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Fortschritte Der Neurologie-Psychiatrie Sep 2022Myotonia congenita was first described as an entity in 1876 by Julius Thomsen. Shortly later in the same year it was criticized by Adolph Seeligmüller who extended the...
Myotonia congenita was first described as an entity in 1876 by Julius Thomsen. Shortly later in the same year it was criticized by Adolph Seeligmüller who extended the clinical findings. Charles Bell, Moritz Benedict and Ernst von Leyden had already partly described the symptoms of the disease before 1876, but did not recognize this as a new entity. A comparison of the publications of Thomsen and Seeligmüller in 1876 and of Seeligmüller's textbook published in 1887, as well as the today's genetically proven disease shows that Seeligmüller correctly criticized two aspects of Thomsen's publication: (i) Thomsen suspected the pathogenesis to be in "one half of the brain's activity, the will" with "seat in the cerebrospinal system" and (ii) he made the assumption of a coordination disorder in the sense of an ataxia [1]. Due to a better understanding of the pathogenesis enabled by Seeligmüller's postulate of a "more difficult mobile muscle substance" [2] without excluding an inborn affection of the lateral cords of the spinal cord, it would have been entirely justified to recognize Seeligmüller's contribution to the conceptual history of Myotonia congenita by including his name in the eponym [3].
Topics: Humans; Male; Muscles; Myotonia Congenita
PubMed: 34448176
DOI: 10.1055/a-1552-3528 -
Genes Jun 2023Congenital myopathies are a group of clinically, genetically, and histologically heterogeneous diseases caused by mutations in a large group of genes. One of these is ,... (Review)
Review
BACKGROUND
Congenital myopathies are a group of clinically, genetically, and histologically heterogeneous diseases caused by mutations in a large group of genes. One of these is , which is recognized as the cause of Dihydropyridine Receptor Congenital Myopathy.
METHODS
To better characterize the phenotypic spectrum of myopathy, we conducted a systematic review of cases in the literature through three electronic databases following the PRISMA guidelines. We selected nine articles describing 23 patients with heterozygous, homozygous, or compound heterozygous mutations in and we added one patient with a compound heterozygous mutation in (c.1394-2A>G; c.1724T>C, p.L575P) followed at our Institute. We collected clinical and genetic data, muscle biopsies, and muscle MRIs when available.
RESULTS
The phenotype of this myopathy is heterogeneous, ranging from more severe forms with a lethal early onset and mild-moderate forms with a better clinical course.
CONCLUSIONS
Our patient presented a phenotype compatible with the mild-moderate form, although she presented peculiar features such as a short stature, myopia, mild sensorineural hearing loss, psychiatric symptoms, and posterior-anterior impairment gradient on thigh muscle MRI.
Topics: Female; Humans; Calcium Channels, L-Type; Muscular Diseases; Mutation; Muscle, Skeletal; Phenotype; Myotonia Congenita
PubMed: 37510268
DOI: 10.3390/genes14071363 -
Neuromuscular Disorders : NMD Jul 2020Skeletal muscle channelopathies, including non-dystrophic myotonia and periodic paralysis, are rare hereditary disorders caused by mutations of various ion channel...
Skeletal muscle channelopathies, including non-dystrophic myotonia and periodic paralysis, are rare hereditary disorders caused by mutations of various ion channel genes. To define the frequency of associated mutations of skeletal muscle channelopathies in Japan, clinical and genetic data of two academic institutions, which provides genetic analysis service, were reviewed. Of 105 unrelated pedigrees genetically confirmed, 66 pedigrees were non-dystrophic myotonias [CLCN1 (n = 30) and SCN4A (n = 36)], 11 were hyperkalemic periodic paralysis (SCN4A), and 28 were hypokalemic periodic paralysis [CACNA1S (n = 16) and SCN4A (n = 12)]. Of the 30 families with myotonia congenita, dominant form (Thomsen type) consisted 67%, and unique mutations, A298T, P480T, T539A, and M560T, not found in Western countries, were commonly identified in CLCN1. Hypokalemic periodic paralysis caused by SCN4A mutations consisted 43% in Japan, which was much higher than previous reports. Furthermore, the quality of life of the patients was assessed using the patient-reported outcome measures, SF-36 and INQoL, for 41 patients. This study indicated that the etiology of skeletal muscle channelopathies in Japan was not identical to previous reports from Western countries, and provided crucial information for genetics as well as future therapeutic interventions.
Topics: Adult; Calcium Channels, L-Type; Channelopathies; Female; Genetic Testing; Health Status; Humans; Hypokalemic Periodic Paralysis; Japan; Male; Middle Aged; Muscle, Skeletal; Mutation; Myotonia; Myotonic Disorders; NAV1.4 Voltage-Gated Sodium Channel; Paralysis, Hyperkalemic Periodic; Pedigree; Quality of Life; Surveys and Questionnaires; Young Adult
PubMed: 32660787
DOI: 10.1016/j.nmd.2020.06.001 -
International Journal of Molecular... Oct 2022Nemaline myopathy (NM), a structural congenital myopathy, presents a significant clinical and genetic heterogeneity. Here, we compiled molecular and clinical data of 30...
Nemaline myopathy (NM), a structural congenital myopathy, presents a significant clinical and genetic heterogeneity. Here, we compiled molecular and clinical data of 30 Brazilian patients from 25 unrelated families. Next-generation sequencing was able to genetically classify all patients: sixteen families (64%) with mutation in NEB, five (20%) in ACTA1, two (8%) in KLHL40, and one in TPM2 (4%) and TPM3 (4%). In the NEB-related families, 25 different variants, 11 of them novel, were identified; splice site (10/25) and frame shift (9/25) mutations were the most common. Mutation c.24579 G>C was recurrent in three unrelated patients from the same region, suggesting a common ancestor. Clinically, the “typical” form was the more frequent and caused by mutations in the different NM genes. Phenotypic heterogeneity was observed among patients with mutations in the same gene. Respiratory involvement was very common and often out of proportion with limb weakness. Muscle MRI patterns showed variability within the forms and genes, which was related to the severity of the weakness. Considering the high frequency of NEB mutations and the complexity of this gene, NGS tools should be combined with CNV identification, especially in patients with a likely non-identified second mutation.
Topics: Brazil; Humans; Muscle Proteins; Muscle, Skeletal; Mutation; Myopathies, Nemaline; Myotonia Congenita
PubMed: 36233295
DOI: 10.3390/ijms231911995 -
Neurological Sciences : Official... Dec 2021Myotonic disorders are a group of diseases affecting the muscle, in different ways. Myotonic dystrophy type 1 (DM1) is related to (CTG)n expansion in the 3-untranslated...
INTRODUCTION
Myotonic disorders are a group of diseases affecting the muscle, in different ways. Myotonic dystrophy type 1 (DM1) is related to (CTG)n expansion in the 3-untranslated region of the dystrophia myotonica protein kinase (DMPK) gene and is the most frequent and disabling form, causing muscular, visibility, respiratory, and cardiac impairment. Non-dystrophic myotonias (NDMs) affect the skeletal muscle alone. In particular, mutations in the chloride channel (CLCN1) gene cause myotonia congenita (MC), which can have autosomal dominant or recessive inheritance.
CASE REPORT
We describe a patient with a family history of asymptomatic or paucisymptomatic myotonia, who presented handgrip myotonia which sharply reduced after mexiletine administration. Molecular analysis showed both a paternally inherited DMPK expansion and a maternally inherited CLCN1 mutation.
CONCLUSIONS
Only one other similar case was reported so far; however, the segregation of the two mutations and the characteristics of the muscle were not studied. Since our patient lacked the classical phenotypical and muscle histopathological characteristics of DM1 and showed mild splicing alterations despite a pathogenic DMPK expansion and the nuclear accumulation of toxic RNA, we may speculate that the co-occurrence of a CLCN1 mutation could have attenuated the severity of DM1 phenotype.
Topics: Chloride Channels; Hand Strength; Humans; Mutation; Myotonia; Myotonia Congenita; Myotonic Dystrophy; Myotonin-Protein Kinase
PubMed: 34386887
DOI: 10.1007/s10072-021-05538-y -
Journal of Veterinary Internal Medicine Jul 2022A 10-month-old castrated male domestic longhair cat was evaluated for increasing frequency of episodic limb rigidity.
CASE DESCRIPTION
A 10-month-old castrated male domestic longhair cat was evaluated for increasing frequency of episodic limb rigidity.
CLINICAL FINDINGS
The cat presented for falling over and lying recumbent with its limbs in extension for several seconds when startled or excited. Upon examination, the cat had hypertrophied musculature, episodes of facial spasm, and a short-strided, stiff gait.
DIAGNOSTICS
Electromyography (EMG) identified spontaneous discharges that waxed and waned in amplitude and frequency, consistent with myotonic discharges. A high impact 8-base pair (bp) deletion across the end of exon 3 and intron 3 of the chloride voltage-gated channel 1 (CLCN1) gene was identified using whole genome sequencing.
TREATMENT AND OUTCOME
Phenytoin treatment was initiated at 3 mg/kg po q24 h and resulted in long-term improvement.
CLINICAL RELEVANCE
This novel mutation within the CLCN1 gene is a cause of myotonia congenita in cats and we report for the first time its successful treatment.
Topics: Animals; Cat Diseases; Cats; Chloride Channels; Electromyography; Exons; Male; Mutation; Myotonia Congenita
PubMed: 35815860
DOI: 10.1111/jvim.16471 -
Frontiers in Neuroscience 2022Optically pumped magnetometers (OPM) are quantum sensors that enable the contactless, non-invasive measurement of biomagnetic muscle signals, i.e., magnetomyography...
Optically pumped magnetometers (OPM) are quantum sensors that enable the contactless, non-invasive measurement of biomagnetic muscle signals, i.e., magnetomyography (MMG). Due to the contactless recording, OPM-MMG might be preferable to standard electromyography (EMG) for patients with neuromuscular diseases, particularly when repetitive recordings for diagnostic and therapeutic monitoring are mandatory. OPM-MMG studies have focused on recording physiological muscle activity in healthy individuals, whereas research on neuromuscular patients with pathological altered muscle activity is non-existent. Here, we report a proof-of-principle study on the application of OPM-MMG in patients with neuromuscular diseases. Specifically, we compare the muscular activity during maximal isometric contraction of the left rectus femoris muscle in three neuromuscular patients with severe (Transthyretin Amyloidosis in combination with Pompe's disease), mild (Charcot-Marie-Tooth disease, type 2), and without neurogenic, but myogenic, damage (Myotonia Congenita). Seven healthy young participants served as the control group. As expected, and confirmed by using simultaneous surface electromyography (sEMG), a time-series analysis revealed a dispersed interference pattern during maximal contraction with high amplitudes. Furthermore, both patients with neurogenic damage (ATTR and CMT2) showed a reduced variability of the MMG signal, quantified as the signal standard deviation of the main component of the frequency spectrum, highlighting the reduced possibility of motor unit recruitment due to the loss of motor neurons. Our results show that recording pathologically altered voluntary muscle activity with OPM-MMG is possible, paving the way for the potential use of OPM-MMG in larger studies to explore the potential benefits in clinical neurophysiology.
PubMed: 36523432
DOI: 10.3389/fnins.2022.1010242 -
Frontiers in Pharmacology 2022Myotonia congenita (MC) is an inherited rare disease characterized by impaired muscle relaxation after contraction, resulting in muscle stiffness. It is caused by...
Myotonia congenita (MC) is an inherited rare disease characterized by impaired muscle relaxation after contraction, resulting in muscle stiffness. It is caused by loss-of-function mutations in the skeletal muscle chloride channel ClC-1, important for the stabilization of resting membrane potential and for the repolarization phase of action potentials. Thanks to functional studies, the molecular mechanisms by which ClC-1 mutations alter chloride ion influx into the cell have been in part clarified, classifying them in "gating-defective" or "expression-defective" mutations. To date, the treatment of MC is only palliative because no direct ClC-1 activator is available. An ideal drug should be one which is able to correct biophysical defects of ClC-1 in the case of gating-defective mutations or a drug capable to recover ClC-1 protein expression on the plasma membrane for trafficking-defective ones. In this study, we tested the ability of niflumic acid (NFA), a commercial nonsteroidal anti-inflammatory drug, to act as a pharmacological chaperone on trafficking-defective MC mutants (A531V, V947E). Wild-type (WT) or MC mutant ClC-1 channels were expressed in HEK293 cells and whole-cell chloride currents were recorded with the patch-clamp technique before and after NFA incubation. Membrane biotinylation assays and western blot were performed to support electrophysiological results. A531V and V947E mutations caused a decrease in chloride current density due to a reduction of ClC-1 total protein level and channel expression on the plasma membrane. The treatment of A531V and V947E-transfected cells with 50 µM NFA restored chloride currents, reaching levels similar to those of WT. Furthermore, no significant difference was observed in voltage dependence, suggesting that NFA increased protein membrane expression without altering the function of ClC-1. Indeed, biochemical experiments confirmed that V947E total protein expression and its plasma membrane distribution were recovered after NFA incubation, reaching protein levels similar to WT. Thus, the use of NFA as a pharmacological chaperone in trafficking defective ClC-1 channel mutations could represent a good strategy in the treatment of MC. Because of the favorable safety profile of this drug, our study may easily open the way for confirmatory human pilot studies aimed at verifying the antimyotonic activity of NFA in selected patients carrying specific ClC-1 channel mutations.
PubMed: 36034862
DOI: 10.3389/fphar.2022.958196 -
Revista de Neurologia Feb 2023Myotonia congenita is the most common form of genetic myotonia and is caused by mutations in the CLCN1 gene. It can be inherited in an autosomal dominant or recessive...
INTRODUCTION
Myotonia congenita is the most common form of genetic myotonia and is caused by mutations in the CLCN1 gene. It can be inherited in an autosomal dominant or recessive manner. We present a series of cases to update its incidence in our environment, to describe its phenotype in relation to the genotype found, and we also review the mutations found, among which we provide a new, undescribed alteration.
CASES REPORT
The medical records of patients with a diagnosis of congenital myotonia studied and followed up in the pediatric neurology section in a tertiary hospital between the years 2015-2020 were reviewed. Demographic variables (age, sex), disease course (age of onset, symptoms and signs, time elapsed until diagnosis, clinical evolution), family history and evaluation of response to treatment were collected. Five cases with a clinical diagnosis of myotonia congenita were identified (three with Becker's disease and two with Thomsen's disease). The incidence in relation to the number of births is estimated at 1:15,000 newborns for cases with the Becker phenotype and 1:21,000 newborns for the Thomsen phenotypes. We found a probably pathogenic mutation not previously described (CLCN1: c.824T> C).
CONCLUSIONS
the approximate incidence in our environment was higher than previously known and we describe a new, undescribed mutation: c.824T> C with pathogenicity predictors that behaved like a Becker recessive phenotype but with an earlier debut.
Topics: Humans; Myotonia Congenita; Incidence; Chloride Channels; Mutation; Muscular Dystrophy, Duchenne; Pedigree
PubMed: 36782350
DOI: 10.33588/rn.7604.2021357 -
PloS One 2020Myotonia congenita and hypokalemic periodic paralysis type 2 are both rare genetic channelopathies caused by mutations in the CLCN1 gene encoding voltage-gated chloride...
Myotonia congenita and hypokalemic periodic paralysis type 2 are both rare genetic channelopathies caused by mutations in the CLCN1 gene encoding voltage-gated chloride channel CLC-1 and the SCN4A gene encoding voltage-gated sodium channel Nav1.4. The patients with concomitant mutations in both genes manifested different unique symptoms from mutations in these genes separately. Here, we describe a patient with myotonia and periodic paralysis in a consanguineous marriage pedigree. By using whole-exome sequencing, a novel F306S variant in the CLCN1 gene and a known R222W mutation in the SCN4A gene were identified in the pedigree. Patch clamp analysis revealed that the F306S mutant reduced the opening probability of CLC-1 and chloride conductance. Our study expanded the CLCN1 mutation database. We emphasized the value of whole-exome sequencing for differential diagnosis in atypical myotonic patients.
Topics: Adolescent; Adult; Aged; Amino Acid Sequence; China; Chloride Channels; Consanguinity; Conserved Sequence; Diagnosis, Differential; Female; HEK293 Cells; Humans; Hypokalemic Periodic Paralysis; Male; Middle Aged; Models, Molecular; Mutant Proteins; Mutation; Myotonia Congenita; NAV1.4 Voltage-Gated Sodium Channel; Pedigree; Recombinant Proteins; Exome Sequencing; Young Adult
PubMed: 32407401
DOI: 10.1371/journal.pone.0233017