Cardiovascular magnetic resonance of cardiomyopathy in limb girdle muscular dystrophy 2B and 2I

Rare disease gene association discovery from burden analysis of the 100,000 Genomes Project data

To discover rare disease-gene associations, we developed a gene burden analytical framework and applied it to rare, protein-coding variants from whole genome sequencing of 35,008 cases with rare diseases and their family members recruited to the 100,000 Genomes Project (100KGP). Following in silico triaging of the results, 88 novel associations were identified including 38 with existing experimental evidence. We have published the confirmation of one of these associations, hereditary ataxia with UCHL1 , and independent confirmatory evidence has recently been published for four more. We highlight a further seven compelling associations: hypertrophic cardiomyopathy with DYSF and SLC4A3 where both genes show high/specific heart expression and existing associations to skeletal dystrophies or short QT syndrome respectively; monogenic diabetes with UNC13A with a known role in the regulation of β cells and a mouse model with impaired glucose tolerance; epilepsy with KCNQ1 where a mouse model shows seizures and the existing long QT syndrome association may be linked; early onset Parkinson's disease with RYR1 with existing links to tremor pathophysiology and a mouse model with neurological phenotypes; anterior segment ocular abnormalities associated with POMK showing expression in corneal cells and with a zebrafish model with developmental ocular abnormalities; and cystic kidney disease with COL4A3 showing high renal expression and prior evidence for a digenic or modifying role in renal disease. Confirmation of all 88 associations would lead to potential diagnoses in 456 molecularly undiagnosed cases within the 100KGP, as well as other rare disease patients worldwide, highlighting the clinical impact of a large-scale statistical approach to rare disease gene discovery.

Focus on Paediatric Restrictive Cardiomyopathy: Frequently Asked Questions

Restrictive cardiomyopathy (RCM) is characterized by restrictive ventricular pathophysiology determined by increased myocardial stiffness. While suspicion of RCM is initially raised by clinical evaluation and supported by electrocardiographic and echocardiographic findings, invasive hemodynamic evaluation is often required for diagnosis and management of patients during follow-up. RCM is commonly associated with a poor prognosis and a high incidence of heart failure, and PH is reported in paediatric patients with RCM. Currently, only a few therapies are available for specific RCM aetiologies. Early referral to centres for advanced heart failure treatment is often necessary. The aim of this review is to address questions frequently asked when facing paediatric patients with RCM, including issues related to aetiologies, clinical presentation, diagnostic process and prognosis.

Patterns of Clinical Progression Among Patients With Autosomal Recessive Limb-Girdle Muscular Dystrophy: A Systematic Review

OBJECTIVES

As the clinical course of autosomal recessive limb-girdle muscular dystrophy (LGMDR) is highly variable, this study characterized the frequency of loss of ambulation (LOA) among patients by subtype (LGMDR1, LGMDR2, LGMDR3-6, LGMDR9, LGMDR12) and progression to cardiac and respiratory involvement among those with and without LOA.

METHODS

Systematic literature review.

RESULTS

From 2929 abstracts screened, 418 patients were identified with ambulatory status data (LOA: 265 [63.4%]). Cardiac and/or respiratory function was reported for 142 patients (34.0%; all with LOA). Among these, respiratory involvement was most frequent in LGMDR3-6 (74.1%; mean [SD] age 23.9 [11.0] years) and cardiac in LGMDR9 (73.3%; mean [SD] age 23.7 [17.7] years). Involvement was less common in patients without LOA except in LGMDR9 (71.4% respiratory and 52.4% cardiac).

CONCLUSIONS

This study described the co-occurrence of LOA, cardiac, and respiratory involvement in LGMDR and provides greater understanding of the clinical progression of LGMDR.

Dysferlinopathy in Tunisia: clinical spectrum, genetic background and prognostic profile

Dysferlinopathy is a rare group of hereditary muscular dystrophy with an autosomal recessive mode of inheritance caused by a mutation in the DYSF gene. It encodes for the dysferlin protein, which has a crucial role in multiple cellular processes, including muscle fiber membrane repair. This deficit has heterogeneous clinical presentations. In this study, we collected 20 Tunisian patients with a sex ratio of 1 and a median age of 50.5 years old (Interquartile range (IQR) = [36,5-54,75]). They were followed for periods ranging from 5 to 48 years. The median age at onset was 17 years old (IQR = [16,8-28,4]). Five major phenotypes were identified: Limb-girdle muscular dystrophy (LGMDR2) (35%), a proximodistal phenotype (35%), Miyoshi myopathy (10%),  Distal myopathy with anterior tibial onset (DMAT) (10%), and asymptomatic HyperCKemia (10%). At the last evaluation, more than half of patients (55%) were on wheelchair. Loss of ambulation occurred generally during the fourth decade. After 20 years of disease progression, two patients with a proximodistal phenotype (10%) developed dilated cardiomyopathy and mitral valve regurgitation. Restrictive respiratory syndrome was observed in three patients (DMAT: 1 patient, proximodistal phenotype: 1 patient, LGMDR2: 1 patient). Genetic study disclosed five mutations. We observed clinical heterogeneity between families and even within the same family. Disease progression was mainly slow to intermediate regardless of the phenotype.

Patterns of cardiac involvement in different muscular dystrophies assessed by magnetic resonance imaging

BACKGROUND

In muscular dystrophies, it is not only skeletal muscles that can be affected, but also the myocardium. This cardiac involvement can represent a major cause of morbidity and mortality.

PURPOSE

To investigate cardiac involvement in Duchenne (DMD), Becker (BMD), and limb girdle muscular dystrophy (LGMD) patients, and carriers of DMD/BMD by cardiac magnetic resonance (CMR) imaging and to search for differences in the pattern of cardiac involvement.

MATERIAL AND METHODS

All patients with genetically or histologically proven DMD, BMD, and LGMD, or confirmed carriers of DMD/BMD who had undergone CMR at our clinic between January 2008 and November 2018 were retrospectively included and re-evaluated for regional and global left ventricular function, increased trabecularization, and late enhancement.

RESULTS

A total of 26 DMD, 10 BMD, 11 LGMD, and seven DMD/BMD carriers were included. Only one carrier of DMD presented with normal CMR results; all other participants showed cardiac abnormalities. Regional wall motion abnormalities (RWMA; prevalence in LGMD patients: 55%) and late enhancement (prevalence in LGMD patients: 82%) were frequent. RWMA were accentuated basal inferolateral in DMD/BMD carriers, while in LGMD they were accentuated apical. In all groups late enhancement was located mainly subepicardial/midmyocardial with a basal inferolateral accentuation. Apart from the different RWMA distribution, no further group-specific differences were found.

CONCLUSION

We found a high rate of cardiac involvement not only in DMD/BMD, but also in LGMD and DMD/BMD carriers with a different RWMA accentuation (apical in LGMD and basal inferolateral in DMD/BMD) as a single group-specific difference.

Childhood muscular dystrophies

Infancy- and childhood-onset muscular dystrophies are associated with a characteristic distribution and progression of motor dysfunction. The underlying causes of progressive childhood muscular dystrophies are heterogeneous involving diverse genetic pathways and genes that encode proteins of the plasma membrane, extracellular matrix, sarcomere, and nuclear membrane components. The prototypical clinicopathological features in an affected child may be adequate to fully distinguish it from other likely diagnoses based on four common features: (1) weakness and wasting of pelvic-femoral and scapular muscles with involvement of heart muscle; (2) elevation of serum muscle enzymes in particular serum creatine kinase; (3) necrosis and regeneration of myofibers; and (4) molecular neurogenetic assessment particularly utilizing next-generation sequencing of the genome of the likeliest candidates genes in an index case or family proband. A number of different animal models of therapeutic strategies have been developed for gene transfer therapy, but so far these techniques have not yet entered clinical practice. Treatment remains for the most part symptomatic with the goal of ameliorating locomotor and cardiorespiratory manifestations of the disease.

SCMR expert consensus statement for cardiovascular magnetic resonance of acquired and non-structural pediatric heart disease

Cardiovascular magnetic resonance (CMR) is widely used for diagnostic imaging in the pediatric population. In addition to structural congenital heart disease (CHD), for which published guidelines are available, CMR is also performed for non-structural pediatric heart disease, for which guidelines are not available. This article provides guidelines for the performance and reporting of CMR in the pediatric population for non-structural ("non-congenital") heart disease, including cardiomyopathies, myocarditis, Kawasaki disease and systemic vasculitides, cardiac tumors, pericardial disease, pulmonary hypertension, heart transplant, and aortopathies. Given important differences in disease pathophysiology and clinical manifestations as well as unique technical challenges related to body size, heart rate, and sedation needs, these guidelines focus on optimization of the CMR examination in infants and children compared to adults. Disease states are discussed, including the goals of CMR examination, disease-specific protocols, and limitations and pitfalls, as well as newer techniques that remain under development.

Progression to Loss of Ambulation Among Patients with Autosomal Recessive Limb-girdle Muscular Dystrophy: A Systematic Review

Background

The impact of age at autosomal recessive limb girdle muscular dystrophy (LGMDR) onset on progression to loss of ambulation (LOA) has not been well established, particularly by subtype.

Objectives:

To describe the characteristics of patients with adult-, late childhood-, and early childhood-onset LGMDR by subtype and characterize the frequency and timing of LOA.

Methods:

A systematic review was conducted in MEDLINE, Embase and the Cochrane library. Frequency and timing of LOA in patients with LGMDR1, LGMDR2/Miyoshi myopathy (MM), LGMDR3-6, LGMDR9, and LGMDR12 were synthesized from published data.

Results:

In 195 studies, 695 (43.4%) patients had adult-, 532 (33.2%) had late childhood-, and 376 (23.5%) had early childhood-onset of disease across subtypes among those with a reported age at onset (n = 1,603); distribution of age at onset varied between subtypes. Among patients with LOA (n = 228), adult-onset disease was uncommon in LGMDR3-6 (14%) and frequent in LGMDR2/MM (42%); LGMDR3-6 cases with LOA primarily had early childhood-onset (74%). Mean (standard deviation [SD]) time to LOA varied between subtypes and was shortest for patients with early childhood-onset LGMDR9 (12.0 [4.9] years, n = 19) and LGMDR3-6 (12.3 [10.7], n = 56) and longest for those with late childhood-onset LGMDR2/MM (21.4 [11.5], n = 36).

Conclusions:

This review illustrated that patients with early childhood-onset disease tend to have faster progression to LOA than those with late childhood- or adult-onset disease, particularly in LGMDR9. These findings provide a greater understanding of progression to LOA by LGMDR subtype, which may help inform clinical trial design and provide a basis for natural history studies.

Cardiac and pulmonary findings in dysferlinopathy: a 3-year, longitudinal study

Introduction/Aims

There is debate about whether and to what extent either respiratory or cardiac dysfunction occurs in patients with dysferlinopathy. This study aimed to establish definitively whether dysfunction in either system is part of the dysferlinopathy phenotype.

Methods

As part of the Jain Foundation's International Clinical Outcome Study (COS) for dysferlinopathy, objective measures of respiratory and cardiac function were collected twice, with a 3‐y interval between tests, in 188 genetically confirmed patients aged 11–86 y (53% female). Measures included forced vital capacity (FVC), electrocardiogram (ECG), and echocardiogram (echo).

Results

Mean FVC was 90% predicted at baseline, decreasing to 88% at year 3. FVC was less than 80% predicted in 44 patients (24%) at baseline and 48 patients (30%) by year 3, including ambulant participants. ECGs showed P‐wave abnormalities indicative of delayed trans‐atrial conduction in 58% of patients at baseline, representing a risk for developing atrial flutter or fibrillation. The prevalence of impaired left ventricular function or hypertrophy was comparable to that in the general population.

Discussion

These results demonstrate clinically significant respiratory impairment and abnormal atrial conduction in some patients with dysferlinopathy. Therefore, we recommend that annual or biannual follow‐up should include FVC measurement, enquiry about arrhythmia symptoms and peripheral pulse palpation to assess cardiac rhythm. However, periodic specialist cardiac review is probably not warranted unless prompted by symptoms or abnormal pulse findings.

Probability of high-risk genetic matching with oocyte and semen donors: complete gene analysis or genotyping test?

PURPOSE

To estimate the probability of high-risk genetic matching when assisted reproductive techniques (ART) are applied with double gamete donation, following an NGS carrier test based on a complete study of the genes concerned. We then determine the results that would have been obtained if the genotyping tests most widely used in Spanish gamete banks had been applied.

METHODS

In this descriptive observational study, 1818 gamete donors were characterised by NGS. The pathogenic variants detected were analysed to estimate the probability of high-risk genetic matching and to determine the results that would have been obtained if the three most commonly used genotyping tests in ART had been applied.

RESULTS

The probability of high-risk genetic matching with gamete donation, screened by NGS and complete gene analysis, was 5.5%, versus the 0.6-2.7% that would have been obtained with the genotyping test. A total of 1741 variants were detected, including 607 different variants, of which only 22.6% would have been detected by all three genotyping tests considered and 44.7% of which would not have been detected by any of these tests.

CONCLUSION

Our study highlights the considerable heterogeneity of the genotyping tests, which present significant differences in their ability to detect pathogenic variants. The complete study of the genes by NGS considerably reduces reproductive risks when genetic matching is performed with gamete donors. Accordingly, we recommend that carrier screening in gamete donors be carried out using NGS and a complete study with nontargeted analysis of the variants of the screened genes.

Diagnostic and Prognostic Value of Cardiovascular Magnetic Resonance in Neuromuscular Cardiomyopathies

Neuromuscular diseases (NMD) encompass a broad spectrum of diseases with variable type of cardiac involvement and there is lack of clinical data on Cardiovascular Magnetic Resonance (CMR) phenotypes or even prognostic value of CMR in NMD. We explored the diagnostic and prognostic value of CMR in NMD-related cardiomyopathies. The study included retrospective analysis of a cohort of 111 patients with various forms of NMD; mitochondrial: n = 14, Friedreich's ataxia (FA): n = 27, myotonic dystrophy: n = 27, Becker/Duchenne's muscular dystrophy (BMD/DMD): n = 15, Duchenne's carriers: n = 6, other: n = 22. Biventricular volumes and function and myocardial late gadolinium enhancement (LGE) pattern and extent were assessed by CMR. Patients were followed-up for the composite clinical endpoint of death, heart failure development or need for permanent pacemaker/intracardiac defibrillator. The major NMD subtypes, i.e. FA, mitochondrial, BMD/DMD, and myotonic dystrophy had significant differences in the incidence of LGE (56%, 21%, 62% & 30% respectively, chi² = 9.86, p = 0.042) and type of cardiomyopathy phenotype (chi² = 13.8, p = 0.008), extent/pattern (p = 0.006) and progression rate of LGE (p = 0.006). In survival analysis the composite clinical endpoint differed significantly between NMD subtypes (p = 0.031), while the subgroup with LGE + and LVEF < 50% had the worst prognosis (Log-rank p = 0.0034). We present data from a unique cohort of NMD patients and provide evidence on the incidence, patterns, and the prognostic value of LGE in NMD-related cardiomyopathy. LGE is variably present in NMD subtypes and correlates with LV remodelling, dysfunction, and clinical outcomes in patients with NMD.

Cardiac magnetic resonance in patients with muscular dystrophies

Muscular dystrophies are inherited disorders sharing similar clinical features and dystrophic changes on muscle biopsy. Duchenne muscular dystrophy is the most common inherited muscle disease of childhood, and Becker muscular dystrophy is a milder allelic variant with a slightly lower prevalence. Myotonic dystrophy is the most frequent form in adults. Cardiac magnetic resonance is the gold standard technique for the quantification of cardiac chamber volumes and function, and also enables a characterisation of myocardial tissue. Most cardiac magnetic resonance studies in the setting of muscular dystrophy were carried out at single centres, evaluated small numbers of patients and used widely heterogeneous protocols. Even more importantly, those studies analysed more or less extensively the patterns of cardiac involvement, but usually did not try to establish the added value of cardiac magnetic resonance to standard echocardiography, the evolution of cardiac disease over time and the prognostic significance of cardiac magnetic resonance findings. As a result, the large and heterogeneous amount of information on cardiac involvement in muscular dystrophies cannot easily be translated into recommendations on the optimal use of cardiac magnetic resonance. In this review, whose targets are cardiologists and neurologists who manage patients with muscular dystrophy, we try to summarise cardiac magnetic resonance findings in patients with muscular dystrophy, and the results of studies evaluating the role of cardiac magnetic resonance as a tool for diagnosis, risk stratification and follow-up. Finally, we provide some practical recommendations about the need and timing of cardiac magnetic resonance examination for the management of patients with muscular dystrophy.

Role of CMR Imaging in Diagnostics and Evaluation of Cardiac Involvement in Muscle Dystrophies

PURPOSE OF REVIEW

This review aims to outline the utility of cardiac magnetic resonance (CMR) in patients with different types of muscular dystrophies for the assessment of myocardial involvement, risk stratification and in guiding therapeutic decisions.

RECENT FINDINGS

In patients suffering from muscular dystrophies (MD), even mild initial dysfunction may lead to severe heart failure over a time course of years. CMR plays an increasing role in the diagnosis and clinical care of these patients, mostly due to its unique capability to precisely characterize subclinical and progressive changes in cardiac geometry, function in order to differentiate myocardial injury it allows the identification of inflammation, focal and diffuse fibrosis as well as fatty infiltration. CMR may provide additional information in addition to the physical examination, laboratory tests, ECG, and echocardiography. Further trials are needed to investigate the potential impact of CMR on the therapeutic decision-making as well as the assessment of long-term prognosis in different forms of muscular dystrophies. In addition to the basic cardiovascular evaluation, CMR can provide a robust, non-invasive technique for the evaluation of subclinical myocardial tissue injury like fat infiltration and focal and diffuse fibrosis. Furthermore, CMR has a unique capability to detect the progression of myocardial tissue damage in patients with a preserved systolic function.

Dysferlin links excitation-contraction coupling to structure and maintenance of the cardiac transverse-axial tubule system

AIMS

The multi-C2 domain protein dysferlin localizes to the T-Tubule system of skeletal and heart muscles. In skeletal muscle, dysferlin is known to play a role in membrane repair and in T-tubule biogenesis and maintenance. Dysferlin deficiency manifests as muscular dystrophy of proximal and distal muscles. Cardiomyopathies have been also reported, and some dysferlinopathy mouse models develop cardiac dysfunction under stress. Generally, the role and functional relevance of dysferlin in the heart is not clear. The aim of this study was to analyse the effect of dysferlin deficiency on the transverse-axial tubule system (TATS) structure and on Ca2+ homeostasis in the heart.

METHODS AND RESULTS

We studied dysferlin localization in rat and mouse cardiomyocytes by immunofluorescence microscopy. In dysferlin-deficient ventricular mouse cardiomyocytes, we analysed the TATS by live staining and assessed Ca2+ handling by patch-clamp experiments and measurement of Ca2+ transients and Ca2+ sparks. We found increasing co-localization of dysferlin with the L-type Ca2+-channel during TATS development and show that dysferlin deficiency leads to pathological loss of transversal and increase in longitudinal elements (axialization). We detected reduced L-type Ca2+-current (ICa,L) in cardiomyocytes from dysferlin-deficient mice and increased frequency of spontaneous sarcoplasmic reticulum Ca2+ release events resulting in pro-arrhythmic contractions. Moreover, cardiomyocytes from dysferlin-deficient mice showed an impaired response to β-adrenergic receptor stimulation.

CONCLUSIONS

Dysferlin is required for TATS biogenesis and maintenance in the heart by controlling the ratio of transversal and axial membrane elements. Absence of dysferlin leads to defects in Ca2+ homeostasis which may contribute to contractile heart dysfunction in dysferlinopathy patients.

Diagnosis of Cardiac Abnormalities in Muscular Dystrophies

Muscular disorders are mainly characterized by progressive skeletal muscle weakness. There are several aspects that can be monitored, which are used to differentiate between the types of muscular disorders, ranging from the targeted muscle up to the mutated gene. An aspect that holds critical importance when managing muscular dystrophies is that most of them exhibit cardiac abnormalities. Therefore, cardiac imaging is an essential part of muscular disorder monitoring and management. In the first section of the review, several cardiac abnormalities are introduced; afterward, different muscular dystrophies' pathogenesis is presented. Not all muscular dystrophies necessarily present cardiac involvement; however, the ones that do are linked with the cardiac abnormalities described in the first section. Moreover, studies from the last 3 years on muscular disorders are presented alongside imaging techniques used to determine cardiac abnormalities.

Subclinical Cardiomyopathy in Miyoshi Myopathy Detected by Late Gadolinium Enhancement Cardiac Magnetic Resonance Imaging

Dysferlin is a sarcolemmal protein present in muscle cells. It is responsible for muscle membrane repair. Dysferlin gene (DYSF) mutation, resulting in deficiency in this protein, is termed dysferlinopathy. Clinically, it manifests as early adulthood onset of muscle weakness with markedly elevated creatine kinase levels. The main phenotypes are limb-girdle muscular dystrophy type 2B (LGMD2B), affecting proximal muscles, and Miyoshi myopathy (MM), affecting distal muscles. Dysferlin is also present in cardiomyocytes, and case reports have emerged of cardiac abnormalities in dysferlinopathy. While routine methods of cardiac screening, namely, electrocardiography or echocardiography, are convenient and noninvasive, they often exhibit insufficient diagnostic sensitivity for detecting subclinical cardiac remodeling during early stages of cardiomyopathy. Cardiac magnetic resonance imaging though can provide accurate assessment of cardiac chamber sizes and function. With gadolinium administration, it can also detect areas of myocardial scarring and fibrosis. Early diagnosis of neuromuscular disease-related cardiomyopathy is of clinical significance, as appropriate treatment can retard myocardial fibrosis, delaying cardiomyopathy progression. We present a case of a patient with MM incidentally diagnosed with concomitant cardiomyopathy.

Cardiac MR Imaging of Muscular Dystrophies

Muscular dystrophies (MDs) are a group of inherited disorders caused by mutations that interfere with muscular structure, contraction, or relaxation. As the cardiac sarcomeric unit shares multiple proteins with the skeletal muscle unit, the heart is affected in several MDs, sometimes without apparent musculoskeletal involvement. Early detection of MD-related cardiomyopathy is crucial as timely initiation of cardioprotective therapy can slow adverse cardiac remodeling. Although transthoracic echocardiography is widely used for the evaluation of cardiac morphology and function, it has limitations in terms of reproducibility and image quality. The need for an optimal acoustic window may be particularly challenging to obtain in patients with MDs given their body habitus and position. Cardiac magnetic resonance (CMR) imaging has emerged as a useful tool in the evaluation of patients with MDs. Its superb tissue characterization capability through late gadolinium enhancement, T1 mapping, extracellular volume fraction quantification, and edema imaging detects early cardiac involvement, even when echocardiography and electrocardiogram are unremarkable. MDs that frequently present with cardiac involvement include Duchenne MD, Becker MD, Emery Dreifuss MD, Limb-Girdle MDs, and myotonic dystrophy. The purpose of this review article is to briefly describe the pathophysiology of these entities, discuss their clinical presentation and expected evolution, explain the role of CMR in the diagnosis and follow-up of these patients, and portray the different CMR findings present in MD patients.

Cardiomyopathy in limb girdle muscular dystrophy R9, FKRP related

Introduction

Reported frequencies of cardiomyopathy in limb girdle muscular dystrophy R9 (LGMDR9) vary. We describe the frequency and age at onset of cardiomyopathy in an LDMDR9 cohort.

Methods

Echocardiograms from 56 subjects (157 echocardiograms) with LGMDR9 were retrospectively reviewed. The cumulative probability of having an abnormal echocardiogram as a function of age was assessed by survival analysis for interval‐censored data by genotype. Correlations between cardiac and clinical function were evaluated.

Results

Twenty‐five (45%) participants had cardiomyopathy. The median age at first abnormal echocardiogram for subjects homozygous for the c.826C>A variant was 54.2 y compared to 18.1 y for all other fukutin‐related protein (FKRP) genotypes (P < .0001). There was a weak correlation between ejection fraction and 10‐Meter Walk Test speed (r = 0.25), but no correlation with forced vital capacity (r = 0.08).

Discussion

Cardiomyopathy is prevalent among those with LGMDR9 and occurs later in subjects homozygous for the c.826C>A mutation. These data will help to guide surveillance and management.

Novel splicing dysferlin mutation causing myopathy with intra-familial heterogeneity

Dysferlinopathies belong to the heterogeneous group of autosomal recessive muscular disorders, caused by mutations in the dysferlin gene and characterized by a high degree of clinical variability even though within the same family. This study aims to describe three cases, belonging to a consanguineous Tunisian family, sharing a new splicing mutation in the dysferlin gene and presenting intra-familial variability of dysferlinopathies: Proximal-distal weakness and distal myopathy with anterior tibial onset. We performed the next generation sequencing for mutation screening and reverse transcriptase-PCR for gene expression analysis. Routine muscle histology was used for muscle biopsy processing. The clinical presentation demonstrated heterogeneous phenotypes between the three cases: Two presented intermediate phenotypes of dysferlinopathy with proximal-distal weakness and the third had a distal myopathy with anterior tibial onset. Genetic analysis yielded a homozygous splicing mutation (c.4597-2A>G) in the dysferlin gene, giving rise to the suppression of 28 bp of the exon 43. The splicing mutation found in our family (c.4597-2A>G) is responsible for the suppression of 28 bp of the exon 43 and a wide clinical intra-familial variability.

Functions of Vertebrate Ferlins

Ferlins are multiple-C2-domain proteins involved in Ca²⁺-triggered membrane dynamics within the secretory, endocytic and lysosomal pathways. In bony vertebrates there are six ferlin genes encoding, in humans, dysferlin, otoferlin, myoferlin, Fer1L5 and 6 and the long noncoding RNA Fer1L4. Mutations in DYSF (dysferlin) can cause a range of muscle diseases with various clinical manifestations collectively known as dysferlinopathies, including limb-girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy. A mutation in MYOF (myoferlin) was linked to a muscular dystrophy accompanied by cardiomyopathy. Mutations in OTOF (otoferlin) can be the cause of nonsyndromic deafness DFNB9. Dysregulated expression of any human ferlin may be associated with development of cancer. This review provides a detailed description of functions of the vertebrate ferlins with a focus on muscle ferlins and discusses the mechanisms leading to disease development.

Comprehensive Assessment of Cardiac Involvement in Muscular Dystrophies by Cardiac MR Imaging

Muscular dystrophy is a group of genetically inherited diseases with irreversible and progressive muscle loss and is associated with cardiac involvement. Particularly in Duchenne and Becker dystrophies, cardiac disorders are the leading causes of mortality. Cardiovascular magnetic resonance imaging (CMR) can detect even incipient myocardial fibrosis (late gadolinium enhancement), which has prognostic significance in patients with preserved left ventricular function by echocardiogram and before the onset of symptoms. Early detection of cardiac abnormalities by CMR enables early cardioprotective treatment, leading to a better prognosis.

Cardiac Phenotypes in Hereditary Muscle Disorders: JACC State-of-the-Art Review

Hereditary muscular diseases commonly involve the heart. Cardiac manifestations encompass a spectrum of phenotypes, including both cardiomyopathies and rhythm disorders. Common biomarkers suggesting cardiomuscular diseases include increased circulating creatine kinase and/or lactic acid levels or disease-specific metabolic indicators. Cardiac and extra-cardiac traits, imaging tests, family studies, and genetic testing provide precise diagnoses. Cardiac phenotypes are mainly dilated and hypokinetic in dystrophinopathies, Emery-Dreifuss muscular dystrophies, and limb girdle muscular dystrophies; hypertrophic in Friedreich ataxia, mitochondrial diseases, glycogen storage diseases, and fatty acid oxidation disorders; and restrictive in myofibrillar myopathies. Left ventricular noncompaction is variably associated with the different myopathies. Conduction defects and arrhythmias constitute a major phenotype in myotonic dystrophies and skeletal muscle channelopathies. Although the actual cardiac management is rarely based on the cause, the cardiac phenotypes need precise characterization because they are often the only or the predominant manifestations and the prognostic determinants of many hereditary muscle disorders.

Systemic Delivery of Dysferlin Overlap Vectors Provides Long-Term Gene Expression and Functional Improvement for Dysferlinopathy

Dysferlinopathies comprise a family of disorders caused by mutations in the dysferlin (DYSF) gene, leading to a progressive dystrophy characterized by chronic muscle fiber loss, fat replacement, and fibrosis. To correct the underlying histopathology and function, expression of full-length DYSF is required. Dual adeno-associated virus vectors have been developed, defined by a region of homology, to serve as a substrate for reconstitution of the full 6.5 kb dysferlin cDNA. Previous work studied the efficacy of this treatment through intramuscular and regional delivery routes. To maximize clinical efficacy, dysferlin-deficient mice were treated systemically to target all muscles through the vasculature for efficacy and safety studies. Mice were evaluated at multiple time points between 4 and 13 months post treatment for dysferlin expression and functional improvement using magnetic resonance imaging and magnetic resonance spectroscopy and membrane repair. A systemic dose of 6 × 1012 vector genomes resulted in widespread gene expression in the muscles. Treated muscles showed a significant decrease in central nucleation, collagen deposition, and improvement of membrane repair to wild-type levels. Treated gluteus muscles were significantly improved compared to placebo-treated muscles and were equivalent to wild type in volume, intra- and extramyocellular lipid accumulation, and fat percentage using magnetic resonance imaging and magnetic resonance spectroscopy. Dual-vector treatment allows for production of full-length functional dysferlin with no toxicity. This confirms previous safety data and validates translation of systemic gene delivery for dysferlinopathy patients.

Skeletal, cardiac, and respiratory muscle function and histopathology in the P448Lneo- mouse model of FKRP-deficient muscular dystrophy

BACKGROUND

Fukutin-related protein (FKRP) mutations are the most common cause of dystroglycanopathies known to cause both limb girdle and congenital muscular dystrophy. The P448Lneo- mouse model has a knock-in mutation in the FKRP gene and develops skeletal, respiratory, and cardiac muscle disease.

METHODS

We studied the natural history of the P448Lneo- mouse model over 9 months and the effects of twice weekly treadmill running. Forelimb and hindlimb grip strength (Columbus Instruments) and overall activity (Omnitech Electronics) assessed skeletal muscle function. Echocardiography was performed using VisualSonics Vevo 770 (FujiFilm VisualSonics). Plethysmography was performed using whole body system (ADInstruments). Histological evaluations included quantification of inflammation, fibrosis, central nucleation, and fiber size variation.

RESULTS

P448Lneo- mice had significantly increased normalized tissue weights compared to controls at 9 months of age for the heart, gastrocnemius, soleus, tibialis anterior, quadriceps, and triceps. There were no significant differences seen in forelimb or hindlimb grip strength or activity monitoring in P448Lneo- mice with or without exercise compared to controls. Skeletal muscles demonstrated increased inflammation, fibrosis, central nucleation, and variation in fiber size compared to controls (p < 0.05) and worsened with exercise. Plethysmography showed significant differences in respiratory rates and decreased tidal and minute volumes in P448Lneo- mice (p < 0.01). There was increased fibrosis in the diaphragm compared to controls (p < 0.01). Echocardiography demonstrated decreased systolic function in 9-month-old mutant mice (p < 0.01). There was increased myocardial wall thickness and mass (p < 0.001) with increased fibrosis in 9-month-old P448Lneo- mice compared to controls (p < 0.05). mRNA expression for natriuretic peptide type A (Nppa) was significantly increased in P448Lneo- mice compared to controls at 6 months (p < 0.05) and for natriuretic peptide type B (Nppb) at 6 and 9 months of age (p < 0.05).

CONCLUSIONS

FKRP-deficient P448Lneo- mice demonstrate significant deficits in cardiac and respiratory functions compared to control mice, and this is associated with increased inflammation and fibrosis. This study provides new functional outcome measures for preclinical trials of FKRP-related muscular dystrophies.

Cardiac complications of congenital disorders of glycosylation (CDG): a systematic review of the literature

Congenital disorders of glycosylation (CDG) are inborn errors of metabolism due to protein and lipid hypoglycosylation. This rapidly growing family of genetic diseases comprises 103 CDG types, with a broad phenotypic diversity ranging from mild to severe poly-organ -system dysfunction. This literature review summarizes cardiac involvement, reported in 20% of CDG. CDG with cardiac involvement were divided according to the associated type of glycosylation: N-glycosylation, O-glycosylation, dolichol synthesis, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, COG complex, V-ATPase complex, and other glycosylation pathways. The aim of this review was to document and interpret the incidence of heart disease in CDG patients. Heart disorders were grouped into cardiomyopathies, structural defects, and arrhythmogenic disorders. This work may contribute to improved early management of cardiac complications in CDG.

Sexually dimorphic skeletal muscle and cardiac dysfunction in a mouse model of limb girdle muscular dystrophy 2i

The fukutin-related protein P448L mutant mouse replicates many pathologies common to limb girdle muscular dystrophy 2i (LGMD2i) and is a potentially strong candidate for relevant drug screening studies. Because striated muscle function remains relatively uncharacterized in this mouse, we sought to identify metabolic, functional and histological metrics of exercise and cardiac performance. This was accomplished by quantifying voluntary exercise on running wheels, forced exercise on respiratory treadmills and cardiac output with echocardiography and isoproterenol stress tests. Voluntary exercise revealed few differences between wild-type and P448L mice. By contrast, peak oxygen consumption (VO₂peak) was either lower in P448L mice or reduced with repeated low intensity treadmill exercise while it increased in wild-type mice. P448L mice fatigued quicker and ran shorter distances while expending 2-fold more calories/meter. They also received over 6-fold more motivational shocks with repeated exercise. Differences in VO₂peak and resting metabolic rate were consistent with left ventricle dysfunction, which often develops in human LGMD2i patients and was more evident in female P448L mice, as indicated by lower fractional shortening and ejection fraction values and higher left ventricle systolic volumes. Several traditional markers of dystrophinopathies were expressed in P448L mice and were exacerbated by exercise, some in a muscle-dependent manner. These include elevated serum creatine kinase and muscle central nucleation, smaller muscle fiber cross-sectional area and more striated muscle fibrosis. These studies together identified several markers of disease pathology that are shared between P448L mice and human subjects with LGMD2i. They also identified novel metrics of exercise and cardiac performance that could prove invaluable in preclinical drug trials.NEW & NOTEWORTHY Limb-girdle muscular dystrophy 2i is a rare dystroglycanopathy that until recently lacked an appropriate animal model. Studies with the FKRP P448L mutant mouse began assessing muscle structure and function as well as running gait. Our studies further characterize systemic muscle function using exercise and cardiac performance. They identified many markers of respiratory, cardiac and skeletal muscle function that could prove invaluable to better understanding the disease and more importantly, to preclinical drug trials.

Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma Developed in a Patient with Progressive Muscular Dystrophy: A Case Report and Review of the Literature

BACKGROUND

Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLS) is an intermediate or locally aggressive form of adipocytic soft tissue sarcoma. Muscular dystrophy (MD) is characterized by progressive muscle atrophy and its replacement by adipose and fibrous tissue. Recently, some authors have reported that MD genes are related to neoplastic formation, but there have been no detailed clinical reports of ALT associated with MD.

CASE PRESENTATION

A 73-year-old woman with a diagnosis of limb-girdle MD visited our department for recurrence of a huge tumor in her left thigh. She had undergone resection of a lipoma at the same site more than 20 years earlier. Imaging studies revealed a lipomatous tumor in her left thigh. We performed marginal resection including the adjacent muscles. Histological diagnosis was atypical lipomatous tumor. The postoperative course was uneventful, with no recurrence at 36 months of follow-up.

CONCLUSION

We encountered a huge atypical tumor in a patient with MD. This is the first detailed report to describe an association between ALT and MD. We hypothesize that degenerative changes occurring in adipose tissue during muscle atrophy can cause lipomatous neoplasms and moreover that the mutation of MD-related genes may lead to the proliferation of tumor cells or to malignancy.

Feature tracking cardiac magnetic resonance imaging: A review of a novel non-invasive cardiac imaging technique

Cardiovascular disease is a leading cause of morbidity and mortality globally. Early diagnostic markers are gaining popularity for better patient care disease outcomes. There is an increasing interest in noninvasive cardiac imaging biomarkers to diagnose subclinical cardiac disease. Feature tracking cardiac magnetic resonance imaging is a novel post-processing technique that is increasingly being employed to assess global and regional myocardial function. This technique has numerous applications in structural and functional diagnostics. It has been validated in multiple studies, although there is still a long way to go for it to become routine standard of care.

Robust genotyping tool for autosomal recessive type of limb-girdle muscular dystrophies

Background

Limb-girdle muscular dystrophies are characterized by predominant involvement of the shoulder and pelvic girdle and trunk muscle groups. Currently, there are 31 genes implicated in the different forms of limb-girdle muscular dystrophies, which exhibit similar phenotypes and clinical overlap; therefore, advanced molecular techniques are required to achieve differential diagnosis.

Methods

We investigated 26 patients from Latvia and 34 patients from Lithuania with clinical symptoms of limb-girdle muscular dystrophies, along with 565 healthy unrelated controls from general and ethnic populations using our developed test kit based on the Illumina VeraCode GoldenGate genotyping platform, Ion AmpliSeq Inherited Disease Panel and direct sequencing of mutations in calpain 3 (CAPN3), anoctamin 5 (ANO5) and fukutin related protein (FKRP) genes.

Results

Analysis revealed a homozygous CAPN3 c.550delA mutation in eight patients and three heterozygous variants in controls: dysferlin (DYSF) c.5028delG, CAPN3 c.2288A > G, and FKRP c.135C > T. Additionally, three mutations within FKRP gene were found: homozygous c.826C > A, and two compound – c.826C > A/c.404_405insT and c.826C > A/c.204_206delCTC mutations, and one mutation within CLCN1 gene – c.2680C > T p.Arg894Ter. ANO5 c.191dupA was not present.

Conclusions

Genetic diagnosis was possible in 12 of 60 patients (20 %). The allele frequency of CAPN3 gene mutation c.550delA in Latvia is 0.0016 and in Lithuania - 0.0029. The allele frequencies of CAPN3 gene mutation c.2288A > G and DYSF gene mutation c.4872delG are 0.003.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1058-z) contains supplementary material, which is available to authorized users.

Heart Disease in Disorders of Muscle, Neuromuscular Transmission, and the Nerves

Little is known regarding cardiac involvement (CI) by neuromuscular disorders (NMDs). The purpose of this review is to summarise and discuss the major findings concerning the types, frequency, and severity of cardiac disorders in NMDs as well as their diagnosis, treatment, and overall outcome. CI in NMDs is characterized by pathologic involvement of the myocardium or cardiac conduction system. Less commonly, additional critical anatomic structures, such as the valves, coronary arteries, endocardium, pericardium, and even the aortic root may be involved. Involvement of the myocardium manifests most frequently as hypertrophic or dilated cardiomyopathy and less frequently as restrictive cardiomyopathy, non-compaction, arrhythmogenic right-ventricular dysplasia, or Takotsubo-syndrome. Cardiac conduction defects and supraventricular and ventricular arrhythmias are common cardiac manifestations of NMDs. Arrhythmias may evolve into life-threatening ventricular tachycardias, asystole, or even sudden cardiac death. CI is common and carries great prognostic significance on the outcome of dystrophinopathies, laminopathies, desminopathies, nemaline myopathy, myotonias, metabolic myopathies, Danon disease, and Barth-syndrome. The diagnosis and treatment of CI in NMDs follows established guidelines for the management of cardiac disease, but cardiotoxic medications should be avoided. CI in NMDs is relatively common and requires complete work-up following the establishment of a neurological diagnosis. Appropriate cardiac treatment significantly improves the overall long-term outcome of NMDs.

Respiratory and cardiac function in japanese patients with dysferlinopathy

INTRODUCTION

We retrospectively reviewed respiratory and cardiac function in patients with dysferlinopathy, including 2 autopsy cases with respiratory dysfunction.

METHODS

Subjects included 48 patients who underwent respiratory evaluation (n = 47), electrocardiography (n = 46), and echocardiography (n = 23).

RESULTS

Of the 47 patients, 10 had reduced percent forced vital capacity (%FVC), and 4 required non-invasive positive pressure ventilation. %FVC was significantly correlated with disease duration, and mean %FVC was significantly lower in non-ambulatory patients, as well as in those aged ≥65 years with normal creatine kinase levels. On electrocardiography, QRS complex duration was prolonged in 19 patients, although no significant association with age, disease duration, or respiratory function was found. Echocardiography indicated no left ventricular dysfunction in any patient. Histopathology of autopsied cases revealed mild cardiomyopathy and moderate diaphragm involvement.

CONCLUSION

Patients with dysferlinopathy may develop severe respiratory failure and latent cardiac dysfunction. Both respiratory and cardiac function should be monitored diligently.

Where do we stand in trial readiness for autosomal recessive limb girdle muscular dystrophies?

Autosomal recessive limb girdle muscular dystrophies (LGMD2) are a group of genetically heterogeneous diseases that are typically characterised by progressive weakness and wasting of the shoulder and pelvic girdle muscles. Many of the more than 20 different conditions show overlapping clinical features with other forms of muscular dystrophy, congenital, myofibrillar or even distal myopathies and also with acquired muscle diseases. Although individually extremely rare, all types of LGMD2 together form an important differential diagnostic group among neuromuscular diseases. Despite improved diagnostics and pathomechanistic insight, a curative therapy is currently lacking for any of these diseases. Medical care consists of the symptomatic treatment of complications, aiming to improve life expectancy and quality of life. Besides well characterised pre-clinical tools like animal models and cell culture assays, the determinants of successful drug development programmes for rare diseases include a good understanding of the phenotype and natural history of the disease, the existence of clinically relevant outcome measures, guidance on care standards, up to date patient registries, and, ideally, biomarkers that can help assess disease severity or drug response. Strong patient organisations driving research and successful partnerships between academia, advocacy, industry and regulatory authorities can also help accelerate the elaboration of clinical trials. All these determinants constitute aspects of translational research efforts and influence patient access to therapies. Here we review the current status of determinants of successful drug development programmes for LGMD2, and the challenges of translating promising therapeutic strategies into effective and accessible treatments for patients.

Dysferlin mediates the cytoprotective effects of TRAF2 following myocardial ischemia reperfusion injury

Background

We have demonstrated that tumor necrosis factor (TNF) receptor‐associated factor 2 (TRAF2), a scaffolding protein common to TNF receptors 1 and 2, confers cytoprotection in the heart. However, the mechanisms for the cytoprotective effects of TRAF2 are not known.

Methods/Results

Mice with cardiac‐restricted overexpression of low levels of TRAF2 (MHC‐TRAF2_LC) and a dominant negative TRAF2 (MHC‐TRAF2_DN) were subjected to ischemia (30‐minute) reperfusion (60‐minute) injury (I/R), using a Langendorff apparatus. MHC‐TRAF2_LC mice were protected against I/R injury as shown by a significant ≈27% greater left ventricular (LV) developed pressure after I/R, whereas mice with impaired TRAF2 signaling had a significantly ≈38% lower LV developed pressure, a ≈41% greater creatine kinase (CK) release, and ≈52% greater Evans blue dye uptake after I/R, compared to LM. Transcriptional profiling of MHC‐TRAF2_LC and MHC‐TRAF2_DN mice identified a calcium‐triggered exocytotic membrane repair protein, dysferlin, as a potential cytoprotective gene responsible for the cytoprotective effects of TRAF2. Mice lacking dysferlin had a significant ≈39% lower LV developed pressure, a ≈20% greater CK release, and ≈29% greater Evans blue dye uptake after I/R, compared to wild‐type mice, thus phenocopying the response to tissue injury in the MHC‐TRAF2_DN mice. Moreover, breeding MHC‐TRAF2_LC onto a dysferlin‐null background significantly attenuated the cytoprotective effects of TRAF2 after I/R injury.

Conclusion

The study shows that dysferlin, a calcium‐triggered exocytotic membrane repair protein, is required for the cytoprotective effects of TRAF2‐mediated signaling after I/R injury.

Dupuytren's Contracture Cosegregation with Limb-Girdle Muscle Dystrophy

Limb-girdle muscular dystrophies (LGMDs) is a heterogeneous group of muscular dystrophies that mostly affect the pelvic and shoulder girdle muscle groups. We report here a case of neuromuscular disease associated with Dupuytren's contracture, which has never been described before as cosegregating with an autosomal dominant type of inheritance. Dupuytren's contracture is a common disease, especially in Northern Europe. Comorbid conditions associated with Dupuytren's contracture are repetitive trauma to the hands, diabetes, and seizures, but it has never before been associated with neuromuscular disease. We hypothesize that patients may harbor mutations in genes with functions related to neuromuscular disease and Dupuytren's contracture development.

Review of Journal of Cardiovascular Magnetic Resonance 2012

There were 90 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2012, which is an 8% increase in the number of articles since 2011. The quality of the submissions continues to increase. The editors are delighted to report that the 2011 JCMR Impact Factor (which is published in June 2012) has risen to 4.44, up from 3.72 for 2010 (as published in June 2011), a 20% increase. The 2011 impact factor means that the JCMR papers that were published in 2009 and 2010 were cited on average 4.44 times in 2011. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is approximately 25%, and has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

Prioritizing disease candidate proteins in cardiomyopathy-specific protein-protein interaction networks based on "guilt by association" analysis

The cardiomyopathies are a group of heart muscle diseases which can be inherited (familial). Identifying potential disease-related proteins is important to understand mechanisms of cardiomyopathies. Experimental identification of cardiomyophthies is costly and labour-intensive. In contrast, bioinformatics approach has a competitive advantage over experimental method. Based on “guilt by association” analysis, we prioritized candidate proteins involving in human cardiomyopathies. We first built weighted human cardiomyopathy-specific protein-protein interaction networks for three subtypes of cardiomyopathies using the known disease proteins from Online Mendelian Inheritance in Man as seeds. We then developed a method in prioritizing disease candidate proteins to rank candidate proteins in the network based on “guilt by association” analysis. It was found that most candidate proteins with high scores shared disease-related pathways with disease seed proteins. These top ranked candidate proteins were related with the corresponding disease subtypes, and were potential disease-related proteins. Cross-validation and comparison with other methods indicated that our approach could be used for the identification of potentially novel disease proteins, which may provide insights into cardiomyopathy-related mechanisms in a more comprehensive and integrated way.

Adeno-associated virus 9 mediated FKRP gene therapy restores functional glycosylation of α-dystroglycan and improves muscle functions

Mutations in the FKRP gene are associated with a wide range of muscular dystrophies from mild limb-girdle muscular dystrophy (LGMD) 2I to severe Walker-Warburg syndrome and muscle-eye-brain disease. The characteristic biochemical feature of these diseases is the hypoglycosylation of α-dystroglycan (α-DG). Currently there is no effective treatment available. In this study, we examined the adeno-associated virus serotype 9 vector (AAV9)-mediated gene therapy in the FKRP mutant mouse model with a proline to leucine missense mutation (P448L). Our results showed that intraperitoneal administration of AAV9-FKRP resulted in systemic FKRP expression in all striated muscles examined with the highest levels in cardiac muscle. Consistent with our previous observations, FKRP protein is localized in the Golgi apparatus in myofibers. Expression of FKRP consequently restored functional glycosylation of α-DG in the skeletal and cardiac muscles. Significant improvement in dystrophic pathology, serum creatine kinase levels and muscle function was observed. Only limited FKRP transgene expression was detected in kidney and liver with no detectable toxicity. Our results provided evidence for the utility of AAV-mediated gene replacement therapy for FKRP-related muscular dystrophies.

The involvement of collagen triple helix repeat containing 1 in muscular dystrophies

Fibrosis is the main complication of muscular dystrophies. We identified collagen triple helix repeat containing 1 (Cthrc1) in skeletal and cardiac muscles of mice, representing Duchenne and congenital muscle dystrophies (DMD and CMD, respectively), and dysferlinopathy. In all of the mice, Cthrc1 was associated with high collagen type I levels; no Cthrc1 or collagen was observed in muscles of control mice. High levels of Cthrc1 were also observed in biopsy specimens from patients with DMD, in whom they were reversibly correlated with that of β-dystroglycan, whereas collagen type I levels were elevated in all patients with DMD. At the muscle sites where collagen and Cthrc1 were adjacent, collagen fibers appeared smaller, suggesting involvement of Cthrc1 in collagen turnover. Halofuginone, an inhibitor of Smad3 phosphorylation downstream of the transforming growth factor-β signaling, reduced Cthrc1 levels in skeletal and cardiac muscles of mice, representing DMD, CMD, and dysferlinopathy. The myofibroblasts infiltrating the dystrophic muscles of the murine models of DMD, CMD, and dysferlinopathy were the source of Cthrc1. Transforming growth factor-β did not affect Cthrc1 levels in the mdx fibroblasts but decreased them in the control fibroblasts, in association with increased migration of mdx fibroblasts and dystrophic muscle invasion by myofibroblasts. To our knowledge, this is the first demonstration of Cthrc1 as a marker of the severity of the disease progression in the dystrophic muscles, and as a possible target for therapy.

Review of Journal of Cardiovascular Magnetic Resonance 2011

There were 83 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2011, which is an 11% increase in the number of articles since 2010. The quality of the submissions continues to increase. The editors had been delighted with the 2010 JCMR Impact Factor of 4.33, although this fell modestly to 3.72 for 2011. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, we remain very pleased with the progress of the journal's impact over the last 5 years. Our acceptance rate is approximately 25%, and has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors feel it is useful to summarize the papers for the readership into broad areas of interest or theme, which we feel would be useful, so that areas of interest from the previous year can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

Homologous recombination mediates functional recovery of dysferlin deficiency following AAV5 gene transfer

The dysferlinopathies comprise a group of untreatable muscle disorders including limb girdle muscular dystrophy type 2B, Miyoshi myopathy, distal anterior compartment syndrome, and rigid spine syndrome. As with other forms of muscular dystrophy, adeno-associated virus (AAV) gene transfer is a particularly auspicious treatment strategy, however the size of the DYSF cDNA (6.5 kb) negates packaging into traditional AAV serotypes known to express well in muscle (i.e. rAAV1, 2, 6, 8, 9). Potential advantages of a full cDNA versus a mini-gene include: maintaining structural-functional protein domains, evading protein misfolding, and avoiding novel epitopes that could be immunogenic. AAV5 has demonstrated unique plasticity with regards to packaging capacity and recombination of virions containing homologous regions of cDNA inserts has been implicated in the generation of full-length transcripts. Herein we show for the first time in vivo that homologous recombination following AAV5.DYSF gene transfer leads to the production of full length transcript and protein. Moreover, gene transfer of full-length dysferlin protein in dysferlin deficient mice resulted in expression levels sufficient to correct functional deficits in the diaphragm and importantly in skeletal muscle membrane repair. Intravascular regional gene transfer through the femoral artery produced high levels of transduction and enabled targeting of specific muscle groups affected by the dysferlinopathies setting the stage for potential translation to clinical trials. We provide proof of principle that AAV5 mediated delivery of dysferlin is a highly promising strategy for treatment of dysferlinopathies and has far-reaching implications for the therapeutic delivery of other large genes.

Childhood onset of limb-girdle muscular dystrophy

Limb-girdle muscular dystrophies comprise a rare heterogeneous group of genetic muscular dystrophies, involving 15 autosomal recessive subtypes and seven autosomal dominant subtypes. Autosomal recessive dystrophy is far more common than autosomal dominant dystrophy. Typical clinical features include progressive limb muscle weakness and atrophy (proximal greater than distal), varying from very mild to severe. Significant overlap of clinical phenotypes, with genetic and clinical heterogeneity, constitutes the rule for this group of diseases. Muscle biopsies are useful for histopathologic and immunolabeling studies, and DNA analysis is the gold standard to establish the specific form of muscular dystrophy. A definitive diagnosis among various subtypes is challenging, and the data presented here provide neuromuscular clinicians with additional information to help attain that goal.