Common Dystrophy Research Articles

P.18.1 The DM-Scope registry: Interfacing myotonic dystrophy clinical care and research

Myotonic dystrophy (DM) is a highly variable multisystemic genetic disease and the commonest muscular dystrophy in adults. Such temporal and phenotypic variability poses particular challenges for clinical management and research. By collecting patient data, registries constitute fundamental tools to increase knowledge on rare diseases and to promote research. However, the benefit of collecting data in a real world setting can be counterbalanced by a lower completeness and quality of data. In DM, cognitive impairment further limits patients direct contribution and input from expert clinicians is required. We developed the DM-Scope registry system to gather most relevant clinical and epidemiological data in a large DM population. The general aim is to promote research and to improve clinical practice in the management of patients with DM. Multidisciplinary physicians from rare diseases reference centers use a concise and structured form during patients annual evaluation, while entering and monitoring of data are independently performed by the coordinating center resources. The system provides a permanent online secure access to own patients data and specific tools such as edition of severity graphs and disease synopsis. Other request applications can be used to screen those patients eligible for clinical studies or identifying available biomaterial at the Genethon biobank. The DM-Scope system is broadly used in 31 French neuromuscular centers, gathering up to 1600 DM patients and fully harmonized with the Quebec DM registry (1100 enrolled patients), i.e. the largest collection of standardized data from the myotonic dystrophy population. The registry already supports several ongoing clinical research studies, including natural history and outcome measures assessment studies. In the context of emerging therapeutic approaches, the DM-scope platform constitutes a powerful device to promote a synergic network and DM research in an international multicenter framework.

P.5.9 Clinical and molecular analysis of a large cohort of patients with anoctaminopathy

Recessive mutations in the ANO5 gene cause a spectrum of phenotypes ranging from isolated hyperCKaemia to limb girdle muscular dystrophy (LGMD2L), characterized by adult onset proximal lower limb muscular weakness and raised CK values. The recurrent exon 5 mutation (c.191dupA) has been found in most of the British and German patients so far reported. We performed molecular analysis of the ANO5 gene in a large cohort of undiagnosed patients with clinical suspicion of anoctaminopathy. We identified two pathogenic mutations in 42/205 unrelated patients (21%), while a single change only was found in further 14 patients. Fifteen pathogenic changes were novel. The founder c.191dupA mutation represents 61% of mutated alleles but is confirmed to be less prevalent in non-Northern European populations. Retrospective clinical analysis of patients with 2 mutations corroborates previous finding such as the male predominance and absence of major cardiac or respiratory involvement, as well as very mild late onset cases of both sexes and isolated hyperCKaemia only. Our results also confirm anoctaminopathy as one of the most common adult muscular dystrophies in Northern Europe, with a prevalence of about 20–25% in undiagnosed patients.

Manumycin A corrects aberrant splicing of Clcn1 in myotonic dystrophy type 1 (DM1) mice

Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults and as yet no cure for DM1. Here, we report the potential of manumycin A for a novel DM1 therapeutic reagent. DM1 is caused by expansion of CTG repeat. Mutant transcripts containing expanded CUG repeats lead to aberrant regulation of alternative splicing. Myotonia (delayed muscle relaxation) is the most commonly observed symptom in DM1 patients and is caused by aberrant splicing of the skeletal muscle chloride channel (CLCN1) gene. Identification of small-molecule compounds that correct aberrant splicing in DM1 is attracting much attention as a way of improving understanding of the mechanism of DM1 pathology and improving treatment of DM1 patients. In this study, we generated a reporter screening system and searched for small-molecule compounds. We found that manumycin A corrects aberrant splicing of Clcn1 in cell and mouse models of DM1.

FNIRS evaluation during a phonemic verbal task reveals prefrontal hypometabolism in patients affected by myotonic dystrophy type 1

ObjectiveMyotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, is characterized by a multisystem involvement. Cognitive involvement predominantly affecting frono-temporal functions is an established clinical feature in this disorder. Brain imaging and metabolic studies showed a predominant involvement of fronto-temporal regions in DM1 patients, yet correlation studies among these findings and neuropsychological data gave contrasting results. In order to contribute to clarify the relationship between the metabolic changes documented in the frontal cortex of DM1 patients and a related cognitive task, we applied the functional near-infrared spectroscopy (fNIRS) during the execution of a phonemic verbal fluency task (pVFT). MethodsWe enrolled 29 consecutive right-handed DM1 patients and 30 controls. A 2-channel fNIRS imaging system was used to investigate changes in oxygenated [O2Hb] and deoxygenated [HHb] hemoglobin concentrations in the prefrontal cortex (PFC) during a pVFT. [O2Hb] and [HHb] baseline-corrected activation values were calculated (respectively [O2Hb]c and [HHb]c). ResultsIn the control group [O2Hb] significantly increased and [HHb] significantly decreased during the pVFT, in the DM1 group no significant variation was found for both parameters revealing no activation of both PFCs during the task. On the other hand, in the DM1 sample, statistical analysis revealed a direct correlation between [O2Hb]c of the left PFC and the pVFT score, while no correlation was observed in the control group. ConclusionsOur study reveals that DM1 patients show prefrontal hypometabolism during a specific frontal cognitive task compared to controls. Moreover the rapid temporal discrimination of fNIRS allows revealing the correlation between the PFC hypometabolism and the cognitive performance in DM1 patients. SignificancefNIRS can be helpful to understand the functional correlates of the frontal cognitive impairment in DM1.

The effect of rocuronium and sugammadex on neuromuscular blockade in a child with congenital myotonic dystrophy type 1

Myotonic dystrophy type 1 (MD1) is the commonest muscular dystrophy found in adults; however, it may present in the neonatal period with hypotonia, talipes, poor feeding, and respiratory failure. Inheritance is autosomal dominant with a defect in the DMPK gene found on the long arm of chromosome 19 with variable expansion of the cytosine-thymine-guanine (CTG) triplet repeat. A 14-month-old boy with congenital MD type 1 was scheduled for percutaneous endoscopic gastrostomy (PEG) insertion, orchidopexy, and division of tongue-tie. Following induction of anesthesia, acceleromyography was used to monitor neuromuscular function. This revealed a very rapid onset of profound neuromuscular block which lasted significantly longer than would be expected in a child without MD1. Sugammadex reversed the block rapidly. The anesthetic management of children with MD1 has been well described but not the acceleromyographic monitored use of rocuronium and its subsequent reversal with the new cyclodextrin sugammadex.

ANO5Gene Analysis in a Large Cohort of Patients with Anoctaminopathy: Confirmation of Male Prevalence and High Occurrence of the Common Exon 5 Gene Mutation

Limb girdle muscular dystrophy type 2L or anoctaminopathy is a condition mainly characterized by adult onset proximal lower limb muscular weakness and raised CK values, due to recessive ANO5 gene mutations. An exon 5 founder mutation (c.191dupA) has been identified in most of the British and German LGMD2L patients so far reported. We aimed to further investigate the prevalence and spectrum of ANO5 gene mutations and related clinical phenotypes, by screening 205 undiagnosed patients referred to our molecular service with a clinical suspicion of anoctaminopathy. A total of 42 unrelated patients had two ANO5 mutations (21%), whereas 14 carried a single change. We identified 34 pathogenic changes, 15 of which are novel. The c.191dupA mutation represents 61% of mutated alleles and appears to be less prevalent in non-Northern European populations. Retrospective clinical analysis corroborates the prevalently proximal lower limb phenotype, the male predominance and absence of major cardiac or respiratory involvement. Identification of cases with isolated hyperCKaemia and very late symptomatic male and female subjects confirms the extension of the phenotypic spectrum of the disease. Anoctaminopathy appears to be one of the most common adult muscular dystrophies in Northern Europe, with a prevalence of about 20%-25% in unselected undiagnosed cases.

Vascular-targeted therapies for Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy and an X-linked recessive, progressive muscle wasting disease caused by the absence of a functional dystrophin protein. Dystrophin has a structural role as a cytoskeletal stabilization protein and protects cells against contraction-induced damage. Dystrophin also serves a signaling role through mechanotransduction of forces and localization of neuronal nitric oxide synthase (nNOS), which produces nitric oxide (NO) to facilitate vasorelaxation. In DMD, the signaling defects produce inadequate tissue perfusion caused by functional ischemia due to a diminished ability to respond to shear stress induced endothelium-dependent dilation. Additionally, the structural defects seen in DMD render myocytes with an increased susceptibility to mechanical stress. The combination of both defects is necessary to generate myocyte damage, which induces successive rounds of myofiber degeneration and regeneration, loss of calcium homeostasis, chronic inflammatory response, fibrosis, and myonecrosis. In individuals with DMD, these processes inevitably cause loss of ambulation shortly after the first decade and an abbreviated life with death in the third or fourth decade due to cardio-respiratory anomalies. There is no known cure for DMD, and although the culpable gene has been identified for more than twenty years, research on treatments has produced few clinically relevant results. Several recent studies on novel DMD therapeutics are vascular targeted and focused on attenuating the inherent functional ischemia. One approach improves vasorelaxation capacity through pharmaceutical inhibition of either phosphodiesterase 5 (PDE5) or angiotensin-converting enzyme (ACE). Another approach increases the density of the underlying vascular network by inducing angiogenesis, and this has been accomplished through either direct delivery of vascular endothelial growth factor (VEGF) or by downregulating the VEGF decoy-receptor type 1 (VEGFR-1 or Flt-1). The pro-angiogenic approaches also seem to be pro-myogenic and could resolve the age-related decline in satellite cell (SC) quantity seen in mdx models through expansion of the SC juxtavascular niche. Here we review these four vascular targeted treatment strategies for DMD and discuss mechanisms, proof of concept, and the potential for clinical relevance associated with each therapy.

Structural myocardial involvement in adult patients with type 1 myotonic dystrophy

Myotonic dystrophy type 1 (DM1) is the commonest muscular dystrophy in adults, affecting multiple organs in addition to skeletal muscles. Cardiac conduction system abnormalities are well recognized as an important component of DM1 phenotype; however, primary structural myocardial abnormalities, which may predispose these patients to congestive heart failure, are not as well characterized. We reviewed the retrospective analysis of the clinical and echocardiographic findings in adult patients with DM1. Among 27 patients (16 male; age 19–61 years) with DM1, the echocardiogram (ECHAO) was abnormal in 10 (37%) including one of 6 patients (16%) with congenital myotonic dystrophy. Reduced left ventricular ejection fraction (LVEF ≤50%) was noted in 5, diastolic dysfunction in 4, left atrial dilatation in 3, left ventricular hypertrophy in 2, apical hypokinesia in 1 and mitral valve prolapse in 3 patients. One patient had paradoxical septal movement in the setting of left bundle branch block. Echocardiographic abnormalities significantly correlated with older age; however, patients with systolic dysfunction on echocardiogram ranged in age from 27 to 52 years including 2 patients aged 27 and 34 years. We can conclude that echocardiographic abnormalities are frequent in adult patients with DM1. The incidence is similar in the classical and congenital type of DM1. Overall, echocardiographic abnormalities in DM1 correlate with increasing age; however, reduced LVEF is observed even at young age. Cardiac assessment and monitoring in adult patients with DM1 should include evaluation for primary myocardial involvement.

Molecular genetics and genetic testing in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is the most common adult onset muscular dystrophy, presenting as a multisystemic disorder with extremely variable clinical manifestation, from asymptomatic adults to severely affected neonates. A striking anticipation and parental-gender effect upon transmission are distinguishing genetic features in DM1 pedigrees. It is an autosomal dominant hereditary disease associated with an unstable expansion of CTG repeats in the 3′-UTR of the DMPK gene, with the number of repeats ranging from 50 to several thousand. The number of CTG repeats broadly correlates with both the age-at-onset and overall severity of the disease. Expanded DM1 alleles are characterized by a remarkable expansion-biased and gender-specific germline instability, and tissue-specific, expansion-biased, age-dependent, and individual-specific somatic instability. Mutational dynamics in male and female germline account for observed anticipation and parental-gender effect in DM1 pedigrees, while mutational dynamics in somatic tissues contribute toward the tissue-specificity and progressive nature of the disease. Genetic test is routinely used in diagnostic procedure for DM1 for symptomatic, asymptomatic, and prenatal testing, accompanied with appropriate genetic counseling and, as recommended, without predictive information about the disease course. We review molecular genetics of DM1 with focus on those issues important for genetic testing and counseling.

Von Hippel–Lindau and myotonic dystrophy of Steinert along with pancreatic neuroendocrine tumor and renal clear cell carcinomal neoplasm: Case report and review of the literature

INTRODUCTIONMyotonic dystrophy of Steinert, DM1, is the most common adult muscular dystrophy and generally is not associated to development on multiple site neoplasm. Von Hippel-Lindau (VHL) disease is a dominantly inherited familial cancer syndrome that is associated to tumors such as hemangioblastoma of the retina or central nervous system, clear-cell renal carcinoma (RCC) and endocrine tumors, most commonly pheochromocytoma and non-secretory pancreatic islet cell cancers. No data exist in literature describing the coexistence of both DM1 and VHL. PRESENTATION OF CASEHerein we report a case of renal and pancreatic neoplasm in a young adult female affected by DM1 and VHL simultaneously. DISCUSSIONDM1 is due to an unstable trinucleotide (CTG) expansion in the 30 antranslated region of the dystrophia myotonica-protein kinase (DMPK) gene, located on chromosome 19q13.3. Several molecular mechanisms thought to be determining the classical DM phenotype have been shown. VHL disease is characterized by marked phenotypic variability and the most common tumors are hemangioblastomas of the retina or central nervous system, clear-cell renal carcinoma (RCC) and endocrine tumors, most commonly pheochromocytoma and non-secretory pancreatic islet cell cancers. The pancreatic manifestations seen in patients with VHL disease are divided into 2 categories: pancreatic neuroendocrine tumor (PNET) as solid tumors, and cystic lesions, including a simple cyst and serous cystadenoma. The surgical approach for these cistic lesions is to consider as golden standard. Blansfield has proposed 3 criteria to predict metastatic disease of PNET in patients with VHL disease: (1) tumor size greater than or equal to 3cm; (2) presence of a mutation in exon 3; and (3) tumor doubling time less than 500d. If the patient has none of these criteria the patient could be followed with physical examination and radiological surveillance on a 2/3 years base.4 If the patient has 1 criterion, the patient should be followed more closely every 6 months to 1 year. If the patient has 2 or 3 criteria, the patient should be considered for surgery given the high risk of future malignancy. Our patient owned only one criterion but in presence of a second malignant tumor. Our hypothesis for this rare findings is that both DM and VHL might be derived from genetic aberration and these might be linked to a major cancer susceptibility. As far as we know this is the first confirmed case of RCC and neuroendocrine pancreatic cancer occurring concurrently with VHL and, at the same time, DM1. According to this case report and the literature data a VHL should be ruled out in the presence of RCC presenting along with pancreatic cysts/tumor. CONCLUSIONAs far as we know this is the first confirmed case of RCC and neuroendocrine pancreatic cancer occurring concurrently with VHL and, at the same time, DM1. Our hypothesis for the unusual findings is that both DM and VHL derived from genetic aberration and these are linked to a major cancer susceptibility.

D.P.2 Next generation sequencing after selected DNA capture as a tool for molecular diagnosis of neuromuscular disorders

Currently in most laboratories, molecular investigations of neuromuscular disorders (NMDs) are based on a differential molecular diagnosis by a complex and time-consuming gene by gene approach guided by a clinical approach. As a consequence, it is estimated that 35–50% of patients remain devoid of a precise molecular diagnosis. On one hand, many causal genes for NMDs are still to be identified but, on the other hand, it becomes evident that the current approaches are not sufficiently powerful and accurate to perform exhaustive screenings even in known genes, and that around 50% of patients without a definite molecular diagnosis carry unidentified mutations in known genes. In the recent years, technological tools have been developed towards performing massive molecular analyses using DNA sequence capture (SC) and next generation sequencing (NGS). In the context of the European project “NMD-Chip” (FP7 Health call), we have taken advantage of these technologies to develop specific custom SC DNA arrays to explore via NGS, known and candidate genes for NMDs. A custom in-solution DNA SC library has been designed. It includes 820 genes: 50 are known to be involved in common muscular dystrophies or myopathies (Duchenne/Becker, limb girdle, congenital), the others are candidate genes for those disorders, selected from experimental and published data. To validate this DNA chip, we have selected 20 patient DNAs: five with one known mutation, including point mutations and large rearrangements (1 COL6A2, 1 COL6A1, 1 DOK7, 1 DES, 1 TNXB) and 15 with no molecular diagnosis. We also explored the DNA of three of these patients via Exome sequencing to further compare and validate our custom SC design. The analysis of our data will help to demonstrate the proof of concept of NGS as a robust and accurate approach towards exploring multiple genes in NMD patients.

Metronidazole-induced Reversible Encephalopathy in a Patient with Facioscapulohumeral Muscular Dystrophy

Introduction Metronidazole is an antibiotic with common adverse effects such as abdominal discomfort, nausea, vomiting, headache, and metallic taste. Rare cases of peripheral neuropathy, ataxia, dizziness, seizures and metronidazole-induced encephalopathy (MIE) have been reported. On the other hand, facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies that is typically not affecting central nervous system (CNS).

The activatory long non-coding RNA DBE-T reveals the epigenetic etiology of facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is a neuromuscular disorder often considered to be the third most common muscular dystrophy. Deletions reducing the copy number of the D4Z4 repeat in the distal end of the 4q arm are the main genetic cause of the disease. The recently highlighted research has identified a transcriptional activatory long non-coding RNA involved in the disease that acts through the recruitment of ASH1L, a protein belonging to the Trithorax family.

Different Molecular Signatures in Magnetic Resonance Imaging-Staged Facioscapulohumeral Muscular Dystrophy Muscles

BackgroundFacioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies and is characterized by a non-conventional genetic mechanism activated by pathogenic D4Z4 repeat contractions. By muscle Magnetic Resonance Imaging (MRI) we observed that T2-short tau inversion recovery (T2-STIR) sequences identify two different conditions in which each muscle can be found before the irreversible dystrophic alteration, marked as T1-weighted sequence hyperintensity, takes place. We studied these conditions in order to obtain further information on the molecular mechanisms involved in the selective wasting of single muscles or muscle groups in this disease.MethodsHistopathology, gene expression profiling and real time PCR were performed on biopsies from FSHD muscles with different MRI pattern (T1-weighted normal/T2-STIR normal and T1-weighted normal/T2-STIR hyperintense). Data were compared with those from inflammatory myopathies, dysferlinopathies and normal controls. In order to validate obtained results, two additional FSHD samples with different MRI pattern were analyzed.ResultsMyopathic and inflammatory changes characterized T2-STIR hyperintense FSHD muscles, at variance with T2-STIR normal muscles. These two states could be easily distinguished from each other by their transcriptional profile. The comparison between T2-STIR hyperintense FSHD muscles and inflammatory myopathy muscles showed peculiar changes, although many alterations were shared among these conditions.ConclusionsAt the single muscle level, different stages of the disease correspond to the two MRI patterns. T2-STIR hyperintense FSHD muscles are more similar to inflammatory myopathies than to T2-STIR normal FSHD muscles or other muscular dystrophies, and share with them upregulation of genes involved in innate and adaptive immunity. Our data suggest that selective inflammation, together with perturbation in biological processes such as neoangiogenesis, lipid metabolism and adipokine production, may contribute to the sequential bursts of muscle degeneration that involve individual muscles in an asynchronous manner in this disease.

Co-segregation of DM2 with a recessive CLCN1 mutation in juvenile onset of myotonic dystrophy type 2

Myotonic dystrophy type 2 (DM2) is a common adult onset muscular dystrophy caused by a dominantly transmitted (CCTG)( n ) expansion in intron 1 of the CNBP gene. In DM2 there is no obvious evidence for an intergenerational increase of expansion size, and no congenital cases have been confirmed. We describe the clinical and histopathological features, and provide the genetic and molecular explanation for juvenile onset of myotonia in a 14-year-old female with DM2 and her affected mother presenting with a more severe phenotype despite a later onset of symptoms. Histological and immunohistochemical findings correlated with disease severity or age at onset in both patients. Southern blot on both muscle and blood samples revealed only a small increase in the CCTG repeat number through maternal transmission. Fluorescence in situ hybridization, in combination with MBNL1 immunofluorescence on muscle sections, showed the presence of mutant mRNA and MBNL1 in nuclear foci; the fluorescence intensity and its area appeared to be similar in the two patients. Splicing analysis of the INSR, CLCN1 and MBNL1 genes in muscle tissue demonstrates that the level of aberrant splicing isoforms was lower in the daughter than in the mother. However, in the CLCN1 gene, a heterozygous mutation c.501C>G p.F167L was present in the daughter's DNA and found to be maternally inherited. Biomolecular findings did not explain the unusual young onset in the daughter. The co-segregation of DM2 with a recessive CLCN1 mutation provided the explanation for the unusual clinical findings.

Mislocalization of Fukutin Protein by Disease-causing Missense Mutations Can Be Rescued with Treatments Directed at Folding Amelioration

Fukuyama-type congenital muscular dystrophy (FCMD), the second most common childhood muscular dystrophy in Japan, is caused by alterations in the fukutin gene. Mutations in fukutin cause abnormal glycosylation of α-dystroglycan, a cell surface laminin receptor; however, the exact function and pathophysiological role of fukutin are unclear. Although the most prevalent mutation in Japan is a founder retrotransposal insertion, point mutations leading to abnormal glycosylation of α-dystroglycan have been reported, both in Japan and elsewhere. To understand better the molecular pathogenesis of fukutin-deficient muscular dystrophies, we constructed 13 disease-causing missense fukutin mutations and examined their pathological impact on cellular localization and α-dystroglycan glycosylation. When expressed in C2C12 myoblast cells, wild-type fukutin localizes to the Golgi apparatus, whereas the missense mutants A170E, H172R, H186R, and Y371C instead accumulated in the endoplasmic reticulum. Protein O-mannose β1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) also mislocalizes when co-expressed with these missense mutants. The results of nocodazole and brefeldin A experiments suggested that these mutant proteins were not transported to the Golgi via the anterograde pathway. Furthermore, we found that low temperature culture or curcumin treatment corrected the subcellular location of these missense mutants. Expression studies using fukutin-null mouse embryonic stem cells showed that the activity responsible for generating the laminin-binding glycan of α-dystroglycan was retained in these mutants. Together, our results suggest that some disease-causing missense mutations cause abnormal folding and localization of fukutin protein, and therefore we propose that folding amelioration directed at correcting the cellular localization may provide a therapeutic benefit to glycosylation-deficient muscular dystrophies.

Immunodetection analysis of muscular dystrophies in Mexico

The muscular dystrophies (MDs) result from perturbations in the myofibers. These alterations are induced in part by mechanical stress due to membrane cell fragility, disturbances in mechanotransduction pathways, muscle cell physiology, and metabolism. We analyzed 290 biopsies of patients with a clinical diagnosis of muscular dystrophy. Using immunofluorescence staining, we searched for primary and secondary deficiencies of 12 different proteins, including membrane, costamere, cytoskeletal, and nuclear proteins. In addition, we analyzed calpain-3 by immunoblot. We identified 212 patients with varying degrees of protein deficiencies, including dystrophin, sarcoglycans, dysferlin, caveolin-3, calpain-3, emerin, and merosin. Moreover, 78 biopsies showed normal expression of all investigated muscle proteins. The frequency rates of protein deficiencies were as follows: 52.36% dystrophinopathies; 18.40% dysferlinopathies; 14.15% sarcoglycanopathies; 11.32% calpainopathies; 1.89% merosinopathies; 1.42% caveolinopathies; and 0.47% emerinopathies. Deficiencies in lamin A/C and telethonin were not detected. We have described the frequency of common muscular dystrophies in Mexico.

Progress in gene therapy of dystrophic heart disease

The heart is frequently afflicted in muscular dystrophy. In severe cases, cardiac lesion may directly result in death. Over the years, pharmacological and/or surgical interventions have been the mainstay to alleviate cardiac symptoms in muscular dystrophy patients. Although these traditional modalities remain useful, the emerging field of gene therapy has now provided an unprecedented opportunity to transform our thinking/approach in the treatment of dystrophic heart disease. In fact, the premise is already in place for genetic correction. Gene mutations have been identified and animal models are available for several types of muscular dystrophy. Most importantly, innovative strategies have been developed to effectively deliver therapeutic genes to the heart. Dystrophin-deficient Duchenne cardiomyopathy is associated with Duchenne muscular dystrophy (DMD), the most common lethal muscular dystrophy. Considering its high incidence, there has been a considerable interest and significant input in the development of Duchenne cardiomyopathy gene therapy. Using Duchenne cardiomyopathy as an example, here we illustrate the struggles and successes experienced in the burgeoning field of dystrophic heart disease gene therapy. In light of abundant and highly promising data with the adeno-associated virus (AAV) vector, we have specially emphasized on AAV-mediated gene therapy. Besides DMD, we have also discussed gene therapy for treating cardiac diseases in other muscular dystrophies such as limb-girdle muscular dystrophy.

A Regional Panorama of Dysferlinopathies

We describe the characteristic features of 11 patients (6 men and 5 women) with dysferlinopathies confirmed by muscle biopsies. In addition, we aimed to provide a realistic comprehensive picture of the severe muscle diseases in the Aegean Region of Turkey. We retrospectively reviewed 90 patients who underwent muscle biopsy examinations between 2008 and 2011 in the pathology laboratory of Izmir Dr.Behcet Uz Children's Hospital. Biopsy specimens of all patients clinically diagnosed as muscular dystrophy referred from 4 different centers of neurological disorders were collected. Dystrophinopathy was the most (n=45) and gammasarcoglycanopathy was the second common (n=13) muscular dystrophy in this series. The mean age of all 90 patients was 8.8 years (3 months- 64 years). Only 14 cases (15.5%) were older than 14, and 23 cases were younger than two years. Dysferlinopathy was the most common dystrophy in the older age group. There were statistical significant differences between the types of dystrophy and inflammation (0.021), creatine kinase levels (p= 0.001), age (p=0.001), and gender (p < 0.001) of the patients. The present study revealed that dysferlinopathies is not an uncommon form of muscular dystrophies in western Turkey. We have concluded that if avoidance from unnecessary therapeutic interventions is desired, we must be aware of the relative frequencies of dysferlinopathies.

Judicious Pacing for Myotonic Dystrophy

Myotonic dystrophy is the most common adult-onset muscular dystrophy. It is a multisystem disease with frequent and substantial cardiac involvement, including asymptomatic electrocardiogram (ECG) abnormalities (commonly prolongation of the PR interval or QRS duration), rhythm disturbances (progressive heart block; atrial tachycardia, flutter, and fibrillation; and ventricular tachycardia and fibrillation), and sudden death from asystole after atrioventricular (AV) block or ventricular tachyarrhythmia. Permanent pacing even for first-degree AV block has …