report here the first families carrying recessive variants in the MSTO1 gene: compound heterozygous mutations were identified in two sisters and in an unrelated singleton case, who presented a multisystem complex phenotype mainly characterized by myopathy and cerebellar ataxia. Human MSTO1 is a poorly studied protein, suggested to have mitochondrial localization and to regulate morphology and distribution of mitochondria. As for other mutations affecting genes involved in mitochondrial dynamics, no biochemical defects typical of mitochondrial disorders were reported. Studies in patients' fibroblasts revealed that MSTO1 protein levels were strongly reduced, the mitochondrial network was fragmented, and the fusion events among mitochondria were decreased, confirming the deleterious effect of the identified variants and the role of MSTO1 in modulating mitochondrial dynamics. We also found that MSTO1 is mainly a cytosolic protein. These findings indicate recessive mutations in MSTO1 as a new cause for inherited neuromuscular disorders with multisystem features.Contract grant sponsors: EU NeurOmics (project N. 2012‐305121‐2); the European Community's Seventh Framework Programme (FP7/2007‐2013); Regione Emilia Romagna; the Telethon (grant GGP15041); the Pierfranco and Luisa Mariani Foundation; the MRC‐QQR (2015‐20120); the ERC advanced grant (FP7‐322424); the NRJ‐Institut de France grant; Telethon Network of Genetic Biobanks (grant GTB12001J); MRC Neuromuscular Centre (for the Biobank); Muscular Dystrophy UK; National Institute for Health Research Biomedical Research Centre at Great Ormond Street Hospital for Children NHS Foundation Trust and University College London

TRANSCRIPTIONAL PROFILING IN DUCHENNE MUSCULAR DYSTROPHY REVEALED A PROFOUND DEREGULATION OF BOTH CIRCADIAN RHYTHM GENES AND GENES INVOLVED IN MUSCLE REGENERATIVE PROCESS AS POSSIBLE NEW DISEASE BIOMARKERS

Introduction: Duchenne muscular dystrophy (DMD) is a severe hereditary muscle wasting disease. It is caused by mutations in the DMD gene, that lead to a complete absence of the protein dystrophin. Different treatments have been developed so far and some of them were successful in ameliorating the disease course, especially due to corticosteroid administration, which have prolonged the autonomous ambulation and the respiratory function. A number of clinical trials (Phase I-IV) are underway, often based on personalized medicine, but still final results have to come. Among these, Eteplirsen (ExonDys51) and Translarna (Ataluren) have received provisional approval as orphan drugs. Circadian rhythm coordinates biological processes with the 24h cycle; its role in maintaining muscle functions is known, both in animal models and in humans. Methods: In order to explore the role of circadian genes in DMD, we designed a low density micro fluidic card-TaqMan based assay, named Fluid-CIRC, including 30 genes related to circadian rhythms and muscle regeneration. These genes were prioritized also based on previous works that documented that circadian genes (Clock) are deregulated in other muscular diseases. We tested gastrocnemius and tibialis anterior muscles from unexercised and exercised mdx mice, these latter both untreated and treated with different drugs currently under active evaluation for their positive effects in the disease. We prioritized the 7 most deregulated genes and performed expression analysis by TaqMan assays in 10 DMD patients with different mutations. We also designed three ELISA antibody-based assays to dose the three mostly deregulated genes (CSNK1ɛ, SIRT1, MYOG) in DMD plasmas. Results: circadian genes were profoundly deregulated in mdx mice, both exercised and unexercised. In untrained mdx mice more than 90% of genes were down-regulated, both in GC and in TA, with the exception of MyoG, Tim and Tgfb1. MyoG, a muscle-specific transcriptional factor involved in muscle differentiation, was the most up-regulated one. Tim, is one of the core clock component genes, and its up-regulation was more evident in TA. Tgfb1, is a key factor involved in fibrosis, and a significant up-regulation was seen in GC. Comparing mdx trained vs untrained mice, we observed an opposite behavior. In GC about 100% of the genes were up-regulated; on the contrary, in TA almost all genes were down-regulated. This peculiar behavior could be explained with the different function and fiber type composition of the two muscles. Among all analyzed genes we selected 7 most de-regulated ones and tested them in treated mdx mice. A trend toward a normalization was clearly evident in all transcripts for almost all the compounds. Only Cry2 was up-regulated but this could possibly be due to the re-established oscillatory pathway of clock core genes. The 7 selected genes were subsequently investigated in muscle biopsies from 10 DMD patients. Most up-regulated genes were CSNK1ɛ, SIRT1, MYOG. In order to explore if such transcript deregulation reflects on protein, we designed an ELISA assay for the up-regulated CSNK1ɛ protein and tested 14 DMD, 2 BMD and 5 male control plasma samples. The CSNK1ɛ showed a variable plasma levels profile however, the sample’s cohort proves to be rather limited and an enlargement of samples number is needed. Conclusion: our data demonstrate for the first time that circadian genes are affected in mdx mice. Arntl, cry1, cry2, sirt1, csnk1ɛ, myod and myog were prioritized and confirmed to be affected also in DMD patients, where MYOG, SIRT1 and CSNK1ɛ were found to be greatly up-regulated. This could suggest a possible role as disease severity biomarkers but a cohort enlargement, including BMD patients, is needed. Furthermore, the normalization trend of all transcripts seen in treated mdx opens the way for the validation of these genes as drug response and monitoring biomarkers for treatments currently under development.Introduzione: la distrofina muscolare di Duchenne (DMD) è una malattia ereditaria grave. Essa è causata da mutazioni del gene DMD che portano all’assenza della proteina distrofina. Diverse terapie sono state sviluppate finora e alcune si sono rivelate efficaci nel migliorare il decorso clinico, in particolare grazie all’ uso di corticosteroidi che hanno prolungato la fase di deambulazione e migliorato la funzione respiratoria. Vari studi clinici (fase I-IV) sono in corso, spesso basati su approcci di medicina personalizzata, ma i risultati non sono ancora disponibili. Tra questi, Eteplirsen (Exon51Dys) e Translarna (Ataluren) hanno avuto l’approvazione come farmaci orfani. Il ritmo circadiano coordina i processi biologici con il caratteristico ciclo di 24h; il suo ruolo nel regolare le funzioni muscolari è noto sia negli animali che nell’uomo. Metodi: allo scopo di studiare il ruolo dei geni del ritmo circadiano nella DMD, abbiamo disegnato ad hoc una micro fluidic card basata su sistemi TaqMan (Fluid-CIRC), che comprende 30 geni del ritmo circadiano e della rigenerazione muscolare. Tali geni sono stati selezionati anche in base a precedenti dati che hanno mostrato che i geni circadiani (Clock) sono deregolati in altre malattie muscolari. Abbiamo analizzato i muscoli gastrocnemio e tibiale anteriore di topi mdx, esercitati e non, e dei primi, sia muscoli non trattati che trattati con composti in corso di valutazione per i loro effetti sulla malattia. Abbiamo poi selezionato i 7 geni più alterati ed analizzata l’espressione con sistemi TaqMan in 10 DMD. Abbiamo inoltre disegnato tre sistemi ELISA per dosare i geni maggiormente up-regolati (CSNK1ɛ, SIRT1, MYOG) nel plasma di DMD. Risultati: i geni circadiani hanno mostrato una profonda de-regolazione negli mdx, sia esercitati che non. Nei non esercitati più del 90% dei geni era down-regolato, sia nel GC che nel TA, fatta eccezione per MyoG, Tim e Tgfb1. MyoG, un fattore di trascrizione muscolare, coinvolto nel differenziamento, era il maggiormente up-regolato. Tim è uno dei geni circadiani e la sua up-regolazione era più evidente nel TA. Tgfb1 è un fattore chiave del processo di fibrosi, e una sua up-regolazione era più evidente nel GC. Il confronto tra non esercitati ed esercitati seguiva un comportamento opposto nei due muscoli. Mentre nel GC circa il 100% dei geni era up-regolato, nel TA tutti i geni erano down-regolati. Questo peculiare comportamento può trovare ragione nella diversa funzione dei due muscoli. Tra i geni analizzati abbiamo poi selezionato i 7 maggiormente de-regolati ed analizzata l’espressione nei topi trattati. Una tendenza verso la normalizzazione era evidente per tutti i trascritti e tutti i composti. I 7 geni selezionati sono stati analizzati in biopsie di 10 pazienti DMD. I geni maggiormente up-regolati erano CSNK1ɛ, SIRT1 e MYOG. Allo scopo di esplorare se tale de-regolazione potesse riflettersi anche a livello proteico, abbiamo disegnato un sistema ELISA per la proteina CSNK1ɛ ed analizzato il plasma di 14 DMD, 2 BMD e 5 controlli. CSNK1ɛ ha mostrato livelli plasmatici variabili ma la coorte di studio è limitata ed un’espansione del numero di pazienti è necessaria. Conclusioni: i dati dimostrano per la prima volta che l’espressione dei geni circadiani è alterata nel topo mdx. Arntl, cry1, cry2, sirt1, csnk1ɛ, myod e myog sono stati prioritizzati e confermati per essere affetti anche in pazienti DMD; MYOG, SIRT1 e CSNK1ɛ sono stati identificati come i maggiormente up-regolati. Ciò suggerisce un possibile ruolo come biomarcatori di severità clinica tuttavia un allargamento della coorte di studio, includendo BMD, è necessaria. Inoltre, il trend verso la normalizzazione di tutti i trascritti osservata nei topi mdx trattati apre interessanti prospettive per la validazione di tali geni come biomarcatori di efficacia per le nuove terapie in via di sviluppo

Huntington's disease-like presentation in Spinocerebellar ataxia type 12

No abstract is available for this article

Paternal germline mosaicism in collagen VI related myopathies

Collagen VI-related disorders are a group of muscular diseases characterized by muscle wasting and weakness, joint contractures, distal laxity, serious respiratory dysfunction and cutaneous alterations, due to mutations in the COL6A1, COL6A2 and COL6A3 genes, encoding for collagen VI, a critical component of the extracellular matrix. The severe Ullrich congenital muscular dystrophy (UCMD) can be due to autosomal recessive mutations in one of the three genes with a related 25% recurrence risk. In the majority of UCMD cases nevertheless, the underlying mutation is thought to arise de novo and the recurrence risk is considered as low

Becker muscular dystrophy due to an intronic splicing mutation inducing a dual dystrophin transcript

We describe a 29-year-old patient who complained of left thigh muscle weakness since he was 23 and of moderate proximal weakness of both lower limbs with difficulty in climbing stairs and running since he was 27. Mild weakness of iliopsoas and quadriceps muscles and muscle atrophy of both the distal forearm and thigh were observed upon clinical examination. He harboured a novel c.1150-3C>G substitution in the DMD gene, affecting the intron 10 acceptor splice site and causing exon 11 skipping and an out-of-frame transcript. However, protein of normal molecular weight but in reduced amounts was observed on Western Blot analysis. Reverse transcription analysis on muscle RNA showed production, via alternative splicing, of a transcript missing exon 11 as well as a low abundant full-length transcript which is enough to avoid the severe Duchenne phenotype. Our study showed that a reduced amount of full length dystrophin leads to a mild form of Becker muscular dystrophy. These results confirm earlier findings that low amounts of dystrophin can be associated with a milder phenotype, which is promising for therapies aiming at dystrophin restoration