SMDT1 variants impair EMRE-mediated mitochondrial calcium uptake in patients with muscle involvement.

Ionic calcium (Ca2+) is a key messenger in signal transduction and its mitochondrial uptake plays an important role in cell physiology. This uptake is mediated by the mitochondrial Ca2+ uniporter (MCU), which is regulated by EMRE (essential MCU regulator) encoded by the SMDT1 (single-pass membrane protein with aspartate rich tail 1) gene. This work presents the genetic, clinical and cellular characterization of two patients harbouring SMDT1 variants and presenting with muscle problems. Analysis of patient fibroblasts and complementation experiments demonstrated that these variants lead to absence of EMRE protein, induce MCU subcomplex formation and impair mitochondrial Ca2+ uptake. However, the activity of oxidative phosphorylation enzymes, mitochondrial morphology and membrane potential, as well as routine/ATP-linked respiration were not affected. We hypothesize that the muscle-related symptoms in the SMDT1 patients result from aberrant mitochondrial Ca2+ uptake.

Pathogenic variants in three families with distal muscle involvement.

Three families suspected of distal hereditary motor neuropathy underwent genetic screening with the aim to identify the molecular defect underlying the disease. The description of the identification reflects the shift in molecular diagnostics that was made during the last decades. Our candidate gene approach yielded a known pathogenic variant in BSCL2 (p.Asn88Ser) in one family, and via a CMT-capture, in HSPB1 (p.Arg127Trp), in addition to five other variations in Charcot-Marie-Tooth-related genes in the proband of the second family. In the third family, using whole exome sequencing, followed by linkage-by-location, a three base pair deletion in exon 33 of MYH7 (p.Glu1508del) was found, a reported pathogenic allele albeit for a myopathy. After identification of the causative molecular defect, cardiac examination was performed for patients of the third family and this demonstrated abnormalities in three out of five affected family members. Heterogeneity and expansion of clinical phenotypes beyond known characteristics requires a wider set of genes to be screened. Whole exome/genome analysis with limited prior clinical information may therefore be used to precede a detailed clinical evaluation in cases of large families, preventing screening of a too narrow set of genes, and enabling the identification of novel disease-associated genes. In our cases, the variants had been reported, and co-segregation analysis confirmed the molecular diagnosis.

Distal spinal muscular atrophy featured by predominant calf muscle involvement in VRK1 associated disease - Case series and review.

We describe the shared clinical, biochemical, radiological and myopathological characteristics of four patients with distal spinal muscular atrophy (dSMA) caused by vaccinia-related kinase 1 (VRK1) variants and provide a review of the literature on phenotype-genotype correlations in VRK1-related disease. The clinical phenotype was characterized by adult-onset dSMA with predominant calf muscle involvement and mildly elevated serum creatinine kinase (CK) levels. Muscle imaging showed predominant atrophy and fatty replacement of calf muscles. We identified the novel compound heterozygous variants c.607C>T (p.Arg203Trp) and c.858G>T (p.Met286Ile) in two siblings with adult-onset dSMA. Additionally, two unrelated patients both carried the known c.583T>G (p.Leu195Val) VRK1 variant, with either c.197C>G (p.Ala66Gly) or c.701A>G (p.Asn234Ser) as a second variant. We conclude that compound heterozygous VRK1 variants cause distal spinal muscular atrophy with predominant posterior leg muscle involvement.

Rhabdomyolysis after COVID-19 Comirnaty Vaccination: A Case Report.

Rhabdomyolysis is an acute disruption in skeletal muscle integrity, leading to the rapid release of 4 muscle contents into the bloodstream, such as creatine kinase (CK). It can have various causes, including infections. Throughout the pandemic, multiple cases of rhabdomyolysis following COVID-19 infections have been reported. However, rhabdomyolysis subsequent to COVID-19 vaccinations appears to be relatively rare. Here, we report such a case after a second COVID-19 Comirnaty (BioNTech/Pfizer) vaccination. Our patient developed rhabdomyolysis 1 day after the second Comirnaty vaccination with high creatine kinase (CK) levels, generalized weakness, and kidney failure. CK levels and muscle weakness resolved after treatment with intravenous fluids, but unfortunately, he remained hemodialysis dependent after discharge. To our knowledge, this is one of the first case reports describing a patient with rhabdomyolysis after a Comirnaty vaccination. However, as millions of people have received the Comirnaty vaccine, it is unclear whether the rhabdomyolysis in our patient is a rare side effect or an unrelated, coincidental event. Large observational studies are needed to elucidate the causality between the Comirnaty vaccination and rhabdomyolysis. Awareness is warranted in patients with myalgia and muscle weakness shortly after COVID-19 vaccination, in order to initiate treatment early and prevent life-threatening complications.

Intravenous immunoglobulins as first-line treatment in idiopathic inflammatory myopathies: a pilot study.

OBJECTIVES: We explored efficacy and safety of IVIg as first-line treatment in patients with an idiopathic inflammatory myopathy. METHODS: In this investigator-initiated phase 2 open-label study, we included 20 adults with a newly diagnosed, biopsy-proven idiopathic inflammatory myopathy, and a disease duration of less than 9 months. Patients with IBM and prior use of immunosuppressants were excluded. The standard treatment regimen consisted of IVIg (Privigen) monotherapy for 9 weeks: a loading dose (2 g/kg body weight) and two subsequent maintenance doses (1 g/kg body weight) with a 3-week interval. The primary outcome was the number of patients with at least moderate improvement on the 2016 ACR/EULAR Total Improvement Score. Secondary outcomes included time to improvement, the number of patients requiring rescue medication and serious adverse events. RESULTS: We included patients with DM (n = 9), immune-mediated necrotizing myopathy (n = 6), non-specific myositis/overlap myositis (n = 4) and anti-synthetase syndrome (n = 1). One patient was excluded from analyses because of minimal weakness resulting in a ceiling effect. Eight patients (8/19 = 42.0%; Clopper-Pearson 95% CI: 19.6, 64.6) had at least moderate improvement by 9 weeks. Of these, six reached improvement by 3 weeks. Seven patients required rescue medication due to insufficient efficacy and prematurely ended the study. Three serious adverse events occurred, of which one was pulmonary embolism. CONCLUSION: First-line IVIg monotherapy led to at least moderate improvement in nearly half of patients with a fast clinical response in the majority of responders. TRIAL REGISTRATION: Netherlands Trial Register identifier, NTR6160.

Biomarker profiles of endothelial activation and dysfunction in rare systemic autoimmune diseases: implications for cardiovascular risk.

OBJECTIVES: Vasculopathy is an important hallmark of systemic chronic inflammatory connective tissue diseases (CICTD) and is associated with increased cardiovascular risk. We investigated disease-specific biomarker profiles associated with endothelial dysfunction, angiogenic homeostasis and (tissue) inflammation, and their relation to disease activity in rare CICTD. METHODS: A total of 38 serum proteins associated with endothelial (dys)function and inflammation were measured by multiplex-immunoassay in treatment-naive patients with localized scleroderma (LoS, 30), eosinophilic fasciitis (EF, 8) or (juvenile) dermatomyositis (34), 119 (follow-up) samples during treatment, and 65 controls. Data were analysed by unsupervised clustering, Spearman correlations, non-parametric t test and ANOVA. RESULTS: The systemic CICTD, EF and dermatomyositis, had distinct biomarker profiles, with 'signature' markers galectin-9 (dermatomyositis) and CCL4, CCL18, CXCL9, fetuin, fibronectin, galectin-1 and TSP-1 (EF). In LoS, CCL18, CXCL9 and CXCL10 were subtly increased. Furthermore, dermatomyositis and EF shared upregulation of markers related to interferon (CCL2, CXCL10), endothelial activation (VCAM-1), inhibition of angiogenesis (angiopoietin-2, sVEGFR-1) and inflammation/leucocyte chemo-attraction (CCL19, CXCL13, IL-18, YKL-40), as well as disturbance of the Angiopoietin-Tie receptor system and VEGF-VEGFR system. These profiles were related to disease activity, and largely normalized during treatment. However, a subgroup of CICTD patients showed continued elevation of CXCL10, CXCL13, galectin-9, IL-18, TNFR2, VCAM-1, and/or YKL-40 during clinically inactive disease, possibly indicating subclinical interferon-driven inflammation and/or endothelial dysfunction. CONCLUSION: CICTD-specific biomarker profiles revealed an anti-angiogenic, interferon-driven environment during active disease, with incomplete normalization under treatment. This warrants further investigation into monitoring of vascular biomarkers during clinical follow-up, or targeted interventions to minimize cardiovascular risk in the long term.

Galectin-9 and CXCL10 as Biomarkers for Disease Activity in Juvenile Dermatomyositis: A Longitudinal Cohort Study and Multicohort Validation.

OBJECTIVE: Objective evaluation of disease activity is challenging in patients with juvenile dermatomyositis (DM) due to a lack of reliable biomarkers, but it is crucial to avoid both under- and overtreatment of patients. Recently, we identified 2 proteins, galectin-9 and CXCL10, whose levels are highly correlated with the extent of juvenile DM disease activity. This study was undertaken to validate galectin-9 and CXCL10 as biomarkers for disease activity in juvenile DM, and to assess their disease specificity and potency in predicting the occurrence of flares. METHODS: Levels of galectin-9 and CXCL10 were measured by multiplex immunoassay in serum samples from 125 unique patients with juvenile DM in 3 international cross-sectional cohorts and a local longitudinal cohort. The disease specificity of both proteins was examined in 50 adult patients with DM or nonspecific myositis (NSM) and 61 patients with other systemic autoimmune diseases. RESULTS: Both cross-sectionally and longitudinally, galectin-9 and CXCL10 outperformed the currently used laboratory marker, creatine kinase (CK), in distinguishing between juvenile DM patients with active disease and those in remission (area under the receiver operating characteristic curve [AUC] 0.86-0.90 for galectin-9 and CXCL10; AUC 0.66-0.68 for CK). The sensitivity and specificity for active disease in juvenile DM was 0.84 and 0.92, respectively, for galectin-9 and 0.87 and 1.00, respectively, for CXCL10. In 10 patients with juvenile DM who experienced a flare and were prospectively followed up, continuously elevated or rising biomarker levels suggested an imminent flare up to several months before the onset of symptoms, even in the absence of elevated CK levels. Galectin-9 and CXCL10 distinguished between active disease and remission in adult patients with DM or NSM (P = 0.0126 for galectin-9 and P < 0.0001 for CXCL10) and were suited for measurement in minimally invasive dried blood spots (healthy controls versus juvenile DM, P = 0.0040 for galectin-9 and P < 0.0001 for CXCL10). CONCLUSION: In this study, galectin-9 and CXCL10 were validated as sensitive and reliable biomarkers for disease activity in juvenile DM. Implementation of these biomarkers into clinical practice as tools to monitor disease activity and guide treatment might facilitate personalized treatment strategies.

Autosomal recessive limb-girdle and Miyoshi muscular dystrophies in the Netherlands: The clinical and molecular spectrum of 244 patients.

In this retrospective study, we conducted a clinico-genetic analysis of patients with autosomal recessive limb-girdle muscular dystrophy (LGMD) and Miyoshi muscular dystrophy (MMD). Patients were identified at the tertiary referral centre for DNA diagnosis in the Netherlands and included if they carried two mutations in CAPN3, DYSF, SGCG, SGCA, SGCB, SGCD, TRIM32, FKRP or ANO5 gene. DNA was screened by direct sequencing and multiplex ligand-dependent probe amplification (MLPA) analysis. A total of 244 patients was identified; 68 LGMDR1/LGMD2A patients with CAPN3 mutations (28%), 67 sarcoglycanopathy patients (LGMDR3-5/LGMD2C-E) (27%), 64 LGMDR12/LGMD2L and MMD3 patients with ANO5 mutations (26%), 25 LGMDR2/LGMD2B and MMD1 with DYSF mutations (10%), 21 LGMDR9/LGMD2I with FKRP mutations (9%) and one LGMDR8/LGMD2H patient with TRIM32 mutations (<1%). The estimated minimum prevalence of AR-LGMD and MMD in the Netherlands amounted to 14.4 × 10-6 . Thirty-three novel mutations were identified. A wide range in age of onset (0-72 years) and loss of ambulation (5-74 years) was found. Fifteen patients (6%) initially presented with asymptomatic hyperCKemia. Cardiac abnormalities were found in 35 patients (17%). Non-invasive ventilation was started in 34 patients (14%). Both cardiac and respiratory involvement occurs across all subtypes, stressing the need for screening in all included subtypes.

Effective cauda equina decompression in two siblings with Charcot-Marie-Tooth disease type 1B.

Two siblings with Charcot-Marie-Tooth (CMT) 1B due to a c.517G>C (p.Gly173Arg) mutation in the MPZ gene both developed an acute cauda syndrome with unbearable back pain radiating to both legs, progressive muscle weakness of the legs, and saddle hypesthesia with fecal and urinary incontinence. MRI showed in both patients a lumbar spinal canal totally filled with hypertrophic caudal nerve roots. We performed acute decompression. Postoperatively, in both patients, the back pain resolved immediately, there was a significant improvement of both the paresis of the legs and the hypesthesia, and there was a full return of continence. There was no recurrence of acute symptoms during respectively 19 years and 1.5 years of follow-up. We conclude that in patients with CMT and a related cauda syndrome because of hypertrophic caudal nerve roots, acute decompression can be an effective and safe treatment with long-term efficacy.

Combining MRI and muscle biopsy improves diagnostic accuracy in subacute-onset idiopathic inflammatory myopathy.

INTRODUCTION: In 10-20% of patients with subacute-onset idiopathic inflammatory myopathy (IIM), muscle biopsy is normal or shows nonspecific findings. MRI can be used as a triage test before muscle biopsy and as an add-on test if the biopsy is nondiagnostic. METHODS: MRI scans of skeletal muscles and muscle biopsies were evaluated prospectively in 48 patients suspected to have IIM. The interpretations of MRI and muscle biopsy were compared with the definite diagnosis (based on European Neuromuscular Centre criteria and response to corticosteroids). RESULTS: The false negative rate (FNR) of all muscle biopsies was 0.23. Biopsies of a muscle showing hyperintensity on MRI (as triage test) had an FNR of 0.19. The result of MRI as an add-on test in patients with a nondiagnostic muscle biopsy decreased the FNR from 0.23 to 0.06. CONCLUSIONS: We recommend both MRI and muscle biopsy in patients suspected of having IIM.

Long-term follow-up of 62 patients with myositis.

The aim of this work is to evaluate disease-related mortality and the course of the disease including functional outcome and quality of life. We did a follow-up study on a large prospective cohort of 62 patients with subacute-onset idiopathic inflammatory myopathy (IIM) (dermatomyositis (n = 24), nonspecific myositis (n = 34), necrotizing autoimmune myopathy (n = 4)) after treatment with corticosteroids only (randomized controlled trial comparing daily high-dosage prednisone with pulse therapy of dexamethasone). Development of connective tissue disease (CTD) or malignancy, disease course and mortality, functional outcome and quality of life were evaluated. After a mean follow-up of 3 years (SD 1.5), 22 % had developed a CTD and 17 % a malignancy. Disease-related mortality was 15 %. A monophasic disease course was found in 27 %. Most patients had a chronic (35 %) or polyphasic disease (35 %) course and experienced single or multiple relapses. Sixteen patients (33 %) were off medication after a mean of 1 year of treatment. Disability scores improved particularly in the first 18 months. At follow-up, 68 % still perceived disabilities. Quality of life scores as measured by the short-form (SF)-36 improved in the first 18 months. After 18 months, scores remained stable during the next years of follow-up and remained low compared to a normal population. (1) Two-thirds of the patients with an IIM have a polyphasic or chronic disease course and need maintenance treatment. (2) The impact on functional outcome and quality of life is considerable and does not improve further after 18 months.

Immunosuppressant and immunomodulatory treatment for dermatomyositis and polymyositis.

BACKGROUND: Idiopathic inflammatory myopathies are chronic diseases with significant mortality and morbidity. Whilst immunosuppressive and immunomodulatory therapies are frequently used, the optimal therapeutic regimen remains unclear. This is an update of a review first published in 2005. OBJECTIVES: To assess the effects of immunosuppressants and immunomodulatory treatments for dermatomyositis and polymyositis. SEARCH METHODS: We searched the Cochrane Neuromuscular Disease Group Specialized Register (August 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 3 2011), MEDLINE (January 1966 to August 2011), EMBASE (January 1980 to August 2011) and clinicaltrials.gov (August 2011). We checked the bibliographies of identified trials and wrote to disease experts. SELECTION CRITERIA: We included all randomised controlled trials (RCTs) or quasi-RCTs involving participants with probable or definite dermatomyositis and polymyositis as defined by the criteria of Bohan and Peter, or definite, probable or mild/early by the criteria of Dalakas. In participants without a classical rash of dermatomyositis, inclusion body myositis should have been excluded by muscle biopsy. We considered any immunosuppressant or immunomodulatory treatment. The two primary outcomes were the change in a function or disability scale measured as the proportion of participants improving one grade, two grades etc, predefined based on the scales used in the studies after at least six months, and a 15% or greater improvement in muscle strength compared with baseline after at least six months. Other outcomes were: the International Myositis Assessment and Clinical Studies Group (IMACS) definition of improvement, number of relapses and time to relapse, remission and time-to-remission, cumulative corticosteroid dose and serious adverse effects. DATA COLLECTION AND ANALYSIS: Two authors independently selected papers, extracted data and assessed risk of bias in included studies. They collected adverse event data from the included studies. MAIN RESULTS: The review authors identified fourteen 14 relevant RCTs. They excluded four trials.The 10 included studies, four of which have been added in this update, included a total of 258 participants. Six studies compared an immunosuppressant or immunomodulator with placebo control, and four studies compared two immunosuppressant regimes with each other. Most of the studies were small (the largest had 62 participants) and many of the reports contained insufficient information to assess risk of bias.Amongst the six studies comparing immunosuppressant with placebo, one study, investigating intravenous immunoglobulin (IVIg), showed statistically significant improvement in scores of muscle strength in the IVIg group over three months. Another study investigating etanercept showed some evidence of a steroid sparing effect, a secondary outcome in this review, but no improvement in other assessed outcomes. The other four randomised placebo-controlled trials assessed either plasma exchange and leukapheresis, eculizumab, infliximab or azathioprine against placebo and all produced negative results.Three of the four studies comparing two immunosuppressant regimes (azathioprine with methotrexate, ciclosporin with methotrexate, and intramuscular methotrexate with oral methotrexate plus azathioprine) showed no statistically significant difference in efficacy between the treatment regimes. The fourth study comparing pulsed oral dexamethasone with daily oral prednisolone and found that the dexamethasone regime had a shorter median time to relapse but fewer side effects.Immunosuppressants were associated with significant side effects. AUTHORS' CONCLUSIONS: This systematic review highlights the lack of high quality RCTs that assess the efficacy and toxicity of immunosuppressants in inflammatory myositis.

WITHDRAWN: Immunosuppressant and immunomodulatory treatment for dermatomyositis and polymyositis.

BACKGROUND: Idiopathic inflammatory myopathies are chronic skeletal diseases with significant mortality and morbidity despite treatment by corticosteroids. Immunosuppressive agents and immunomodulatory therapy are used to improve disease control and reduce the long-term side effects of corticosteroids. While these treatments are used commonly in routine clinical practice, the optimal therapeutic regimen remains unclear. OBJECTIVES: To systematically review the evidence for the effectiveness of immunosuppressants and immunomodulatory treatments for dermatomyositis and polymyositis. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group trials register (searched February 2002 and updated in November 2003) and MEDLINE (January 1966 to December 2002). We checked bibliographies of identified trials and wrote to disease experts. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials including patients with probable or definite dermatomyositis and polymyositis as defined by the criteria of Bohan and Peter or definite, probable or mild/early by the criteria of Dalakas. Patients with inclusion body myositis should have been excluded by muscle biopsies. Any immunosuppressant or immunomodulatory treatment including corticosteroids, azathioprine, methotrexate, ciclosporin, chlorambucil, cyclophosphamide, intravenous immunoglobulin, interferon and plasma exchange was considered. Primary outcome was assessment of muscle strength after at least six months. Other outcomes were: change in disability, number of relapses and time to relapse, number of patients in remission and time-to-remission, cumulative corticosteroid dose and serious adverse effects. DATA COLLECTION AND ANALYSIS: Two authors (EC and JH) independently selected trials for inclusion in the review. Four authors independently assessed each study. Methodological criteria and the results of each study were recorded on data extraction forms. MAIN RESULTS: Seven potentially relevant randomised controlled trials were identified. One trial was excluded. Three studies compared immunosuppressant with placebo control, one trial compared one immunosuppressant (methotrexate) with another (azathioprine), another trial compared ciclosporin A with methotrexate and the final trial compared intramuscular methotrexate with oral methotrexate plus azathioprine. The study comparing intravenous immunoglobulin with placebo concluded that the former was superior. Two randomised placebo-controlled trials assessing plasma exchange, leukapheresis and azathioprine produced negative results. The fourth study compared azathioprine with methotrexate and found azathioprine and methotrexate equally effective but methotrexate had a better side effect profile. The fifth study comparing ciclosporin A with methotrexate and the sixth study comparing intramuscular methotrexate with oral methotrexate plus azathioprine found no statistically significant differences between the treatment groups. Immunosuppressants are associated with significant side effects. AUTHORS' CONCLUSIONS: This systematic review highlights the lack of high quality randomised controlled trials that assess the efficacy and toxicity of immunosuppressants in inflammatory myositis.

Tubuloreticular structures in different types of myositis: implications for pathogenesis.

In dermatomyositis (DM) there is strong histopathological evidence of a microvascular pathogenesis, including endothelial microtubular inclusions. In nonspecific myositis, perimysial and perivascular infiltrates in the muscle biopsy similar to DM are found. Microtubular inclusions in endothelial cells were systematically searched for and found in 4 of the 20 muscle biopsies of nonspecific myositis patients (20%). Three had a CTD (SLE, scleroderma, and Sjogren syndrome). Ten patients with DM and 5 patients with sporadic inclusion body myositis served as positive and negative controls, respectively.

Inclusion body myositis. Clinical features and clinical course of the disease in 64 patients.

The clinical features of inclusion body myositis (IBM) were of minor importance in the design of consensus diagnostic criteria, mainly because of controversial views on the specificity of signs and symptoms, although some authors reported "typical" signs. To re-assess the clinical spectrum of IBM, a single investigator using a standard protocol studied a cohort of 64 patients cross-sectionally. Symptom onset was before the age of 50 years in 20% of cases. Only a few patients (14 %) started with weakness other than that of quadriceps, finger flexor or pharyngeal muscles. The sequence of power loss was erratic, but onset of symptoms with quadriceps weakness predicted an earlier onset of dysphagia in older patients (> or = 56 years) compared with younger ones (< 56 years) (p = 0.02). Despite widespread weakness patients had favourable scores on three commonly used function scales and they kept their employment. Complete wheel-chair dependency was rare (3 %). A dominant characteristic was the anatomical distribution of afflicted muscles: ventral extremity muscle groups were more affected than dorsal muscle groups and girdle muscles were least affected, the latter preserving postural stability. Ankylosis, especially in extension of the fingers,was frequently present. Together with the sparing of intrinsic hand muscles it was helpful in the preservation of many skillful movements. IBM has a unique distribution of muscle weakness. Ankylotic contractures are common. We feel that their joint impact on daily functioning is characteristic for the disease.

Polymyositis: an ongoing discussion about a disease entity.

Since its first description more than a century ago, there has been much debate about the diagnostic entity polymyositis. Because initial observations were of individuals with dermatomyositis, it appeared that polymyositis was not possible without skin lesions. Distinctive clinical and histologic features of polymyositis were not established until the late 20th century. The identification of inclusion body myositis as a distinct entity has further refined nosographic classification.

Comparison of weakness progression in inclusion body myositis during treatment with methotrexate or placebo.

We investigated whether 5 to 20mg per week oral methotrexate could slow down disease progression in 44 patients with inclusion body myositis in a randomized double-blind placebo-controlled study over 48 weeks. Mean change of quantitative muscle strength testing sum scores was the primary study outcome measure. Quantitative muscle strength testing sum scores declined in both treatment groups, -0.2% for methotrexate and -3.4% for placebo (95% confidence interval = -2.5% to +9.1% for difference). There were also no differences in manual muscle testing sum scores, activity scale scores and patients' own assessments after 48 weeks of treatment. Serum creatine kinase activity decreased significantly in the methotrexate group. We conclude that oral methotrexate did not slow down progression of muscle weakness but decreased serum creatine kinase activity.