Comprehensive genetic analysis of facioscapulohumeral muscular dystrophy by Nanopore long-read whole-genome sequencing.

BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD) is a high-prevalence autosomal dominant neuromuscular disease characterized by significant clinical and genetic heterogeneity. Genetic diagnosis of FSHD remains a challenge because it cannot be detected by standard sequencing methods and requires a complex diagnosis workflow. METHODS: We developed a comprehensive genetic FSHD detection method based on Oxford Nanopore Technologies (ONT) whole-genome sequencing. Using a case-control design, we applied this procedure to 29 samples and compared the results with those from optical genome mapping (OGM), bisulfite sequencing (BSS), and whole-exome sequencing (WES). RESULTS: Using our ONT-based method, we identified 59 haplotypes (35 4qA and 24 4qB) among the 29 samples (including a mosaic sample), as well as the number of D4Z4 repeat units (RUs). The pathogenetic D4Z4 RU contraction identified by our ONT-based method showed 100% concordance with OGM results. The methylation levels of the most distal D4Z4 RU and the double homeobox 4 gene (DUX4) detected by ONT sequencing are highly consistent with the BSS results and showed excellent diagnostic efficiency. Additionally, our ONT-based method provided an independent methylation profile analysis of two permissive 4qA alleles, reflecting a more accurate scenario than traditional BSS. The ONT-based method detected 17 variations in three FSHD2-related genes from nine samples, showing 100% concordance with WES. CONCLUSIONS: Our ONT-based FSHD detection method is a comprehensive method for identifying pathogenetic D4Z4 RU contractions, methylation level alterations, allele-specific methylation of two 4qA haplotypes, and variations in FSHD2-related genes, which will all greatly improve genetic testing for FSHD.

Exchange of subtelomeric regions between chromosomes 4q and 10q reverts the FSHD genotype and phenotype.

The most common form of facioscapulohumeral dystrophy (FSHD1) is caused by a partial loss of the D4Z4 macrosatellite repeat array in the subtelomeric region of chromosome 4. Patients with FSHD1 typically carry 1 to 10 D4Z4 repeats, whereas nonaffected individuals have 11 to 150 repeats. The ~150-kilobyte subtelomeric region of the chromosome 10q exhibits a ~99% sequence identity to the 4q, including the D4Z4 array. Nevertheless, contractions of the chr10 array do not cause FSHD or any known disease, as in most people D4Z4 array on chr10 is flanked by the nonfunctional polyadenylation signal, not permitting the DUX4 expression. Here, we attempted to correct the FSHD genotype by a CRISPR-Cas9-induced exchange of the chr4 and chr10 subtelomeric regions. We demonstrated that the induced t(4;10) translocation can generate recombinant genotypes translated into improved FSHD phenotype. FSHD myoblasts with the t(4;10) exhibited reduced expression of the DUX4 targets, restored PAX7 target expression, reduced sensitivity to oxidative stress, and improved differentiation capacity.

Muscle strength, quantity and quality and muscle fat quantity and their association with oxidative stress in patients with facioscapulohumeral muscular dystrophy: Effect of antioxidant supplementation.

The purpose of this study was to identify causes of quadriceps muscle weakness in facioscapulohumeral muscular dystrophy (FSHD). To this aim, we evaluated quadriceps muscle and fat volumes by magnetic resonance imaging and their relationships with muscle strength and oxidative stress markers in adult patients with FSHD (n = 32) and healthy controls (n = 7), and the effect of antioxidant supplementation in 20 of the 32 patients with FSHD (n = 10 supplementation and n = 10 placebo) (NCT01596803). Compared with healthy controls, the dominant quadriceps strength and quality (muscle strength per unit of muscle volume) were decreased in patients with FSHD. In addition, fat volume was increased, without changes in total muscle volume. Moreover, in patients with FSHD, the lower strength of the non-dominant quadriceps was associated with lower muscle quality compared with the dominant muscle. Antioxidant supplementation significantly changed muscle and fat volumes in the non-dominant quadriceps, and muscle quality in the dominant quadriceps. This was associated with improved muscle strength (both quadriceps) and antioxidant response. These findings suggest that quadriceps muscle strength decline may not be simply explained by atrophy and may be influenced also by the muscle intrinsic characteristics. As FSHD is associated with increased oxidative stress, supplementation might reduce oxidative stress and increase antioxidant defenses, promoting changes in muscle function.

Optimization of Xenografting Methods for Generating Human Skeletal Muscle in Mice.

Xenografts of human skeletal muscle generated in mice can be used to study muscle pathology and to test drugs designed to treat myopathies and muscular dystrophies for their efficacy and specificity in human tissue. We previously developed methods to generate mature human skeletal muscles in immunocompromised mice starting with human myogenic precursor cells (hMPCs) from healthy individuals and individuals with facioscapulohumeral muscular dystrophy (FSHD). Here, we examine a series of alternative treatments at each stage in order to optimize engraftment. We show that (i) X-irradiation at 25Gy is optimal in preventing regeneration of murine muscle while supporting robust engraftment and the formation of human fibers without significant murine contamination; (ii) hMPC lines differ in their capacity to engraft; (iii) some hMPC lines yield grafts that respond better to intermittent neuromuscular electrical stimulation (iNMES) than others; (iv) some lines engraft better in male than in female mice; (v) coinjection of hMPCs with laminin, gelatin, Matrigel, or Growdex does not improve engraftment; (vi) BaCl2 is an acceptable replacement for cardiotoxin, but other snake venom preparations and toxins, including the major component of cardiotoxin, cytotoxin 5, are not; and (vii) generating grafts in both hindlimbs followed by iNMES of each limb yields more robust grafts than housing mice in cages with running wheels. Our results suggest that replacing cardiotoxin with BaCl2 and engrafting both tibialis anterior muscles generates robust grafts of adult human muscle tissue in mice.

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 p38ß 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.

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.

The DUX4-HIF1α Axis in Murine and Human Muscle Cells: A Link More Complex Than Expected.

FacioScapuloHumeral muscular Dystrophy (FSHD) is one of the most prevalent inherited muscle disorders and is linked to the inappropriate expression of the DUX4 transcription factor in skeletal muscles. The deregulated molecular network causing FSHD muscle dysfunction and pathology is not well understood. It has been shown that the hypoxia response factor HIF1α is critically disturbed in FSHD and has a major role in DUX4-induced cell death. In this study, we further explored the relationship between DUX4 and HIF1α. We found that the DUX4 and HIF1α link differed according to the stage of myogenic differentiation and was conserved between human and mouse muscle. Furthermore, we found that HIF1α knockdown in a mouse model of DUX4 local expression exacerbated DUX4-mediated muscle fibrosis. Our data indicate that the suggested role of HIF1α in DUX4 toxicity is complex and that targeting HIF1α might be challenging in the context of FSHD therapeutic approaches.

Muscle eosinophilia is a hallmark of chronic disease in facioscapulohumeral muscular dystrophy.

Facioscapulohumeral muscular dystrophy (FSHD) is a progressive myopathy caused by the aberrant increased expression of the DUX4 retrogene in skeletal muscle cells. The DUX4 gene encodes a transcription factor that functions in zygotic genome activation and then is silenced in most adult somatic tissues. DUX4 expression in FSHD disrupts normal muscle cell function; however, the downstream pathogenic mechanisms are still unclear. Histologically, FSHD affected muscles show a characteristic dystrophic phenotype that is often accompanied by a pronounced immune cell infiltration, but the role of the immune system in FSHD is not understood. Previously, we used ACTA1;FLExDUX4 FSHD-like mouse models varying in severity as discovery tools to identify increased Interleukin 6 and microRNA-206 levels as serum biomarkers for FSHD disease severity. In this study, we use the ACTA1;FLExDUX4 chronic FSHD-like mouse model to provide insight into the immune response to DUX4 expression in skeletal muscles. We demonstrate that these FSHD-like muscles are enriched with the chemoattractant eotaxin and the cytotoxic eosinophil peroxidase, and exhibit muscle eosinophilia. We further identified muscle fibers with positive staining for eosinophil peroxidase in human FSHD muscle. Our data supports that skeletal muscle eosinophilia is a hallmark of FSHD pathology.

Fitness and walking outcomes following aerobic and lower extremity strength training in facioscapulohumeral dystrophy: a case series.

Facioscapulohumeral muscular dystrophy (FSHD) is a common form of adult muscular dystrophy often resulting also in cardiorespiratory deconditioning and weakness of the lower limbs. Although previous studies examined outcomes of interventions aimed at improving either cardiorespiratory fitness or muscle strength, the potential benefits of a rehabilitation program targeting both remain unexplored. Thus, the aim of this study was to evaluate changes following participation in a rehabilitation program combining aerobic and strength exercises. We conducted a retrospective analysis of 10 subjects with FSHD who participated in our rehabilitation program during 2018 and 2019. Each of the 20 sessions consisted of aerobic training on a cycloergometer and a moderate lower limb strength exercises on an isokinetic machine in combination with conventional therapy. The primary outcomes were walking speed, aerobic performance and isokinetic strength of the knee extensors and flexors. The secondary outcomes were fatigue, insomnia. VO2max and walking speed increased significantly by 2.125 ml·kg-1·min-1 [95% confidence interval (CI): 0.75-3.62, P = 0.022] and 0.28 m/s (95% CI: 0.16-0.4, P = 0.002), respectively. The effect size was small for V02max (Hedge's g, 0.44; 95% CI: -0.5 to 1.37) and large for walking speed (Hedge's g, 0.99; 95% CI: 0.06-1.92). The knee flexor strength significantly increased at rehabilitation discharge (repeated measures analysis of variance P = 0.004). Positive changes in fatigue and insomnia were also observed. Our preliminary results provide evidence that a relatively short course of a comprehensive rehabilitation program targeting both cardiorespiratory fitness and knee muscle strength can be beneficial for people with FSHD, which warrants further prospective studies.

First-trimester noninvasive prenatal diagnosis of seven facioscapulohumeral muscular dystrophy type 1 families using SNP-based amplicon sequencing: An earlier, rapid and safer way.

The study is to explore the feasibility and value of SNP-based noninvasive prenatal diagnosis (NIPD) for facioscapulohumeral muscular dystrophy type 1 (FSHD1) in early pregnancy weeks. We prospectively collected seven FSHD1 families, with an average gestational age of 8+6. Among these seven couples, there were three affected FSHD1 mothers and four affected fathers. A multiplex-PCR panel comprising 402 amplicons was designed to selective enrich for highly heterozygous SNPs upstream of the DUX4 gene. Risk haplotype was constructed based on familial linkage analysis. Fetal genotypes were accurately inferred through relative haplotype dosage analysis using Bayes Factor. All tests were successfully completed in a single attempt, and no recombination events were detected. NIPD results were provided within a week, which is 4 weeks earlier than karyomapping and 7 weeks earlier than Bionano single-molecule optical mapping (BOM). Ultimately, five FSHD1 fetuses and two normal fetuses were successfully identified, with a 100% concordance rate with karyomapping and BOM. Therefore, SNP-based NIPD for FSHD1 was demonstrated to be feasible and accurate in early weeks of gestation, although the risk of recombination events cannot be completely eliminated. In the future, testing of more cases is still necessary to fully determine the clinical utility.

An up-to-date myopathologic characterisation of facioscapulohumeral muscular dystrophy type 1 muscle biopsies shows sarcolemmal complement membrane attack complex deposits and increased skeletal muscle regeneration.

The aim of this study was to identify key routinely used myopathologic biomarkers of FSHD1. Needle muscle biopsies were taken in 34 affected muscles (m. quadriceps femoris (QF), n = 20, m. tibialis anterior (TA), n = 13, m. biceps brachii, n = 1) from 22 patients (age, 53.5 (10) years; M = 12, F = 10). Eleven patients had more than one biopsy (2xQF, n = 1; QF+TA, n = 9; 2xQF+TA, n = 1). Histochemistry, immunoperoxidase, and immunofluorescence stainings were performed and compared to age and muscle type matched muscle specimens of 11 healthy controls. Myopathologic features observed in our FSHD1 cohort were internalized nuclei, type 1 fibre hypertrophy and NADH central clearances/cores. We observed a prominent inflammatory response with MAC deposits, MHC I expression, and muscle regeneration that correlated with the inflammatory score. Our up-to-date characterization of FSHD1 points towards MHC I, MAC, and embryonic Myosin Heavy Chain/muscle regeneration as useful myopathologic readouts of FSHD1.

IL-6 and TNF are Potential Inflammatory Biomarkers in Facioscapulohumeral Muscular Dystrophy.

Background: FSHD is a highly prevalent inherited myopathy with a still poorly understood pathology. Objective: To investigate whether proinflammatory cytokines are associated with FSHD and which specific innate immune cells are involved in its pathology. Methods: First, we measured circulating cytokines in serum samples: IL-6 (FSHD, n = 150; HC, n = 98); TNF (FSHD, n = 150; HC, n = 59); IL-1α (FSHD, n = 150; HC, n = 66); IL-1ß (FSHD, n = 150; HC, n = 98); MCP-1 (FSHD, n = 14; HC, n = 14); VEGF-A (FSHD, n = 14; HC, n = 14). Second, we tested trained immunity in monocytes (FSHD, n = 15; HC, n = 15) and NK cells (FSHD, n = 11; HC, n = 11). Next, we explored the cytokine production capacity of NK cells in response to different stimuli (FSHD, n = 39; HC, n = 22). Lastly, we evaluated the cytokine production of ex vivo stimulated MRI guided inflamed (TIRM+) and paired MRI guided non inflamed (TIRM-) muscle biopsies of 21 patients and of 8 HC muscle biopsies. Results: We included a total of 190 FSHD patients (N = 190, 48±14 years, 49% men) and of 135 HC (N = 135, 44±15 years, 47% men). We found that FSHD patients had higher concentrations of IL-6 and TNF measured (a) in the circulation, (b) after ex-vivo stimulation of NK cells, and (c) in muscle specimens. Besides, IL-6 circulating concentrations, as well as its production by NK cells and IL-6 content of FSHD muscle specimens, showed a mild correlation with disease duration, disease severity, and muscle weakness. Conclusion: These results show that IL-6 and TNF may contribute to FSHD pathology and suggest novel therapeutic targets. Additionally, the activation of NK cells in FSHD may be a novel pathway contributing to FSHD pathology.

Facioscapulohumeral Muscular Dystrophy European Patient Survey: Assessing Patient Reported Disease Burden and Preferences in Clinical Trial Participation.

Background: Facioscapulohumeral muscular dystrophy (FSHD) is a genetic disorder characterized by progressive muscle weakness leading to permanent disability. There are no curative treatments, however, there are several upcoming clinical trials testing new therapies in FSHD. Objective: This study aimed to explore the disease burden and patient preferences of people with FSHD to ensure that clinical trials can be designed to include outcome measures that are relevant and important to patients. Methods: A survey was developed with a steering committee clinicians and physiotherapists with relevant experience in the disease, patient representatives, a registry expert and industry consultants. Themes of the survey included; participant demographics, disease progression and impact on function, factors encouraging or discouraging clinical trial participation, and positive outcomes of a clinical trial. Results: 1147 participants responded to the online survey, representing 26 countries across Europe and a range of disease severities. The study highlighted the key symptoms causing concern for FSHD patients - muscle weakness and mobility issues - reflecting what participants want targeted for future therapies. The need for clear information and communication throughout clinical trials was emphasised. Factors most encouraging trial participation included access to new investigational therapies, access to trial results and benefits for the FSHD community. Factors most discouraging trial participation included travel related issues and fear of side effects. Conclusions: The results from this study identify the patient reported burden of FSHD and should provide researchers and industry with areas of therapeutic research that would be meaningful to patients, as well as supporting the development of patient centric outcome measures in clinical trials.

Living with facioscapulohumeral muscular dystrophy during the first two COVID-19 outbreaks: a repeated patient survey in the Netherlands.

BACKGROUND: Patients with facioscapulohumeral dystrophy (FSHD) suffer from slowly progressive muscle weakness. Approximately 20% of FSHD patients end up wheelchair-dependent. FSHD patients benefit from physical activity to maintain their muscle strength as much as possible. The impact of the COVID-19 pandemic on the health of FSHD patients was unknown. OBJECTIVE: This study assessed changes in daily care received, perceived psychosocial stress, and worsening of FSHD complaints in 2020. Furthermore, we compared COVID-19 infection incidence and severity of symptoms between FSHD patients and non-FSHD housemates. METHODS: Three online survey rounds were sent out to all adult participants of the Dutch FSHD registry regarding daily care received, perceived psychosocial stress, COVID-19 infection rate, and COVID-19 symptoms severity. They also included COVID-19-related questions regarding the participants' housemates, which served as control group. RESULTS: Participation rate was 210 (61%), 186 (54%), and 205 (59%) for survey 1, 2, and 3, respectively. Care reduction was reported by 42.7%, 40%, and 28.8% of the participants in the respective surveys. Perceived psychosocial stress increased in 44%, 30%, and 40% of the participants. Compared to the 197 non-FSHD housemates, the 213 FSHD patients reported more possibly COVID-19-related symptoms (27% vs. 39%, p = 0.017) of mostly minimal severity (63%). No difference in (possible) COVID-19 infection incidence rates was found (2.0% vs. 2.8%, p = 0.527). CONCLUSIONS: The COVID-19 pandemic negatively impacted care received and increased perceived psychosocial stress in FSHD patients. However, COVID-19 infection incidence in FSHD patients was similar to their non-FSHD housemates.

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.

Regional and bilateral MRI and gene signatures in facioscapulohumeral dystrophy: implications for clinical trial design and mechanisms of disease progression.

Identifying the aberrant expression of DUX4 in skeletal muscle as the cause of facioscapulohumeral dystrophy (FSHD) has led to rational therapeutic development and clinical trials. Several studies support the use of MRI characteristics and the expression of DUX4-regulated genes in muscle biopsies as biomarkers of FSHD disease activity and progression. We performed lower-extremity MRI and muscle biopsies in the mid-portion of the tibialis anterior (TA) muscles bilaterally in FSHD subjects and validated our prior reports of the strong association between MRI characteristics and expression of genes regulated by DUX4 and other gene categories associated with FSHD disease activity. We further show that measurements of normalized fat content in the entire TA muscle strongly predict molecular signatures in the mid-portion of the TA, indicating that regional biopsies can accurately measure progression in the whole muscle and providing a strong basis for inclusion of MRI and molecular biomarkers in clinical trial design. An unanticipated finding was the strong correlations of molecular signatures in the bilateral comparisons, including markers of B-cells and other immune cell populations, suggesting that a systemic immune cell infiltration of skeletal muscle might have a role in disease progression.

Physical activity practiced at a young age is associated with a less severe subsequent clinical presentation in facioscapulohumeral muscular dystrophy.

BACKGROUND: In facioscapulohumeral muscular dystrophy (FSHD), it is not known whether physical activity (PA) practiced at young age is associated with the clinical presentation of disease. To assess this issue, we performed a retrospective cohort study concerning the previous practice of sports and, among them, those with medium-high cardiovascular commitment in clinically categorized carriers of a D4Z4 reduced allele (DRA). METHODS: People aged between 18 and 60 were recruited as being DRA carriers. Subcategory (classical phenotype, A; incomplete phenotype, B; asymptomatic carriers, C; complex phenotype, D) and FSHD score, which measures muscle functional impairment, were assessed for all participants. Information on PAs was retrieved by using an online survey dealing with the practice of sports at a young age. RESULTS: 368 participants were included in the study, average age 36.6 years (SD = 9.4), 47.6% male. The FSHD subcategory A was observed in 157 (42.7%) participants with average (± SD) FSHD score of 5.8 ± 3.0; the incomplete phenotype (category B) in 46 (12.5%) participants (average score 2.2 ± 1.7) and the D phenotype in 61 (16.6%, average score 6.5 ± 3.8). Asymptomatic carriers were 104 (subcategory C, 28.3%, score 0.0 ± 0.2). Time from symptoms onset was higher for patients with A (15.8 ± 11.1 years) and D phenotype (13.3 ± 11.9) than for patients with B phenotype (7.3 ± 9.0). The practice of sports was associated with lower FSHD score (-17%) in participants with A phenotype (MR = 0.83, 95% CI = 0.73-0.95, p = 0.007) and by 33% in participants with D phenotype (MR = 0.67, 95% CI = 0.51-0.89, p = 0.006). Conversely, no improvement was observed in participants with incomplete phenotype with mild severity (B). CONCLUSIONS: PAs at a young age are associated with a lower clinical score in the adult A and D FSHD subcategories. These results corroborate the need to consider PAs at the young age as a fundamental indicator for the correct clinical stratification of the disease and its possible evolution.

FSHD muscle shows perturbation in fibroadipogenic progenitor cells, mitochondrial function and alternative splicing independently of inflammation.

Facioscapulohumeral muscular dystrophy (FSHD) is a prevalent, incurable myopathy. FSHD is highly heterogeneous, with patients following a variety of clinical trajectories, complicating clinical trials. Skeletal muscle in FSHD undergoes fibrosis and fatty replacement that can be accelerated by inflammation, adding to heterogeneity. Well controlled molecular studies are thus essential to both categorize FSHD patients into distinct subtypes and understand pathomechanisms. Here, we further analyzed RNA-sequencing data from 24 FSHD patients, each of whom donated a biopsy from both a non-inflamed (TIRM-) and inflamed (TIRM+) muscle, and 15 FSHD patients who donated peripheral blood mononucleated cells (PBMCs), alongside non-affected control individuals. Differential gene expression analysis identified suppression of mitochondrial biogenesis and up-regulation of fibroadipogenic progenitor (FAP) gene expression in FSHD muscle, which was particularly marked on inflamed samples. PBMCs demonstrated suppression of antigen presentation in FSHD. Gene expression deconvolution revealed FAP expansion as a consistent feature of FSHD muscle, via meta-analysis of 7 independent transcriptomic datasets. Clustering of muscle biopsies separated patients in an unbiased manner into clinically mild and severe subtypes, independently of known disease modifiers (age, sex, D4Z4 repeat length). Lastly, the first genome-wide analysis of alternative splicing in FSHD muscle revealed perturbation of autophagy, BMP2 and HMGB1 signalling. Overall, our findings reveal molecular subtypes of FSHD with clinical relevance and identify novel pathomechanisms for this highly heterogeneous condition.

Face to Face: deciphering facial involvement in inclusion body myositis.

OBJECTIVE: The objective of this study is to evaluate the frequency and characteristics of facial involvement in inclusion body myositis (IBM) patients and to compare it to the one previously described in facioscapulohumeral dystrophy (FSHD) patients. METHODS: Thirty-two IBM patients were included and compared to 29 controls and 39 FSHD patients. All participants were recorded in a video as they performed a series of seven facial tasks. Five raters independently assessed facial weakness using both a qualitative evaluation and a semi-quantitative facial weakness score (FWS). RESULTS: IBM patients had higher FWS than controls (7.89 ± 7.56 vs 1.06 ± 0.88, p < 0.001). Twenty IBM patients (63%) had a facial weakness with a FWS above the maximum value for controls. All facial tasks were significantly more impaired in IBM patients compared to controls (p < 0.001), task 2 evaluating orbiculari oculi muscle weakness being the most affected. IBM patients with facial weakness reported more swallowing troubles than IBM patients without facial weakness (p = 0.03). FSHD patients displayed higher FWS than IBM patients (12.16 ± 8.37 vs 7.89 ± 7.56, p = 0.01) with more pronounced facial asymmetry (p = 0.01). FWS inter-rater ICC was 0.775. CONCLUSION: This study enabled us to estimate the frequency of facial impairment in IBM in more than half of patients, to detail its characteristics and to compare them with those of FSHD patients. The standardized, semi-quantitative FWS is an interesting diagnostic help in IBM as it appeared more sensitive than qualitative evaluation to detect mild facial weakness.