Risk of functional impairment in Facioscapulohumeral muscular dystrophy

An open-label pilot study of losmapimod to evaluate the safety, tolerability, and changes in biomarker and clinical outcome assessments in participants with facioscapulohumeral muscular dystrophy type 1

INTRODUCTION

Facioscapulohumeral muscular dystrophy (FSHD) is a genetic disease caused by aberrant DUX4 expression, leading to progressive muscle weakness. No effective pharmaceutical treatment is available. Losmapimod, a small molecule selective inhibitor of p38 α/β MAPK, showed promising results in a phase 1 trial for the treatment of FSHD, prompting additional studies. We report the findings of an open-label phase 2 trial (NCT04004000) investigating the safety, tolerability, pharmacokinetics, pharmacodynamics, and exploratory efficacy of losmapimod in participants with FSHD1.

METHODS

This study was conducted at a single site in the Netherlands from August 2019 to March 2021, with an optional, ongoing open-label extension. Participants aged 18 to 65 years with FSHD1 took 15 mg of losmapimod twice daily for 52 weeks. Primary endpoints were measures of losmapimod safety and tolerability. Secondary endpoints were assessments of losmapimod pharmacokinetics and pharmacodynamics.

RESULTS

Fourteen participants were enrolled. No deaths, serious treatment-emergent adverse events (TEAEs), or discontinuations due to TEAEs were reported. Losmapimod achieved blood concentrations and target engagements that were previously associated with decreased DUX4 expression in vitro. Clinical outcome measures showed a trend toward stabilization or improvement.

CONCLUSIONS

Losmapimod was well tolerated and may be a promising new treatment for FSHD; a larger phase 3 study is ongoing.

Recognizing Myopathy in Patients with Muscle Weakness or Pain

Muscle weakness and pain can be seen in orthopedic, rheumatologic, cardiac, and musculoskeletal conditions in addition to neurologic disorders. Myopathy, which describes a heterogenous group of hereditary and acquired disorders that affect muscle channels, structure, and metabolism, is one possible cause. This review focuses on essential information to support primary care providers as they assess patients with muscle weakness and pain for myopathy. As with most neurologic disorders, a thorough clinical history and physical examination are essential first steps. These findings will then guide diagnostic testing and facilitate appropriate management or referral for further neuromuscular care.

Safety and efficacy of losmapimod in facioscapulohumeral muscular dystrophy (ReDUX4): a randomised, double-blind, placebo-controlled phase 2b trial

BACKGROUND

Facioscapulohumeral muscular dystrophy is a hereditary progressive myopathy caused by aberrant expression of the transcription factor DUX4 in skeletal muscle. No approved disease-modifying treatments are available for this disorder. We aimed to assess the safety and efficacy of losmapimod (a small molecule that inhibits p38α MAPK, a regulator of DUX4 expression, and p38β MAPK) for the treatment of facioscapulohumeral muscular dystrophy.

METHODS

We did a randomised, double-blind, placebo-controlled phase 2b trial at 17 neurology centres in Canada, France, Spain, and the USA. We included adults aged 18-65 years with type 1 facioscapulohumeral muscular dystrophy (ie, with loss of repression of DUX4 expression, as ascertained by genotyping), a Ricci clinical severity score of 2-4, and at least one skeletal muscle judged using MRI to be suitable for biopsy. Participants were randomly allocated (1:1) to either oral losmapimod (15 mg twice a day) or matching placebo for 48 weeks, via an interactive response technology system. The investigator, study staff, participants, sponsor, primary outcome assessors, and study monitor were masked to the treatment allocation until study closure. The primary endpoint was change from baseline to either week 16 or 36 in DUX4-driven gene expression in skeletal muscle biopsy samples, as measured by quantitative RT-PCR. The primary efficacy analysis was done in all participants who were randomly assigned and who had available data for assessment, according to the modified intention-to-treat principle. Safety and tolerability were assessed as secondary endpoints. This study is registered at ClinicalTrials.gov, number NCT04003974. The phase 2b trial is complete; an open-label extension is ongoing.

FINDINGS

Between Aug 27, 2019, and Feb 27, 2020, 80 people were enrolled. 40 were randomly allocated to losmapimod and 40 to placebo. 54 (68%) participants were male and 26 (33%) were female, 70 (88%) were White, and mean age was 45·7 (SD 12·5) years. Least squares mean changes from baseline in DUX4-driven gene expression did not differ significantly between the losmapimod (0·83 [SE 0·61]) and placebo (0·40 [0·65]) groups (difference 0·43 [SE 0·56; 95% CI -1·04 to 1·89]; p=0·56). Losmapimod was well tolerated. 29 treatment-emergent adverse events (nine drug-related) were reported in the losmapimod group compared with 23 (two drug-related) in the placebo group. Two participants in the losmapimod group had serious adverse events that were deemed unrelated to losmapimod by the investigators (alcohol poisoning and suicide attempt; postoperative wound infection) compared with none in the placebo group. No treatment discontinuations due to adverse events occurred and no participants died during the study.

INTERPRETATION

Although losmapimod did not significantly change DUX4-driven gene expression, it was associated with potential improvements in prespecified structural outcomes (muscle fat infiltration), functional outcomes (reachable workspace, a measure of shoulder girdle function), and patient-reported global impression of change compared with placebo. These findings have informed the design and choice of efficacy endpoints for a phase 3 study of losmapimod in adults with facioscapulohumeral muscular dystrophy.

FUNDING

Fulcrum Therapeutics.

A longitudinal study of disease progression in facioscapulohumeral muscular dystrophy (FSHD)

INTRODUCTION/AIMS

In preparation for clinical trials, it is important to better understand how disease burden changes over time in facioscapulohumeral muscular dystrophy (FSHD) and to assess the capability of select metrics to detect these changes. This study aims to evaluate FSHD disease progression over 1 year and to examine the sensitivity of several outcome measures in detecting changes during this interval.

METHODS

We conducted a 12-month prospective observational study of 41 participants with FSHD. Participants were evaluated at baseline, 6 months, and 12 months with serial strength testing (manual muscle testing or MMT and maximum voluntary isometric contraction testing or MVICT), functional testing (FSHD-Composite Outcome Measure or FSHD-COM, FSHD Clinical Severity Score or CSS, and FSHD Evaluation Score or FES), sleep and fatigue assessments, lean body mass measurements, respiratory testing, and the FSHD-Health Index patient-reported outcome. Changes in these outcome measures were assessed over the 12-month period. Associations between changes in outcome measures and both age and sex were also examined.

RESULTS

In a 12-month period, FSHD participant function remained largely stable with a mild worsening of strength, measured by MMT and standardized MVICT scores, and a mild loss in lean body mass.

DISCUSSION

The abilities and disease burden of adults with FSHD are largely static over a 12-month period with participants demonstrating a mild average reduction in some measures of strength. Selection of patients, outcome measures, and trial duration should be carefully considered during the design and implementation of future clinical studies involving FSHD patients.

Treatment Approaches for Altered Facial Expression: A Systematic Review in Facioscapulohumeral Muscular Dystrophy and Other Neurological Diseases

Background

Facial weakness is a key feature of facioscapulohumeral muscular dystrophy (FSHD) and may lead to altered facial expression and subsequent psychosocial impairment. There is no cure and supportive treatments focus on optimizing physical fitness and compensation of functional disabilities.

Objective

We hypothesize that symptomatic treatment options and psychosocial interventions for other neurological diseases with altered facial expression could be applicable to FSHD. Therefore, the aim of this review is to collect symptomatic treatment approaches that target facial muscle function and psychosocial interventions in various neurological diseases with altered facial expression in order to discuss the applicability to FSHD.

Methods

A systematic search was performed. Selected studies had to include FSHD, Bell's palsy, Moebius syndrome, myotonic dystrophy type 1, or Parkinson's disease and treatment options which target altered facial expression. Data was extracted for study and patients' characteristics, outcome assessment tools, treatment, outcome of facial expression and or psychosocial functioning.

Results

Forty studies met the inclusion criteria, of which only three studies included FSHD patients exclusively. Most, twenty-one, studies were performed in patients with Bell's palsy. Studies included twelve different therapy categories and results were assessed with different outcomes measures.

Conclusions

Five therapy categories were considered applicable to FSHD: training of (non-verbal) communication compensation strategies, speech training, physical therapy, conference attendance, and smile restoration surgery. Further research is needed to establish the effect of these therapies in FSHD. We recommend to include outcome measures in these studies that cover at least cosmetic, functional, communication, and quality of life domains.

Muscle fibrosis as a prognostic biomarker in facioscapulohumeral muscular dystrophy: a retrospective cohort study

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant epigenetic disorder with highly variable muscle involvement and disease progression. Ongoing clinical trials, aimed at counteracting muscle degeneration and disease progression in FSHD patients, increase the need for reliable biomarkers. Muscle magnetic resonance imaging (MRI) studies showed that the appearance of STIR-positive (STIR+) lesions in FSHD muscles represents an initial stage of muscle damage, preceding irreversible adipose changes. Our study aimed to investigate fibrosis, a parameter of muscle degeneration undetectable by MRI, in relation to disease activity and progression of FSHD muscles. We histologically evaluated collagen in FSHD1 patients' (STIR+ n = 27, STIR- n = 28) and healthy volunteers' (n = 12) muscles by picrosirius red staining. All patients (n = 55) performed muscle MRI before biopsy, 45 patients also after 1 year and 36 patients also after 2 years. Fat content (T1 signal) and oedema/inflammation (STIR signal) were evaluated at baseline and at 1- and 2-year MRI follow-up. STIR+ muscles showed significantly higher collagen compared to both STIR- (p = 0.001) and healthy muscles (p < 0.0001). STIR- muscles showed a higher collagen content compared to healthy muscles (p = 0.0194). FSHD muscles with a worsening in fatty infiltration during 1- (P = 0.007) and 2-year (P < 0.0001) MRI follow-up showed a collagen content of 3.6- and 3.7-fold higher compared to FSHD muscles with no sign of progression. Moreover, the fibrosis was significantly higher in STIR+ muscles who showed a worsening in fatty infiltration in a timeframe of 2 years compared to both STIR- (P = 0.0006) and STIR+ muscles with no sign of progression (P = 0.02). Fibrosis is a sign of muscle degeneration undetectable at MRI never deeply investigated in FSHD patients. Our data show that 23/27 of STIR+ and 12/28 STIR- muscles have a higher amount of collagen deposition compared to healthy muscles. Fibrosis is higher in FSHD muscles with a worsening in fatty infiltration thus suggesting that its evaluation with innovative non-invasive techniques could be a candidate prognostic biomarker for FSHD, to be used to stratify patients and to evaluate the efficacy of therapeutic treatments.

MATR3 is an endogenous inhibitor of DUX4 in FSHD muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common neuromuscular disorders and has no cure. Due to an unknown molecular mechanism, FSHD displays overlapping manifestations with the neurodegenerative disease amyotrophic lateral sclerosis (ALS). FSHD is caused by aberrant gain of expression of the transcription factor double homeobox 4 (DUX4), which triggers a pro-apoptotic transcriptional program resulting in inhibition of myogenic differentiation and muscle wasting. Regulation of DUX4 activity is poorly known. We identify Matrin 3 (MATR3), whose mutation causes ALS and dominant distal myopathy, as a cellular factor controlling DUX4 expression and activity. MATR3 binds to the DUX4 DNA-binding domain and blocks DUX4-mediated gene expression, rescuing cell viability and myogenic differentiation of FSHD muscle cells, without affecting healthy muscle cells. Finally, we characterize a shorter MATR3 fragment that is necessary and sufficient to directly block DUX4-induced toxicity to the same extent as the full-length protein. Collectively, our data suggest MATR3 as a candidate for developing a treatment for FSHD.

Deciphering D4Z4 CpG methylation gradients in fascioscapulohumeral muscular dystrophy using nanopore sequencing

Fascioscapulohumeral muscular dystrophy (FSHD) is caused by a unique genetic mechanism that relies on contraction and hypomethylation of the D4Z4 macrosatellite array on the Chromosome 4q telomere allowing ectopic expression of the DUX4 gene in skeletal muscle. Genetic analysis is difficult because of the large size and repetitive nature of the array, a nearly identical array on the 10q telomere, and the presence of divergent D4Z4 arrays scattered throughout the genome. Here, we combine nanopore long-read sequencing with Cas9-targeted enrichment of 4q and 10q D4Z4 arrays for comprehensive genetic analysis including determination of the length of the 4q and 10q D4Z4 arrays with base-pair resolution. In the same assay, we differentiate 4q from 10q telomeric sequences, determine A/B haplotype, identify paralogous D4Z4 sequences elsewhere in the genome, and estimate methylation for all CpGs in the array. Asymmetric, length-dependent methylation gradients were observed in the 4q and 10q D4Z4 arrays that reach a hypermethylation point at approximately 10 D4Z4 repeat units, consistent with the known threshold of pathogenic D4Z4 contractions. High resolution analysis of individual D4Z4 repeat methylation revealed areas of low methylation near the CTCF/insulator region and areas of high methylation immediately preceding the DUX4 transcriptional start site. Within the DUX4 exons, we observed a waxing/waning methylation pattern with a 180-nucleotide periodicity, consistent with phased nucleosomes. Targeted nanopore sequencing complements recently developed molecular combing and optical mapping approaches to genetic analysis for FSHD by adding precision of the length measurement, base-pair resolution sequencing, and quantitative methylation analysis.

A Systemically Administered Unconjugated Antisense Oligonucleotide Targeting DUX4 Improves Muscular Injury and Motor Function in FSHD Model Mice

Facioscapulohumeral muscular dystrophy (FSHD), one of the most common muscular dystrophies, is caused by an abnormal expression of the DUX4 gene in skeletal muscles, resulting in muscle weakness. In this study, we investigated MT-DUX4-ASO, a novel gapmer antisense oligonucleotide (ASO). MT-DUX4-ASO decreased the expression of DUX4 and its target genes in FSHD patient-derived myoblasts. For the first time, we demonstrated that a systemically administered ASO, even without a ligand for drug delivery, could significantly improve muscle injury and motor function in the ACTA1-MCM/FLExDUX4 (DUX4-TG) mouse model of FSHD. Tamoxifen (TMX) injection transiently induces skeletal-muscle-specific DUX4 expression in DUX4-TG mice, while the skeletal muscles of TMX-untreated DUX4-TG mice have leaky DUX4 expression in a small subset of myofibers similar to those of FSHD patients. Subcutaneous 10 mg/kg of MT-DUX4-ASO at two-week intervals significantly suppressed muscular DUX4 target gene expression, histological muscle injury, and blood muscle injury marker elevation in TMX-untreated DUX4-TG mice. Notably, MT-DUX4-ASO at 10 mg/kg every other week significantly prevented the TMX-induced declines in treadmill test running speed and muscle force in DUX4-TG mice. Thus, the systemically administered unconjugated MT-DUX4-ASO suppressed disease progression in DUX4-TG mice, extending the potential of unconjugated ASOs as a promising FSHD treatment strategy.

Atypical progression of motor symptoms in facio-scapulo-humeral dystrophy: clinical worsening or overlap?

Facio-scapulo-humeral dystrophy (FSHD) is a common muscular dystrophy featuring progressive weakness, mostly involving facial muscles and the scapular cingulum. FSHD is an autosomal-dominant inherited disease driven by the contraction of the D4Z4 region of chromosome 4. Patients with FSHD have a high life expectancy, about 20% of FSHD subjects need wheelchairs in their 50s, and extramuscular involvement is rare, however, no epidemiological studies have been carried out on this data.Our case describes a man affected by FSHD who, in his 60s, developed atypical Parkinsonism diagnosed as progressive supranuclear palsy (PSP).FSHD symptoms can hide other neuromuscular diseases developed on ageing. This case highlights the importance of considering possible overlaps with other neurodegenerative diseases.

Deciphering D4Z4 CpG methylation gradients in fascioscapulohumeral muscular dystrophy using nanopore sequencing

Fascioscapulohumeral muscular dystrophy (FSHD) is caused by a unique genetic mechanism that relies on contraction and hypomethylation of the D4Z4 macrosatellite array on the chromosome 4q telomere allowing ectopic expression of the DUX4 gene in skeletal muscle. Genetic analysis is difficult due to the large size and repetitive nature of the array, a nearly identical array on the 10q telomere, and the presence of divergent D4Z4 arrays scattered throughout the genome. Here, we combine nanopore long-read sequencing with Cas9-targeted enrichment of 4q and 10q D4Z4 arrays for comprehensive genetic analysis including determination of the length of the 4q and 10q D4Z4 arrays with base-pair resolution. In the same assay, we differentiate 4q from 10q telomeric sequences, determine A/B haplotype, identify paralogous D4Z4 sequences elsewhere in the genome, and estimate methylation for all CpGs in the array. Asymmetric, length-dependent methylation gradients were observed in the 4q and 10q D4Z4 arrays that reach a hypermethylation point at approximately 10 D4Z4 repeat units, consistent with the known threshold of pathogenic D4Z4 contractions. High resolution analysis of individual D4Z4 repeat methylation revealed areas of low methylation near the CTCF/insulator region and areas of high methylation immediately preceding the DUX4 transcriptional start site. Within the DUX4 exons, we observed a waxing/waning methylation pattern with a 180-nucleotide periodicity, consistent with phased nucleosomes. Targeted nanopore sequencing complements recently developed molecular combing and optical mapping approaches to genetic analysis for FSHD by adding precision of the length measurement, base-pair resolution sequencing, and quantitative methylation analysis.

Smartphone and Wearable Sensors for the Estimation of Facioscapulohumeral Muscular Dystrophy Disease Severity: Cross-sectional Study

BACKGROUND

Facioscapulohumeral muscular dystrophy (FSHD) is a progressive neuromuscular disease. Its slow and variable progression makes the development of new treatments highly dependent on validated biomarkers that can quantify disease progression and response to drug interventions.

OBJECTIVE

We aimed to build a tool that estimates FSHD clinical severity based on behavioral features captured using smartphone and remote sensor data. The adoption of remote monitoring tools, such as smartphones and wearables, would provide a novel opportunity for continuous, passive, and objective monitoring of FSHD symptom severity outside the clinic.

METHODS

In total, 38 genetically confirmed patients with FSHD were enrolled. The FSHD Clinical Score and the Timed Up and Go (TUG) test were used to assess FSHD symptom severity at days 0 and 42. Remote sensor data were collected using an Android smartphone, Withings Steel HR+, Body+, and BPM Connect+ for 6 continuous weeks. We created 2 single-task regression models that estimated the FSHD Clinical Score and TUG separately. Further, we built 1 multitask regression model that estimated the 2 clinical assessments simultaneously. Further, we assessed how an increasingly incremental time window affected the model performance. To do so, we trained the models on an incrementally increasing time window (from day 1 until day 14) and evaluated the predictions of the clinical severity on the remaining 4 weeks of data.

RESULTS

The single-task regression models achieved an R² of 0.57 and 0.59 and a root-mean-square error (RMSE) of 2.09 and 1.66 when estimating FSHD Clinical Score and TUG, respectively. Time spent at a health-related location (such as a gym or hospital) and call duration were features that were predictive of both clinical assessments. The multitask model achieved an R² of 0.66 and 0.81 and an RMSE of 1.97 and 1.61 for the FSHD Clinical Score and TUG, respectively, and therefore outperformed the single-task models in estimating clinical severity. The 3 most important features selected by the multitask model were light sleep duration, total steps per day, and mean steps per minute. Using an increasing time window (starting from day 1 to day 14) for the FSHD Clinical Score, TUG, and multitask estimation yielded an average R² of 0.65, 0.79, and 0.76 and an average RMSE of 3.37, 2.05, and 4.37, respectively.

CONCLUSIONS

We demonstrated that smartphone and remote sensor data could be used to estimate FSHD clinical severity and therefore complement the assessment of FSHD outside the clinic. In addition, our results illustrated that training the models on the first week of data allows for consistent and stable prediction of FSHD symptom severity. Longitudinal follow-up studies should be conducted to further validate the reliability and validity of the multitask model as a tool to monitor disease progression over a longer period.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04999735; https://www.clinicaltrials.gov/ct2/show/NCT04999735.

The Muscular Dystrophy Association's neuroMuscular ObserVational Research Data Hub (MOVR): Design, Methods, and Initial Observations

BACKGROUND

Neuromuscular disease (NMD) research is experiencing tremendous growth as a result of progress in diagnostics and therapeutics yet there continues to be a significant clinical data shortage for these rare diseases. To maximize the development and impact of new therapies, the Muscular Dystrophy Association (MDA) created the neuroMuscular ObserVational Research Data Hub (MOVR) as an observational research study that collects disease-specific measures from individuals living with NMDs in the United States.

OBJECTIVE

This manuscript provides a description of MOVR, participants enrolled in MOVR, and longitudinal data availability.

METHODS

MOVR collects longitudinal data from individuals diagnosed with ALS, BMD, DMD, FSHD, LGMD, Pompe disease, or SMA, and who are seen for care at a participating MDA Care Center. Data are entered from medical records into standardized electronic case report forms (eCRFs). These eCRFs capture participants' demographics, diagnostic journeys, clinical visits, and discontinuation from the study.

RESULTS

From January 2019 to May 2022, MOVR collected data from 50 participating care centers and 1,957 participants. Data from 1,923 participants who participated in MDA's pilot registry were migrated into MOVR, creating a total of 3,880 participants in MOVR. Initial analysis of aggregated data demonstrated that 91% of eCRFs were complete. Forty-three percent of participants had 3 or more encounters and 50% of all encounters were 5 months or less from the previous encounter.

DISCUSSION

As a centralized data hub for multiple NMDs, MOVR serves as a platform that can be used to inform disease understanding, guide clinical trial design, and accelerate drug development for NMDs.

Facioscapulohumeral muscular dystrophy: the road to targeted therapies

Advances in the molecular understanding of facioscapulohumeral muscular dystrophy (FSHD) have revealed that FSHD results from epigenetic de-repression of the DUX4 gene in skeletal muscle, which encodes a transcription factor that is active in early embryonic development but is normally silenced in almost all somatic tissues. These advances also led to the identification of targets for disease-altering therapies for FSHD, as well as an improved understanding of the molecular mechanism of the disease and factors that influence its progression. Together, these developments led the FSHD research community to shift its focus towards the development of disease-modifying treatments for FSHD. This Review presents advances in the molecular and clinical understanding of FSHD, discusses the potential targeted therapies that are currently being explored, some of which are already in clinical trials, and describes progress in the development of FSHD-specific outcome measures and assessment tools for use in future clinical trials.

Facioscapulohumeral Muscular Dystrophy

PURPOSE OF REVIEW

This article reviews the current knowledge on the clinical characteristics and disease mechanism of facioscapulohumeral muscular dystrophy (FSHD), as well as advances in targeted therapy development.

RECENT FINDINGS

FSHD has a wide range of severity, yet a distinct phenotype characterized by weakness of the facial, shoulder, and upper arm muscles, followed by weakness of the trunk and leg muscles. It can be caused by two genetic mechanisms that share a common downstream pathway, namely, the epigenetic derepression and subsequent misexpression of the myotoxic DUX4 transcription factor. Treatment is currently supportive and outlined in evidence-based guidelines. Advances in the understanding of the pathogenic mechanism of FSHD are paving the way for targeted therapy development. Approaches for targeted therapies to reduce DUX4 expression that are currently being explored include small molecules, antisense oligonucleotides, vector-based RNA interference, and gene therapy. In anticipation of more clinical trials, "clinical trial preparedness," including the development of sensitive biomarkers and clinical outcome measures, are needed.

SUMMARY

The cornerstones of the diagnosis of FSHD are clinical observation and genetic testing. Management is currently supportive, but progress in the understanding of the disease mechanism has shifted the field of FSHD toward targeted therapy development.

Milestones of progression in myotonic dystrophy type 1 and type 2

INTRODUCTION/AIMS

Disease progression in myotonic dystrophy (DM) is marked by milestone events, when functional thresholds are crossed. DM type 2 (DM2) is considered less severe than DM type 1 (DM1), but whether this applies uniformly to all features is unknown. We compared the age-dependent risk for milestone events in DM1 and DM2, and tested for associations with age of onset and sex.

METHODS

We studied a large cohort of adult participants in a national registry of DM1 and DM2. Using annual surveys from participants, we ascertained milestone events for motor involvement (use of cane, walker, ankle brace, wheelchair, or ventilatory device), systemic involvement (diabetes, pacemaker, cancer), loss of employment due to DM, and death.

RESULTS

Mean follow-up of registry participants (DM1 = 929, DM2=222) was 7 years. Disability and motor milestones occurred at earlier ages in DM1 than in DM2. In contrast, the risk of diabetes was higher and tended to occur earlier in DM2 (HR=0.56, p=<0.001). In DM1, the milestone events tended to occur earlier, and life expectancy was reduced, when symptoms began at younger ages. In DM1, men were at greater risk for disability (HR=1.34, p=<0.01), use of ankle braces (HR=1.41, p=0.02), and diabetes (HR=2.2, p=<0.0001), whereas women were at greater risk for using walkers (HR=0.68, p=0.001) or malignancy (0.66, p=<0.01).

DISCUSSION

Milestone events recorded through registries can be used to assess long-term impact of DM in large cohorts. Except for diabetes, the age-related risk of milestone events is greater in DM1 than in DM2.

Convergence of patient- and physician-reported outcomes in the French National Registry of Facioscapulohumeral Dystrophy

Background

Facioscapulohumeral muscular dystrophy (FSHD) is among the most prevalent muscular dystrophies and currently has no treatment. Clinical and genetic heterogeneity are the main challenges to a full comprehension of the physiopathological mechanism. Improving our knowledge of FSHD is crucial to the development of future therapeutic trials and standards of care. National FSHD registries have been set up to this end. The French National Registry of FSHD combines a clinical evaluation form (CEF) and a self-report questionnaire (SRQ), filled out by a physician with expertise in neuromuscular dystrophies and by the patient, respectively. Aside from favoring recruitment, our strategy was devised to improve data quality. Indeed, the pairwise comparison of data from 281 patients for 39 items allowed for evaluating data accuracy. Kappa or intra-class coefficient (ICC) values were calculated to determine the correlation between answers provided in both the CEF and SRQ.

Results

Patients and physicians agreed on a majority of questions common to the SRQ and CEF (24 out of 39). Demographic, diagnosis- and care-related questions were generally answered consistently by the patient and the medical practitioner (kappa or ICC values of most items in these groups were greater than 0.8). Muscle function-related items, i.e. FSHD-specific signs, showed an overall medium to poor correlation between data provided in the two forms; the distribution of agreements in this section was markedly spread out and ranged from poor to good. In particular, there was very little agreement regarding the assessment of facial motricity and the presence of a winged scapula. However, patients and physicians agreed very well on the Vignos and Brooke scores. The report of symptoms not specific to FSHD showed general poor consistency.

Conclusions

Patient and physician answers are largely concordant when addressing quantitative and objective items. Consequently, we updated collection forms by relying more on patient-reported data where appropriate. We hope the revised forms will reduce data collection time while ensuring the same quality standard. With the advent of artificial intelligence and automated decision-making, high-quality and reliable data are critical to develop top-performing algorithms to improve diagnosis, care, and evaluate the efficiency of upcoming treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01793-6.

Speech and swallowing characteristics in patients with facioscapulohumeral muscular dystrophy

BACKGROUND

Although facial muscle weakness is common in patients with Facioscapulohumeral Muscular Dystrophy (FSHD), the literature is scarce on the speech and swallowing aspects.

OBJECTIVE

To investigate speech and swallowing patterns in FSHD and assess the correlation with clinical data.

METHODS

A cross-sectional study was conducted. Patients with clinical confirmation of FSHD and aged above 18 years were included and paired with healthy control individuals by age and gender. Individuals who had neurological conditions that could interfere with test results were excluded. The following assessments were applied: speech tests (acoustic and auditory-perceptual analysis); swallowing tests with the Northwestern Dysphagia Patient Check Sheet (NDPCS), the Eat Assessment Tool (EAT-10), the Speech Therapy Protocol for Dysphagia Risk (PARD), and the Functional Oral Intake Scale (FOIS); disease staging using the modified Gardner-Medwin-Walton scale (GMWS); and quality of life with the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36). The correlation between test results and clinical data was verified by non-parametric statistics.

RESULTS

Thirteen individuals with FSHD and 10 healthy controls were evaluated. The groups presented significant differences in the motor bases of phonation and breathing. Regarding swallowing, two (15%) individuals presented mild dysphagia and seven (53.8%) showed reduced facial muscles strength. These results were not correlated with duration of the disease, age at symptoms onset, and quality of life. Dysphagia was related to worsening disease severity.

CONCLUSIONS

FSHD patients presented mild dysarthria and dysphagia. Frequent monitoring of these symptoms could be an important way to provide early rehabilitation and better quality of life.

Facioscapulohumeral dystrophy transcriptome signatures correlate with different stages of disease and are marked by different MRI biomarkers

With several therapeutic strategies for facioscapulohumeral muscular dystrophy (FSHD) entering clinical testing, outcome measures are becoming increasingly important. Considering the spatiotemporal nature of FSHD disease activity, clinical trials would benefit from non-invasive imaging-based biomarkers that can predict FSHD-associated transcriptome changes. This study investigated two FSHD-associated transcriptome signatures (DUX4 and PAX7 signatures) in FSHD skeletal muscle biopsies, and tested their correlation with a variety of disease-associated factors, including Ricci clinical severity score, disease duration, D4Z4 repeat size, muscle pathology scorings and functional outcome measures. It establishes that DUX4 and PAX7 signatures both show a sporadic expression pattern in FSHD-affected biopsies, possibly marking different stages of disease. This study analyzed two imaging-based biomarkers—Turbo Inversion Recovery Magnitude (TIRM) hyperintensity and fat fraction—and provides insights into their predictive power as non-invasive biomarkers for FSHD signature detection in clinical trials. Further insights in the heterogeneity of—and correlation between—imaging biomarkers and molecular biomarkers, as provided in this study, will provide important guidance to clinical trial design in FSHD. Finally, this study investigated the role of infiltrating non-muscle cell types in FSHD signature expression and detected potential distinct roles for two fibro-adipogenic progenitor subtypes in FSHD.

Prevalence and disease progression of genetically-confirmed facioscapulohumeral muscular dystrophy type 1 (FSHD1) in China between 2001 and 2020: a nationwide population-based study

Background

Facioscapulohumeral muscular dystrophy type 1 (FSHD1) is a rare disease, which is often underdiagnosed due to its heterogeneous presentations and complex molecular genetic basis, leading to a lack of population-based epidemiology data, especially of prevalence and disease progression.

Methods

Fujian Neuromedical Centre (FNMC) is a diagnosis centre for clinical-genetic FSHD in China, and the only one employing pulsed-field gel electrophoresis (PFGE)-based Southern blotting for all FSHD1 genetic tests. Three sources distributed across all six spatial zones in China, were used to obtain information regarding FSHD1 events, namely, FNMC, Genetic and Myopathy Group (branches of the Neurology Society of the Chinese Medical Association), and "FSHD-China" (an organization supported by FSHD patients). During 2001-2020, all genetically-confirmed FSHD1 from China were registered in FNMC. Follow-up was conducted in the 20-year period to obtain data on disease progression, which was mainly described in terms of independent ambulation loss.

Findings

Of the 1,744 FSHD1 genetic tests (total test number 1,802) included in the analysis, 997 (57.2%) patients from 620 families were diagnosed with FSHD1. The estimated prevalence of genetically-confirmed FSHD1 in China is 0.75 per million (95% confidence interval [CI], 0.70-0.79) during 2001-2020, with 0.78 (95% CI, 0.72-0.85) in males and 0.71 (95% CI, 0.65-0.78) in females. The estimated prevalence increased from 0.22 (95% CI, 0.19-0.26) per million in 2001-2015 to 0.53 (95% CI, 0.49-0.57) per million in 2016-2020 (p < 0.001). The prevalence in Fujian province was 7.10 per million, 4.66 per million, and 2.44 per million, during 2001-2020, 2001-2015, and 2016-2020, respectively. Among the 861 symptomatic plus asymptomatic patients of the total 997 patients, the median onset age at first-ever muscle weakness was 16 years of age (range 1-81); the median number of contracted D4Z4 repeats was 5 units (range 1-9); the median 4qA-allele-specific methylation level was 41% (range 14%-69%). Of the 977 symptomatic patients followed-up during 2001-2020, 117 patients (12.0%) lost independent ambulation. The expected duration from onset of first-ever muscle weakness to onset of independent ambulation loss was 40 years. The group with loss of independent ambulation had a smaller number of contracted D4Z4 repeats (p < 0.001) and had an earlier onset age of first-ever muscle weakness (p < 0.001) compared to the group without loss of independent ambulation.

Interpretation

Our research captures the largest genetically-confirmed FSHD1 population worldwide, to calculate its prevalence of 0.75 per million in China from 2001 to 2020. Approximately 12.0% of symptomatic plus asymptomatic patients of FSHD1 will lose independent ambulation in 40 years from onset of first-ever muscle weakness.

Funding

This work has been supported by the grants (U2005201, 81870902, N.W.) and (81974193, 81671237, Z.Q.W.) from the National Natural Science Foundation of China; Joint Funds for the Innovation of Science and Technology of Fujian Province (2018Y9082) (N.W.), and the Key Clinical Specialty Discipline Construction Program of Fujian (N.W.).

Systemic Manifestations and Symptom Burden of Facioscapulohumeral Muscular Dystrophy in a Referral Cohort

INTRODUCTION/AIMS

The full spectrum of the clinical phenotype of facioscapulohumeral muscular dystrophy (FSHD), beyond skeletal muscle weakness, remains poorly characterized. In this study, we describe systemic manifestations and symptom burden in a large series of FSHD patients.

METHODS

We performed a retrospective chart review of FSHD patients seen at our institution between 2000 and 2017. We reviewed patients' responses to a comprehensive review of symptoms and the results of diagnostic testing for sensorineural hearing loss, cardiac disease, dysphagia, ocular abnormalities, and respiratory insufficiency. We assessed the association between disease manifestations and age of onset, genetic profile, and disease duration.

RESULTS

We identified 87 patients with FSHD. The most common reported symptoms included pain (71%), difficulty sleeping (41%), headaches (27%), and altered mood (24%). When tested, 7/16 (44%) patients had sensorineural hearing loss, 20/60 (33%) had cardiac arrhythmias or conduction defects, 17/45 (38%) had echocardiogram abnormalities, 12/25 (48%) had reduced forced vital capacity, and 4/10 (40%) had oropharyngeal dysphagia. However, patients with these abnormalities represented 8%, 23%, 20%, 14%, and 5% of total number of patients respectively, as uniform screening was lacking. Ocular pathology attributable to FSHD was not detected.

DISCUSSION

FSHD demonstrates a broad clinical phenotype. Increased vigilance among neurologists to screen for systemic manifestations of the disease is warranted. More uniform screening and future population-based studies are needed to compare the findings in FSHD patients to the general population.

Feasibility and Safety of Applying the Functional Electrical Stimulation to Child with Facioscapulohumeral Dystrophy: A Case Report

AIMS

This study aims to investigate the feasibility and safety of short-term functional electrical stimulation (FES) training of the quadriceps femoris muscles in a child with facioscapulohumeral muscular dystrophy (FSHD).

METHODS

A 7-year-old child with FSHD received treatment due to a decrease in functional performance and difficulty climbing stairs. The child was followed up with a home-based exercise program. FES was applied twice a week during stair climbing for six weeks. Muscle activation of the quadriceps femoris was measured using superficial electromyography, muscle strength was measured with a hand-held dynamometer, and functional performance was assessed with the 6-Minute Walk and the Stair Climb Tests before and after the treatment period.

RESULTS

At the end of the treatment, there was an improvement in muscle activation. While muscle strength increased in the quadriceps femoris muscle of the non-dominant side, it remained constant on the dominant side. Functional performance test results also improved.

CONCLUSIONS

FES was a feasible and safe tool to use in our case, a child with FSHD.

Predictors of functional outcomes in patients with facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most prevalent muscular dystrophies characterized by considerable variability in severity, rates of progression and functional outcomes. Few studies follow FSHD cohorts long enough to understand predictors of disease progression and functional outcomes, creating gaps in our understanding which impacts clinical care and the design of clinical trials. Efforts to identify molecularly targeted therapies create a need to better understand disease characteristics with predictive value to help refine clinical trial strategies and understand trial outcomes. Here we analyzed a prospective cohort from a large, longitudinally-followed registry of patients with FSHD in the United States to determine predictors of outcomes such as need for wheelchair use. This study analyzed de-identified data from 578 individuals with confirmed FSHD type 1 enrolled in the United States National Registry for FSHD Patients and Family members. Data were collected from January 2002 to September 2019 and included an average of nine years (range 0 to 18) of follow up surveys. Data were analyzed using descriptive epidemiological techniques, and risk of wheelchair use was determined using cox proportional hazards models. Supervised machine learning analysis was completed using Random Forest modeling and included all 189 unique features collected from registry questionnaires. A separate medications-only model was created that included 359 unique medications reported by participants. Here we show that smaller allele sizes were predictive of earlier age at onset, diagnosis and likelihood of wheelchair use. Additionally, we show that women were more likely overall to progress to wheelchair use and at a faster rate as compared to men, independent of genetics. Use of machine learning models that included all reported clinical features showed that the effect of allele size on progression to wheelchair use is small compared to disease duration, which may be important to consider in trial design. Medical comorbidities and medication use add to the risk for need for wheelchair dependence, raising the possibility for better medical management impacting outcomes in FSHD. The findings in this study will require further validation in additional, larger datasets but could have implications for clinical care, and inclusion criteria for future clinical trials in FSHD.

Resting metabolic rate in adults with facioscapulohumeral muscular dystrophy

This study aimed to determine whether resting metabolic rate (RMR) is altered in adults with facioscapulohumeral muscular dystrophy (FSHD). Eleven people with FSHD (51 ± 12yrs, 2 females) and 11 controls (48 ± 14 yrs, 2 females) completed 1 visit, including 30-minutes of indirect calorimetry and dual-energy X-ray absorptiometry (DXA) scanning. RMR was calculated from resting oxygen consumption/carbon dioxide production; regional/whole-body fat mass and lean mass were collected from the DXA scan. Absolute RMR was 15% lower in FSHD (p = 0.04); when normalized to regional/local lean mass, no differences in RMR were observed (p > 0.05). Absolute RMR was correlated with total lean mass for all participants combined (p < 0.01, r = 0.70, males only: p < 0.01, r = 0.81) and when analyzed separately (FSHD males: p = 0.001, r = 0.92 and control males: p = 0.004, r = 0.85). Whole-body lean mass was 16% lower in FSHD and leg, arm and appendicular lean mass were lower in FSHD (p < 0.05 for all), though trunk lean mass was not (p = 0.15). Whole-body fat mass was 45% higher in FSHD, with greater leg fat mass (p = 0.01), but not trunk or arm fat mass (p > 0.05 for both). When RMR was expressed relative to lean body mass, no differences in RMR were found, indicating that the lower levels of lean mass observed in FSHD patients likely contribute to the lower absolute RMR values. Novelty: RMR is lower among people with FSHD, as compared with controls. The reduced RMR among people with FSHD is due to disease-related loss in muscle mass and likely related to lower physical activity and/or exercise levels.

Rasch analysis to evaluate the motor function measure for patients with facioscapulohumeral muscular dystrophy

Patient-relevant outcome measures for facioscapulohumeral muscular dystrophy (FSHD) are needed. The motor function measure (MFM) is an ordinal-based outcome measure for neuromuscular disorders, but its suitability to measure FSHD patients is questionable. Here, we performed Rasch analyses on MFM data from 194 FSHD patients to assess clinimetric properties in this patient group. Both the total scale and its three domains were analyzed (D1: standing position and transfers; D2: axial and proximal motor function; D3: distal motor function). Fit to the Rasch model, sample-item targeting, individual item fit, threshold ordering, sex- and age-based differential item functioning, response dependency and unidimensionality were assessed. Rasch analysis revealed multiple limitations of the MFM for FSHD, the most important being a large ceiling effect and suboptimal sample-item targeting, which were most pronounced for domains D2 and D3. There were disordered thresholds for most items, often resulting in items functioning in a dichotomous fashion. It was not possible to remodel the MFM into a Rasch-built interval scale. Remodeling of domain D1 into an interval scale with adequate fit statistics was achieved, but sample-item targeting remained suboptimal. Therefore, the MFM should be used with caution in FSHD patients, as it is not optimally suited to measure functional abilities in this patient group.

Current Therapeutic Approaches in FSHD

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies. Over the last decade, a consensus was reached regarding the underlying cause of FSHD allowing—for the first time—a targeted approach to treatment. FSHD is the result of a toxic gain-of-function from de-repression of the DUX4 gene, a gene not normally expressed in skeletal muscle. With a clear therapeutic target, there is increasing interest in drug development for FSHD, an interest buoyed by the recent therapeutic successes in other neuromuscular diseases. Herein, we review the underlying disease mechanism, potential therapeutic approaches as well as the state of trial readiness in the planning and execution of future clinical trials in FSHD.

Case Studies on the Genetic and Clinical Diagnosis of Facioscapulohumeral Muscular Dystrophy

Facioscapulohumeral muscular dystrophy is the second most common adult muscular dystrophy and is caused by DUX4 protein. DUX4 is expressed when the locus on chromosome 4q35 is hypomethylated. The clinical features can be nearly pathognomonic with facial weakness, scapular winging, and abdominal weakness with a positive Beevor sign. Diagnosis of late-onset or milder disease is often more challenging. Diseases mimicking the facioscapulohumeral muscular dystrophy phenotype should be recognized. We present 6 cases to illustrate both clinical and genetic diagnostic challenges in facioscapulohumeral muscular dystrophy and provide examples on how to navigate the different steps of genetic testing.

Cellular and animal models for facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common forms of muscular dystrophy and presents with weakness of the facial, scapular and humeral muscles, which frequently progresses to the lower limbs and truncal areas, causing profound disability. Myopathy results from epigenetic de-repression of the D4Z4 microsatellite repeat array on chromosome 4, which allows misexpression of the developmentally regulated DUX4 gene. DUX4 is toxic when misexpressed in skeletal muscle and disrupts several cellular pathways, including myogenic differentiation and fusion, which likely underpins pathology. DUX4 and the D4Z4 array are strongly conserved only in primates, making FSHD modeling in non-primate animals difficult. Additionally, its cytotoxicity and unusual mosaic expression pattern further complicate the generation of in vitro and in vivo models of FSHD. However, the pressing need to develop systems to test therapeutic approaches has led to the creation of multiple engineered FSHD models. Owing to the complex genetic, epigenetic and molecular factors underlying FSHD, it is difficult to engineer a system that accurately recapitulates every aspect of the human disease. Nevertheless, the past several years have seen the development of many new disease models, each with their own associated strengths that emphasize different aspects of the disease. Here, we review the wide range of FSHD models, including several in vitro cellular models, and an array of transgenic and xenograft in vivo models, with particular attention to newly developed systems and how they are being used to deepen our understanding of FSHD pathology and to test the efficacy of drug candidates.

Summary: Owing to its complex etiology and the toxicity of DUX4, modeling facioscapulohumeral muscular dystrophy (FSHD) is uniquely challenging. Here, we review the approaches that overcame these difficulties to develop highly relevant FSHD models.

Early-Onset Infantile Facioscapulohumeral Muscular Dystrophy: A Timely Review

Facioscapulohumeral muscular dystrophy (FSHD)—the worldwide third most common inherited muscular dystrophy caused by the heterozygous contraction of a 3.3 kb tandem repeat (D4Z4) on a chromosome with a 4q35 haplotype—is a progressive genetic myopathy with variable onset of symptoms, distribution of muscle weakness, and clinical severity. While much is known about the clinical course of adult FSHD, data on the early-onset infantile phenotype, especially on the progression of the disease, are relatively scarce. Contrary to the classical form, patients with infantile FSHD more often have a rapid decline in muscle wasting and systemic features with multiple extramuscular involvements. A rough correlation between the phenotypic severity of FSHD and the D4Z4 repeat size has been reported, and the majority of patients with infantile FSHD obtain a very short D4Z4 repeat length (one to three copies, EcoRI size 10–14 kb), in contrast to the classical, slowly progressive, form of FSHD (15–38 kb). With the increasing identifications of case reports and the advance in genetic diagnostics, recent studies have suggested that the infantile variant of FSHD is not a genetically separate entity but a part of the FSHD spectrum. Nevertheless, many questions about the clinical phenotype and natural history of infantile FSHD remain unanswered, limiting evidence-based clinical management. In this review, we summarize the updated research to gain insight into the clinical spectrum of infantile FSHD and raise views to improve recognition and understanding of its underlying pathomechanism, and further, to advance novel treatments and standard care methods.

Correlations between radiographic spinopelvic parameters and health-related quality of life: A prospective evaluation of 37 patients with facioscapulohumeral muscular dystrophy

OBJECTIVE

The purpose of this study was to evaluate the relationship between spinopelvic parameters and health-related quality of life.

METHODS

Patients with Facioscapulohumeral muscular dystrophy (FSHD) were asked to volunteer to participate in this study from April 2018 to December 2019. Patient data, including age, sex, body mass index (BMI), and duration of the diagnosis of FSHD were obtained. Short Form (SF-36) questionnaire was completed for all patients. All patients underwent lateral radiography of the whole spine. The radiographic parameters examined were pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), cervical lordosis (CL), T1 spinopelvic inclination (T1 SPI), thoracic kyphosis (TK), Pelvic incidence- lumbar lordosis (PI-LL) and sagittal vertical axis (SVA).

RESULTS

Thirty-seven patients (16 females and 21 males) were included in the study, with a mean age of 39.1 years. The mean duration of diagnosis was 13.5 ± 11.4 years and mean BMI was 24.2 kg/m2. Physical composite score (PCS) was 38.7 and mental composite score (MCS) 60.8 detected. Radiographic analyses included the following: the mean PT was 9.1°, PI 52.1°, SS 43.5°, LL 67.9°, CL 9.8°, T1 SPI -2.5°, TK 23.1°, SVA 37.6 mm. PI-LL was -13.1°. We identified 31 patients with match (left) PI-LL and six patients with mismatch (right) PI-LL.

CONCLUSION

Hyperlordosis inlumbar spine, hypolordosis in cervical spine and negative sagittal balance were the most common spinal misalignments in patients with FSHD. These patients have lower composite PCS than composite MCS. There was a significantly negative correlation between LL, PI-LL and PCS.

LEVEL OF EVIDENCE

Level IV Cross-sectional study.

Sarcopenic Obesity in Facioscapulohumeral Muscular Dystrophy

Background

Sarcopenic obesity has been observed in people with neuromuscular impairment, and is linked to adverse health outcomes. It is unclear, however, if sarcopenic obesity develops in adults with facioscapulohumeral muscular dystrophy (FSHD).

Methods

The purpose of this study was to determine if adults with FSHD meet criteria for sarcopenic obesity (appendicular lean mass index (ALMI) scores of < 7.26 or 5.45 kg/m²; % fat mass (FM) ≥ 28 or 40% in men/women). Ten people with FSHD (50 ± 11 years, 2 females) and ten age/sex-matched controls (47 ± 13 years, 2 females) completed one visit, which included a full-body dual-energy x-ray absorptiometry (DXA) scan. Regional and whole body total mass, fat mass (FM), and lean mass (LM) were collected and body mass index (BMI) and sarcopenia measures were computed.

Results

People with FSHD and controls had a similar whole body total mass (84.5 ± 12.9 vs. 81.8 ± 13.5 kg, respectively, p = 0.65). Though BMI was 2% lower in the FSHD group (p = 0.77), the % FM was 46% higher in FSHD, compared with controls (p < 0.01). In addition, ALM volume was 23% lower (p = 0.02) and ALMI was 27% lower in FSHD compared with controls (p < 0.01). Whole body LM trended to be lower in FSHD vs. controls (p = 0.05), and arm and leg LM were both lower in FSHD compared with controls (p < 0.05). Furthermore, the % LM was 18% lower in FSHD vs. controls (p < 0.01). FSHD participants exhibited greater total body FM (p < 0.01) and total leg FM (p < 0.01), but were similar in volume of total arm FM compared with controls (p = 0.09).

Conclusion

Findings from this study suggest that people with FSHD, although similar in BMI and total body mass compared with controls, commonly meet the definition of sarcopenic obesity. Adults with co-existing FSHD and sarcopenic obesity may be at risk for significant impairments in quality of life, and encounter additional challenges in the management of FSHD manifestations.

Tracking muscle wasting and disease activity in facioscapulohumeral muscular dystrophy by qualitative longitudinal imaging

BACKGROUND

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most frequent late-onset muscular dystrophies, characterized by progressive fatty replacement and degeneration involving single muscles in an asynchronous manner. With clinical trials at the horizon in this disease, the knowledge of its natural history is of paramount importance to understand the impact of new therapies. The aim of this study was to assess disease progression in FSHD using qualitative muscle magnetic resonance imaging, with a focus on the evolution of hyperintense lesions identified on short-tau inversion recovery (STIR+) sequences, hypothesized to be markers of active muscle injury.

METHODS

One hundred genetically confirmed consecutive FSHD patients underwent lower limb muscle magnetic resonance imaging at baseline and after 365 ± 60 days in this prospective longitudinal study. T1 weighted (T1w) and STIR sequences were used to assess fatty replacement using a semiquantitative visual score and muscle oedema. The baseline and follow-up scans of each patient were also evaluated by unblinded direct comparison to detect the changes not captured by the scoring system.

RESULTS

Forty-nine patients showed progression on T1w sequences after 1 year, and 30 patients showed at least one new STIR+ lesion. Increased fat deposition at follow-up was observed in 13.9% STIR+ and in only 0.21% STIR- muscles at baseline (P < 0.001). Overall, 89.9% of the muscles that showed increased fatty replacement were STIR+ at baseline and 7.8% were STIR+ at 12 months. A higher number of STIR+ muscles at baseline was associated with radiological worsening (odds ratio 1.17, 95% confidence interval 1.06-1.30, P = 0.003).

CONCLUSIONS

Our study confirms that STIR+ lesions represent prognostic biomarkers in FSHD and contributes to delineate its radiological natural history, providing useful information for clinical trial design. Given the peculiar muscle-by-muscle involvement in FSHD, MRI represents an invaluable tool to explore the modalities and rate of disease progression.

Clinical trial readiness to solve barriers to drug development in FSHD (ReSolve): protocol of a large, international, multi-center prospective study

Background

Facioscapulohumeral muscular dystrophy (FSHD) is a dominantly-inherited progressive muscular dystrophy caused by de-repression of the DUX4 gene, which causes disease by a toxic-gain-of-function. As molecularly targeted drugs move from preclinical testing into human trials, it is essential that we validate clinical trial tools and methodology to facilitate the drug development process.

Methods/design

The primary goal of this study is to hasten drug development for FSHD by validating two novel clinical outcome assessments (COAs) and refining clinical trial strategies. We will perform an 18-month longitudinal study in 220 genetically confirmed and clinically affected participants using our FSHD Clinical Trial Research Network, comprised of 8 sites in the United States, and 3 collaborating sites in Europe. Visits occur at baseline and months 3, 12, and 18. At each visit we will collect: 1) a novel FSHD functional composite COA made up of 18 evaluator-administered motor tasks in the domains of shoulder/arm, hand, core/abdominal, leg, and balance function; and 2) electrical impedance myography as a novel muscle quality biomarker (US sites). Other COAs include 1) Domain 1 of the Motor Function Measure; 2) Reachable workspace; 3) orofacial strength using the Iowa Oral Performance Instrument; 4) lean muscle mass using dual-energy X-ray absorptiometry (DEXA); 5) strength as measured by quantitative myometry and manual muscle testing; and 6) the FSHD Health Index and other patient-reported outcomes. Plasma, DNA, RNA, and serum will be collected for future biomarker studies. We will use an industry standard multi-site training plan. We will evaluate the test-retest reliability, validity, and sensitivity to disease progression, and minimal clinically important changes of our new COAs. We will assess associations between demographic and genetic factors and the rate of disease progression to inform refinement of eligibility criteria for future clinical trials.

Discussion

To the best of our knowledge, this is the largest collaborative study of patients with FSHD performed in the US and Europe. The results of this study will enable more efficient clinical trial design. During the conduct of the study, relevant data will be made available for investigators or companies pursuing novel FSHD therapeutics.

Trial registration

clinicaltrials.gov NCT03458832; Date of registration: 1/11/2018

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1452-x) contains supplementary material, which is available to authorized users.

Superficial Shoulder Muscle Synergy Analysis in Facioscapulohumeral Dystrophy During Humeral Elevation Tasks

Facioscapulohumeral dystrophy (FSHD) is a progressive muscle-wasting disease which leads to a decline in upper extremity functionality. Although the scapulohumeral joint's stability and functionality are affected, evidence on the synergetic control of the shoulder muscles in FSHD individuals is still lacking. The aim of this paper is to understand the neuromuscular changes in shoulder muscle control in people with FSHD. Upper arm kinematics and electromyograms (EMG) of eight upper extremity muscles were recorded during shoulder abduction-adduction and flexion-extension tasks in eleven participants with FSHD and 11 healthy participants. Normalized muscle activities were extracted from EMG signals. Non-negative matrix factorization was used to compute muscle synergies. Maximum muscle activities were compared using non-parametric analysis of variance. Similarities between synergies were also calculated using correlation. The Biceps Brachii was significantly more active in the FSHD group (25±2%) while Trapezius Ascendens and Serratus Anterior were less active (32±7% and 39±4%, respectively). Muscle synergy weights were altered in FSHD individuals and showed greater diversity while controls mostly used one synergy for both tasks. The decreased activity by selected scapula rotator muscles and muscle synergy weight alterations show that neuromuscular control of the scapulohumeral joint is less consistent in people with FSHD compared to healthy participants. Assessments of muscle coordination strategies can be used to evaluate motor output variability and assist in management of the disease.

Effects of weakness of orofacial muscles on swallowing and communication in FSHD

OBJECTIVE

This study explores the use of quantitative data on strength and fatigability of orofacial muscles in patients with facioscapulohumeral muscular dystrophy (FSHD) and assesses the frequency of swallowing and communication difficulties and their relationship to orofacial muscle involvement.

METHODS

We included 43 patients with FSHD and 35 healthy controls and used the Iowa Oral Performance Instrument (IOPI) to obtain quantitative measurements of strength and endurance of lip compression, cheek (buccodental) compression, and tongue elevation. For the assessment of swallowing and communication difficulties, we used the dysphagia-specific quality of life (SWAL-QOL) and Communicative Participation Item Bank questionnaires.

RESULTS

Cheek compression strength was reduced in patients with FSHD compared to healthy controls. Dysphagia and difficulty with verbal communication were reported by 25% and 35% of patients, respectively, and correlated to cheek compression strength and endurance and to anterior tongue elevation endurance. Prolonged cheek compression or anterior tongue elevation endurance (decreased fatigability) made swallowing or speech problems less likely to occur.

CONCLUSION

Cheek compression strength is the most sensitive IOPI measure for orofacial weakness in FSHD. Orofacial weakness contributes to dysphagia and speech difficulties in FSHD, which are both common, though generally mild. Higher endurance of orofacial muscles was associated with a lower chance of dysphagia or speech problems. More research is required for further refinement of the pattern of facial muscle involvement in FSHD and to provide new insights for improvement of speech and language therapy.

The French National Registry of patients with Facioscapulohumeral muscular dystrophy

Background

Facioscapulohumeral muscular dystrophy is a rare inherited neuromuscular disease with an estimated prevalence of 1/20,000 and France therefore harbors about 3000 FSHD patients. With research progress and the development of targeted therapies, patients’ identification through registries can facilitate and improve recruitment in clinical trials and studies.

Results

The French National Registry of FSHD patients was designed as a mixed model registry involving both patients and physicians, through self-report and clinical evaluation questionnaires respectively, to collect molecular and clinical data. Because of the limited number of patients, data quality is a major goal of the registry and various automatic data control features have been implemented in the bioinformatics system. In parallel, data are manually validated by molecular and clinical curators. Since its creation in 2013, data from 638 FSHD patients have been collected, representing about 21% of the French FSHD population. The mixed model strategy allowed to collect 59.1% of data from both patients and clinicians; 26 and 14.9% from respectively patients and clinicians only. With the identification of the FSHD1 and FSHD2 forms, specific questionnaires have been designed. Though FSHD2 patients are progressively included, FSHD1 patients still account for the majority (94.9%). The registry is compatible with the FAIR principles as data are Findable, Accessible and Interoperable. We thus used molecular standards and standardized clinical terms used by the FILNEMUS French network of reference centers for the diagnosis and follow-up of patients suffering from a rare neuromuscular disease. The implemented clinical terms mostly map to dictionaries and terminology systems such as SNOMED-CT (75% of terms), CTV3 (61.7%) and NCIt (53.3%). Because of the sensitive nature of data, they are not directly reusable and can only be accessed as aggregated data after evaluation and approval by the registry oversight committee.

Conclusions

The French National Registry of FSHD patients belongs to a national effort to develop databases, which should now interact with other initiatives to build a European and/or an international FSHD virtual registry for the benefits of patients. It is accessible at www.fshd.fr and various useful information, links, and documents, including a video, are available for patients and professionals.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0960-x) contains supplementary material, which is available to authorized users.

AAV-mediated follistatin gene therapy improves functional outcomes in the TIC-DUX4 mouse model of FSHD

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant or digenic disorder linked to derepression of the toxic DUX4 gene in muscle. There is currently no pharmacological treatment. The emergence of DUX4 enabled development of cell and animal models that could be used for basic and translational research. Since DUX4 is toxic, animal model development has been challenging, but progress has been made, revealing that tight regulation of DUX4 expression is critical for creating viable animals that develop myopathy. Here, we report such a model - the tamoxifen-inducible FSHD mouse model called TIC-DUX4. Uninduced animals are viable, born in Mendelian ratios, and overtly indistinguishable from WT animals. Induced animals display significant DUX4-dependent myopathic phenotypes at the molecular, histological, and functional levels. To demonstrate the utility of TIC-DUX4 mice for therapeutic development, we tested a gene therapy approach aimed at improving muscle strength in DUX4-expressing muscles using adeno-associated virus serotype 1.Follistatin (AAV1.Follistatin), a natural myostatin antagonist. This strategy was not designed to modulate DUX4 but could offer a mechanism to improve muscle weakness caused by DUX4-induced damage. AAV1.Follistatin significantly increased TIC-DUX4 muscle mass and strength even in the presence of DUX4 expression, suggesting that myostatin inhibition may be a promising approach to treat FSHD-associated weakness. We conclude that TIC-DUX4 mice are a relevant model to study DUX4 toxicity and, importantly, are useful in therapeutic development studies for FSHD.

Phenotype-genotype relations in facioscapulohumeral muscular dystrophy type 1

To determine how much of the clinical variability in facioscapulohumeral muscular dystrophy type 1 (FSHD1) can be explained by the D4Z4 repeat array size, D4Z4 methylation and familial factors, we included 152 carriers of an FSHD1 allele (23 single cases, 129 familial cases from 37 families) and performed state-of-the-art genetic testing, extensive clinical evaluation and quantitative muscle MRI. Familial factors accounted for 50% of the variance in disease severity (FSHD clinical score). The explained variance by the D4Z4 repeat array size for disease severity was limited (approximately 10%), and varied per body region (facial muscles, upper and lower extremities approximately 30%, 15% and 3%, respectively). Unaffected gene carriers had longer repeat array sizes compared to symptomatic individuals (7.3 vs 6.0 units, P = 0.000) and slightly higher Delta1 methylation levels (D4Z4 methylation corrected for repeat size, 0.96 vs -2.46, P = 0.048). The D4Z4 repeat array size and D4Z4 methylation contribute to variability in disease severity and penetrance, but other disease modifying factors must be involved as well. The larger effect of the D4Z4 repeat array on facial muscle involvement suggests that these muscles are more sensitive to the influence of the FSHD1 locus itself, whereas leg muscle involvement seems highly dependent on modifying factors.

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.

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.

Facioscapulohumeral muscular dystrophy functional composite outcome measure

INTRODUCTION

We developed an evaluator-administered functional facioscapulohumeral muscular dystrophy composite outcome measure (FSHD-COM) comprising patient-identified areas of functional burden for future clinical trials.

METHODS

We performed a prospective observational study of 41 patients with FSHD at 2 sites. The FSHD-COM includes functional assessment of the legs, shoulders and arms, trunk, hands, and balance/mobility. We determined the test-retest reliability and convergent validity compared to established FSHD disease metrics.

RESULTS

The FSHD-COM demonstrated excellent test-retest reliability (intraclass correlation coefficient [ICC] 0.96; subscale ICC range, 0.90-0.94). Cross-sectional associations between the FSHD-COM and disease duration, clinical severity, and strength were moderate to strong (Pearson correlation coefficient range |0.51-0.92|).

DISCUSSION

The FSHD-COM is a disease-relevant, functional composite outcome measure suitable for future FSHD clinical trials that shows excellent test-retest reliability and cross-sectional associations to disease measures. Future directions include determining multisite reliability, sensitivity to change, and the minimal clinically important change in the FSHD-COM. Muscle Nerve, 2018.

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.