Hyperckemia and myalgia are common presentations of anoctamin-5-related myopathy in French patients.

Introduction: Patients with anoctamin-5 (ANO5) mutations may present not only with limb-girdle muscular dystrophy type 2L or adult-onset Miyoshi-type myopathy but also with asymptomatic hyperCKemia, exercise intolerance, or rhabdomyolysis.

Materials And Methods: Data from 38 patients in France with ANO5 mutations with and without muscle weakness on first examination were compared.

Results: Twenty patients presented without muscle weakness.

ORAI1 Mutations with Distinct Channel Gating Defects in Tubular Aggregate Myopathy.

Calcium (Ca ) is a physiological key factor, and the precise modulation of free cytosolic Ca levels regulates multiple cellular functions. Store-operated Ca entry (SOCE) is a major mechanism controlling Ca homeostasis, and is mediated by the concerted activity of the Ca sensor STIM1 and the Ca channel ORAI1. Dominant gain-of-function mutations in STIM1 or ORAI1 cause tubular aggregate myopathy (TAM) or Stormorken syndrome, whereas recessive loss-of-function mutations are associated with immunodeficiency.

Dihydropyridine receptor (DHPR, CACNA1S) congenital myopathy.

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 Ca channel (dihydropyridine receptor; DHPR) located on the T-tubule with a Ca 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.

Incidence and predictors of sudden death, major conduction defects and sustained ventricular tachyarrhythmias in 1388 patients with myotonic dystrophy type 1.

Aims: To describe the incidence and identify predictors of sudden death (SD), major conduction defects and sustained ventricular tachyarrhythmias (VTA) in myotonic dystrophy type 1 (DM1).

Methods And Results: We retrospectively enrolled 1388 adults with DM1 referred to six French medical centres between January 2000 and October 2013. We confirmed their vital status, classified all deaths, and determined the incidence of major conduction defects requiring permanent pacing and sustained VTA.

Tubular aggregate myopathy with features of Stormorken disease due to a new STIM1 mutation.

STIM1 is a reticular Ca sensor composed of a luminal and a cytosolic domain. Missense mutations in the luminal domain have been associated with tubular aggregate myopathy (TAM), while cytosolic mutations can cause Stormorken syndrome, a multisystemic disease associating TAM with asplenia, thrombocytopenia, miosis, ichthyosis, short stature and dyslexia. Here we present the case of a 41-year-old female complaining of exercise intolerance.

Non Random Distribution of DMD Deletion Breakpoints and Implication of Double Strand Breaks Repair and Replication Error Repair Mechanisms.

Background: Dystrophinopathies are mostly caused by copy number variations, especially deletions, in the dystrophin gene (DMD). Despite the large size of the gene, deletions do not occur randomly but mainly in two hot spots, the main one involving exons 45 to 55. The underlying mechanisms are complex and implicate two main mechanisms: Non-homologous end joining (NHEJ) and micro-homology mediated replication-dependent recombination (MMRDR).

Recessive mutations in the kinase ZAK cause a congenital myopathy with fibre type disproportion.

Congenital myopathies define a heterogeneous group of neuromuscular diseases with neonatal or childhood hypotonia and muscle weakness. The genetic cause is still unknown in many patients, precluding genetic counselling and better understanding of the physiopathology. To identify novel genetic causes of congenital myopathies, exome sequencing was performed in three consanguineous families.

Variants in the Oxidoreductase PYROXD1 Cause Early-Onset Myopathy with Internalized Nuclei and Myofibrillar Disorganization.

This study establishes PYROXD1 variants as a cause of early-onset myopathy and uses biospecimens and cell lines, yeast, and zebrafish models to elucidate the fundamental role of PYROXD1 in skeletal muscle. Exome sequencing identified recessive variants in PYROXD1 in nine probands from five families. Affected individuals presented in infancy or childhood with slowly progressive proximal and distal weakness, facial weakness, nasal speech, swallowing difficulties, and normal to moderately elevated creatine kinase.

What have we learned about glycogenosis in recent years?

The field of glycogenosis has been greatly expanded over the past few years with the discovery of new metabolic diseases that have allowed new metabolic pathways to be deciphered. Described here are the clinical and pathological features of four recently described muscle glycogenoses caused by GYS1, GYG1, RBCK1 and PGM1 gene mutations. The initial steps of glycogen synthesis are involved in deficiencies of glycogenin-1 (GYG1) and muscle glycogen synthase (GYS1).

Nemaline myopathies: State of the art.

Nemaline myopathy (NM) is one of the most common forms of congenital myopathy. The condition is defined by the histopathological finding of nemaline bodies (rods) on muscle biopsy and is associated with hypotonia and muscle weakness. The clinical spectrum encompasses lethal forms presenting in the neonatal period with profound weakness and less severe congenital diseases of later onset.

Cardiac arrhythmia and late-onset muscle weakness caused by a myofibrillar myopathy with unusual histopathological features due to a novel missense mutation in FLNC.

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.

A novel neuromuscular form of glycogen storage disease type IV with arthrogryposis, spinal stiffness and rare polyglucosan bodies in muscle.

Glycogen storage disease type IV (GSD IV) is an autosomal recessive disorder causing polyglucosan storage in various tissues. Neuromuscular forms present with fetal akinesia deformation sequence, lethal myopathy, or mild hypotonia and weakness. A 3-year-old boy presented with arthrogryposis, motor developmental delay, weakness, and rigid spine.

Relationship between muscle impairments, postural stability, and gait parameters assessed with lower-trunk accelerometry in myotonic dystrophy type 1.

This study evaluated gait using lower-trunk accelerometry and investigated relationships between gait abnormalities, postural instability, handgrip myotonia, and weakness in lower-limb and axial muscle groups commonly affected in myotonic dystrophy type 1 (DM1). Twenty-two patients (11 men, 11 women; age = 42 years (range: 26-51)) with DM1 and twenty healthy controls (9 men, 11 women; age = 44 years (range: 24-50)) participated in this study. Gait analysis using lower-trunk accelerometry was performed at self-selected walking pace.

High risk of cancer in autoimmune necrotizing myopathies: usefulness of myositis specific antibody.

Cancer can occur in patients with inflammatory myopathies. This association is mainly observed in dermatomyositis, and myositis-specific antibodies have allowed us to delineate patients at an increased risk. Malignancy is also reported in patients with necrotizing autoimmune myopathies, but the risk remains elusive.

Multiple acyl-CoA dehydrogenase deficiency (MADD) as a cause of late-onset treatable metabolic disease.

Introduction: Late-onset multiple acyl-CoA dehydrogenase deficiency (MADD) is a rare, treatable, beta-oxidation disorder responsible for neuromuscular symptoms in adults. This case series describes the clinical and biochemical features of 13 French patients with late-onset MADD.

Methods And Results: Thirteen ambulant patients (eight women, five men), with a median age at onset of 27 years, initially experienced exercise intolerance (n=9), isolated muscle weakness (n=1) and a multisystemic pattern with either central nervous system or hepatic dysfunction (n=3).

[GNE myopathy].

GNE myopathy is a rare neuromuscular disease whose description is fairly recent. It predominantly affects the adult population and is an inherited autosomal recessive disorder. Although universal and ubiquitous, GNE myopathy prevails in the Jewish community of Persian origin, living in Iran, Israel or in the United States.

Expanding the clinical spectrum of hereditary fibrosing poikiloderma with tendon contractures, myopathy and pulmonary fibrosis due to FAM111B mutations.

Background: Hereditary Fibrosing Poikiloderma (HFP) with tendon contractures, myopathy and pulmonary fibrosis (POIKTMP [MIM 615704]) is a very recently described entity of syndromic inherited poikiloderma. Previously by using whole exome sequencing in five families, we identified the causative gene, FAM111B (NM_198947.3), the function of which is still unknown.

Bilateral foot-drop as predominant symptom in nebulin (NEB) gene related "core-rod" congenital myopathy.

Background: Congenital myopathies (CM) are a group of rare inherited muscle disorders characterized by particular histopathological alterations on muscle biopsy. Core-rod myopathy is a CM presenting with cores and rods as distinctive muscle morphological features.

Methods/results: We describe 3 young patients presenting congenital core-rod myopathy with bilateral foot-drop associated with autosomal recessive nebulin gene (NEB) mutations detected by exome sequencing.

Myofibrillar myopathies: State of the art, present and future challenges.

Myofibrillar myopathies (MFM) have been described in the mid-1990s as a group of diseases sharing common histological features, including an abnormal accumulation of intrasarcoplasmic proteins, the presence of vacuoles and a disorganization of the intermyofibrillar network beginning at the Z-disk. The boundaries of this concept are still uncertain, and whereas six genes (DES, CRYAB, LDB3/ZASP, MYOT, FLNC and BAG3) are now classically considered as responsible for MFM, other entities such as FHL1 myopathy or Hereditary Myopathy with Early Respiratory Failure linked to mutations of titin can now as well be included in this group. The diagnosis of MFM is not always easy; as histological lesions can be focal, and muscle biopsy may be disappointing; this has led to a growing importance of muscle imaging, and the selectivity of muscle involvement has now been described in several disorders.

A Premature Stop Codon in MYO18B is Associated with Severe Nemaline Myopathy with Cardiomyopathy.

Background: Nemaline myopathies (NM) are rare and severe muscle diseases characterized by the presence of nemaline bodies (rods) in muscle fibers. Although ten genes have been implicated in the etiology of NM, an important number of patients remain without a molecular diagnosis.

Objective: Here we describe the clinical and histopathological features of a sporadic case presenting with severe NM and cardiomyopathy.

Respiratory muscle dysfunction in facioscapulohumeral muscular dystrophy.

Respiratory insufficiency in facioscapulohumeral muscular dystrophy has rarely been studied. We compared two age- and sex-matched groups of 29 patients, with and without respiratory dysfunction. Tests in the 29 patients with respiratory dysfunction suggested predominant expiratory muscle dysfunction, leading to ineffective cough in 17 patients.

Cylindrical spirals associated with severe congenital muscle weakness and epileptic encephalopathy.

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.

Endplate denervation correlates with Nogo-A muscle expression in amyotrophic lateral sclerosis patients.

Objective: Data from mouse models of amyotrophic lateral sclerosis (ALS) suggest early morphological changes in neuromuscular junctions (NMJs), with loss of nerve-muscle contact. Overexpression of the neurite outgrowth inhibitor Nogo-A in muscle may play a role in this loss of endplate innervation.

Methods: We used confocal and electron microscopy to study the structure of the NMJs in muscle samples collected from nine ALS patients (five early-stage patients and four long-term survivors).

Skeletal muscle metabolism is impaired during exercise in glycogen storage disease type III.

Objective: Glycogen storage disease type IIIa (GSDIIIa) is classically regarded as a glycogenosis with fixed weakness, but we hypothesized that exercise intolerance in GSDIIIa is related to muscle energy failure and that oral fructose ingestion could improve exercise tolerance in this metabolic myopathy.

Methods: We challenged metabolism with cycle-ergometer exercise and measured substrate turnover and oxidation rates using stable isotope methodology and indirect calorimetry in 3 patients and 6 age-matched controls on 1 day, and examined the effect of fructose ingestion on exercise tolerance in the patients on another day.

Results: Total fatty acid oxidation rates during exercise were higher in patients than controls, 32.