Search

The identification of genes implicated in myopathies is essential for diagnosis and for revealing novel therapeutic targets. Here we characterize a novel subclass of congenital myopathy at the morphological, molecular, and functional level. Through exome sequencing, we identified de novo ACTN2 mutations, a missense and a deletion, in two unrelated patients presenting with progressive early-onset muscle weakness and respiratory involvement. Morphological and ultrastructural analyses of muscle biopsies revealed a distinctive pattern with the presence of muscle fibers containing small structured cores and jagged Z-lines. Deeper analysis of the missense mutation revealed mutant alpha-actinin-2 properly localized to the Z-line in differentiating myotubes and its level was not altered in muscle biopsy. Modelling of the disease in zebrafish and mice by exogenous expression of mutated alpha-actinin-2 recapitulated the abnormal muscle function and structure seen in the patients. Motor deficits were noted in zebrafish, and muscle force was impaired in isolated muscles from AAV-transduced mice. In both models, sarcomeric disorganization was evident, while expression of wild-type alpha-actinin-2 did not result in muscle anomalies. The murine muscles injected with mutant ACTN2 displayed cores and Z-line defects. Dominant ACTN2 mutations were previously associated with cardiomyopathies, and our data demonstrate that specific mutations in the well-known Z-line regulator alpha-actinin-2 can cause a skeletal muscle disorder.

ObjectiveTo clarify the prevalence, long-term natural history, and severity determinants of SEPN1-related myopathy (SEPN1-RM), we analyzed a large international case series.MethodsRetrospective clinical, histologic, and genetic analysis of 132 pediatric and adult patients (2–58 years) followed up for several decades.ResultsThe clinical phenotype was marked by severe axial muscle weakness, spinal rigidity, and scoliosis (86.1%, from 8.9 ± 4 years), with relatively preserved limb strength and previously unreported ophthalmoparesis in severe cases. All patients developed respiratory failure (from 10.1±6 years), 81.7% requiring ventilation while ambulant. Histopathologically, 79 muscle biopsies showed large variability, partly determined by site of biopsy and age. Multi-minicores were the most common lesion (59.5%), often associated with mild dystrophic features and occasionally with eosinophilic inclusions. Identification of 65 SEPN1 mutations, including 32 novel ones and the first pathogenic copy number variation, unveiled exon 1 as the main mutational hotspot and revealed the first genotype–phenotype correlations, bi-allelic null mutations being significantly associated with disease severity (p = 0.017). SEPN1-RM was more severe and progressive than previously thought, leading to loss of ambulation in 10% of cases, systematic functional decline from the end of the third decade, and reduced lifespan even in mild cases. The main prognosis determinants were scoliosis/respiratory management, SEPN1 mutations, and body mass abnormalities, which correlated with disease severity. We propose a set of severity criteria, provide quantitative data for outcome identification, and establish a need for age stratification.ConclusionOur results inform clinical practice, improving diagnosis and management, and represent a major breakthrough for clinical trial readiness in this not so rare disease.

OBJECTIVE: To clarify the prevalence, long-term natural history, and severity determinants of SEPN1-related myopathy (SEPN1-RM), we analyzed a large international case series. METHODS: Retrospective clinical, histologic, and genetic analysis of 132 pediatric and adult patients (2–58 years) followed up for several decades. RESULTS: The clinical phenotype was marked by severe axial muscle weakness, spinal rigidity, and scoliosis (86.1%, from 8.9 ± 4 years), with relatively preserved limb strength and previously unreported ophthalmoparesis in severe cases. All patients developed respiratory failure (from 10.1±6 years), 81.7% requiring ventilation while ambulant. Histopathologically, 79 muscle biopsies showed large variability, partly determined by site of biopsy and age. Multi-minicores were the most common lesion (59.5%), often associated with mild dystrophic features and occasionally with eosinophilic inclusions. Identification of 65 SEPN1 mutations, including 32 novel ones and the first pathogenic copy number variation, unveiled exon 1 as the main mutational hotspot and revealed the first genotype–phenotype correlations, bi-allelic null mutations being significantly associated with disease severity (p = 0.017). SEPN1-RM was more severe and progressive than previously thought, leading to loss of ambulation in 10% of cases, systematic functional decline from the end of the third decade, and reduced lifespan even in mild cases. The main prognosis determinants were scoliosis/respiratory management, SEPN1 mutations, and body mass abnormalities, which correlated with disease severity. We propose a set of severity criteria, provide quantitative data for outcome identification, and establish a need for age stratification. CONCLUSION: Our results inform clinical practice, improving diagnosis and management, and represent a major breakthrough for clinical trial readiness in this not so rare disease.

International audience; Mutations in GFPT1 (glutamine-fructose-6-phosphate transaminase 1), a gene encoding an enzyme involved in glycosylation of ubiquitous proteins, cause a limb-girdle congenital myasthenic syndrome (LG-CMS) with tubular aggregates (TAs) characterized predominantly by affection of the proximal skeletal muscles and presence of highly organized and remodeled sarcoplasmic tubules in patients’ muscle biopsies. We report here the first long-term clinical follow-up of 11 French individuals suffering from LG-CMS with TAs due to GFPT1 mutations, of which nine are new. Our retrospective clinical evaluation stresses an evolution toward a myopathic weakness that occurs concomitantly to ineffectiveness of usual CMS treatments. Analysis of neuromuscular biopsies from three unrelated individuals demonstrates that the maintenance of neuromuscular junctions (NMJs) is dramatically impaired with loss of post-synaptic junctional folds and evidence of denervation–reinnervation processes affecting the three main NMJ components. Moreover, molecular analyses of the human muscle biopsies confirm glycosylation defects of proteins with reduced O-glycosylation and show reduced sialylation of transmembrane proteins in extra-junctional area. Altogether, these results pave the way for understanding the etiology of this rare neuromuscular disorder that may be considered as a “tubular aggregates myopathy with synaptopathy”.

Congenital myopathies are phenotypically and genetically heterogeneous. We describe homozygous truncating mutations in MYPN in 2 unrelated families with a slowly progressive congenital cap myopathy. MYPN encodes the Z-line protein myopalladin implicated in sarcomere integrity. Functional experiments demonstrate that the mutations lead to mRNA defects and to a strong reduction in full-length protein expression. Myopalladin signals accumulate in the caps together with alpha-actinin. Dominant MYPN mutations were previously reported in cardiomyopathies. Our data uncover that mutations in MYPN cause either a cardiac or a congenital skeletal muscle disorder through different modes of inheritance. Ann Neurol 2017;81:467-473.

Introduction Mutations in the EXOSC3 gene are responsible for type 1 pontocerebellar hypoplasia, an autosomal recessive congenital disorder characterized by cerebellar atrophy, developmental delay, and anterior horn motor neuron degeneration. Muscle biopsies of these patients often show characteristics resembling classic spinal muscle atrophy, but to date, no distinct features have been identified. Methods Clinical data and muscle biopsy findings of 3 unrelated patients with EXOSC3 mutations are described. Results All patients presented as a severe congenital cognitive and neuromuscular phenotype with short survival, harboring the same point mutation (c.92G>C; p.Gly31Ala). Muscle biopsies consistently showed variable degrees of sarcomeric disorganization with myofibrillar remnants, Z-line thickening, and small nemaline bodies. Conclusions In this uniform genetic cohort of patients with EXOSC3 mutations, sarcomeric disruption and rod structures were prominent features of muscle biopsies. In the context of neonatal hypotonia, ultrastructural studies might provide early clues for the diagnosis of EXOSC3-related pontocerebellar hypoplasia. Muscle Nerve 59:137-141, 2019.

L’analyse de l’innervation motrice terminale (IMT) a marque un premier virage majeur dans l’analyse des biopsies musculaires, jusque la examinees sur coupes en paraffine et colorations histologiques classiques. Ce fut des 1952, essentiellement grâce aux travaux de Christian Coers, bientot suivi par A.L. Woolf [] utilisant des colorations vitales au Bleu de Methylene. Ces travaux, entrepris sous l’inspiration de J.G. Greenfield, avaient pour but de mieux differencier les atteintes neuropathiques des atrophies par non-utilisation, ou par cachexie, et des atteintes myopathiques. Ces travaux ont precede de plusieurs annees l’application aux biopsies humaines des techniques cytochimiques et cytoenzymologiques ainsi que les premieres etudes en microscopie electronique.

Protein aggregate myopathies (PAM) represent a group of familial or sporadic neuromuscular conditions with marked clinical and genetic heterogeneity that occur in children and adults. Familial PAM includes myofibrillar myopathies defined by the presence of desmin-positive protein aggregates and degenerative intermyofibrillar network changes. PAM is often caused by dysfunctional genes, such as DES, PLEC 1, CRYAB, FLNC, MYOT, ZASP, BAG3, FHL1, and DNAJB6.To retrospectively analyze genetic mutations and demographic, clinical, and morphological aspects of PAM in a French population.Forty-eight PAM patients (29 men, 19 women) were divided into two groups, those with genetically (GIM) and nongenetically identified (NGIM) mutations associated with myofibrillar myopathy.Age of myopathy onset ranged from 13 to 68 years. GIM group mutations (81.25%) included DES (14), ZASP (8), FLNC (4), MYOT (4), BAG3 (1), CRYAB (2), and DNAJB6 (6). The MYOT subgroup displayed a significantly older onset age (p = 0.029). Autosomal dominant inheritance was found in 74.3% of GIM and 44.4% of NGIM subjects. Overall, 22.9% had Maghrebian heritage, 72.9% Caucasian, and 4.2% Asian. The most common clinical sign was distal muscle weakness (66%) followed by simultaneous distal and proximal weakness in 49%. Eleven patients had contractures, one had a rigid spine, and five had respiratory dysfunction. GIM subjects had greater cardiac involvement (51.7%) versus the NGIM group (33.3%). The average serum creatine kinase level was 393 U/L in GIM and 382 U/L in NGIM subjects. Morphological analysis showed significant differences among GIM subgroups, including the number of vacuoles and regenerated fibers (ZASP), group atrophy (ZASP), and rubbed out fibers (MYOT). Ultrastructural findings showed significant differences in intranuclear rods, Z-disc thickness, and intranuclear inclusions between gene mutation subgroups. Paracrystalline inclusions were present in three patients (DNAJB6). The most frequent mutation in was in DES, followed by ZASP.GIM and NGIM PAM subjects showed similar results, suggesting that any unknown genes, which cause this disease have characteristics similar to those already described. Considering the complexity of clinical, morphological, and genetic data related to PAM, particularly myofibrillar myopathies, physicians should be careful when diagnosing patients with sporadic PAM.

International audience

Introduction: Cylindrical spirals are characteristic muscular inclusions consisting of spiraling double-laminated membranes. They are found in heterogeneous clinical conditions. Methods: We obtained muscle biopsies from 2 young sisters with severe congenital hypotonia, muscle weakness, and epileptic encephalopathy, and identified cylindrical spirals. Results: We found an association between congenital encephalomyopathy and cylindrical spirals. Conclusions: In this morphological and ultrastructural study, we speculate on the origin of these peculiar structures. Muscle Nerve 52: 895–899, 2015

The limb girdle and congenital muscular dystrophies (LGMD and CMD) are characterized by skeletal muscle weakness and dystrophic muscle changes. The onset of symptoms in CMD is within the first few months of life, whereas in LGMD they can occur in late childhood, adolescence or adult life. We have recently demonstrated that the fukutin-related protein gene (FKRP) is mutated in a severe form of CMD (MDC1C), characterized by the inability to walk, leg muscle hypertrophy and a secondary deficiency of laminin alpha2 and alpha-dystroglycan. Both MDC1C and LGMD2I map to an identical region on chromosome 19q13.3. To investigate whether these are allelic disorders, we undertook mutation analysis of FKRP in 25 potential LGMD2I families, including some with a severe and early onset phenotype. Mutations were identified in individuals from 17 families. A variable reduction of alpha-dystroglycan expression was observed in the skeletal muscle biopsy of all individuals studied. In addition, several cases showed a deficiency of laminin alpha2 either by immunocytochemistry or western blotting. Unexpectedly, affected individuals from 15 families had an identical C826A (Leu276Ileu) mutation, including five that were homozygous for this change. Linkage analysis identified at least two possible haplotypes in linkage disequilibrium with this mutation. Patients with the C826A change had the clinically less severe LGMD2I phenotype, suggesting that this is a less disruptive FKRP mutation than those found in MDC1C. The spectrum of LGMD2I phenotypes ranged from infants with an early presentation and a Duchenne-like disease course including cardiomyopathy, to milder phenotypes compatible with a favourable long-term outcome.

Contains fulltext : 182328.pdf (Publisher’s version ) (Closed access) X-linked myotubular myopathy (XLMTM), a severe congenital myopathy, is caused by mutations in the MTM1 gene located on the X chromosome. A majority of affected males die in the early postnatal period, whereas female carriers are believed to be usually asymptomatic. Nevertheless, several affected females have been reported. To assess the phenotypic and pathological spectra of carrier females and to delineate diagnostic clues, we characterized 17 new unrelated affected females and performed a detailed comparison with previously reported cases at the clinical, muscle imaging, histological, ultrastructural and molecular levels. Taken together, the analysis of this large cohort of 43 cases highlights a wide spectrum of clinical severity ranging from severe neonatal and generalized weakness, similar to XLMTM male, to milder adult forms. Several females show a decline in respiratory function. Asymmetric weakness is a noteworthy frequent specific feature potentially correlated to an increased prevalence of highly skewed X inactivation. Asymmetry of growth was also noted. Other diagnostic clues include facial weakness, ptosis and ophthalmoplegia, skeletal and joint abnormalities, and histopathological signs that are hallmarks of centronuclear myopathy such as centralized nuclei and necklace fibers. The histopathological findings also demonstrate a general disorganization of muscle structure in addition to these specific hallmarks. Thus, MTM1 mutations in carrier females define a specific myopathy, which may be independent of the presence of an XLMTM male in the family. As several of the reported affected females carry large heterozygous MTM1 deletions not detectable by Sanger sequencing, and as milder phenotypes present as adult-onset limb-girdle myopathy, the prevalence of this myopathy is likely to be greatly underestimated. This report should aid diagnosis and thus the clinical management and genetic counseling of MTM1 carrier females. Furthermore, the clinical and pathological history of this cohort may be useful for therapeutic projects in males with XLMTM, as it illustrates the spectrum of possible evolution of the disease in patients surviving long term.

Congenital myopathies are phenotypically and genetically heterogeneous. We describe homozygous truncating mutations in MYPN in 2 unrelated families with a slowly progressive congenital cap myopathy. MYPN encodes the Z-line protein myopalladin implicated in sarcomere integrity. Functional experiments demonstrate that the mutations lead to mRNA defects and to a strong reduction in full-length protein expression. Myopalladin signals accumulate in the caps together with alpha-actinin. Dominant MYPN mutations were previously reported in cardiomyopathies. Our data uncover that mutations in MYPN cause either a cardiac or a congenital skeletal muscle disorder through different modes of inheritance. Ann Neurol 2017;81:467-473.

We report on a 5-year-old girl who presented with an association of symptoms reminiscent of an Ullrich-like congenital muscular dystrophy including congenital hypotonia, proximal joint contractures, hyperlaxity of distal joints, normal cognitive development, and kyphoscoliosis. There was an excess of neuromuscular spindles on the skeletal muscle biopsy. This very peculiar feature on muscle biopsy has been reported only in patients with mutations in the HRAS gene. Sequence analysis of the subject's HRAS gene from blood leukocytes and skeletal muscle revealed a previously described heterozygous missense mutation (c.187G>A, p. Glu63Lys). The present report thus extends the differential diagnosis of congenital muscular dystrophy with major "retractile" phenotypes and adds congenital muscular dystrophy to the clinical spectrum of HRAS-related disorders.

Congenital myasthenic syndromes CMS) form a heterogeneous group of genetic diseases characterized by abnormal neuromuscular transmission. The associated muscular weakness is exacerbated by exertion and usually starts during infancy/childhood In 2002 a national Congenital Myasthenic Syndromes Network was created in France, composed of neurologists, neuropediatricians, pathologists, molecular geneticists and neurobiologists. The network has now identified nearly 300 cases of CMS, as well as three new culprit genes. Based on our personal experience and data from the most recent studies, we describe the 18 principal culprit genes so far identified, along with diagnostic pitfalls, the disease course, prognosis and treatment. The underlying genetic defect remains to be identified in nearly half of CMS patients.

Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders caused by genetic defects affecting neuromuscular transmission and leading to muscle weakness accentuated by exertion. Three different aspects have been investigated by members of the national French CMS Network: the difficulties in making a proper diagnosis; the course and long-term prognosis; and the response to therapy, especially for CMS that do not respond to cholinesterase inhibitors. CMS diagnosis is late in most cases because of confusion with other entities such as: congenital myopathies, due to the frequent presentation in patients of myopathies such as permanent muscle weakness, atrophy and scoliosis, and the abnormalities of internal structure, diameter and distribution of fibers (type I predominance, type II atrophy) seen on biopsy; seronegative autoimmune myasthenia gravis, when CMS is of late onset; and metabolic myopathy, with the presence of lipidosis in muscle. The long-term prognosis of CMS was studied in a series of 79 patients recruited with the following gene mutations: CHRNA; CHRNE; DOK7; COLQ; RAPSN; AGRN; and MUSK. Disease-course patterns (progressive worsening, exacerbation, stability, improvement) could be variable throughout life in a given patient. DOK7 patients had the most severe disease course with progressive worsening: of the eight wheelchair-bound and ventilated patients, six had mutations of this gene. Pregnancy was a frequent cause of exacerbation. Anticholinesterase agents are the first-line therapy for CMS patients, except for cases of slow-channel CMS, COLQ and DOK7. In our experience, 3,4-DAP was a useful complement for several patients harboring CMS with AChR loss or RAPSN gene mutations. Ephedrine was given to 18 patients (eight DOK7, five COLQ, four AGRN and one RAPSN). Tolerability was good. Therapeutic responses were encouraging even in the most severely affected patients, particularly with DOK7 and COLQ. Salbutamol was a good alternative in one patient who was allergic to ephedrine.

Oculopharyngeal muscular dystrophy (OPMD) is mainly characterized by ptosis and dysphagia. The genetic cause is a short expansion of a (GCN)10 repeat encoding for polyalanine in the poly(A) binding protein nuclear 1 (PABPN1) gene to (GCN)12–17 repeats. The (GCN)11/Ala11 allele has so far been described to be either a polymorphism or a recessive allele with no effect on the phenotype in the heterozygous state. Here we report the clinical and histopathological phenotype of a patient carrying a single (GCN)11/Ala11 heterozygous allele and presenting an atypical form of OPMD with dysphagia and late and mild oculomotor symptoms. Intranuclear inclusions were observed in his muscle biopsy. This suggests a dominant mode of expression of the (GCN)11/Ala11 allele associated with a partial penetrance of OPMD.

Muscle contraction upon nerve stimulation relies on excitation-contraction coupling (ECC) to promote the rapid and generalized release of calcium within myofibers. In skeletal muscle, ECC is performed by the direct coupling of a voltage-gated L-type Ca2+ channel (dihydropyridine receptor; DHPR) located on the T-tubule with a Ca2+ release channel (ryanodine receptor; RYR1) on the sarcoplasmic reticulum (SR) component of the triad. Here, we characterize a novel class of congenital myopathy at the morphological, molecular, and functional levels. We describe a cohort of 11 patients from 7 families presenting with perinatal hypotonia, severe axial and generalized weakness. Ophthalmoplegia is present in four patients. The analysis of muscle biopsies demonstrated a characteristic intermyofibrillar network due to SR dilatation, internal nuclei, and areas of myofibrillar disorganization in some samples. Exome sequencing revealed ten recessive or dominant mutations in CACNA1S (Cav1.1), the pore-forming subunit of DHPR in skeletal muscle. Both recessive and dominant mutations correlated with a consistent phenotype, a decrease in protein level, and with a major impairment of Ca2+ release induced by depolarization in cultured myotubes. While dominant CACNA1S mutations were previously linked to malignant hyperthermia susceptibility or hypokalemic periodic paralysis, our findings strengthen the importance of DHPR for perinatal muscle function in human. These data also highlight CACNA1S and ECC as therapeutic targets for the development of treatments that may be facilitated by the previous knowledge accumulated on DHPR.

Myofibrillar myopathies (MFM) are mostly adult-onset diseases characterized by progressive morphological alterations of the muscle fibers beginning in the Z-disk and the presence of protein aggregates in the sarcoplasm. They are mostly caused by mutations in different genes that encode Z-disk proteins, including DES, CRYAB, LDB3, MYOT, FLNC and BAG3. A large family of French origin, presenting an autosomal dominant pattern, characterized by cardiac arrhythmia associated to late-onset muscle weakness, was evaluated to clarify clinical, morphological and genetic diagnosis. Muscle weakness began during adult life (over 30 years of age), and had a proximal distribution. Histology showed clear signs of a myofibrillar myopathy, but with unusual, large inclusions. Subsequently, genetic testing was performed in MFM genes available for screening at the time of clinical/histological diagnosis, and desmin (DES), αB-crystallin (CRYAB), myotilin (MYOT) and ZASP (LDB3), were excluded. LMNA gene screening found the p.R296C variant which did not co-segregate with the disease. Genome wide scan revealed linkage to 7q.32, containing the FLNC gene. FLNC direct sequencing revealed a heterozygous c.3646T>A p.Tyr1216Asn change, co-segregating with the disease, in a highly conserved amino acid of the protein. Normal filamin C levels were detected by Western-blot analysis in patient muscle biopsies and expression of the mutant protein in NIH3T3 showed filamin C aggregates. This is an original FLNC mutation in a MFM family with an atypical clinical and histopathological presentation, given the presence of significantly focal lesions and prominent sarcoplasmic masses in muscle biopsies and the constant heart involvement preceding significantly the onset of the myopathy. Though a rare etiology, FLNC gene should not be excluded in early-onset arrhythmia, even in the absence of myopathy, which occurs later in the disease course.

Objective Limb-girdle muscular dystophy 2A (LGMD2A, OMIM) is a slowly progressive myopathy caused by the deficiency in calpain 3, a calcium-dependent cysteine protease of the skeletal muscle. Methods In this study, we carried out an observational study of clinical manifestations and disease progression in genetically confirmed LGMD2A patients for up to 4 years. A total of 85 patients, aged 14–65 years, were recruited in three centers located in metropolitan France, the Basque country, and the Reunion Island. They were followed up every 6 months for 2 years and a subgroup was assessed annually thereafter for two more years. Data collected for all patients included clinical history, blood parameters, muscle strength assessed by manual muscle testing (MMT) and quantitative muscle testing, functional scores, and pulmonary and cardiac functions. In addition, CT scans of the lower limbs were performed in a subgroup of patients. Results Our study confirms the clinical description of a slowly progressive disorder with onset in the first or second decade of life with some degree of variability related to gender and mutation type. The null mutations lead to a more severe phenotype while compound heterozygote patients are the least affected. Muscle weakness is remarkably symmetrical and predominant in the axial muscles of the trunk and proximal muscles of the lower limb. There was a high correlation between the weakness at individual muscle level as assessed by MMT and the loss of density in CT scan analysis. Interpretation All the generated data will help to determine the endpoints for further clinical studies.

Deux jeunes gens venus des deux bouts du monde se rencontrer a Paris, avec le meme desir de faire leur medecine, la meme ambition de reussir, puis la meme vocation pour la Neurologie. Deux jeunes gens qui vont travailler ensemble, s’aimer, et ne plus jamais se quitter. Dix ans separent les dates de naissance de Jules et d’Augusta, dix ans separeront leurs dates de disparition. Il y a quelque chose de presque trop beau, de trop clair dans cette breve synthese de leur biographie : ce n’est pourtant que la realite. Jules Dejerine est ne dans une famille modeste de paysans savoyards, venus a Geneve pour que leur enfant ait la meilleure education possible ; il laissera au College Calvin le souvenir d’un enfant tres robuste et un peu batailleur, mais il y obtiendra ses Certificats de maturite et ses Baccalaureats, il demandera alors a ses parents s’ils accepteraient de le laisser faire sa medecine a Paris. Augusta Klumpke est nee, elle, dans une famille tres aisee de San Francisco, ou son pere a fait fortune au moment de la ruee vers l’Ouest. Elle y a recu une tres bonne education, et laisse entendre tres jeune qu’elle aimerait devenir medecin. Elle decouvre l’Europe a sept ans, sa sœur ainee, Anna, ayant contracte une osteomyelite dont les seuls specialistes sont alors en France et en Allemagne. Apres un retour de quelques annees aux Etats-Unis et le divorce de ses parents, elle reviendra en Europe a douze ans avec sa mere, ses quatre sœurs et son frere, en Allemagne d’abord, puis en Suisse. Elle reussit brillamment dans ses etudes secondaires a Lausanne ; la famille Klumpke s’installera finalement a Paris pour que chaque enfant trouve le meilleur endroit pour sa formation ou ses etudes superieures. Le hasard les fera se rencontrer rue Jacob, a l’hopital de la Vieille Charite, dans le service du professeur Hardy. Lui est deja chef de clinique et travaille assidument au laboratoire ; elle y arrive comme simple stagiaire, tres vite appreciee pour son energie et pour ses talents linguistiques. Ils vont travailler ensemble. Jules initiera Augusta a l’usage du microscope et aux techniques histologiques, sous la direction de leur maitre commun et venere, Alfred Vulpian. Bientot va s’ebaucher entre eux une vraie passion amoureuse, mais Jules ne peut se declarer, sa situation « n’etant pas faite ». Ils vont tous les deux rencontrer de gros obstacles dans leur carriere. Elle, parce que les femmes ne sont admises qu’a contre-cœur a la faculte de medecine, et qu’il leur faudra se battre tres dur pour acceder aux concours hospitaliers : Lui, parce que son gout pour la pathologie du systeme nerveux se developpe en dehors de l’Ecole dominante en neurologie, celle de Jean-Martin Charcot. Augusta reussira tout de meme a etre nommee Interne des hopitaux de Paris – elle sera la premiere femme nommee a ce concours – Jules sera enfin nomme a l’Agregation la meme annee, en 1886. Ils uniront leurs vies en 1888 : il a trente-neuf ans, elle en a vingt-neuf. Ils vont desormais se consacrer a leur passion commune, la neurologie. Lui essentiellement comme clinicien et neuropathologiste, elle, d’abord comme neuroanatomiste : elle arretera son internat en seconde annee pour se consacrer entierement a ses travaux anatomiques. Les resultats qu’ils obtiennent leur valent tres vite de prestigieuses visites dans leur petit laboratoire de Bicetre, et une grande reputation internationale. Ils publient ensemble une Anatomie du Systeme Nerveux, et Jules Dejerine, un peu plus tard, une Semiologie des Affections du Systeme Nerveux : veritables monuments d’erudition emplis d’une quantite de faits nouveaux. Dans certains domaines ceux-ci s’opposent aux enseignements de l’Ecole Charcot, en particulier sur la physiopathologie des aphasies. L’apport des donnees anatomiques d’Augusta joue dans cette querelle un role majeur. Jules et Augusta ( Figure 1 ) sont desormais entoures d’eleves tres fideles, avec lesquels les liens sont pratiquement familiaux, et s’opposent en cela a l’atmosphere tres hierarchisee propre a l’ecole creee par Jean-Martin Charcot. Apres etre passe par une Chaire d’Histoire de la Medecine, puis de Pathologie Interne, Jules Dejerine est finalement nomme en 1910 dans la Chaire de Clinique des Maladies du Systeme Nerveux. Augusta, en vraie « patronne » y dirige le laboratoire. La declaration de la Guerre de 1914 va briser cet elan. Jules est mobilise comme medecin chef du Centre neurologique de la Salpetriere, il s’y donne corps et âme alors meme qu’il est malade depuis quelques annees, atteint d’un mal de Bright (une nephrite). Elle va le seconder avec tous leurs eleves aupres des blesses, et en particulier affiner la semiologie des blessures du systeme du nerveux peripherique et central ; Augusta est devenue Presidente de la Societe de Neurologie. Jules meurt le 26 fevrier 1917. Pierre Marie qui lui succede dans la Chaire de Charcot, donne quinze jours a Augusta pour quitter la Salpetriere avec toutes ses pieces et ses documents. Ceux-ci ne devront jamais, par obligation testamentaire, y revenir : ils sont envoyes a la Faculte de Medecine, ou est cree un Fond Dejerine, et a leur domicile prive. Dans les annees qui suivent le deces de Jules, Augusta est appelee a diriger le Centre des Grands Infirmes du Systeme Nerveux a l’Institution Nationale des Invalides, auquel elle donne une impulsion tres novatrice. Elle recoit a son tour de nombreuses distinctions. Atteinte d’un cancer du sein, elle decede en 1927 – dix ans apres son mari. Sans doute, avec le recul, peut-on mieux analyser aujourd’hui ce que fut la contribution de chacun, d’abord medicale et semiologique pour Jules, essentiellement scientifique et neuroanatomique pour Augusta [1] . Mais il ne faut jamais oublier le lien tres fort et inalterable qui les a unis dans cette œuvre comme dans leur vie.

Two young people, coming from both ends of the world to meet each other in Paris, with the same willingness to study medicine, the same ambition for success, then the same commitment to Neurology. Two young people who are going to work together, love each other and never be apart again. Jules and Augusta are only born ten years apart from each other and they will die ten years apart from each other. There is almost something too beautiful, too clear in their biographies brief synthesis: it is only reality though. Jules Dejerine was born in a modest family of Savoyard farmers gone to Geneva in order for their child to benefit from the best education possible; people at Calvin's College will remember him as a very robust and a bit pugnacious child but he will obtain his High School Certificates and A levels there; then he will ask his parents if they would allow him to study medicine in Paris. Augusta Klumpke was born in a very wealthy family in San Francisco where her father has made a fortune at the time of the stampede to the West. She had received a very good education there and when she was very young, she had let her parents know that she would like to become a doctor. She discovered Europe at the age of seven, her eldest sister, Anna, having developed osteomyelitis for which there were only French or German specialists at that time. After having spent some years in the USA and after her parents’ divorce, she will come back to Europe at the age of twelve with her mother, her four sisters and her brother, first to Germany then to Switzerland. She will obtain great success in high school in Lausanne. Klumpke's family finally settled in Paris in order for each child to find the best place for training or higher education. Chance will have them to meet each other on rue Jacob at the Vieille Charite Hospital, in Professor Hardy's clinical department. Jules is already a “Chef de Clinique” and is working very hard in the lab. Augusta will arrive there as a mere trainee, very quickly appreciated for her energy and linguistic talents. They will work together. Jules will show her how to use a microscope and histological techniques under the supervision of Alfred Vulpian, their venerated master. Soon a true love story will start between them, but Jules is not able to declare himself, his situation “not being made”. Both of them will have to deal with major obstacles in their carrier path. For her, it's because women are only admitted unwillingly at the Faculty of Medicine and because they will have to fight very hard to access the competitions to enter hospitals; for him, it is because his taste for diseases of the nervous system is developing outside the dominant school in Neurology, headed at the time by Jean-Martin Charcot. Augusta will manage in spite of everything to be nominated as an “ interne des hopitaux de Paris ” – she will be the first woman named in this very tough competition – Jules will finally be nominated at the “ agregation ” in medicine in the same year, in 1886. They will marry in 1888: he is thirty-nine years old, she is twenty-nine. From this time onwards, they will devote themselves to their shared passion: Neurology. Jules mainly as a clinician and a neuro-pathologist, Augusta, first as a brain anatomist: she will stop her internship in the second year to devote herself entirely to anatomical studies. The results they are obtaining will very quickly grant them prestigious visits in their small lab at the Bicetre hospital and a major international reputation. They are publishing together an “Anatomy of the Nervous System” and Jules Dejerine will publish a bit later a “Semiology of Nervous System Diseases”: real monuments of knowledge full of new data. In several fields, they are opposed to Charcot's school, specifically about aphasias pathology. The addition of anatomical data provided by Augusta played a major role in this dispute. At that time, Jules and Augusta ( Figure 1 ) were surrounded by very faithful pupils in an almost family-like relationship. They are opposed in this regard to the very stiff atmosphere typical to the Jean-Martin Charcot's school. After being nominated in a Chair of Medical History, then in Medical Pathology, Jules Dejerine was finally nominated in 1910 to the “Chaire de Clinique des Maladies du Systeme Nerveux” Clinical. Augusta, as a true “boss” is heading the lab there. The Declaration of War in 1914 will break this impulse. Jules is recruited as a head doctor of the military neurological center in the Salpetriere hospital. He completely devoted himself even suffering for some years from Bright's disease. Augusta will assist him with all their pupils working with the injured and specifically help him to revisit the semiology for the injuries of the peripheral and central Nervous System; at that time, Augusta became President of the Neurology Society. Jules died on February 26th, 1917. Pierre Marie, who is his successor in Charcot's Chair will give a fortnight to Augusta to leave the Salpetriere Hospital with all her material and documents. The latter should never come back to the Salpetriere, by use of a will: they were sent to the Faculty of Medicine where a special section is created and to their own home. In the years following Jules’ death, Augusta is called to head the center for soldiers suffering from major nervous system diseases at the Institution Nationale des Invalides, to which she gave a very innovative impulse. She received numerous prizes and distinctions. Suffering from breast cancer, she will die in 1927, ten years after her husband. Undoubtedly, taking a step backwards, we are able to better analyze nowadays each of their contributions, first medical and semiological for Jules, mainly scientific and neuro-anatomical for Augusta [1] . But one should never forget the very strong and steadfast relationship which united them in their work as well as in their lives.

J. A. Bevilacqua, N. Monnier, M. Bitoun, B. Eymard, A. Ferreiro, S. Monges, F. Lubieniecki, A. L. Taratuto, A. Laquerriere, K. G. Claeys, I. Marty, M. Fardeau, P. Guicheney, J. Lunardi and N. B. Romero (2011) Neuropathology and Applied Neurobiology37, 271–284 Recessive RYR1 mutations cause unusual congenital myopathy with prominent nuclear internalization and large areas of myofibrillar disorganization Aims: To report the clinical, pathological and genetic findings in a group of patients with a previously not described phenotype of congenital myopathy due to recessive mutations in the gene encoding the type 1 muscle ryanodine receptor channel (RYR1). Methods: Seven unrelated patients shared a predominant axial and proximal weakness of varying severity, with onset during the neonatal period, associated with bilateral ptosis and ophthalmoparesis, and unusual muscle biopsy features at light and electron microscopic levels. Results: Muscle biopsy histochemistry revealed a peculiar morphological pattern characterized by numerous internalized myonuclei in up to 51% of fibres and large areas of myofibrillar disorganization with undefined borders. Ultrastructurally, such areas frequently occupied the whole myofibre cross section and extended to a moderate number of sarcomeres in length. Molecular genetic investigations identified recessive mutations in the ryanodine receptor (RYR1) gene in six compound heterozygous patients and one homozygous patient. Nine mutations are novel and four have already been reported either as pathogenic recessive mutations or as changes affecting a residue associated with dominant malignant hyperthermia susceptibility. Only two mutations were located in the C-terminal transmembrane domain whereas the others were distributed throughout the cytoplasmic region of RyR1. Conclusion: Our data enlarge the spectrum of RYR1 mutations and highlight their clinical and morphological heterogeneity. A congenital myopathy featuring ptosis and external ophthalmoplegia, concomitant with the novel histopathological phenotype showing fibres with large, poorly delimited areas of myofibrillar disorganization and internal nuclei, is highly suggestive of an RYR1-related congenital myopathy.

International audience; We report the case of a congenital myasthenic syndrome due to a mutation in AGRN, the gene encoding agrin, an extracellular matrix molecule released by the nerve and critical for formation of the neuromuscular junction. Gene analysis identified a homozygous missense mutation, c.5125G>C, leading to the p.Gly1709Arg variant. The muscle-biopsy specimen showed a major disorganization of the neuromuscular junction, including changes in the nerve-terminal cytoskeleton and fragmentation of the synaptic gutters. Experiments performed in nonmuscle cells or in cultured C2C12 myotubes and using recombinant mini-agrin for the mutated and the wild-type forms showed that the mutated form did not impair the activation of MuSK or change the total number of induced acetylcholine receptor aggregates. A solid-phase assay using the dystrophin glycoprotein complex showed that the mutation did not affect the binding of agrin to alpha-dystroglycan. Injection of wild-type or mutated agrin into rat soleus muscle induced the formation of nonsynaptic acetylcholine receptor clusters, but the mutant protein specifically destabilized the endogenous neuromuscular junctions. Importantly, the changes observed in rat muscle injected with mutant agrin recapitulated the pre- and post-synaptic modifications observed in the patient. These results indicate that the mutation does not interfere with the ability of agrin to induce postsynaptic structures but that it dramatically perturbs the maintenance of the neuromuscular junction.

We report the clinical, histological and genetic findings in 10 families (19 patients) presenting mutations in the valosin-containing protein (VCP). The mean age at onset was 42 years. The clinical pattern was characterized by an early involvement of the proximal upper limbs with scapular winging. Axial and lower limb muscles were often affected, whereas facial, oculobulbar muscles were spared. Ten patients were wheelchair bound after a mean disease course of 9 years and six patients required canes for walking. Two patients required mechanically assisted ventilation and seven patients had reduced vital capacity. There was no cardiac involvement. Paget's disease of bone was observed in eight patients and cognitive impairment in nine patients. Seven patients died as a consequence of weakness and respiratory distress. Muscle biopsy showed rimmed vacuolar myopathy. Genetic analysis revealed missense heterozygous mutations mostly located in exon 5 of the VCP gene, four of which were not previously reported. We observed intrafamilial and interfamilial variability in terms of severity, distribution of weakness and presence or not of Paget's disease or cognitive impairment.

Mutations in the gene encoding the phosphoinositide phosphatase myotubularin 1 protein (MTM1) are usually associated with severe neonatal X-linked myotubular myopathy (XLMTM). However, mutations in MTM1 have also been recognized as the underlying cause of "atypical" forms of XLMTM in newborn boys, female infants, female manifesting carriers and adult men. We reviewed systematically the biopsies of a cohort of patients with an unclassified form of centronuclear myopathy (CNM) and identified four patients presenting a peculiar histological alteration in some muscle fibers that resembled a necklace ("necklace fibers"). We analyzed further the clinical and morphological features and performed a screening of the genes involved in CNM. Muscle biopsies in all four patients demonstrated 4-20% of fibers with internalized nuclei aligned in a basophilic ring (necklace) at 3 microm beneath the sarcolemma. Ultrastructurally, such necklaces consisted of myofibrils of smaller diameter, in oblique orientation, surrounded by mitochondria, sarcoplasmic reticulum and glycogen granules. In the four patients (three women and one man), myopathy developed in early childhood but was slowly progressive. All had mutations in the MTM1 gene. Two mutations have previously been reported (p.E404K and p.R241Q), while two are novel; a c.205_206delinsAACT frameshift change in exon 4 and a c.1234AG mutation in exon 11 leading to an abnormal splicing and the deletion of nine amino acids in the catalytic domain of MTM1. Necklace fibers were seen neither in DNM2- or BIN1-related CNM nor in males with classical XLMTM. The presence of necklace fibers is useful as a marker to direct genetic analysis to MTM1 in CNM.

Desminopathy represents a subgroup of myofibrillar myopathies caused by mutations in the desmin gene. Three novel disease-associated mutations in the desmin gene were identified in unrelated Spanish families affected by cardioskeletal myopathy. A selective pattern of muscle involvement, which differed from that observed in myofibrillar myopathy resulting from mutations in the myotilin gene, was observed in each of the three families with novel mutations and each of three desminopathy patients with known desmin mutations. Prominent joint retractions at the ankles and characteristic nasal speech were observed early in the course of illness. These findings suggest that muscle imaging in combination with routine clinical and pathological examination may be helpful in distinguishing desminopathy from other forms of myofibrillar myopathy and ordering appropriate molecular investigations.

Myofibrillar myopathy (MFM) encompasses a genetically heterogeneous group of human diseases caused by mutations in genes coding for structural proteins of muscle. Mutations in the intermediate filament (IF) protein desmin (DES), a major cytoskeletal component of myocytes, lead to severe forms of "desminopathy," which affects cardiac, skeletal, and smooth muscle. Most mutations described reside in the central alpha-helical rod domain of desmin. Here we report three novel mutations--c.1325C>T (p.T442I), c.1360C>T (p.R454W), and c.1379G>T (p.S460I)--located in desmin's non-alpha-helical carboxy-terminal "tail" domain. We have investigated the impact of these and four--c.1237G>A (p.E413K), c.1346A>C (p.K449T), c.1353C>G (p.I451M), and c.1405G>A (p.V469M)--previously described "tail" mutations on in vitro filament formation and on the generation of ordered cytoskeletal arrays in transfected myoblasts. Although all but two mutants (p.E413K, p.R454W) assembled into IFs in vitro and all except p.E413K were incorporated into IF arrays in transfected C2C12 cells, filament properties differed significantly from wild-type desmin as revealed by viscometric assembly assays. Most notably, when coassembled with wild-type desmin, these mutants revealed a severe disturbance of filament-formation competence and filament-filament interactions, indicating an inherent incompatibility of mutant and wild-type protein to form mixed filaments. The various clinical phenotypes observed may reflect altered interactions of desmin's tail domain with different components of the myoblast cytoskeleton leading to diminished biomechanical properties and/or altered metabolism of the individual myocyte. Our in vitro assembly regimen proved to be a very sensible tool to detect if a particular desmin mutation is able to cause filament abnormalities.

Congenital myasthenic syndromes CMS) form a heterogeneous group of genetic diseases characterized by abnormal neuromuscular transmission. The associated muscular weakness is exacerbated by exertion and usually starts during infancy/childhood In 2002 a national Congenital Myasthenic Syndromes Network was created in France, composed of neurologists, neuropediatricians, pathologists, molecular geneticists and neurobiologists. The network has now identified nearly 300 cases of CMS, as well as three new culprit genes. Based on our personal experience and data from the most recent studies, we describe the 18 principal culprit genes so far identified, along with diagnostic pitfalls, the disease course, prognosis and treatment. The underlying genetic defect remains to be identified in nearly half of CMS patients.

Cylindrical spirals are characteristic muscular inclusions consisting of spiraling double-laminated membranes. They are found in heterogeneous clinical conditions.We obtained muscle biopsies from 2 young sisters with severe congenital hypotonia, muscle weakness, and epileptic encephalopathy, and identified cylindrical spirals.We found an association between congenital encephalomyopathy and cylindrical spirals.In this morphological and ultrastructural study, we speculate on the origin of these peculiar structures.

Objective: To characterize the muscle involvement of patients with central core disease (CCD) caused by mutations in the ryanodine receptor 1 gene ( RYR1 ) and to compare these findings with those from patients with core myopathies unlinked to the RYR1 gene. Methods: We performed a systematic muscular imaging assessment in 11 patients with an RYR1 gene mutation and compared these findings with those of 5 patients from two unrelated families with autosomal dominant core myopathies not linked to RYR1 , ACTA1 , or MYH7 gene loci. Results: All patients with RYR1 CCD had a characteristic pattern with predominant involvement of the gluteus maximus, adductor magnus, sartorius, vastus intermediolateralis, soleus, and lateral gastrocnemius muscles. In contrast, muscle CT in the first family not linked to RYR1 showed predominant affection of the gluteus minimus and hamstring muscles, whereas the second family presented with predominant involvement of the gluteus minimus, vastus intermediolateralis, tibialis anterior, and medial gastrocnemius muscles. In addition to muscle imaging data, we present detailed information on the clinical and pathologic findings of these novel phenotypes of core myopathies not linked to RYR1 . Conclusions: Our data suggest genetic heterogeneity in autosomal dominant core myopathies and the existence of additional unidentified genes.

Mutations in titin are well known cause of late onset autosomal dominant distal myopathy. Mutations in another sarcomeric protein, myotilin, were first identified in two families with dominant limb girdle muscular phenotype. Recently, however, myotilin mutations have been associated with more distal phenotypes in patients with late onset myofibrillar myopathy. We report here a multigenerational French family in which gene sequencing identified a S60F myotilin mutation in all patients with full penetrance despite very late onset. The family was originally reported as a distal myopathy but intrafamilial variability was remarkable with proximal or distal muscle weakness or both. Extended morphological characteristics of muscle biopsy findings in myotilinopathy indicate that immunohistochemistry may be important for selection of molecular genetic approach in myofibrillar myopathy.

Un premier essai de therapie genique a ete realise chez des patients atteints de myopathie de Duchenne/ Becker, a l'aide d'un plasmide contenant l'integralite de la sequence codante du gene dystrophine. Cet essai de Phase I etait destine a apprecier le degre de transfection obtenue et a evaluer la tolerance au produit injecte ainsi qu'a l'expression du segment de dystrophine nouvellement synthetise. Neuf patients ont ete inclus dans l'essai, repartis en trois cohortes de trois. La premiere cohorte a recu une injection intramusculaire dans les muscles radicaux de 200 μg, la seconde une injection de 600 μg, et la troisieme deux injections a deux semaines d'intervalle de 600 μg. L'inclusion des patients s'est faite de facon sequentielle, apres examen des resultats du patient precedent par un comite de pilotage comprenant des experts independants. Le plasmide a ete retrouve dans les neuf prelevements effectues trois semaines apres la premiere (ou unique) injection. Une expression de la dystrophine exogene a ete retrouvee chez 6 patients sur 9. Cette expression a toujours ete faible, jusqu'a 6 % de fibres presentant un marquage peripherique complet, et jusqu'a 26 % de fibres presentant un marquage partiel. Les messagers de la dystrophine ont ete detectes par une RT-PCR « nichee » dans cinq des six prelevements presentant des fibres marquees. Il est remarquable de noter qu'aucune reponse immunitaire humorale ou cellulaire vis-a-vis de la dystrophine exogene n'a ete detectee. Aucune reaction secondaire locale ou generale n'a ete observee. Ces resultats, modestes mais significatifs, ouvrent la voie a de nouveaux developpements en terme de therapie genique des maladies musculaires humaines, et en particulier dans les myopathies de Duchenne et de Becker.

Nine patients with Duchenne or Becker muscular dystrophy were injected via the radialis muscle with a full-length human dystrophin plasmid, either once with 200 or 600 microg of DNA or twice, 2 weeks apart, with 600 microg of DNA. In the biopsies taken 3 weeks after the initial injection, the vector was detected at the injection site in all patients. Immunohistochemistry and nested reverse transcription-polymerase chain reaction indicated dystrophin expression in six of nine patients. The level of expression was low (up to 6% weak, but complete sarcolemmal dystrophin staining, and up to 26% partial sarcolemmal labeling). No side effects were observed, nor any cellular or humoral anti-dystrophin responses. These results suggest that exogenous dystrophin expression can be obtained in Duchenne/Becker patients after intramuscular transfer of plasmid, without adverse effects, hence paving the way for future developments in gene therapy of hereditary muscular diseases.

The 121st European Neuromuscular Centre (ENMC)sponsored International Workshop on ‘DESMIN and Protein Aggregate Myopathies’, attended by 16 active participants from France, Germany, Poland, Spain, Sweden, the United Kingdom and the USA, was actually the fourth one in a row addressing the pathology of the muscle fibre intermediate filament desmin, its associated and similar diseases, all four [1–3] organized by Michel Fardeau and Hans H. Goebel. In his introduction, the chairman, Hans H. Goebel (Mainz), recorded the evolution of ‘Protein Aggregate Myopathies (PAM)’ which are marked by the accumulation of diverse proteins within muscle fibres as a morphologic hallmark in separate myopathies which now comprise several diverse entities (Table 1). Desmin-related myopathies were first reported as cytoplasmic myopathy, granulofilamentous myopathy [4], spheroid body myopathy [5] and a form of congenital muscular dystrophy [6]. Subsequently, they have been found to have accumulation of desmin as a common morphological denominator but are genetically diverse, comprising desminopathies [7,8] owing to mutations in the desmin gene, a-B crystallinopathy [9–11] owing to mutations in the a-B crystallin gene, recently selenoproteinopathies owing to mutations in the selenoprotein N1 gene [12] and newly, added, myotilinopathies [13]. In addition to desmin, a multitude of fibre proteins accrue to respective inclusions or granulofilamentous material. Only briefly, because belonging to other ENMC Consortia, such as one on ‘Nemaline myopathy’

Desmin-related myopathies (DRMs) are a heterogeneous group of muscle disorders, morphologically defined by intrasarcoplasmic aggregates of desmin. Mutations in the desmin and the alpha-B crystallin genes account for approximately one third of the DRM cases. The genetic basis of the other forms remain unknown, including the early-onset, recessive form with Mallory body-like inclusions (MB-DRMs), first described in five related German patients. Recently, we identified the selenoprotein N gene (SEPN1) as responsible for SEPN-related myopathy (SEPN-RM), a unique early-onset myopathy formerly divided in two different nosological categories: rigid spine muscular dystrophy and the severe form of classical multiminicore disease. The finding of Mallory body-like inclusions in two cases of genetically documented SEPN-RM led us to suspect a relationship between MB-DRM and SEPN1. In the original MB-DRM German family, we demonstrated a linkage of the disease to the SEPN1 locus (1p36), and subsequently a homozygous SEPN1 deletion (del 92 nucleotide -19/+73) in the affected patients. A comparative reevaluation showed that MB-DRM and SEPN-RM share identical clinical features. Therefore, we propose that MB-DRM should be categorized as SEPN-RM. These findings substantiate the molecular heterogeneity of DRM, expand the morphological spectrum of SEPN-RM, and implicate a necessary reassessment of the nosological boundaries in early-onset myopathies.

Congenital myasthenic syndromes are rare heterogeneous hereditary disorders, which lead to defective neuromuscular transmission resulting in fatigable muscle weakness. Post-synaptic congenital myasthenic syndromes are caused by acetylcholine receptor kinetic abnormalities or by acetylcholine receptor deficiency. Most of the congenital myasthenic syndromes with acetylcholine receptor deficiency are due to mutations in acetylcholine receptor subunit genes. Some have recently been attributed to mutations in the rapsyn gene. Here, we report the case of a 28-year-old French congenital myasthenic syndrome patient who had mild diplopia and fatigability from the age of 5 years. His muscle biopsy revealed a marked reduction in rapsyn and acetylcholine receptor at neuromuscular junctions together with a simplification of the subneural apparatus structure. In this patient, we excluded mutations in the acetylcholine receptor subunit genes and identified the homozygous N88K rapsyn mutation, which has already been shown by cell expression to impair rapsyn and acetylcholine receptor aggregation at the neuromuscular junction. The detection of the N88K mutation at the heterozygous state in five of 300 unrelated control subjects shows that this mutation is not infrequent in the healthy population. Electrophysiological measurements on biopsied intercostal muscle from this patient showed that his rapsyn mutation-induced fatigable weakness is expressed not only in a diminution in acetylcholine receptor membrane density but also in a decline of endplate potentials evoked at low frequency.

We studied seven patients (fetuses/infants) from six unrelated families affected by central core disease (CCD) and presenting with a fetal akinesia syndrome. Two fetuses died before birth (at 31 and 32 weeks) and five infants presented severe symptoms at birth (multiple arthrogryposis, congenital dislocation of the hips, severe hypotonia and hypotrophy, skeletal and feet deformities, kyphoscoliosis, etc.). Histochemical and ultrastructural studies of muscle biopsies confirmed the diagnosis of CCD showing unique large eccentric cores. Molecular genetic investigations led to the identification of mutations in the ryanodine receptor (RYR1) gene in three families, two with autosomal recessive (AR) and one with autosomal dominant (AD) inheritance. RYR1 gene mutations were located in the C-terminal domain in two families (AR and AD) and in the N-terminal domain of the third one (AR). This is the first report of mutations in the RYR1 gene involved in a severe form of CCD presenting as a fetal akinesia syndrome with AD and AR inheritances.