Evidence-based guideline summary: Evaluation, diagnosis, and management of facioscapulohumeral muscular dystrophy: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology and the Practice Issues Review Panel of the American Association of Neuromuscular & Electrodiagnostic Medicine

Facioscapulohumeral Muscular Dystrophy: Update on Pathogenesis and Future Treatments

A reliable model of a disease pathomechanism is the first step to develop targeted treatment. In facioscapulohumeral muscular dystrophy (FSHD), the third most common muscular dystrophy, recent advances in understanding the complex genetics and epigenetics have led to the identification of a disease mechanism, moving the field towards targeted therapy development. FSHD is caused by expression of DUX4, a retrogene located on the D4Z4 macrosatellite repeat array on chromosome 4q35, a gene expressed in the germline but typically repressed in somatic tissue. DUX4 derepression results from opening of the chromatin structure either by contraction of the number of repeats (FSHD1) or by chromatin hypomethylation of the D4Z4 repeats resulting from mutations in SMCHD1, a gene involved in chromatin methylation (FSHD2). The resulting expression of DUX4, a transcriptional regulator, and its target genes is toxic to skeletal muscle. Efforts for targeted treatment currently focus on disrupting DUX4 expression or blocking 1 or more of several downstream effects of DUX4. This review article focuses on the underlying FSHD genetics, current understanding of the pathomechanism, and potential treatment strategies in FSHD. In addition, recent advances in the development of new clinical outcome measures as well as biomarkers, critical for the success of future clinical trials, are reviewed.

The cardiorespiratory response and physiological determinants of the assisted 6-minute handbike cycle test in adult males with muscular dystrophy

INTRODUCTION

The assisted 6-minute cycle test (A6MCT) distance was assessed in adults with muscular dystrophy (MD).

METHODS

Forty-eight males, including those with Duchenne MD (DMD), limb-girdle MD (LGMD), fascioscapulohumeral MD (FSHD), and Becker MD (BMD), as well as a group without MD (CTRL), completed handgrip strength (HGS), lung function [forced expiratory volume in 1 second (FEV1 ) and forced vital capacity (FVC)], body fat, and biceps thickness assessments. During the A6MCT, ventilation (VE), oxygen uptake (VO2 ), carbon dioxide (VCO2 ), and heart rate (HR) were recorded.

RESULTS

A6MCT and HGS were lower in MD than CTRL subjects. FEV1 , FVC, and biceps thickness were lower in MD than CTRL; lower in DMD than BMD, LGMD, and FSHD; but were not different between BMD, LGMD, and FSHD. A6MCT correlated with HGS, FEV1 , FVC, body fat, VO2 , VCO2 , HR, and VE (r = 0.455-0.708) in pooled BMD, LGMD, and FSHD participants.

DISCUSSION

A shorter A6MCT distance in adult males with MD was attributable to HGS and lung function. The A6MCT is appropriate for assessment of physical function in adults with MD. Muscle Nerve 58: 427-433, 2018.

A 22-year follow-up reveals a variable disease severity in early-onset facioscapulohumeral dystrophy

AIM

To assess the long-term natural course of early-onset facioscapulohumeral dystrophy (FSHD), which is important for patient management and trial-readiness, and is currently lacking.

METHODS

We had the unique opportunity to evaluate 10 patients with early-onset FSHD after 22 years follow-up. Patients underwent a semi-structured interview, physical examination and additional genotyping.

RESULTS

Nine initial study participants (median age 37 years) were included, one patient died shortly after first publication. At first examination, one patient was wheelchair dependent, one patient walked aided, and eight patients walked unaided. After 22 years, four patients were wheelchair dependent, three walked aided, and two walked unaided. Systemic features, including hearing loss (56%), intellectual disability (44%), and a decreased respiratory function (56%), were frequent. Patients participated socially and economically with most patients living in a regular house (n = 6) and/or having a paid job (n = 4).

DISCUSSION

Patients with early-onset FSHD generally had a severe phenotype compared to classical onset FSHD. However, after 22 years of follow up they showed a wide variation in severity and, despite these physical limitations, participated socially and economically. These observations are important for patient management and should be taken into account in clinical trials.

A Pediatric Review of Facioscapulohumeral Muscular Dystrophy

Facioscapulohumeral dystrophy is one of the most common forms of muscular dystrophies worldwide. It is a complex and heterogeneous disease secondary to insufficient epigenetic repression of D4Z4 repeats and aberrant expression of DUX4 in skeletal muscles. Type 1 facioscapulohumeral muscular dystrophy (FSHD) is caused by contraction of D4Z4 repeats on 4q35, whereas type 2 FSHD is associated with mutations of the SMCHD1 or DNMT3B gene in the presence of a disease-permissive 4qA haplotype. Classical FSHD is a slowly progressive disorder with gradual-onset of muscle atrophy and a descending pattern of muscle weakness. In contrast, early-onset FSHD is associated with a large deletion of D4Z4 repeats and a more severe disease phenotype, including early loss of independent ambulation as well as extramuscular manifestations, such as retinal vasculopathy, hearing loss, and central nervous system (CNS) involvement. However, the correlation between D4Z4 repeats and disease severity remains imprecise. The current standard of care guidelines offers comprehensive assessment and symptomatic management of secondary complications. Several clinical trials are currently underway for FSHD. New and emerging treatments focus on correcting the transcriptional misregulation of D4Z4 and reversing the cytotoxic effects of DUX4. Other potential therapeutic targets include reduction of inflammation, improving muscle mass, and activating compensatory molecular pathways. The utility of disease-modifying treatments will depend on selection of sensitive clinical endpoints as well as validation of muscle magnetic resonance imaging (MRI) and other biomarkers to detect meaningful changes in disease progression. Correction of the epigenetic defects using new gene editing as well as other DUX4 silencing technologies offers potential treatment options for many individuals with FSHD.

Retrospective natural history of thymidine kinase 2 deficiency

Background

Thymine kinase 2 (TK2) is a mitochondrial matrix protein encoded in nuclear DNA and phosphorylates the pyrimidine nucleosides: thymidine and deoxycytidine. Autosomal recessive TK2 mutations cause a spectrum of disease from infantile onset to adult onset manifesting primarily as myopathy.

Objective

To perform a retrospective natural history study of a large cohort of patients with TK2 deficiency.

Methods

The study was conducted by 42 investigators across 31 academic medical centres.

Results

We identified 92 patients with genetically confirmed diagnoses of TK2 deficiency: 67 from literature review and 25 unreported cases. Based on clinical and molecular genetics findings, we recognised three phenotypes with divergent survival: (1) infantile-onset myopathy (42.4%) with severe mitochondrial DNA (mtDNA) depletion, frequent neurological involvement and rapid progression to early mortality (median post-onset survival (POS) 1.00, CI 0.58 to 2.33 years); (2) childhood-onset myopathy (40.2%) with mtDNA depletion, moderate-to-severe progression of generalised weakness and median POS at least 13 years; and (3) late-onset myopathy (17.4%) with mild limb weakness at onset and slow progression to respiratory insufficiency with median POS of 23 years. Ophthalmoparesis and facial weakness are frequent in adults. Muscle biopsies show multiple mtDNA deletions often with mtDNA depletion.

Conclusions

In TK2 deficiency, age at onset, rate of weakness progression and POS are important variables that define three clinical subtypes. Nervous system involvement often complicates the clinical course of the infantile-onset form while extraocular muscle and facial involvement are characteristic of the late-onset form. Our observations provide essential information for planning future clinical trials in this disorder.

A multinational study on motor function in early-onset FSHD

OBJECTIVES

To investigate motor function associations with age, sex, and D4Z4 repeats among participants with early-onset facioscapulohumeral muscular dystrophy (FSHD) type 1 as defined by weakness onset before 10 years of age.

METHODS

We collected standardized motor assessments, including manual muscle testing (MMT), quantitative muscle testing, functional motor evaluations, and clinical severity scores (CSSs), at 12 Cooperative International Neuromuscular Research Group centers. To measure associations, we used linear regression models adjusted for sex, evaluation age, age at onset of weakness, and D4Z4 repeats.

RESULTS

Among 52 participants (60% female, mean age 22.9 ± 14.7 years), weakness was most pronounced in the shoulder and abdominal musculature. Older enrollment age was associated with greater CSSs (p = 0.003). When adjusted for enrollment age, sex, and D4Z4 repeats, younger age at onset of facial weakness was associated with greater CSSs, slower velocities in timed function tests, and lower MMT scores (p < 0.05).

CONCLUSION

Significant clinical variability was observed in early-onset FSHD. Earlier age at onset of facial weakness was associated with greater disease severity. Longitudinal assessments are needed to determine the rate of disease progression in this population.

Integrating clinical and genetic observations in facioscapulohumeral muscular dystrophy

PURPOSE OF REVIEW

This review gives an overview of the currently known key clinical and (epi)genetic aspects of facioscapulohumeral muscular dystrophy (FSHD) and provides perspectives to facilitate future research.

RECENT FINDINGS

Clinically, imaging studies have contributed to a detailed characterization of the FSHD phenotype, and a model is proposed with five stages of disease progression. A number of clinical trials have been conducted regarding exercise and diet aiming to reduce symptoms. Genetically, at least two different mechanisms (FSHD1 and FSHD2) lead to double homeobox 4 (DUX4) expression in skeletal myocytes, which is expected to be necessary for the disease. Disease severity is most likely determined by a combination of the D4Z4 repeat size and its epigenetic state.

SUMMARY

FSHD is one of the most common muscular dystrophies and is characterized by a typical distribution of muscle weakness. Progress has been made on clinical as well as on (epi)genetic aspects of the disease. Currently, there is no cure available for FSHD. For successful development of new treatments targeting the disease process, integration of clinical and pathogenetic knowledge is essential. A clinical trial toolbox that consists of patient registries, biomarkers and clinical outcome measures will be required to effectively conduct future clinical trials.

Kinematic analysis of scapular movements in patients with facioscapulohumeral muscular dystrophy

The purpose of this study is to evaluate scapular movements by the three-dimensional electromagnetic system during shoulder elevation in FSHMD patients, and to compare the results with healthy individuals. 10 patients with FSHMD and 10 healthy individuals were included in the study. Scapular anterior-posterior tilt, upward-downward rotation and internal-external rotation at 30°, 60° and 90° were evaluated using the three-dimensional electromagnetic system during the elevation of the upper limbs in the scapular plane. Humerothoracic elevation levels on the dominant and non-dominant sides were found to be lower in the patients than healthy individuals (p < .001). Both scapula were rotated downwards at 30° (dominant/non-dominant p < .001) and 60° (dominant p = .009, non-dominant p = .04) of humerothoracic elevation, the scapula was rotated internally at 30° of humerothoracic elevation on the non-dominant side (p = .03), and the scapula was tilted posteriorly at 90° of humerothoracic elevation on the non-dominant side (p = .009) in patients. These existing abnormal patterns of the scapula in the patients increase the risk of impairment, pain, impingement and instability especially in the activities that require arm elevation. It is thought that physiotherapy approaches should first be emphasized to improve scapular stabilization and strengthening exercises should then be performed for the shoulder girdle muscles.

Early onset facioscapulohumeral dystrophy - a systematic review using individual patient data

Infantile or early onset is estimated to occur in around 10% of all facioscapulohumeral dystrophy (FSHD) patients. Although small series of early onset FSHD patients have been reported, comprehensive data on the clinical phenotype is missing. We performed a systematic literature search on the clinical features of early onset FSHD comprising a total of 43 articles with individual data on 227 patients. Additional data from four cohorts was provided by the authors. Mean age at reporting was 18.8 years, and 40% of patients were wheelchair-dependent at that age. Half of the patients had systemic features, including hearing loss (40%), retinal abnormalities (37%) and developmental delay (8%). We found an inverse correlation between repeat size and disease severity, similar to adult-onset FSHD. De novo FSHD1 mutations were more prevalent than in adult-onset FSHD. Compared to adult FSHD, our findings indicate that early onset FSHD is overall characterized by a more severe muscle phenotype and a higher prevalence of systemic features. However, similar as in adults, a significant clinical heterogeneity was observed. Based on this, we consider early onset FSHD to be on the severe end of the FSHD disease spectrum. We found natural history studies and treatment studies to be very scarce in early onset FSHD, therefore longitudinal studies are needed to improve prognostication, clinical management and trial-readiness.

Neuromuscular Disorders and the Role of the Clinical Electrophysiologist

Cardiac involvement is common and may be the presenting or predominant manifestation in a variety of neuromuscular disorders, most notably the inherited muscle disorders, or muscular dystrophies. Cardiac manifestations of the neuromuscular disorders result from pathological involvement of the myocardium and the cardiac conduction system, with resulting cardiomyopathy or rhythm disturbances including supraventricular arrhythmias, life-threatening ventricular arrhythmias, and sudden cardiac death. Many of these neuromuscular disorders are rare and may be unrecognized by even experienced specialists in internal and cardiovascular medicine. Furthermore, the initial cardiac manifestations in these patients are often asymptomatic. The goal of this investigation is to review the scope of cardiac conduction defects and rhythm disturbances in these disorders and to propose some practical recommendations for arrhythmia monitoring and management of these patients.

Developing multidisciplinary clinics for neuromuscular care and research

Multidisciplinary care is considered the standard of care for both adult and pediatric neuromuscular disorders and has been associated with improved quality of life, resource utilization, and health outcomes. Multidisciplinary care is delivered in multidisciplinary clinics that coordinate care across multiple specialties by reducing travel burden and streamlining care. In addition, the multidisciplinary care setting facilitates the integration of clinical research, patient advocacy, and care innovation (e.g., telehealth). Yet, multidisciplinary care requires substantial commitment of staff time and resources. We calculated personnel costs in our ALS clinic in 2015 and found an average cost per patient visit of $580, of which only 45% was covered by insurance reimbursement. In this review, we will describe classic and emerging concepts in multidisciplinary care models for adult and pediatric neuromuscular disease. We will then explore the financial impact of multidisciplinary care with emphasis on sustainability and metrics to demonstrate quality and value. Muscle Nerve 56: 848-858, 2017.

Surgical correction of hyperlordosis in facioscapulohumeral muscular dystrophy: A case report

Background

Hyperlordosis is common in facioscapulohumeral muscular dystrophy (FSHD), which cannot be controlled by bracing. While the surgical treatment is neither reported nor recommended in previous studies, we report the first corrective surgery for hyperlordosis in one wheelchair-dependent FSHD patient.

Case presentation

A 15-year-old, wheelchair-dependent girl complaining of hyperlordosis and lower extremity weakness was diagnosed as FSHD. Preoperative examination showed hyperlordosis of 116° with scoliosis of 44°. Posterior correction and bone graft fusion was performed. Postoperatively, the hyperlordosis was corrected to 72° and better sitting posture was gotten. 12 months’ follow-up showed favorable correction with improvement in SF-36 and ODI score.

Conclusions

The correction for hyperlordosis in FSHD is controversial. We report the first successful case of operative treatment by corrective spine surgery in these rare and demanding patient collective. Corrective surgery for spinal deformity, such as hyperlordosis and scoliosis, could do some help in posture and improve the quality of life especially in wheelchair-dependent patients.

The utility of genetic testing in neuromuscular disease: A consensus statement from the AANEM on the clinical utility of genetic testing in diagnosis of neuromuscular disease

INTRODUCTION

The aim of this consensus statement is to provide a recommendation from AANEM experts on the clinical utility of genetic testing. It is not meant to recommend or endorse any specific genetic testing methodology or algorithm.

METHODS

The AANEM Professional Practice Committee reached a consensus based on expert opinion on the utility of genetic testing in neuromuscular diseases and made recommendations on factors that physicians and patients should consider when deciding whether to proceed with such testing.

RESULTS

Despite the costs of genetic testing, these tests can be both valuable and beneficial in the diagnosis and treatment of neuromuscular diseases in many situations.

CONCLUSIONS

The AANEM believes that performing genetic testing to arrive at a specific molecular diagnosis is a critical step in providing high-quality care to neuromuscular patients. The cost of testing should not be a deterrent, as there are important clinical, safety, psychosocial, and research benefits. Muscle Nerve 54: 1007-1009, 2016.

Respiratory involvement in ambulant and non-ambulant patients with facioscapulohumeral muscular dystrophy

Understand the occurrence and predictors of respiratory impairment in FSHD. Data from 100 FSHD patients was collected regarding demographics, genetics, respiratory status and pulmonary function tests, clinical manifestations and Clinical Severity Scale (CSS) scores. Patients were assigned to two severity groups using CSS: mild (scores <3.5) and moderate/severely affected (scores ≥3.5). Forced Vital Capacity (FVC) was classified as severely impaired if less than 50% of the predicted. Statistical analysis was performed using IBM SPSS Statistics 23, tests were two-tailed and the level of significance set at 5%. Spirometry was available for 94 patients; 41.5% had abnormal results with a restrictive pattern in 38.3% patients. There was a correlation between FVC; CSS score and D4Z4 fragment length with a higher probability of severe respiratory involvement in the early onset group, moderate/severe disease and D4Z4 fragments <18 kb. Patients with severe respiratory involvement showed a high prevalence of sleep-disordered breathing. FVC decline over time was indicative of three progression groups. Respiratory involvement for both ambulant and non-ambulant patients with FSHD is more frequent and severe than previously suggested. Sleep-disordered breathing is frequent and negatively influences the respiratory status. Annual screening of the respiratory status with spirometry and clinical assessment is thus warranted in FSHD patients, even while ambulant.

Estrogens enhance myoblast differentiation in facioscapulohumeral muscular dystrophy by antagonizing DUX4 activity

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant neuromuscular disorder that is characterized by extreme variability in symptoms, with females being less severely affected than males and presenting a higher proportion of asymptomatic carriers. The sex-related factors involved in the disease are not known. Here, we have utilized myoblasts isolated from FSHD patients (FSHD myoblasts) to investigate the effect of estrogens on muscle properties. Our results demonstrated that estrogens counteract the differentiation impairment of FSHD myoblasts without affecting cell proliferation or survival. Estrogen effects are mediated by estrogen receptor β (ERβ), which reduces chromatin occupancy and transcriptional activity of double homeobox 4 (DUX4), a protein whose aberrant expression has been implicated in FSHD pathogenesis. During myoblast differentiation, we observed that the levels and activity of DUX4 increased progressively and were associated with its enhanced recruitment in the nucleus. ERβ interfered with this recruitment by relocalizing DUX4 in the cytoplasm. This work identifies estrogens as a potential disease modifier that underlie sex-related differences in FSHD by protecting against myoblast differentiation impairments in this disease.

Antisense Oligonucleotides Used to Target the DUX4 mRNA as Therapeutic Approaches in FaciosScapuloHumeral Muscular Dystrophy (FSHD)

FacioScapuloHumeral muscular Dystrophy (FSHD) is one of the most prevalent hereditary myopathies and is generally characterized by progressive muscle atrophy affecting the face, scapular fixators; upper arms and distal lower legs. The FSHD locus maps to a macrosatellite D4Z4 repeat array on chromosome 4q35. Each D4Z4 unit contains a DUX4 gene; the most distal of which is flanked by a polyadenylation site on FSHD-permissive alleles, which allows for production of stable DUX4 mRNAs. In addition, an open chromatin structure is required for DUX4 gene transcription. FSHD thus results from a gain of function of the toxic DUX4 protein that normally is only expressed in germ line and stem cells. Therapeutic strategies are emerging that aim to decrease DUX4 expression or toxicity in FSHD muscle cells. We review here the heterogeneity of DUX4 mRNAs observed in muscle and stem cells; and the use of antisense oligonucleotides (AOs) targeting the DUX4 mRNA to interfere either with transcript cleavage/polyadenylation or intron splicing. We show in primary cultures that DUX4-targeted AOs suppress the atrophic FSHD myotube phenotype; but do not improve the disorganized FSHD myotube phenotype which could be caused by DUX4c over-expression. Thus; DUX4c might constitute another therapeutic target in FSHD.

MRI as outcome measure in facioscapulohumeral muscular dystrophy: 1-year follow-up of 45 patients

There is no effective treatment available for facioscapulohumeral muscular dystrophy type 1 (FSHD1), but emerging therapies are under way that call for a better understanding of natural history in this condition. In this prospective, longitudinal study, we used quantitative MRI to assess yearly disease progression in patients with FSHD1. Ambulatory patients with confirmed diagnosis of FSHD1 (25/20 men/women, age 20-75 years, FSHD score: 0-12) were tested with 359-560-day interval between tests. Using the MRI Dixon technique, muscle fat replacement was evaluated in paraspinal, thigh, and calf muscles. Changes were compared with those in FSHD score, muscle strength (hand-held dynamometry), 6-minute-walk-distance, 14-step-stair-test, and 5-time-sit-to-stand-test. Composite absolute fat fraction of all assessed muscles increased by 0.036 (CI 0.026-0.046, P < 0.001), with increases in all measured muscle groups. The clinical severity FSHD score worsened (10%, P < 0.05), muscle strength decreased over the hip (8%), neck (8%), and back (17%) (P < 0.05), but other strength measures, 6-minute-walk-distance, 5-times-sit-to-stand-test, and 14-step-stair-test were unchanged. Changes in muscle strength, FSHD score, and fat fraction did not correlate. This first study to systemically monitor quantitative fat replacement longitudinally in FSHD1 shows that MRI provides an objective measure of disease progression, often before changes can be appreciated in strength and functional tests. The study indicates that quantitative MRI can be a helpful end-point in follow-up and therapeutic trials of patients with FSHD1.

Bone health measured using quantitative ultrasonography in adult males with muscular dystrophy

OBJECTIVES

To compare muscle and bone health markers in adult males (aged 20-59 yrs) with and without muscular dystrophy (MD).

METHODS

Participants included 11 Fascioscapulohumeral (FSH), 11 Becker's (Be), 9 limb girdle (LG), 11 Duchenne (DMD), and 14 non-dystrophic controls (CTRL). Physical activity was assessed using Bone (BPAQ) and disability specific (PASIPD) questionnaires. Bone QUS provided T- and Z scores from the Distal Radius (DR) and Mid-shaft tibia (MST). Tibialis anterior cross sectional area (TAACSA) was measured using B-mode ultrasound. Grip strength was measured in all but DMD.

RESULTS

Physical activity was lower in DMD, FSH and BeMD than CTRL (P<0.05), and lower in DMD than other MDs (P<0.01). T and Z scores were lower in DMD and Be than CTRL (DR, P<0.05); and lower in DMD than CTRL, LG, and FSH (MST, P<0.01). TAACSA and grip strength was 35-59% and 50-58% smaller in MD than CTRL, respectively (P<0.01). Within MD, BPAQ correlated with bone QUS measures (r=0.42-0.38, P<0.01). PASIPD correlated with grip strength (r=0.65, P<0.01) and TAACSA (r=0.46, P<0.01).

CONCLUSION

Muscle size, strength, and bone health was lower in adult males with MD compared to adult males without MD, the extent of this is partially determined by physical activity.

Facioscapulohumeral Muscular Dystrophy

PURPOSE OF REVIEW

This article describes the clinical characteristics, diagnosis, molecular pathogenesis, and treatment of facioscapulohumeral muscular dystrophy (FSHD).

RECENT FINDINGS

FSHD comprises two genetically distinct types that converge on a common downstream pathway of the expression of the toxic protein DUX4. Approximately 95% of patients have FSHD type 1 (FSHD1), in which loss of DNA repetitive elements (D4Z4 repeats) in the subtelomeric region of chromosome 4q causes decreased methylation and epigenetic derepression of DUX4, a gene contained within each D4Z4 repeat. FSHD type 2 (FSHD2) occurs through a deletion-independent mechanism but, similar to FSHD1, leads to decreased methylation and epigenetic derepression in the same region of chromosome 4q. Whereas FSHD1 is dominantly inherited, FSHD2 shows digenic inheritance, and about 80% of patients will have a mutation in the SMCHD1 gene. DUX4 lacks a polyadenylation signal, so both FSHD1 and FSHD2 only occur in the presence of permissive 4q polymorphisms, which provide a stabilizing polyadenylation sequence. FSHD is an epigenetic disease, and penetrance and severity are related to both the number of residual D4Z4 units and D4Z4 methylation.

SUMMARY

Recent consensus guidelines outline standards for care for FSHD, and identification of potential therapeutic targets have shifted emphasis in the research community toward drug development and clinical trial planning.

Facioscapulohumeral dystrophy in children: design of a prospective, observational study on natural history, predictors and clinical impact (iFocus FSHD)

Background

Facioscapulohumeral muscular dystrophy (FSHD; OMIM 158900 & 158901) is a progressive skeletal muscle dystrophy, characterized by an autosomal dominant inheritance pattern. One of the major unsolved questions in FSHD is the marked clinical heterogeneity, ranging from asymptomatic individuals to severely affected patients with an early onset. An estimated 10 % of FSHD patients have an early onset (onset before 10 years of age) and are traditionally classified as infantile FSHD. This subgroup is regarded as severely affected and extra-muscular symptoms, such as hearing loss and retinopathy, are frequently described. However, information on the prevalence, natural history and clinical management of early onset FSHD is currently lacking, thereby hampering adequate patient counselling and management. Therefore, a population-based prospective cohort study on FSHD in children is highly needed.

Methods/design

This explorative study aims to recruit all children (aged 0–17 years) with a genetically confirmed diagnosis of FSHD in The Netherlands. The children will be assessed at baseline and at 2-year follow-up. The general aim of the study is the description of the clinical features and genetic characteristics of this paediatric cohort. The primary outcome is the motor function as measured by the Motor Function Measure. Secondary outcomes include quantitative and qualitative description of the clinical phenotype, muscle imaging, genotyping and prevalence estimations. The ultimate objective will be a thorough description of the natural history, predictors of disease severity and quality of life in children with FSHD.

Discussion

The results of this population-based study are vital for adequate patient management and clinical trial-readiness. Furthermore, this study is expected to provide additional insight in the epigenetic and environmental disease modifying factors. In addition to improve counselling, this could contribute to unravelling the aetiology of FSHD.

Trial registration

clinicaltrials.gov NCT02625662.

Targeting mRNA for the treatment of facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is an inherited autosomal dominant disorder characterized clinically by progressive muscle degeneration. Currently, no curative treatment for this disorder exists. FSHD patients are managed through physiotherapy to improve function and quality of life. Over the last two decades, FSHD has been better understood as a disease genetically characterized by a pathogenic contraction of a subset of macrosatellite repeats on chromosome 4. Specifically, several studies support an FSHD pathogenesis model involving the aberrant expression of the double homeobox protein 4 (DUX4) gene. Hence, potential therapies revolving around inhibition of DUX4 have been explored. One of the potential treatment options is the use of effective antisense oligonucleotides (AOs) to knockdown expression of the myopathic DUX4 gene and its downstream molecules including paired-like homeodomain transcription factor 1 (PITX1). Success in the suppression of PITX1 expression has already been demonstrated systemically in vivo in recent studies. In this article, we will review the pathogenesis of FSHD and the latest research involving the use of antisense knockdown therapy.

Target resequencing of neuromuscular disease-related genes using next-generation sequencing for patients with undiagnosed early-onset neuromuscular disorders

Neuromuscular disorders are clinically and genetically heterogeneous diseases with broadly overlapping clinical features. Progress in molecular genetics has led to the identification of numerous causative genes for neuromuscular disorders, but Sanger sequencing-based diagnosis remains labor-intensive and expensive because the genes are large, the genotypes and phenotypes of neuromuscular disorders overlap and multiple genes related to a single phenotype exist. Recently, the advent of next-generation sequencing (NGS) has enabled efficient, concurrent examination of several related genes. Thus, we used NGS for target resequencing of neuromuscular disease-related genes from 42 patients in whom undiagnosed early-onset neuromuscular disorders. Causative genes were identified in 19/42 (45.2%) patients (six, congenital muscular dystrophy; two, Becker muscular dystrophy (BMD); three, limb-girdle muscular dystrophy; one, concurrent BMD and Fukuyama congenital muscular dystrophy; three, nemaline myopathy; one, centronuclear myopathy; one, congenital fiber-type disproportion; one, myosin storage myopathy; and one, congenital myasthenic syndrome). We detected variants of uncertain significance in two patients. In 6/19 patients who received a definitive diagnosis, the diagnosis did not require muscle biopsy. Thus, for patients with suspected neuromuscular disorders not identified using conventional genetic testing alone, NGS-based target resequencing has the potential to serve as a powerful tool that allows definitive diagnosis.

Design, set-up and utility of the UK facioscapulohumeral muscular dystrophy patient registry

Facioscapulohumeral dystrophy (FSHD) is a rare inherited neuromuscular disease estimated to affect 1/15,000 people. Through basic research, remarkable progress has been made towards the development of targeted therapies. Patient identification, through registries or other means is essential for trial-readiness. The UK FSHD Patient Registry is a patient initiated registry that collects standardised and internationally agreed dataset of self-reported clinical details combined with professionally verified genetic information. It includes four additional questionnaires to capture patient reported outcomes related to pain, quality of life and scapular fixation. Between 2013 and 2015, 518 patients registered 243 males, 241 females with a mean age of 47.8 years. Most of the patients have FSHD type 1 (91.7 %), and weakness of the facial (59.2 %) was the most prevalent symptom at onset, followed by shoulder-girdle muscles (53.3 %) and distal (22.45 %) or proximal lower limb weakness (14.8 %). 85.57 % patients were ambulant or ambulant with assistance at the time of registration, 7.9 % report respiratory insufficiency. The registry has demonstrated utility with the recruitment of patients for a natural history study of infantile onset FSHD, and the longitudinal analysis of patient-related outcomes will provide much-needed baseline information to power future trials. The internationally agreed core dataset enables national registries to participate in a “Global FSHD registry”. We suggest that the registry’s ability to interoperate with other large datasets will be instrumental for sharing and exploiting data globally.

A novel clinical tool to classify facioscapulohumeral muscular dystrophy phenotypes

Based on the 7-year experience of the Italian Clinical Network for FSHD, we revised the FSHD clinical form to describe, in a harmonized manner, the phenotypic spectrum observed in FSHD. The new Comprehensive Clinical Evaluation Form (CCEF) defines various clinical categories by the combination of different features. The inter-rater reproducibility of the CCEF was assessed between two examiners using kappa statistics by evaluating 56 subjects carrying the molecular marker used for FSHD diagnosis. The CCEF classifies: (1) subjects presenting facial and scapular girdle muscle weakness typical of FSHD (category A, subcategories A1–A3), (2) subjects with muscle weakness limited to scapular girdle or facial muscles (category B subcategories B1, B2), (3) asymptomatic/healthy subjects (category C, subcategories C1, C2), (4) subjects with myopathic phenotype presenting clinical features not consistent with FSHD canonical phenotype (D, subcategories D1, D2). The inter-rater reliability study showed an excellent concordance of the final four CCEF categories with a κ equal to 0.90; 95 % CI (0.71; 0.97). Absolute agreement was observed for categories C and D, an excellent agreement for categories A [κ = 0.88; 95 % CI (0.75; 1.00)], and a good agreement for categories B [κ = 0.79; 95 % CI (0.57; 1.00)]. The CCEF supports the harmonized phenotypic classification of patients and families. The categories outlined by the CCEF may assist diagnosis, genetic counseling and natural history studies. Furthermore, the CCEF categories could support selection of patients in randomized clinical trials. This precise categorization might also promote the search of genetic factor(s) contributing to the phenotypic spectrum of disease.

A protocol to develop clinical guidelines for inclusion-body myositis

INTRODUCTION

Inclusion-body myositis (IBM) is a late-onset idiopathic inflammatory myopathy associated with selective and progressive muscle weakness and atrophy. Current clinical management of IBM is largely supportive due to its uncertain etiology and lack of effective treatment. Establishing a consensus of opinion on questions relating to diagnosis and management of IBM is expected to help reduce inconsistencies in the care and resources allocated to those living with this condition.

METHODS

A protocol has been developed to produce best practice clinical guidelines for IBM based on a combination of published research and expert consensus.

CONCLUSIONS

In this study we describe the proposed protocol for developing methods for producing robust and transparent clinical guidance on aspects of diagnosis, drug treatment, physical and practical management, respiration, nutrition and cardiac management, psychosocial management, and multidisciplinary care.

What's in a name? The clinical features of facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is an inherited and progressive muscle disorder. Although its name suggests otherwise, it comprises weakness of the facial, shoulder and upper arm muscles, and also of the trunk and leg muscles. Its severity and disease course vary greatly and mild or early FSHD can be difficult to recognise. Knowledge of its subtle signs and symptoms can lead directly to the correct diagnosis without diagnostic delay and without needing multiple diagnostic procedures. We give an overview of the signs and symptoms of FSHD in severe as well as in mild cases, to facilitate correct and instant recognition of this relatively common muscle disorder.