Publications by authors named "Tanya Stojkovic"

156 Publications

Charcot-Marie-Tooth disease misdiagnosed as chronic inflammatory demyelinating polyradiculoneuropathy: An international multicentric retrospective study.

Eur J Neurol 2021 Jun 1. Epub 2021 Jun 1.

Neurology Department, APHP, CHU de Bicêtre, Le Kremlin-Bicêtre, France.

Background And Purpose: Charcot-Marie-Tooth (CMT) disease, an untreatable hereditary polyneuropathy, may mimic chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), a treatable neuropathy.

Methods: In this retrospective study, we analyzed the characteristics of CMT patients misdiagnosed as CIDP at 16 university hospitals in three countries, compared these patients with a reference group of CIDP patients, and estimated the cost of misdiagnosis.

Results: Among 1104 CIDP cases, we identified 35 CMT patients misdiagnosed as CIDP (3.2%). All were initially diagnosed with definite or probable CIDP (European Federation of Neurological Societies/Peripheral Nerve Society criteria), and mutations in PMP22, MPZ, and 10 other CMT genes were found in 34%, 31%, and 35% of cases, respectively. In comparison with a reference group of 35 CIDP patients, CMT patients were younger (median age at disease onset = 39 vs. 56 years) and more frequently had motor weakness at disease onset (80% vs. 29%), hearing loss (14% vs. 0%), normal brachial plexus imaging (70% vs. 40%), lower cerebrospinal fluid protein content (median = 0.5 vs. 0.8 g/L), and lower treatment response (20% vs. 69%). Treatment cost in these 35 misdiagnosed patients was estimated at 4.6 million euros (M€), whereas the cost of CMT genetic analysis in 1104 patients was estimated at 2.7 M€.

Conclusions: In this study, 35 of 1104 (3.2%) patients initially diagnosed with CIDP had CMT. Importantly, the cost of treating these 35 misdiagnosed patients was significantly higher than the cost of performing CMT genetic analysis in 1104 patients (4.6 M€ vs. 2.7 M€), suggesting that CMT genetic investigations should be more widely used before diagnosing CIDP.
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http://dx.doi.org/10.1111/ene.14950DOI Listing
June 2021

Genotype-phenotype correlation in French patients with myelin protein zero gene-related inherited neuropathy.

Eur J Neurol 2021 Jun 1. Epub 2021 Jun 1.

Reference center for neuromuscular disorders and ALS, APHM, CHU La Timone.

Background: Preparations for clinical trials of unfolded protein response (UPR) inhibitors (such as Sephin 1) that target the upregulated UPR in patients with CMT carrying MPZ mutations are currently underway. The inclusion criteria for these trials are still being formulated. Our objective was to characterize the relation between genotypes and phenotypes in patients with CMT caused by MPZ mutations, and to refine the inclusion criteria for future trials.

Patients And Methods: Clinical and neurophysiological data of CMT patients with MPZ mutations were retrospectively collected at 11 French reference centers.

Results: Forty-four mutations in MPZ were identified in 91 patients from 61 families. There was considerable heterogeneity. The same mutation was found to cause either axonal or demyelinating neuropathy. Three groups were identified according to the age at disease onset. CMTES tended to be higher in the early (≤22 years) and adult (23-47 years) onset groups (mean CMTESv2: 10.4 and 10.0, respectively) than in the late onset group (>47 years, mean CMTESv2=8.6, p=0.47). There was a significant positive correlation between CMTESv2 and the age of patients in groups I (p=0.027) and II (p=0.023), indicating that clinical severity progressed with age in these patients.

Conclusion: To optimize the selection of CMT patients carrying MPZ mutations for the upcoming trials, inclusion criteria should take into account the pathophysiology of the disease (upregulated UPR). Recruited patients should have a mild to moderate disease severity and a disease onset between 18 and 50 years as these patients exhibit significant disease progression over time.
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http://dx.doi.org/10.1111/ene.14948DOI Listing
June 2021

Prevalence and clinical outcomes of dystrophin-associated dilated cardiomyopathy without severe skeletal myopathy.

Eur J Heart Fail 2021 May 28. Epub 2021 May 28.

Leviev Heart Center, Sheba Medical Center and The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.

Aims: Dilated cardiomyopathy (DCM) associated with dystrophin gene (DMD) mutations in individuals with mild or absent skeletal myopathy is often indistinguishable from other DCM forms. We sought to describe the phenotype and prognosis of DMD associated DCM in DMD mutation carriers without severe skeletal myopathy.

Methods And Results: At 26 European centres, we retrospectively collected clinical characteristics and outcomes of 223 DMD mutation carriers (83% male, 33 ± 15 years). A total of 112 individuals (52%) had DCM at first evaluation [n = 85; left ventricular ejection fraction (LVEF) 34 ± 11.2%] or developed DCM (n = 27; LVEF 41.3 ± 7.5%) after a median follow-up of 96 months (interquartile range 5-311 months). DCM penetrance was 45% in carriers older than 40 years. DCM appeared earlier in males and was independent of the type of mutation, presence of skeletal myopathy, or elevated serum creatine kinase levels. Major adverse cardiac events (MACE) occurred in 22% individuals with DCM, 18% developed end-stage heart failure and 9% sudden cardiac death or equivalent. Skeletal myopathy was not associated with survival free of MACE in patients with DCM. Decreased LVEF and increased left ventricular end-diastolic diameter at baseline were associated with MACE. Individuals without DCM had favourable prognosis without MACE or death during follow-up.

Conclusions: DMD-associated DCM without severe skeletal myopathy is characterized by incomplete penetrance but high risk of MACE, including progression to end-stage heart failure and ventricular arrhythmias. DCM onset is the major determinant of prognosis with similar survival regardless of the presence of skeletal myopathy.
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http://dx.doi.org/10.1002/ejhf.2250DOI Listing
May 2021

Missense mutations in small muscle protein X-linked (SMPX) cause distal myopathy with protein inclusions.

Acta Neuropathol 2021 May 11. Epub 2021 May 11.

Folkhälsan Research Center, Helsinki, Finland.

Using deep phenotyping and high-throughput sequencing, we have identified a novel type of distal myopathy caused by mutations in the Small muscle protein X-linked (SMPX) gene. Four different missense mutations were identified in ten patients from nine families in five different countries, suggesting that this disease could be prevalent in other populations as well. Haplotype analysis of patients with similar ancestry revealed two different founder mutations in Southern Europe and France, indicating that the prevalence in these populations may be higher. In our study all patients presented with highly similar clinical features: adult-onset, usually distal more than proximal limb muscle weakness, slowly progressing over decades with preserved walking. Lower limb muscle imaging showed a characteristic pattern of muscle involvement and fatty degeneration. Histopathological and electron microscopic analysis of patient muscle biopsies revealed myopathic findings with rimmed vacuoles and the presence of sarcoplasmic inclusions, some with amyloid-like characteristics. In silico predictions and subsequent cell culture studies showed that the missense mutations increase aggregation propensity of the SMPX protein. In cell culture studies, overexpressed SMPX localized to stress granules and slowed down their clearance.
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http://dx.doi.org/10.1007/s00401-021-02319-xDOI Listing
May 2021

A form of muscular dystrophy associated with pathogenic variants in JAG2.

Am J Hum Genet 2021 05 15;108(5):840-856. Epub 2021 Apr 15.

Centre de Référence Neuromusculaire and Paediatric Neurology Department, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, 1020 Brussels, Belgium.

JAG2 encodes the Notch ligand Jagged2. The conserved Notch signaling pathway contributes to the development and homeostasis of multiple tissues, including skeletal muscle. We studied an international cohort of 23 individuals with genetically unsolved muscular dystrophy from 13 unrelated families. Whole-exome sequencing identified rare homozygous or compound heterozygous JAG2 variants in all 13 families. The identified bi-allelic variants include 10 missense variants that disrupt highly conserved amino acids, a nonsense variant, two frameshift variants, an in-frame deletion, and a microdeletion encompassing JAG2. Onset of muscle weakness occurred from infancy to young adulthood. Serum creatine kinase (CK) levels were normal or mildly elevated. Muscle histology was primarily dystrophic. MRI of the lower extremities revealed a distinct, slightly asymmetric pattern of muscle involvement with cores of preserved and affected muscles in quadriceps and tibialis anterior, in some cases resembling patterns seen in POGLUT1-associated muscular dystrophy. Transcriptome analysis of muscle tissue from two participants suggested misregulation of genes involved in myogenesis, including PAX7. In complementary studies, Jag2 downregulation in murine myoblasts led to downregulation of multiple components of the Notch pathway, including Megf10. Investigations in Drosophila suggested an interaction between Serrate and Drpr, the fly orthologs of JAG1/JAG2 and MEGF10, respectively. In silico analysis predicted that many Jagged2 missense variants are associated with structural changes and protein misfolding. In summary, we describe a muscular dystrophy associated with pathogenic variants in JAG2 and evidence suggests a disease mechanism related to Notch pathway dysfunction.
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http://dx.doi.org/10.1016/j.ajhg.2021.03.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8206160PMC
May 2021

Improved Cardiac Outcomes by Early Treatment with Angiotensin-Converting Enzyme Inhibitors in Becker Muscular Dystrophy.

J Neuromuscul Dis 2021 Mar 29. Epub 2021 Mar 29.

AP-HP, Cochin Hospital, Cardiology Department, Paris, France.

Background: The latest practice guidelines from the American College of Cardiology/American Heart Association recommend the prescription of an ACE-i for patients presenting with non-ischemic cardiomyopathy when left ventricular ejection fraction (LVEF) falls below 40%.

Objective: To determine if the initiation of treatment with an angiotensin-converting enzyme inhibitor (ACE-i) earlier than recommended by practice guidelines issued by professional societies improves the long-term cardiac outcomes of patients presenting with Becker muscular dystrophy (MD) cardiomyopathy.

Methods: From a multicenter registry of Becker MD, we selected retrospectively patients presenting between January 1990 and April 2019 with a LVEF ≥40 and ≤49%. We used a propensity score analysis to compare the risk of a) hospitalization for management of heart failure (HF), and b) a decrease in LVEF to <35% in patients who received an ACE-i when LVEF fell below 40% (conventional treatment), versus below 50% (early treatment).

Results: From the 183 patients entered in our registry, we identified 85 whose LVEF was between 40 and 49%, 51 of whom received early and 34 received conventional ACE-i treatment. Among patients with early versus conventional treatments, 2 (3.9%) versus 4 (11.8%) were hospitalized for management of HF [hazard ratio (HR) 0.151; 95% confidence interval (CI) 0.028 to 0.822; p = 0.029], and 9 (17.6%) versus 10 (29.4%) had a decrease in LVEF below 35% (HR 0.290; 95% CI 0.121 to 0.694; p = 0.005).

Conclusions: The long-term cardiac outcome of patients presenting with Becker MD was significantly better when treatment with ACE-i was introduced after a decrease in LVEF below 50%, instead of below 40% as recommended in the current practice guidelines issued by professional societies.
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http://dx.doi.org/10.3233/JND-200620DOI Listing
March 2021

A novel PHKA1 mutation associating myopathy and cognitive impairment: Expanding the spectrum of phosphorylase kinase b (PhK) deficiency.

J Neurol Sci 2021 May 18;424:117391. Epub 2021 Mar 18.

APHP-GH Pitié-Salpêtrière, Centre de référence des maladies neuromusculaires Nord/Est/Ile de France, Myology Institute, Paris, France. Electronic address:

Muscle phosphorylase kinase b deficiency (PhK) is a rare disorder of glycogen metabolism characterized by exercise-induced myalgia and cramps, myoglobinuria and progressive muscle weakness. PhK deficiency is due to mutations in the PHKA1 gene inherited in an X-linked manner and is associated to glycogenosis type VIII (GSD VIII also called GSD IXd). PHKA1 gene codes for the αM subunit of the PhK, a multimeric protein complex responsible for the control of glycogen breakdown in muscle. Until now, few patients have been reported with X-linked recessive muscle PhK deficiency due to PHKA1 mutations. All reported patients presented with exercise intolerance and mild myopathy and one of them had cognitive impairment, leading to speculate about a central nervous system involvement in GSD VIII. Here we report in a sibling a novel mutation in the PHKA1 gene associated with a progressive myopathy, exercise intolerance, muscle hypertrophy and cognitive impairment as an associated feature. This report expands the genetic and clinical spectrum of the extremely rare PHKA1-related PhK deficiency and presents new evidences about its involvement in brain development.
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http://dx.doi.org/10.1016/j.jns.2021.117391DOI Listing
May 2021

Association between prophylactic angiotensin-converting enzyme inhibitors and overall survival in Duchenne muscular dystrophy-analysis of registry data.

Eur Heart J 2021 05;42(20):1976-1984

Service d'Explorations Fonctionnelles, Hôpital Raymond Poincaré, Garches, FranceINSERM Université de Versailles Saint Quentin en Yvelines, France.

Aims: To estimate the effect of prophylactic angiotensin-converting enzyme inhibitors (ACEi) on survival in Duchenne muscular dystrophy (DMD).

Methods And Results: We analysed the data from the French multicentre DMD Heart Registry (ClinicalTrials.gov: NCT03443115). We estimated the association between the prophylactic prescription of ACEi and event-free survival in 668 patients aged 8 to 13 years, with normal left ventricular function, using (i) a Cox model with intervention as a time-dependent covariate, (ii) a propensity-based analysis comparing ACEi treatment vs. no treatment, and (iii) a set of sensitivity analyses. The study outcomes were overall survival and hospitalizations for heart failure (HF) or acute respiratory failure. Among the 668 patients included in the DMD Heart Registry, 576 (mean age 6.1 ± 2.8 years) were eligible for this study, of whom 390 were treated with ACEi prophylactically. Death occurred in 53 patients (13.5%) who were and 60 patients (32.3%) who were not treated prophylactically with ACEi, respectively. In a Cox model with intervention as a time-dependent variable, the hazard ratio (HR) associated with ACEi treatment was 0.49 [95% confidence interval (CI) 0.34-0.72] and 0.47 (95% CI 0.31-0.17) for overall mortality after adjustment for baseline variables. In the propensity-based analysis, 278 patients were included in the treatment group and 834 in the control group, with 18.5% and 30.4% 12-year estimated probability of death, respectively. ACEi were associated with a lower risk of death (HR 0.39; 95% CI 0.17-0.92) and hospitalization for HF (HR 0.16; 95% CI 0.04-0.62). All other sensitivity analyses yielded similar results.

Conclusion: Prophylactic ACEi treatment in DMD was associated with a significantly higher overall survival and lower rates of hospitalization for HF.
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http://dx.doi.org/10.1093/eurheartj/ehab054DOI Listing
May 2021

Deep phenotyping of an international series of patients with late-onset dysferlinopathy.

Eur J Neurol 2021 Jun 1;28(6):2092-2102. Epub 2021 Apr 1.

Nord/Est/Ile-de-France Neuromuscular Reference Center, Institute of Myology, Pitié-Salpêtrière Hospital, APHP, Sorbonne University, Paris, France.

Background: To describe the clinical, pathological, and molecular characteristics of late-onset (LO) dysferlinopathy patients.

Methods: Retrospective series of patients with LO dysferlinopathy, defined by an age at onset of symptoms ≥30 years, from neuromuscular centers in France and the International Clinical Outcome Study for dysferlinopathy (COS). Patients with early-onset (EO) dysferlinopathy (<30 years) were randomly selected from the COS study as a control group, and the North Star Assessment for Dysferlinopathy (NSAD) and Activity Limitation (ACTIVLIM) scores were used to assess functionality. Muscle biopsies obtained from 11 LO and 11 EO patients were revisited.

Results: Forty-eight patients with LO dysferlinopathy were included (28 females). Median age at onset of symptoms was 37 (range 30-57) years and most patients showed a limb-girdle (n = 26) or distal (n = 10) phenotype. However, compared with EO dysferlinopathy patients (n = 48), LO patients more frequently showed atypical phenotypes (7 vs. 1; p = 0.014), including camptocormia, lower creatine kinase levels (2855 vs. 4394 U/L; p = 0.01), and higher NSAD (p = 0.008) and ACTIVLIM scores (p = 0.016). Loss of ambulation in LO patients tended to occur later (23 ± 4.4 years after disease onset vs. 16.3 ± 6.8 years; p = 0.064). Muscle biopsy of LO patients more frequently showed an atypical pattern (unspecific myopathic changes) as well as significantly less necrosis regeneration and inflammation. Although LO patients more frequently showed missense variants (39.8% vs. 23.9%; p = 0.021), no differences in dysferlin protein expression were found on Western blot.

Conclusions: Late-onset dysferlinopathy patients show a higher frequency of atypical presentations, are less severely affected, and show milder dystrophic changes in muscle biopsy.
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http://dx.doi.org/10.1111/ene.14821DOI Listing
June 2021

Miyoshi myopathy and limb girdle muscular dystrophy R2 are the same disease.

Neuromuscul Disord 2021 04 21;31(4):265-280. Epub 2021 Jan 21.

The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Central Parkway, Newcastle upon Tyne, United Kingdom. Electronic address:

This study aims to determine clinically relevant phenotypic differences between the two most common phenotypic classifications in dysferlinopathy, limb girdle muscular dystrophy R2 (LGMDR2) and Miyoshi myopathy (MMD1). LGMDR2 and MMD1 are reported to involve different muscles, with LGMDR2 showing predominant limb girdle weakness and MMD1 showing predominant distal lower limb weakness. We used heatmaps, regression analysis and principle component analysis of functional and Magnetic Resonance Imaging data to perform a cross-sectional review of the pattern of muscle involvement in 168 patients from the Jain Foundation's international Clinical Outcomes Study for Dysferlinopathy. We demonstrated that there is no clinically relevant difference in proximal vs distal involvement between diagnosis. There is a continuum of distal involvement at any given degree of proximal involvement and patients do not fall into discrete distally or proximally affected groups. There appeared to be geographical preference for a particular diagnosis, with MMD1 being more common in Japan and LGMDR2 in Europe and the USA. We conclude that the dysferlinopathies do not form two distinct phenotypic groups and therefore should not be split into separate cohorts of LGMDR2 and MM for the purposes of clinical management, enrolment in clinical trials or access to subsequent treatments.
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http://dx.doi.org/10.1016/j.nmd.2021.01.009DOI Listing
April 2021

Assessing Dysferlinopathy Patients Over Three Years With a New Motor Scale.

Ann Neurol 2021 05 26;89(5):967-978. Epub 2021 Feb 26.

Department of Neurology Children's National Health System, Washington, DC.

Objective: Dysferlinopathy is a muscular dystrophy with a highly variable clinical presentation and currently unpredictable progression. This variability and unpredictability presents difficulties for prognostication and clinical trial design. The Jain Clinical Outcomes Study of Dysferlinopathy aims to establish the validity of the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) scale and identify factors that influence the rate of disease progression using NSAD.

Methods: We collected a longitudinal series of functional assessments from 187 patients with dysferlinopathy over 3 years. Rasch analysis was used to develop the NSAD, a motor performance scale suitable for ambulant and nonambulant patients. Generalized estimating equations were used to evaluate the impact of patient factors on outcome trajectories.

Results: The NSAD detected significant change in clinical progression over 1 year. The steepest functional decline occurred during the first 10 years after symptom onset, with more rapid decline noted in patients who developed symptoms at a younger age (p = 0.04). The most rapidly deteriorating group over the study was patients 3 to 8 years post symptom onset at baseline.

Interpretation: The NSAD is the first validated limb girdle specific scale of motor performance, suitable for use in clinical practice and clinical trials. Longitudinal analysis showed it may be possible to identify patient factors associated with greater functional decline both across the disease course and in the short-term for clinical trial preparation. Through further work and validation in this cohort, we anticipate that a disease model incorporating functional performance will allow for more accurate prognosis for patients with dysferlinopathy. ANN NEUROL 2021;89:967-978.
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http://dx.doi.org/10.1002/ana.26044DOI Listing
May 2021

Impact of Coronavirus Disease 2019 in a French Cohort of Myasthenia Gravis.

Neurology 2021 04 10;96(16):e2109-e2120. Epub 2021 Feb 10.

From the Referral Center for Neuromuscular Diseases AOC (G.S., S.M., G.L.M., A.S., F.D., L.C., M.-H.V.) and ALS Center (S.M., G.L.M., A.S., L.C.), Nerve-Muscle Unit, University Hospitals of Bordeaux (Pellegrin Hospital), University of Bordeaux; Department of Intensive Care (D.F., D.A., B.C.), Raymond Poincare University Hospital, Garches; Referral Center for Neuromuscular Diseases and ALS (E.S.-C., S.A.) and Referral Center for Neuromuscular Diseases, Neuropediatric Unit (F.A.), Timone University Hospital, Aix-Marseille University, Marseille; Department of Neurology, Referral Center for Neuromuscular Diseases (C.T.), University Hospitals of Lille; ENMG Unit, Referral Center for Neuromuscular Diseases (F.B.), University Hospitals of Lyon (Neurologic Hospital Pierre Wertheimer); Referral Center for Neuromuscular Diseases (A.M.), University Hospitals of Nantes; Inserm, UMR1219 (T.S., A.F.-S.), Bordeaux Population Health Research Center, ISPED, University of Bordeaux; Neurodegenerative Diseases Institute, French Reference Centre for MSA (T.S., A.F.-S.), University Hospitals of Bordeaux; AFM-Téléthon (S.S.-K.), Evry; Department of Neurology (L.K.), General Hospital of Le Mans; Department of Neurology (J.-C.A.), University Hospital of Saint-Etienne; Clinical Neurophysiology and Epileptology Department (G.B.), University Hospital of Bicêtre, Le Kremlin-Bicêtre; Neurology Department (L.K., J.-B.C., A.N.-P.), Referral Center for Neuromuscular Diseases "Nord-Est-Ile de France," University Hospitals of Strasbourg; APHP (Pitié-Salpêtrière Hospital) (T.S.), Referral Center for Neuromuscular Diseases "Nord-Est-Ile de France," Sorbonne University, Paris; Referral Center for Neuromuscular Diseases, Department of Neurology (P.C.), University Hospitals of Toulouse (Purpan Hospital); and Referral Center for Neuromuscular Diseases, Department of Neurology (M.S.), University Hospital of Angers, France.

Objective: To describe the clinical characteristics and outcomes of coronavirus disease 2019 (COVID-19) among patients with myasthenia gravis (MG) and identify factors associated with COVID-19 severity in patients with MG.

Methods: The CO-MY-COVID registry was a multicenter, retrospective, observational cohort study conducted in neuromuscular referral centers and general hospitals of the FILNEMUS (Filière Neuromusculaire) network (between March 1, 2020, and June 8, 2020), including patients with MG with a confirmed or highly suspected diagnosis of COVID-19. COVID-19 was diagnosed based on a PCR test from a nasopharyngeal swab or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology, thoracic CT scan, or typical symptoms. The main outcome was COVID-19 severity based on location of treatment/management (home, hospitalized in a medical unit, or in an intensive care unit). We collected information on demographic variables, general history, and risk factors for severe COVID-19. Multivariate ordinal regression models were used to identify factors associated with severe COVID-19 outcomes.

Results: Among 3,558 patients with MG registered in the French database for rare disorders, 34 (0.96%) had COVID-19. The mean age at COVID-19 onset was 55.0 ± 19.9 years (mean MG duration: 8.5 ± 8.5 years). By the end of the study period, 28 patients recovered from COVID-19, 1 remained affected, and 5 died. Only high Myasthenia Gravis Foundation of America (MGFA) class (≥IV) before COVID-19 was associated with severe COVID-19 ( 0.004); factors that were not associated included sex, MG duration, and medium MGFA classes (≤IIIb). The type of MG treatment had no independent effect on COVID-19 severity.

Conclusions: This registry-based cohort study shows that COVID-19 had a limited effect on most patients, and immunosuppressive medications and corticosteroids used for MG management are not risk factors for poorer outcomes. However, the risk of severe COVID-19 is elevated in patients with high MGFA classes (odds ratio, 102.6 [4.4-2,371.9]). These results are important for establishing evidence-based guidelines for the management of patients with MG during the COVID-19 pandemic.
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http://dx.doi.org/10.1212/WNL.0000000000011669DOI Listing
April 2021

[Limb-Girdle Muscular Dystrophy type R9 linked to the FKRP gene: state of the art and therapeutic perspectives].

Med Sci (Paris) 2020 Dec 11;36 Hors série n° 2:28-33. Epub 2021 Jan 11.

Centre de Référence des maladies neuromusculaires Nord/Est/Île-de-France, APHP, Groupe Hospitalier Pitié-Salpêtrière, Sorbonne Université, Paris, France.

Mutations in the FKRP gene encoding the fukutin-related protein (FKRP) cause a wide spectrum of myopathies, ranging from severe forms of congenital muscular dystrophies associated with structural abnormalities of the central nervous system, to exertional myalgia or asymptomatic hyperCKemia, and to a form of limb girdle muscular dystrophy, LGMD-R9, (ex-LGMD-2I). LGMD-R9 is characterized by a proximal girdle deficit predominantly in the lower limbs to start with, with respiratory and cardiac damage that may affect the vital prognosis. Serum CK levels are markedly elevated and, on muscle biopsy, is detected a dystrophic formula associated with a reduction in the glycosylation of α-dystroglycan by immunostains and immunoblotting. Muscle MRI typically shows damage to proximal muscles (iliopsoas, adductors, gluteus maximus, quadriceps) with relative preservation of the muscles of the anterior compartment of the thighs (gracilis and sartorius). Genetic analysis, by specific sequencing of the FKRP gene or of a panel grouping together all the genes involved in the glycosylation of α-dystroglycan, or a larger panel of genes, generally confirms the diagnosis, the most frequent mutation being the missense p.(Leu276Ile). Currently, treatment of LGMD-R9 is symptomatic, requiring a multidisciplinary approach. A prospective study of the natural history of the disease is currently underway in Europe (GNT-015-FKRP). New therapeutic approaches are envisaged, such as gene therapy mediated by vectors derived from the adeno-associated virus (AAV). This is effective in animal models, allowing correction of defects in the glycosylation of alpha-dystroglycan and an increase in its binding capacity to the extracellular matrix. At the same time, preclinical studies have shown, in an animal model, the efficacy of ribitol, an alcohol pentose found in natural compounds, which has led to a phase I trial whose clinical development is underway.
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http://dx.doi.org/10.1051/medsci/2020239DOI Listing
December 2020

[Sarcoglycanopathies: state of the art and therapeutic perspectives].

Med Sci (Paris) 2020 Dec 11;36 Hors série n° 2:22-27. Epub 2021 Jan 11.

Centre de Référence des maladies neuromusculaires Nord/Est/Île-de-France, APHP, Groupe Hospitalier Pitié-Salpêtrière, Sorbonne Université, Paris, France.

Sarcoglycanopathies are the third most common cause of autosomal recessive limb girdle muscular dystrophies (LGMD). They are the result of a deficiency in one of the sarcoglycans a, b, g, or d. The usual clinical presentation is that of a symmetrical involvement of the muscles of the pelvic and scapular girdles as well as of the trunk, associated with more or less severe cardio-respiratory impairment and a marked increase of serum CK levels. The first symptoms appear during the first decade, the loss of ambulation occurring often during the second decade. Lesions observed on the muscle biopsy are dystrophic. This is associated with a decrease or an absence of immunostaining of the sarcoglycan corresponding to the mutated gene and, to a lesser degree, of the other three sarcoglycans. Many mutations have been reported in the four incriminated genes and some of them are prevalent in certain populations. To date, there is no curative treatment, which does not prevent the development of many clinical trials, especially in gene therapy.
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http://dx.doi.org/10.1051/medsci/2020243DOI Listing
December 2020

Intensive Teenage Activity Is Associated With Greater Muscle Hyperintensity on T1W Magnetic Resonance Imaging in Adults With Dysferlinopathy.

Front Neurol 2020 16;11:613446. Epub 2020 Dec 16.

The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.

Practice of sports during childhood or adolescence correlates with an earlier onset and more rapidly progressing phenotype in dysferlinopathies. To determine if this correlation relates to greater muscle pathology that persists into adulthood, we investigated the effect of exercise on the degree of muscle fatty replacement measured using muscle MRI. We reviewed pelvic, thigh and leg T1W MRI scans from 160 patients with genetically confirmed dysferlinopathy from the Jain Foundation International clinical outcomes study in dysferlinopathy. Two independent assessors used the Lamminen-Mercuri visual scale to score degree of fat replacement in each muscle. Exercise intensity for each individual was defined as no activity, minimal, moderate, or intensive activity by using metabolic equivalents and patient reported frequency of sports undertaken between the ages of 10 and 18. We used ANCOVA and linear modeling to compare the mean Lamminen-Mercuri score for the pelvis, thigh, and leg between exercise groups, controlling for age at assessment and symptom duration. Intensive exercisers showed greater fatty replacement in the muscles of the pelvis than moderate exercisers, but no significant differences of the thigh or leg. Within the pelvis, Psoas was the muscle most strongly associated with this exercise effect. In patients with a short symptom duration of <15 years there was a trend toward greater fatty replacement in the muscles of the thigh. These findings define key muscles involved in the exercise-phenotype effect that has previously been observed only clinically in dysferlinopathy and support recommendations that pre-symptomatic patients should avoid very intensive exercise.
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http://dx.doi.org/10.3389/fneur.2020.613446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7773023PMC
December 2020

Development of new outcome measures for adult SMA type III and IV: a multimodal longitudinal study.

J Neurol 2021 May 2;268(5):1792-1802. Epub 2021 Jan 2.

Laboratoire D'Imagerie Biomédicale, Sorbonne Université, CNRS, INSERM, Paris, France.

Objective: The aim of this study was the comprehensive characterisation of longitudinal clinical, electrophysiological and neuroimaging measures in type III and IV adult spinal muscular atrophy (SMA) with a view to propose objective monitoring markers for future clinical trials.

Methods: Fourteen type III or IV SMA patients underwent standardised assessments including muscle strength testing, functional evaluation (SMAFRS and MFM), MUNIX (abductor pollicis brevis, APB; abductor digiti minimi, ADM; deltoid; tibialis anterior, TA; trapezius) and quantitative cervical spinal cord MRI to appraise segmental grey and white matter atrophy. Patients underwent a follow-up assessment with the same protocol 24 months later. Longitudinal comparisons were conducted using the Wilcoxon-test for matched data. Responsiveness was estimated using standardized response means (SRM) and a composite score was generated based on the three most significant variables.

Results: Significant functional decline was observed based on SMAFRS (p = 0.019), pinch and knee flexion strength (p = 0.030 and 0.027), MUNIX and MUSIX value in the ADM (p = 0.0006 and 0.043) and in TA muscle (p = 0.025). No significant differences were observed based on cervical MRI measures. A significant reduction was detected in the composite score (p = 0.0005, SRM = -1.52), which was the most responsive variable and required a smaller number of patients than single variables in the estimation of sample size for clinical trials.

Conclusions: Quantitative strength testing, SMAFRS and MUNIX readily capture disease progression in adult SMA patients. Composite multimodal scores increase predictive value and may reduce sample size requirements in clinical trials.
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http://dx.doi.org/10.1007/s00415-020-10332-5DOI Listing
May 2021

Global versus individual muscle segmentation to assess quantitative MRI-based fat fraction changes in neuromuscular diseases.

Eur Radiol 2021 Jun 21;31(6):4264-4276. Epub 2020 Nov 21.

NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France.

Objectives: Magnetic resonance imaging (MRI) constitutes a powerful outcome measure in neuromuscular disorders, yet there is a broad diversity of approaches in data acquisition and analysis. Since each neuromuscular disease presents a specific pattern of muscle involvement, the recommended analysis is assumed to be the muscle-by-muscle approach. We, therefore, performed a comparative analysis of different segmentation approaches, including global muscle segmentation, to determine the best strategy for evaluating disease progression.

Methods: In 102 patients (21 immune-mediated necrotizing myopathy/IMNM, 21 inclusion body myositis/IBM, 10 GNE myopathy/GNEM, 19 Duchenne muscular dystrophy/DMD, 12 dysferlinopathy/DYSF, 7 limb-girdle muscular dystrophy/LGMD2I, 7 Pompe disease, 5 spinal muscular atrophy/SMA), two MRI scans were obtained at a 1-year interval in thighs and lower legs. Regions of interest (ROIs) were drawn in individual muscles, muscle groups, and the global muscle segment. Standardized response means (SRMs) were determined to assess sensitivity to change in fat fraction (ΔFat%) in individual muscles, muscle groups, weighted combinations of muscles and muscle groups, and in the global muscle segment.

Results: Global muscle segmentation gave high SRMs for ΔFat% in thigh and lower leg for IMNM, DYSF, LGMD2I, DMD, SMA, and Pompe disease, and only in lower leg for GNEM and thigh for IBM.

Conclusions: Global muscle segment Fat% showed to be sensitive to change in most investigated neuromuscular disorders. As compared to individual muscle drawing, it is a faster and an easier approach to assess disease progression. The use of individual muscle ROIs, however, is still of interest for exploring selective muscle involvement.

Key Points: • MRI-based evaluation of fatty replacement in muscles is used as an outcome measure in the assessment of 1-year disease progression in 8 different neuromuscular diseases. • Different segmentation approaches, including global muscle segmentation, were evaluated for determining 1-year fat fraction changes in lower limb skeletal muscles. • Global muscle segment fat fraction has shown to be sensitive to change in lower leg and thigh in most of the investigated neuromuscular diseases.
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http://dx.doi.org/10.1007/s00330-020-07487-0DOI Listing
June 2021

Pathogenic Variants in the Myosin Chaperone UNC-45B Cause Progressive Myopathy with Eccentric Cores.

Am J Hum Genet 2020 12 19;107(6):1078-1095. Epub 2020 Nov 19.

Department of Clinical Genome Analysis, Medical Genome Center, National Center of Neurology and Psychiatry, 187-8551 Tokyo, Japan.

The myosin-directed chaperone UNC-45B is essential for sarcomeric organization and muscle function from Caenorhabditis elegans to humans. The pathological impact of UNC-45B in muscle disease remained elusive. We report ten individuals with bi-allelic variants in UNC45B who exhibit childhood-onset progressive muscle weakness. We identified a common UNC45B variant that acts as a complex hypomorph splice variant. Purified UNC-45B mutants showed changes in folding and solubility. In situ localization studies further demonstrated reduced expression of mutant UNC-45B in muscle combined with abnormal localization away from the A-band towards the Z-disk of the sarcomere. The physiological relevance of these observations was investigated in C. elegans by transgenic expression of conserved UNC-45 missense variants, which showed impaired myosin binding for one and defective muscle function for three. Together, our results demonstrate that UNC-45B impairment manifests as a chaperonopathy with progressive muscle pathology, which discovers the previously unknown conserved role of UNC-45B in myofibrillar organization.
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http://dx.doi.org/10.1016/j.ajhg.2020.11.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7820787PMC
December 2020

The genetic landscape of axonal neuropathies in the middle-aged and elderly: Focus on .

Neurology 2020 12 3;95(24):e3163-e3179. Epub 2020 Nov 3.

From the Friedrich-Baur-Institute (J.S., B.S.-W., M.W.), Department of Neurology, LMU Munich, Germany; DNA Laboratory (P.L., P.S.), Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and University Hospital Motol, Czech Republic; Neuromuscular Unit (D.K., A.K.), Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland; Dr. John T. Macdonald Foundation Department of Human Genetics (L.A., A.R., S.Z.), John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, FL; Neurogenetics Group (J.B., T.D., P.D.J.), Center for Molecular Neurology, University of Antwerp; Institute Born-Bunge (J.B., T.D., P.D.J.), University of Antwerp; Neuromuscular Reference Centre (J.B., P.D.J.), Department of Neurology, Antwerp University Hospital, Belgium; Department of Clinical Chemistry and Laboratory Medicine (C.B.), Jena University Hospital; Centogene AG (C.B.), Rostock, Germany; Department of Medical Genetics (G.J.B., H.H.), Telemark Hospital Trust, Skien, Norway; Neurology Department (D.B., A.L., J. Weishaupt), Ulm University, Germany; Department of Neurology (J.D., D. Walk), University of Minnesota, Minneapolis; Department of Neurology (L.D.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia; Department of Sleep Medicine and Neuromuscular Diseases (B.D., A.S., P.Y.), University of Münster; Institute of Human Genetics (K.E., I.K.), Medical Faculty, RWTH Aachen University, Germany; Sydney Medical School (M.E., M.K., G.N.), Concord Hospital, Northcott Neuroscience Laboratory, ANZAC Research Institute, Concord, Australia; Department of Orthopaedics and Trauma Surgery (C.F., K.K., D. Weinmann, R.W., S.T., M.A.-G.), Medical University of Vienna, Austria; AP-HP (T.S.), Institut de Myologie, Centre de référence des maladies neuromusculaires Nord/Est/Ile-de-France, G-H Pitié-Salpêtrière, Paris, France; Department of Neurology (D.N.H.), University of Rochester, NY; Department of Clinical Neurosciences (R.H.), University of Cambridge School of Clinical Medicine, UK; Department of Neurology (S.I.), Konventhospital der Barmherzigen Brüder Linz; Karl Chiari Lab for Orthopaedic Biology (K.K., D. Weinmann, S.T.), Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Austria; Stanford Center for Undiagnosed Diseases (J.N.K.), Stanford, CA; Undiagnosed Diseases Network (UDN) (J.N.K., S.Z.); Centre for Medical Research (N.G.L., R.O., G.Ravenscroft), University of Western Australia, Nedlands; Harry Perkins Institute of Medical Research (N.G.L., R.O., G. Ravenscroft), Nedlands; Neurogenetic Unit (P.J.L.), Royal Perth Hospital, Perth, Australia; Department of Neurology (W.N.L., J. Wanschitz), Medical University of Innsbruck, Austria; Department of Neurosciences and Behavior (W.M.), Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; Department of Neurology (S.P.), Hannover Medical School, Germany; Department of Clinical and Experimental Medicine (G. Ricci), University of Pisa, Italy; Institute of Human Genetics (S.R.-S.), Medical University of Innsbruck, Austria; Department of Neurodegenerative Diseases Hertie-Institute for Clinical Brain Research and Center of Neurology (L.S., R.S., M.S.), University of Tübingen; German Center for Neurodegenerative Diseases (DZNE) (L.S., R.S., M.S.), Tübingen, Germany; AP-HP (B.F.), Laboratoire de génétique moléculaire, pharmacogénétique et hormonologie, Hôpital de Bicêtre; Le Kremlin-Bicêtre, France; Institute of Human Genetics (T.M.S.), Helmholtz Zentrum Munich-German Research Center for Environmental Health, Neuherberg; Institute for Human Genetics (T.M.S.), Technical University Munich; and Institut für Klinische Genetik (J. Wagner), Technische Universität Dresden, Medizinische Fakultät Carl Gustav Carus, Germany.

Objective: To test the hypothesis that monogenic neuropathies such as Charcot-Marie-Tooth disease (CMT) contribute to frequent but often unexplained neuropathies in the elderly, we performed genetic analysis of 230 patients with unexplained axonal neuropathies and disease onset ≥35 years.

Methods: We recruited patients, collected clinical data, and conducted whole-exome sequencing (WES; n = 126) and single-gene sequencing (n = 104). We further queried WES repositories for variants and measured blood levels of the -encoded protein neprilysin.

Results: In the WES cohort, the overall detection rate for assumed disease-causing variants in genes for CMT or other conditions associated with neuropathies was 18.3% (familial cases 26.4%, apparently sporadic cases 12.3%). was most frequently involved and accounted for 34.8% of genetically solved cases. The relevance of for late-onset neuropathies was further supported by detection of a comparable proportion of cases in an independent patient sample, preponderance of variants among patients compared to population frequencies, retrieval of additional late-onset neuropathy patients with variants from WES repositories, and low neprilysin levels in patients' blood samples. Transmission of variants was often consistent with an incompletely penetrant autosomal-dominant trait and less frequently with autosomal-recessive inheritance.

Conclusions: A detectable fraction of unexplained late-onset axonal neuropathies is genetically determined, by variants in either CMT genes or genes involved in other conditions that affect the peripheral nerves and can mimic a CMT phenotype. variants can act as completely penetrant recessive alleles but also confer dominantly inherited susceptibility to axonal neuropathies in an aging population.
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http://dx.doi.org/10.1212/WNL.0000000000011132DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7836667PMC
December 2020

Metformin rescues muscle function in BAG3 myofibrillar myopathy models.

Autophagy 2020 Oct 19:1-17. Epub 2020 Oct 19.

School of Biological Sciences, Monash University, Melbourne, Australia.

Dominant mutations in the co-chaperone BAG3 cause a severe form of myofibrillar myopathy, exhibiting progressive muscle weakness, muscle structural failure, and protein aggregation. To elucidate the mechanism of disease in, and identify therapies for, BAG3 myofibrillar myopathy, we generated two zebrafish models, one conditionally expressing BAG3 and one with a nonsense mutation in . While transgenic BAG3-expressing fish display protein aggregation, modeling the early phase of the disease, fish exhibit exercise dependent fiber disintegration, and reduced swimming activity, consistent with later stages of the disease. Detailed characterization of the fish, revealed an impairment in macroautophagic/autophagic activity, a defect we confirmed in patient samples. Taken together, our data highlights that while BAG3 expression is sufficient to promote protein aggregation, it is the loss of BAG3 due to its sequestration within aggregates, which results in impaired autophagic activity, and subsequent muscle weakness. We therefore screened autophagy-promoting compounds for their effectiveness at removing protein aggregates, identifying nine including metformin. Further evaluation demonstrated metformin is not only able to bring about the removal of protein aggregates in zebrafish and human myoblasts but is also able to rescue the fiber disintegration and swimming deficit observed in the fish. Therefore, repurposing metformin provides a promising therapy for BAG3 myopathy.ACTN: actinin, alpha; BAG3: BAG cochaperone 3; CRYAB: crystallin alpha B; DES: desmin; DMSO: dimethyl sulfoxide; DNAJB6: DnaJ heat shock protein family (Hsp40) member B6; dpf: days post fertilization; eGFP: enhanced green fluorescent protein; FDA: Food and Drug Administration; FHL1: four and a half LIM domains 1; FLNC: filamin C; hpf: hours post-fertilization; HSPB8: heat shock protein family B [small] member 8; LDB3/ZASP: LIM domain binding 3; MYOT: myotilin; TTN: titin; WT: wild-type.
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http://dx.doi.org/10.1080/15548627.2020.1833500DOI Listing
October 2020

Confounding clinical presentation and different disease progression in CMT4B1.

Neuromuscul Disord 2020 07 16;30(7):576-582. Epub 2020 May 16.

APHP, Centre de référence des maladies neuromusculaires, Institut de Myologie, Sorbonne Université, APHP, Hôpital Pitié-Salpêtrière; Paris, France. Electronic address:

We report seven Charcot-Marie-Tooth 4B1 (CMT4B1) patients from four families with distinctive features, presenting with severe distal weakness and cranial nerve involvement. Patient from family 1 presented with congenital varus foot deformity, progressive distal and proximal weakness leading to loss of ambulation at 14 years, bilateral facial palsy and prominent bulbar involvement. In three siblings from family 2, still ambulant in the second decade, neuropathy was associated with marked sweating and Arnold-Chiari syndrome. Patient from family 3, wheelchair-bound by 17 years, suffered from recurrent intestinal occlusion due to a mesenteric malformation. Patients from family 4, wheelchair-bound from age 6 years, were first diagnosed with type 1 Usher syndrome with congenital deafness and retinitis pigmentosa. CMT4B1 diagnosis was based upon suggestive clinical features and confirmed by the presence of recessive mutations in the MTMR2 gene. Our results expand the genetic and phenotypic spectrum of CMT4B1, which may include autonomic system involvement.
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http://dx.doi.org/10.1016/j.nmd.2020.05.003DOI Listing
July 2020

Ganglionopathies Associated with MERRF Syndrome: An Original Report.

J Neuromuscul Dis 2020 ;7(4):419-423

Department of Neurology, Neuromuscular Reference Center Nord/Est/Ile de France, Raymond-Poincaré Teaching Hospital, AP-HP, Garches, Paris Saclay University, France.

Neuropathies in Myoclonic Epilepsy with Ragged Red Fibers (MERRF) syndrome are frequent but ganglionopathies have never been reported. We retrospectively identified 24 patients with MERRF mutations in the neuromuscular center Nord/Est/Ile de France (Pitié-Salpêtrière, Paris, France). Seventeen nerve conduction studies (NCS) were available. Five patients had MERRF syndrome and ganglionopathy, a pure sensory neuropathy. All of them displayed ataxia and mild clinical sensory abnormalities. Ganglionopathies have been reported in mitochondrial diseases but never in MERRF syndrome. We suggest that patients presenting with ganglionopathy, especially if associated with myopathy, lipomatosis or epilepsy, should be screened for MERRF mutations.
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http://dx.doi.org/10.3233/JND-200513DOI Listing
January 2020

GGPS1 Mutations Cause Muscular Dystrophy/Hearing Loss/Ovarian Insufficiency Syndrome.

Ann Neurol 2020 08 18;88(2):332-347. Epub 2020 Jun 18.

Botnar Research Centre, National Institute for Health Research Biomedical Research Centre Oxford, University of Oxford, Oxford, United Kingdom.

Objective: A hitherto undescribed phenotype of early onset muscular dystrophy associated with sensorineural hearing loss and primary ovarian insufficiency was initially identified in 2 siblings and in subsequent patients with a similar constellation of findings. The goal of this study was to understand the genetic and molecular etiology of this condition.

Methods: We applied whole exome sequencing (WES) superimposed on shared haplotype regions to identify the initial biallelic variants in GGPS1 followed by GGPS1 Sanger sequencing or WES in 5 additional families with the same phenotype. Molecular modeling, biochemical analysis, laser membrane injury assay, and the generation of a Y259C knock-in mouse were done.

Results: A total of 11 patients in 6 families carrying 5 different biallelic pathogenic variants in specific domains of GGPS1 were identified. GGPS1 encodes geranylgeranyl diphosphate synthase in the mevalonate/isoprenoid pathway, which catalyzes the synthesis of geranylgeranyl pyrophosphate, the lipid precursor of geranylgeranylated proteins including small guanosine triphosphatases. In addition to proximal weakness, all but one patient presented with congenital sensorineural hearing loss, and all postpubertal females had primary ovarian insufficiency. Muscle histology was dystrophic, with ultrastructural evidence of autophagic material and large mitochondria in the most severe cases. There was delayed membrane healing after laser injury in patient-derived myogenic cells, and a knock-in mouse of one of the mutations (Y259C) resulted in prenatal lethality.

Interpretation: The identification of specific GGPS1 mutations defines the cause of a unique form of muscular dystrophy with hearing loss and ovarian insufficiency and points to a novel pathway for this clinical constellation. ANN NEUROL 2020;88:332-347.
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http://dx.doi.org/10.1002/ana.25772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496979PMC
August 2020

Genomic sequencing highlights the diverse molecular causes of Perrault syndrome: a peroxisomal disorder (PEX6), metabolic disorders (CLPP, GGPS1), and mtDNA maintenance/translation disorders (LARS2, TFAM).

Hum Genet 2020 Oct 12;139(10):1325-1343. Epub 2020 May 12.

Reproductive Development Group, Murdoch Children's Research Institute, Melbourne, Australia.

Perrault syndrome is a rare heterogeneous condition characterised by sensorineural hearing loss and premature ovarian insufficiency. Additional neuromuscular pathology is observed in some patients. There are six genes in which variants are known to cause Perrault syndrome; however, these explain only a minority of cases. We investigated the genetic cause of Perrault syndrome in seven affected individuals from five different families, successfully identifying the cause in four patients. This included previously reported and novel causative variants in known Perrault syndrome genes, CLPP and LARS2, involved in mitochondrial proteolysis and mitochondrial translation, respectively. For the first time, we show that pathogenic variants in PEX6 can present clinically as Perrault syndrome. PEX6 encodes a peroxisomal biogenesis factor, and we demonstrate evidence of peroxisomal dysfunction in patient serum. This study consolidates the clinical overlap between Perrault syndrome and peroxisomal disorders, and highlights the need to consider ovarian function in individuals with atypical/mild peroxisomal disorders. The remaining patients had variants in candidate genes such as TFAM, involved in mtDNA transcription, replication, and packaging, and GGPS1 involved in mevalonate/coenzyme Q biosynthesis and whose enzymatic product is required for mouse folliculogenesis. This genomic study highlights the diverse molecular landscape of this poorly understood syndrome.
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http://dx.doi.org/10.1007/s00439-020-02176-wDOI Listing
October 2020

Biallelic mutations in SORD cause a common and potentially treatable hereditary neuropathy with implications for diabetes.

Nat Genet 2020 05 4;52(5):473-481. Epub 2020 May 4.

Istituiti Clinici Scientifici Maugeri IRCCS, Environmental Research Center, Pavia, Italy.

Here we report biallelic mutations in the sorbitol dehydrogenase gene (SORD) as the most frequent recessive form of hereditary neuropathy. We identified 45 individuals from 38 families across multiple ancestries carrying the nonsense c.757delG (p.Ala253GlnfsTer27) variant in SORD, in either a homozygous or compound heterozygous state. SORD is an enzyme that converts sorbitol into fructose in the two-step polyol pathway previously implicated in diabetic neuropathy. In patient-derived fibroblasts, we found a complete loss of SORD protein and increased intracellular sorbitol. Furthermore, the serum fasting sorbitol levels in patients were dramatically increased. In Drosophila, loss of SORD orthologs caused synaptic degeneration and progressive motor impairment. Reducing the polyol influx by treatment with aldose reductase inhibitors normalized intracellular sorbitol levels in patient-derived fibroblasts and in Drosophila, and also dramatically ameliorated motor and eye phenotypes. Together, these findings establish a novel and potentially treatable cause of neuropathy and may contribute to a better understanding of the pathophysiology of diabetes.
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http://dx.doi.org/10.1038/s41588-020-0615-4DOI Listing
May 2020

A new congenital multicore titinopathy associated with fast myosin heavy chain deficiency.

Ann Clin Transl Neurol 2020 05 19;7(5):846-854. Epub 2020 Apr 19.

Laboratoire de Génétique Moléculaire, CHU de Montpellier, Montpellier, France.

Congenital titinopathies are myopathies with variable phenotypes and inheritance modes. Here, we fully characterized, using an integrated approach (deep phenotyping, muscle morphology, mRNA and protein evaluation in muscle biopsies), two siblings with congenital multicore myopathy harboring three TTN variants predicted to affect titin stability and titin-myosin interactions. Muscle biopsies showed multicores, type 1 fiber uniformity and sarcomeric structure disruption with some thick filament loss. Immunohistochemistry and Western blotting revealed a marked reduction of fast myosin heavy chain isoforms. This is the first observation of a titinopathy suggesting that titin defect leads to secondary loss of fast myosin heavy chain isoforms.
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http://dx.doi.org/10.1002/acn3.51031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7261750PMC
May 2020