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Anoctamin-5 related muscle disease is caused by biallelic pathogenic variants in the anoctamin-5 gene (ANO5) and shows variable clinical phenotypes: limb-girdle muscular dystrophy type 12 (LGMD-R12), distal muscular dystrophy type 3 (MMD3), pseudometabolic myopathy or asymptomatic hyperCKaemia. In this retrospective, observational, multicentre study we gathered a large European cohort of patients with ANO5-related muscle disease to study the clinical and genetic spectrum and genotype–phenotype correlations. We included 234 patients from 212 different families, contributed by 15 centres from 11 European countries. The largest subgroup was LGMD-R12 (52.6%), followed by pseudometabolic myopathy (20.5%), asymptomatic hyperCKaemia (13.7%) and MMD3 (13.2%). In all subgroups, there was a male predominance, except for pseudometabolic myopathy. Median age at symptom onset of all patients was 33 years (range 23–45 years). The most frequent symptoms at onset were myalgia (35.3%) and exercise intolerance (34.1%), while at last clinical evaluation most frequent symptoms and signs were proximal lower limb weakness (56.9%) and atrophy (38.1%), myalgia (45.1%) and atrophy of the medial gastrocnemius muscle (38.4%). Most patients remained ambulatory (79.4%). At last evaluation, 45.9% of patients with LGMD-R12 additionally had distal weakness in the lower limbs and 48.4% of patients with MMD3 also showed proximal lower limb weakness. Age at symptom onset did not differ significantly between males and females. However, males had a higher risk of using walking aids earlier (P = 0.035). No significant association was identified between sportive versus non-sportive lifestyle before symptom onset and age at symptom onset nor any of the motor outcomes. Cardiac and respiratory involvement that would require treatment occurred very rarely. Ninety-nine different pathogenic variants were identified in ANO5 of which 25 were novel. The most frequent variants were c.191dupA (p.Asn64Lysfs*15) (57.7%) and c.2272C>T (p.Arg758Cys) (11.1%). Patients with two loss-of function variants used walking aids at a significantly earlier age (P = 0.037). Patients homozygous for the c.2272C>T variant showed a later use of walking aids compared to patients with other variants (P = 0.043). We conclude that there was no correlation of the clinical phenotype with the specific genetic variants, and that LGMD-R12 and MMD3 predominantly affect males who have a significantly worse motor outcome. Our study provides useful information for clinical follow up of the patients and for the design of clinical trials with novel therapeutic agents.

Neurofilament light (NFL) is one of the proteins forming multimeric neuron-specific intermediate filaments, neurofilaments, which fill the axonal cytoplasm, establish caliber growth, and provide structural support. Dominant missense mutations and recessive nonsense mutations in the neurofilament light gene (

Eight patients from five families with undiagnosed dominant distal myopathy underwent clinical, neurophysiological and muscle biopsy examinations. Molecular genetic studies were performed using targeted sequencing of all known myopathy genes followed by segregation of the identified mutations in the affected families using Sanger sequencing. Two novel mutations in DNAJB6 J domain, c.149C>T (p.A50V) and c.161A>C (p.E54A), were identified as the cause of disease. The muscle involvement with p.A50V was distal calf-predominant, and the p.E54A was more proximo-distal. Histological findings were similar to those previously reported in DNAJB6 myopathy. In line with reported pathogenic mutations in the glycine/phenylalanine (G/F) domain of DNAJB6, both the novel mutations showed reduced anti-aggregation capacity by filter trap assay and TDP-43 disaggregation assays. Modeling of the protein showed close proximity of the mutated residues with the G/F domain. Myopathy-causing mutations in DNAJB6 are not only located in the G/F domain, but also in the J domain. The identified mutations in the J domain cause dominant distal and proximo-distal myopathy, confirming that mutations in DNAJB6 should be considered in distal myopathy cases.

Objective To clinically and pathologically characterize a cohort of patients presenting with a novel form of distal myopathy and to identify the genetic cause of this new muscular dystrophy. Methods We studied 4 families (3 from Spain and 1 from Sweden) suffering from an autosomal dominant distal myopathy. Affected members showed adult onset asymmetric distal muscle weakness with initial involvement of ankle dorsiflexion later progressing also to proximal limb muscles. Results In all 3 Spanish families, we identified a unique missense variant in the ACTN2 gene cosegregating with the disease. The affected members of the Swedish family carry a different ACTN2 missense variant. Interpretation ACTN2 encodes for alpha actinin2, which is highly expressed in the sarcomeric Z-disk with a major structural and functional role. Actininopathy is thus a new genetically determined distal myopathy. ANN NEUROL 2019;85:899-906.

Sarcoglycanopathies comprise four subtypes of autosomal recessive limb-girdle muscular dystrophies (LGMDR3, LGMDR4, LGMDR5 and LGMDR6) that are caused, respectively, by mutations in the SGCA, SGCB, SGCG and SGCD genes. In 2016, several clinicians involved in the diagnosis, management and care of patients with LGMDR3–6 created a European Sarcoglycanopathy Consortium. The aim of the present study was to determine the clinical and genetic spectrum of a large cohort of patients with sarcoglycanopathy in Europe. This was an observational retrospective study. A total of 33 neuromuscular centres from 13 different European countries collected data of the genetically confirmed patients with sarcoglycanopathy followed-up at their centres. Demographic, genetic and clinical data were collected for this study. Data from 439 patients from 13 different countries were collected. Forty-three patients were not included in the analysis because of insufficient clinical information available. A total of 159 patients had a confirmed diagnosis of LGMDR3, 73 of LGMDR4, 157 of LGMDR5 and seven of LGMDR6. Patients with LGMDR3 had a later onset and slower progression of the disease. Cardiac involvement was most frequent in LGMDR4. Sixty per cent of LGMDR3 patients carried one of the following mutations, either in a homozygous or heterozygous state: c.229C>T, c.739G>A or c.850C>T. Similarly, the most common mutations in LMGDR5 patients were c.525delT or c.848G>A. In LGMDR4 patients the most frequent mutation was c.341C>T. We identified onset of symptoms before 10 years of age and residual protein expression lower than 30% as independent risk factors for losing ambulation before 18 years of age, in LGMDR3, LGMDR4 and LGMDR5 patients. This study reports clinical, genetic and protein data of a large European cohort of patients with sarcoglycanopathy. Improving our knowledge about these extremely rare autosomal recessive forms of LGMD was helped by a collaborative effort of neuromuscular centres across Europe. Our study provides important data on the genotype-phenotype correlation that is relevant for the design of natural history studies and upcoming interventional trials in sarcoglycanopathies.

International audience; Background and purposeThe aim was to determine the genetic background of unknown muscular dystrophy in five French families.MethodsTwelve patients with limb girdle muscular dystrophy or distal myopathy were clinically evaluated. Gene mutations were identified using targeted exon sequencing and mutated DNAJB6 was tested invitro.ResultsFive patients presented with distal lower limb weakness whilst others had proximal presentation with a variable rate of progression starting at the mean age of 38.5years. Two novel mutations (c.284A>T, p.Asn95Ile, two families; and c.293_295delATG, p.Asp98del, one family) as well as the previously reported c.279C>G (p.Phe93Leu, two families) mutation in DNAJB6 were identified. All showed a reduced capacity to prevent protein aggregation.ConclusionsThe mutational and phenotypical spectrum of DNAJB6-caused muscle disease is larger than previously reported, including also dysphagia. The originally reported c.279C>G (p.Phe93Leu) mutation is now identified in four different populations and appears to be a mutational hotspot. Our report confirms that some DNAJB6 mutations cause distal-onset myopathy and hence DNAJB6 defects should be considered broadly in dominant muscular dystrophy families.

INTRODUCTION The p.A1156T mutation alters the function of the voltage-gated sodium channel Nav1.4 on the muscle sarcolemma, causing a channelopathy without overt myotonia or periodic paralysis but with myalgic pain. METHODS A postal survey was conducted to assess the prevalence and characteristics of pain and related symptoms in individuals with the p.A1156T mutation. A specific questionnaire, intensity and interference subscales of the Brief Pain Inventory, pain drawing, Widespread Pain Index, quality of life (RAND-36), and the Beck Depression Inventory were completed. RESULTS Twenty of 24 patients replied. Current pain was reported by 16 respondents; the other 4 had experienced pain previously. Most commonly, pain was widespread and exercise-induced. The severity and the impact of pain on daily life were considerable, although varied. DISCUSSION This sodium channelopathy is another entity in the growing number of diseases causing widespread myalgic pain that resembles the pain seen in fibromyalgia syndrome. Muscle Nerve 57: 1014-1017, 2018.

Background The symptoms and their progression in amyotrophic lateral sclerosis (ALS) are typically studied after the diagnosis has been confirmed. However, many people with ALS already have severe dysarthria and loss of adequate speech at the time of diagnosis. Speech-and-language therapy interventions should be targeted timely based on communicative need in ALS. Aims To investigate how long natural speech will remain functional and to identify the changes in the speech of persons with ALS. Methods & procedures Altogether 30 consecutive participants were studied and divided into two groups based on the initial type of ALS, bulbar or spinal. Their speech disorder was evaluated on severity, articulation rate and intelligibility during the 2-year follow-up. Outcome & results The ability to speak deteriorated to poor and necessitated augmentative and alternative communication (AAC) methods with 60% of the participants. Their speech remained adequate on average for 18 months from the first bulbar symptom. Severity, articulation rate and intelligibility declined with nearly all participants during the study. To begin with speech deteriorated more in the bulbar group than in the spinal group and the difference remained during the whole follow-up with some exceptions. Conclusions & implications The onset of bulbar symptoms indicated the time to loss of speech better than when assessed from ALS diagnosis or the first speech therapy evaluation. In clinical work, it is important to take the initial type of ALS into consideration when determining the urgency of AAC measures as people with bulbar-onset ALS are more susceptible to delayed evaluation and AAC intervention.

We report on how functional capacity of communication and the use of augmentative and alternative communication (AAC) technology changed in persons with amyotrophic lateral sclerosis (ALS) and progressive dysarthria during a period of two years. The initial sample comprised 30 participants, nine of them survived the whole two years. The data was gathered in 157 communication assessments by a speech-language pathologist. Functional capacity of communication was evaluated with combined severity scales of speech and upper and lower limb function. Communication strategies used were gathered based on the participants’ own reports, and their use was confirmed during the clinical visits. A total of 57% of the participants either supported or substituted their natural speech with high- or low- technology strategies. The majority of them reported that they used high-technology rather than low-technology AAC as the main communication means after speech had deteriorated. The classification of functional capa...

Objective:To characterize the clinical phenotype in patients with p.A1156T sodium channel mutation.Methods:Twenty-nine Finnish patients identified with the c.3466G>A p.A1156T mutation in the SCN4A gene were extensively examined. In a subsequent study, 63 patients with similar myalgic phenotype and with negative results in myotonic dystrophy type 2 genetic screening (DM2-neg group) and 93 patients diagnosed with fibromyalgia were screened for the mutation. Functional consequences of the p.A1156T mutation were studied in HEK293 cells with whole-cell patch clamp.Results:The main clinical manifestation in p.A1156T patients was not myotonia or periodic paralysis but exercise- and cold-induced muscle cramps, muscle stiffness, and myalgia. EMG myotonic discharges were detected in most but not all. Electrophysiologic compound muscle action potentials exercise test showed variable results. The p.A1156T mutation was identified in one patient in the DM2-neg group but not in the fibromyalgia group, making a total of 30 patients so far identified. Functional studies of the p.A1156T mutation showed mild attenuation of channel fast inactivation.Conclusions:The unspecific symptoms of myalgia stiffness and exercise intolerance without clinical myotonia or periodic paralysis in p.A1156T patients make the diagnosis challenging. The symptoms of milder SCN4A mutations may be confused with other similar myalgic syndromes, including fibromyalgia and myotonic dystrophy type 2.

ObjectiveWe report a second family with autosomal dominant transportinopathy presenting with congenital or early-onset myopathy and slow progression, causing proximal and less pronounced distal muscle weakness.MethodsPatients had clinical examinations, muscle MRI, EMG, and muscle biopsy studies. The MYOcap gene panel was used to identify the gene defect in the family. Muscle biopsies were used for histopathologic and protein expression studies, and TNPO3 constructs were used to study the effect of the mutations in transfected cells.ResultsWe identified a novel heterozygous mutation, c.2757delC, in the last part of the transportin-3 (TNPO3) gene in the affected family members. The mutation causes an almost identical frameshift affecting the stop codon and elongating the C-term protein product of the TNPO3 transcript, as was previously reported in the first large Spanish-Italian LGMD1F kindred. TNPO3 protein was increased in the patient muscle and accumulated in the subsarcolemmal and perinuclear areas. At least one of the cargo proteins, the splicing factor SRRM2 was normally located in the nucleus. Transiently transfected mutant TNPO3 constructs failed to localize to cytoplasmic annulate lamellae pore complexes in cells.ConclusionsWe report the clinical, molecular genetic, and histopathologic features of the second transportinopathy family. The variability of the clinical phenotype together with histopathologic findings suggests that several molecular pathways may be involved in the disease pathomechanism, such as nucleocytoplasmic shuttling, protein aggregation, and defective protein turnover.

Tibial muscular dystrophy (TMD) is the first described human titinopathy. It is a mild adult-onset slowly progressive myopathy causing weakness and atrophy in the anterior lower leg muscles. TMD is caused by mutations in the last two exons, Mex5 and Mex6, of the titin gene (TTN). The first reported TMD mutations were dominant, but the Finnish founder mutation FINmaj, an 11-bp insertion/deletion in Mex6, in homozygosity caused a completely different severe early-onset limb-girdle muscular dystrophy 2J (LGMD2J). Later, we reported that not all TMD mutations cause LGMD when homozygous or compound heterozygous with truncating mutation, but some of them rather cause a more severe TMD-like distal disease. We have now performed targeted next-generation sequencing of myopathy-related genes on seven families from Albania, Bosnia, Iran, Tunisia, Belgium, and Spain with juvenile or early adult onset recessive distal myopathy. Novel mutations in TTN Mex5, Mex6 and A-band exon 340 were identified in homozygosity or compound heterozygosity with a frameshift or nonsense mutation in TTN I- or A-band region. Family members having only one of these TTN mutations were healthy. Our results add yet another entity to the list of distal myopathies: juvenile or early adult onset recessive distal titinopathy.

Limb-girdle muscular dystrophies (LGMD) are genetic disorders characterized by weakness of predominantly proximal limb and trunk muscles due to progressive loss of muscle tissue. Collagen VI-related muscular dystrophies usually display more generalized muscle involvement combined with contractures and/or hyperlaxity of distal finger joints. LGMD-like phenotype of collagenopathy has only rarely been described and as reported is usually of childhood onset. We identified a Finnish family with COL6A2-related LGMD with autosomal dominant inheritance and very late onset at 40–60 years of age. Since the mutation was previously unreported, the pathognomonic findings on muscle MRI were the decisive clue for the correct diagnosis.

Journal of neurology 266(3), 680-690 (2019). doi:10.1007/s00415-019-09187-2, Published by Springer, Berlin ; Heidelberg

To identify the genetic and physiologic basis for recessive myasthenic congenital myopathy in 2 families, suggestive of a channelopathy involving the sodium channel gene,A combination of whole exome sequencing and targeted mutation analysis, followed by voltage-clamp studies of mutant sodium channels expressed in fibroblasts (HEK cells) andMissense mutations of the same residue in the skeletal muscle sodium channel, R1460 of NaNovel mutations in families with myasthenic congenital myopathy have been identified at p.R1460 of the sodium channel. Recessive inheritance, with experimentally established loss-of-function, is a consistent feature of sodium channel based myasthenia, whereas the mixed gain of function for p.R1460 may also cause susceptibility to myotonia.

Over fifty missense mutations in the gene coding for valosin-containing protein (VCP) are associated with a unique autosomal dominant adult-onset progressive disease associated with combinations of proximo-distal inclusion body myopathy (IBM), Paget's disease of bone (PDB), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS). We report the clinical, histological, and molecular findings in four new patients/families carrying novel VCP mutations: c.474 G > A (p.M158I); c.478 G > C (p.A160P); c.383G > C (p.G128A); and c.382G > T (p.G128C). Clinical features included myopathy, PDB, ALS and Parkinson's disease though frontotemporal dementia was not an associated feature in these families. One of the patients was noted to have severe manifestations of PDB and was suspected of having neoplasia. There were wide inter- and intra-familial variations making genotype-phenotype correlations difficult between the novel mutations and frequency or age of onset of IBM, PDB, FTD, ALS and Parkinson's disease. Increasing awareness of the full spectrum of clinical presentations will improve diagnosis of VCP-related diseases and thus proactively manage or prevent associated clinical features such as PDB. (C) 2018 Published by Elsevier B.V.

DNAJB6 is the causative gene for limb-girdle muscular dystrophy 1D (LGMD1D). Four different coding missense mutations, p.F89I, p.F93I, p.F93L, and p.P96R, have been reported in families from Europe, North America and Asia. The previously known mutations cause mainly adult-onset proximal muscle weakness with moderate progression and without respiratory involvement. A Finnish family and a British patient have been studied extensively due to a severe muscular dystrophy. The patients had childhood-onset LGMD, loss of ambulation in early adulthood and respiratory involvement; one patient died of respiratory failure aged 32. Two novel mutations, c.271T > A (p.F91I) and c.271T > C (p.F91L), in DNAJB6 were identified by whole exome sequencing as a cause of this severe form of LGMD1D. The results were confirmed by Sanger sequencing. The anti-aggregation effect of the mutant DNAJB6 was investigated in a filter-trap based system using transient transfection of mammalian cell lines and polyQ-huntingtin as a model for an aggregation-prone protein. Both novel mutant proteins show a significant loss of ability to prevent aggregation. (C) 2015 Elsevier B.V. All rights reserved.

Purpose Adipokines, especially leptin and adiponectin, have gained increasing importance in pathophysiology of various neurological diseases including epilepsy. There are experimental data suggesting a role for leptin in the genesis of seizures and neuroprotection related to seizures. However there are no clinical studies on the effects of epileptic seizures on adipokines. Methods We measured cerebrospinal fluid (CSF) and plasma levels of leptin, adiponectin and adipsin after provoked or unprovoked primary or secondarily generalized tonic–clonic seizures in 13 female patients and seven controls. The samples were taken within 24h after the seizure onset. Results Leptin plasma levels correlated negatively with the time to sample withdrawal, i.e. the longer the time interval between the seizure and the sample the lower the leptin levels in the patients. Interestingly, plasma adiponectin levels were significantly increased after the seizure episode. Conclusion This study provides further evidence that there are seizure-induced acute changes in adipokine metabolism. Leptin concentrations seem to decrease during the first 24h after the seizure whereas adiponectin levels increase. The meaning of this response is far from clear, but it might be an endogenous attempt to prevent harmful effects of epileptic seizures in the central nervous system.

There is limited data on electromyography (EMG) findings in other motor neuron disorders than amyotrophic lateral sclerosis (ALS). We assessed whether the distribution of active denervation detected by EMG, i.e. fibrillations and fasciculations, differs between ALS and slowly progressive motor neuron disorders. We compared the initial EMG findings of 43 clinically confirmed, consecutive ALS patients with those of 41 genetically confirmed Late-onset Spinal Motor Neuronopathy and 14 Spinal and Bulbar Muscular Atrophy patients. Spontaneous activity was more frequently detected in the first dorsal interosseus and deltoid muscles of ALS patients than in patients with the slowly progressive motor neuron diseases. The most important observation was that absent fibrillations in the first dorsal interosseus muscle identified the benign forms with sensitivities of 66%-77% and a specificity of 93%. The distribution of active denervation may help to separate ALS from mimicking disorders at an early stage.

The p.A1156T mutation alters the function of the voltage-gated sodium channel Nav1.4 on the muscle sarcolemma, causing a channelopathy without overt myotonia or periodic paralysis but with myalgic pain.A postal survey was conducted to assess the prevalence and characteristics of pain and related symptoms in individuals with the p.A1156T mutation. A specific questionnaire, intensity and interference subscales of the Brief Pain Inventory, pain drawing, Widespread Pain Index, quality of life (RAND-36), and the Beck Depression Inventory were completed.Twenty of 24 patients replied. Current pain was reported by 16 respondents; the other 4 had experienced pain previously. Most commonly, pain was widespread and exercise-induced. The severity and the impact of pain on daily life were considerable, although varied.This sodium channelopathy is another entity in the growing number of diseases causing widespread myalgic pain that resembles the pain seen in fibromyalgia syndrome. Muscle Nerve 57: 1014-1017, 2018.

Multisystem proteinopathy (MSP) involves disturbances of stress granule (SG) dynamics and autophagic protein degradation that underlie the pathogenesis of a spectrum of degenerative diseases that affect muscle, brain, and bone. Specifically, identical mutations in the autophagic adaptor SQSTM1 can cause varied penetrance of 4 distinct phenotypes: amyotrophic lateral sclerosis (ALS), frontotemporal dementia, Paget's disease of the bone, and distal myopathy. It has been hypothesized that clinical pleiotropy relates to additional genetic determinants, but thus far, evidence has been lacking. Here, we provide evidence that a TIA1 (p.N357S) variant dictates a myodegenerative phenotype when inherited, along with a pathogenic SQSTM1 mutation. Experimentally, the TIA1-N357S variant significantly enhances liquid-liquid-phase separation in vitro and impairs SG dynamics in living cells. Depletion of SQSTM1 or the introduction of a mutant version of SQSTM1 similarly impairs SG dynamics. TIA1-N357S-persistent SGs have increased association with SQSTM1, accumulation of ubiquitin conjugates, and additional aggregated proteins. Synergistic expression of the TIA1-N357S variant and a SQSTM1-A390X mutation in myoblasts leads to impaired SG clearance and myotoxicity relative to control myoblasts. These findings demonstrate a pathogenic connection between SG homeostasis and ubiquitin-mediated autophagic degradation that drives the penetrance of an MSP phenotype.

Myotonic dystrophy type 2 (DM2) is a multisystemic disorder caused by a (CCTG)n repeat expansion in intron 1 of CNBP. Transcription of the repeats causes a toxic RNA gain of function involving their accumulation in ribonuclear foci. This leads to sequestration of splicing factors and alters pre-mRNA splicing in a range of downstream effector genes, which is thought to contribute to the diverse DM2 clinical features. Hyperlipidemia is frequent in DM2 patients, but the treatment is problematic because of an increased risk of statin-induced adverse reactions. Hypothesizing that shared pathways lead to the increased risk, we compared the skeletal muscle expression profiles of DM2 patients and controls with patients with hyperlipidemia on statin therapy. Neural precursor cell expressed, developmentally downregulated-4 (NEDD4), an ubiquitin ligase, was one of the dysregulated genes identified in DM2 patients and patients with statin-treated hyperlipidemia. In DM2 muscle, NEDD4 mRNA was abnormally spliced, leading to aberrant NEDD4 proteins. NEDD4 was down-regulated in persons taking statins, and simvastatin treatment of C2C12 cells suppressed NEDD4 transcription. Phosphatase and tensin homologue (PTEN), an established NEDD4 target, was increased and accumulated in highly atrophic DM2 muscle fibers. PTEN ubiquitination was reduced in DM2 myofibers, suggesting that the NEDD4-PTEN pathway is dysregulated in DM2 skeletal muscle. Thus, this pathway may contribute to the increased risk of statin-adverse reactions in patients with DM2.

Background and purpose We have previously reported clinical, genetic and molecular pathomechanistic findings in DNAJB6 mutated LGMD1D. After publishing clinical findings of the original Finnish family we identified more Finnish, Italian and US families with the same disease, ultimately confirmed by mutations in the same gene. Methods Of the total number of 28 examined Finnish and Italian patients 23 underwent lower limb muscle imaging. Results At the early stages of the disease fatty degeneration in T1-weighed MRI sequences were observed in the soleus, adductor magnus, semimembranosus and biceps femoris muscles followed by medial gastrocnemius, adductor longus and later by vasti muscles of the quadriceps. Rectus femoris, lateral gastrocnemius, sartorius, gracilis and the anterolateral group of the lower leg muscles were spared until late senecence. The pattern of differential involvement could be identified at different stages of the disease process. Conclusions Since the general clinical findings do not provide clues for diagnosis this distinct pattern of muscle involvement and pathognomonic imaging findings are highly relevant in the clinical setting. The pattern of muscle involvement is so typical that it can be used as a differential diagnostic tool for LGMD1D. The final diagnosis however requires molecular genetic confirmation.

A novel FLNC c.5161delG (p.Gly1722ValfsTer61) mutation was identified in two members of a French family affected by distal myopathy and in one healthy relative. This FLNC c.5161delG mutation is one nucleotide away from a previously reported FLNC mutation (c.5160delC) that was identified in patients and in asymptomatic carriers of three Bulgarian families with distal muscular dystrophy, indicating a low penetrance of the FLNC frameshift mutations. Given these similarities, we believe that the two FLNC mutations alone can be causative of distal myopathy without full penetrance. Moreover, comparative analysis of the clinical manifestations indicates that patients of the French family show an earlier onset and a complete segregation of the disease. As a possible explanation of this, the two French patients also carry a OBSCN c.13330C>T (p.Arg4444Trp) mutation. The p.Arg4444Trp variant is localized within the OBSCN Ig59 domain that, together with Ig58, binds to the ZIg9/ZIg10 domains of titin at Z-disks. Structural and functional studies indicate that this OBSCN p.Arg4444Trp mutation decreases titin binding by similar to 15-fold. On this line, we suggest that the combination of the OBSCN p.Arg4444Trp variant and of the FLNC c.5161delG mutation, can cooperatively affect myofibril stability and increase the penetrance of muscular dystrophy in the French family.

Motor neuron disorders (MNDs) are a heterogeneous group of diseases that result from degeneration of motor neurons. If both upper and lower motor neurons (UMNs and LMNs) are affected, the disease is classified as amyotrophic lateral sclerosis (ALS). Primary lateral sclerosis (PLS) and progressive muscular atrophy (PMA) selectively affect the UMNs or LMNs, respectively, but are sometimes considered to be incomplete ALS variants because their phenotype may evolve into typical ALS over time. Bulbar affection in a UMN disease would favour a diagnosis of PLS over hereditary spastic paraplegia (HSP), whereas rapid progression may separate PMA from adult-onset spinal muscular atrophy (SMA). Some SMA-like or even ALS-like phenotypes have been incorporated into the large category of sensorimotor axonal neuropathies (Charcot-Marie-Tooth disease type 2, CMT2),1 although sensory abnormalities may be subtle in some forms.2 On the other hand, spinal and bulbar muscular atrophy (Kennedy disease) is classified as a form of adult-onset SMA despite prominent sensory abnormalities. It has recently been argued that the current classification system of MNDs is unsatisfactory and should be revised to include genetically and prognostically important categories.3 We have recently identified a new form of motor neuron disease in 55 patients from 17 Finnish families, where distinctive phenotype did not match any pre-existing neuromuscular disease category.4–6 Spinal muscular atrophy Jokela type (SMAJ, OMIM #615048) is characterised by painful cramps, fasciculations, decreased or absent tendon reflexes, elevated creatine kinase and hand tremor. The first symptoms appear commonly after age 30–40. Electromyography (EMG) and muscle biopsy display widespread neurogenic findings and a proportion of patients show sensory abnormalities. Muscle weakness and atrophy appear much later in the disease course, and patients have remained ambulant for several decades and their life expectancy is within normal range.4 ,5 SMAJ is caused by a dominant …

Mutations in GMPPB gene have been reported in patients with early-onset disease ranging from severe congenital muscular dystrophies to limb-girdle muscular dystrophy (LGMD) with mental retardation. More recently mutations in GMPPB have been identified with congenital myasthenic syndromes as well as milder phenotypes. We report two unrelated cases with LGMD that underwent clinical, histopathological and genetic studies. In both cases, we found identical compound heterozygous GMPPB mutations c.79G>C p.D27H and c.859C>T p.R287W, leading to a glycosylation defect of alpha-dystroglycan. The onset of muscle weakness was 30-40 years and the progression rate mild to moderate. Case 2 became wheelchair-bound at the age of 60. No cognitive or behavioral symptoms were noted. These cases provide further evidence that GMPPB mutations can also cause late-onset recessive LGMD with milder phenotypes than previously reported, and thus should be considered in the differential diagnosis of patients with adult-onset muscular dystrophies. (C) 2017 Elsevier B.V. All rights reserved.

Background and purpose The aim was to identify potential genetic risk factors associated with sporadic inclusion body myositis (sIBM). Methods An association based case-control approach was utilized on whole exome sequencing data of 30 Finnish sIBM patients and a control cohort (n = 193). A separate Italian cohort of sIBM patients (n = 12) was used for evaluation of the results. Results Seven single nucleotide polymorphisms were identified in five genes that have a considerably higher observed frequency in Finnish sIBM patients compared to the control population, and the previous association of the genetic human leukocyte antigen region was confirmed. Conclusions All seven identified variants could individually or in combination increase the susceptibility for sIBM.

Key Clinical Message Autosomal recessive spastic ataxia of Charlevoix-Saguenay is a rare disorder outside Quebec causing childhood-onset cerebellar ataxia, peripheral neuropathy, and pyramidal tract signs. A Finnish family with milder form of ARSACS was found to harbor three mutations, p.E1100K, p.N1489S, and p.M1359T, in SACS gene. The mutations segregated with the disease.

Objective: To characterize the clinical phenotype in patients with p.A1156T sodium channel mutation. Methods: Twenty-nine Finnish patients identified with the c.3466G>A p.A1156T mutation in the SCN4A gene were extensively examined. In a subsequent study, 63 patients with similar myalgic phenotype and with negative results in myotonic dystrophy type 2 genetic screening (DM2-neg group) and 93 patients diagnosed with fibromyalgia were screened for the mutation. Functional consequences of the p.A1156T mutation were studied in HEK293 cells with whole-cell patch clamp. Results: The main clinical manifestation in p.A1156T patients was not myotonia or periodic paralysis but exercise- and cold-induced muscle cramps, muscle stiffness, and myalgia. EMG myotonic discharges were detected in most but not all. Electrophysiologic compound muscle action potentials exercise test showed variable results. The p.A1156T mutation was identified in one patient in the DM2-neg group but not in the fibromyalgia group, making a total of 30 patients so far identified. Functional studies of the p.A1156T mutation showed mild attenuation of channel fast inactivation. Conclusions: The unspecific symptoms of myalgia stiffness and exercise intolerance without clinical myotonia or periodic paralysis in p.A1156T patients make the diagnosis challenging. The symptoms of milder SCN4A mutations may be confused with other similar myalgic syndromes, including fibromyalgia and myotonic dystrophy type 2.

Distal myopathies and myofibrillar myopathies are both rare subcategories of muscle diseases. Myofibrillar myopathies are genetically heterogeneous group of diseases characterized by distinctive histopathology of abnormal protein aggregations and myofibrillar disintegration. All genes causing myofibrillar myopathy encode proteins that either reside in or associate with the Z-disc. Distal myopathies are also genetically heterogeneous muscular dystrophies in which muscle weakness presents distally in the feet and/or hands. A subgroup of distal myopathies, desminopathy, distal myotilinopathy, ZASPopathy and alpha-B crystallin-mutated distal myopathy, belong to myofibrillar myopathies and show similar pathological changes in muscle biopsies. Common features of these diseases are dominant inheritance and adult-onset of symptoms starting in the feet and slowly progressing to encompass other muscle groups. Cardiomyopathy is not a common feature in distal MFM myopathies.

Late-onset autosomal dominant vocal cord and pharyngeal distal myopathy (VCPDM) was first described in an American family.1 A p.Ser85Cys mutation in MATR3 gene was later identified in this family, and also in one Bulgarian family and very recently, in seven families—six German and one Asian.2–4 Muscle pathology of VCPDM was dominated by rimmed-vacuolar fibre degeneration.1 ,2 This year, two other mutations in MATR3 , p.Phe115Cys and p.Thr622Ala, have been reported to cause autosomal dominant amyotrophic lateral sclerosis (ALS).5 The original American p.Ser85Cys mutated family was re-evaluated and the authors stated: “These clinical findings supported reclassification of this condition as slowly progressive ALS, and the presence of upper motor neuron signs in the form of brisk reflexes ruled out myopathy as the only cause of disease in this family.”5 We report a new family with the p.Ser85Cys mutation in MATR3 , in which muscle atrophy and weakness are caused by progressive degenerative myopathy without any evidence of lower motor neuron defects. We investigated an American family with four affected siblings. Patients II.1, II.2 and II.4 were more extensively examined and followed for 7, 9 and 8 years, respectively. The father and one of his brothers were affected (figure 1A). Muscle MRI was performed in the proband (II.2) and in the younger brother (II.4). Muscle biopsies were obtained from three patients and examined by standard histochemical and immunohistochemical stainings with antibodies for Matrin 3, TDP-43, p62, SMI-31 and myosin A4.74, slow (MHCs), neonatal (MHCn) and developmental (MHCd) isoforms. Immunofluorescence analysis was performed with conventional methods using antibodies for G3BP and TIA1 C-terminus. Matrin 3 distribution was analysed from soluble cytoplasmic and nuclear fractions using western blotting. Figure 1 Pedigree and muscle findings of the family. Pedigree of the family (A). Wasting of the first dorsal interossei and thenar …

Objective: To report novel disease and pathology due to HSPB8 mutations in 2 families with autosomal dominant distal neuromuscular disease showing both myofibrillar and rimmed vacuolar myopathy together with neurogenic changes. Methods: We performed whole-exome sequencing (WES) in tandem with linkage analysis and candidate gene approach as well as targeted next-generation sequencing (tNGS) to identify causative mutations in 2 families with dominant rimmed vacuolar myopathy and a motor neuropathy. Pathogenic variants and familial segregation were confirmed using Sanger sequencing. Results: WES and tNGS identified a heterozygous change in HSPB8 in both families: c.421A > G p.K141E in family 1 and c.151insC p.P173SfsX43 in family 2. Affected patients had a distal myopathy that showed myofibrillar aggregates and rimmed vacuoles combined with a clear neurogenic component both on biopsy and neurophysiologic studies. MRI of lower limb muscles demonstrated diffuse tissue changes early in the disease stage progressing later to fatty replacement typical of a myopathy. Conclusion: We expand the understanding of disease mechanisms, tissue involvement, and phenotypic outcome of HSPB8 mutations. HSPB8 is part of the chaperone-assisted selective autophagy (CASA) complex previously only associated with Charcot-Marie-Tooth type 2L (OMIM 60673) and distal hereditary motor neuronopathy type IIa. However, we now demonstrate that patients can develop a myopathy with histologic features of myofibrillar myopathy with aggregates and rimmed vacuoles, similar to the pathology in myopathies due to gene defects in other compounds of the CASA complex such as BAG3 and DNAJB6 after developing the early neurogenic effects.

Limb-girdle muscular dystrophy type 1D (LGMD1D) was linked to chromosome 7q36 over a decade ago, but its genetic cause has remained elusive. Here we studied nine LGMD-affected families from Finland, the United States and Italy and identified four dominant missense mutations leading to p.Phe93Leu or p.Phe89Ile changes in the ubiquitously expressed co-chaperone DNAJB6. Functional testing in vivo showed that the mutations have a dominant toxic effect mediated specifically by the cytoplasmic isoform of DNAJB6. In vitro studies demonstrated that the mutations increase the half-life of DNAJB6, extending this effect to the wild-type protein, and reduce its protective anti-aggregation effect. Further, we show that DNAJB6 interacts with members of the CASA complex, including the myofibrillar myopathy-causing protein BAG3. Our data identify the genetic cause of LGMD1D, suggest that its pathogenesis is mediated by defective chaperone function and highlight how mutations in a ubiquitously expressed gene can exert effects in a tissue-, isoform- and cellular compartment-specific manner.

Inclusion body myopathy with Paget disease and frontotemporal dementia (IBMPFD) is caused by mutations in the valosin-containing protein (VCP) gene. We report a new distal phenotype caused by VCP gene mutation in a Finnish family with nine affected members in three generations. Patients had onset of distal leg muscle weakness and atrophy in the anterior compartment muscles after age 35, which caused a foot drop at age 50. None of the siblings had scapular winging, proximal myopathy, cardiomyopathy or respiratory problems during long-term follow-up. Three distal myopathy patients developed rapidly progressive dementia, became bedridden and died of cachexia and pneumonia and VCP gene mutation P137L (c.410C>T) was then identified in the family. Late onset autosomal dominant distal myopathy with rimmed vacuolar muscle pathology was not sufficient for exact diagnosis in this family until late-occurring dementia provided the clue for molecular diagnosis. VCP needs to be considered in the differential diagnostic work-up in patients with distal myopathy phenotype.

ObjectiveWe used patient-specific neuronal cultures to characterize the molecular genetic mechanism of recessive nonsense mutations in neurofilament light (NEFL) underlying early-onset Charcot-Marie-Tooth (CMT) disease.MethodsMotor neurons were differentiated from induced pluripotent stem cells of a patient with early-onset CMT carrying a novel homozygous nonsense mutation in NEFL. Quantitative PCR, protein analytics, immunocytochemistry, electron microscopy, and single-cell transcriptomics were used to investigate patient and control neurons.ResultsWe show that the recessive nonsense mutation causes a nearly total loss of NEFL messenger RNA (mRNA), leading to the complete absence of NEFL protein in patient's cultured neurons. Yet the cultured neurons were able to differentiate and form neuronal networks and neurofilaments. Single-neuron gene expression fingerprinting pinpointed NEFL as the most downregulated gene in the patient neurons and provided data of intermediate filament transcript abundancy and dynamics in cultured neurons. Blocking of nonsense-mediated decay partially rescued the loss of NEFL mRNA.ConclusionsThe strict neuronal specificity of neurofilament has hindered the mechanistic studies of recessive NEFL nonsense mutations. Here, we show that such mutation leads to the absence of NEFL, causing childhood-onset neuropathy through a loss-of-function mechanism. We propose that the neurofilament accumulation, a common feature of many neurodegenerative diseases, mimics the absence of NEFL seen in recessive CMT if aggregation prevents the proper localization of wild-type NEFL in neurons. Our results suggest that the removal of NEFL as a proposed treatment option is harmful in humans.