Internal Nuclei Research Articles

HMGCS1 variants cause rigid spine syndrome amenable to mevalonic acid treatment in an animal model.

Rigid spine syndrome is a rare childhood-onset myopathy characterised by slowly progressive or non-progressive scoliosis, neck and spine contractures, hypotonia, and respiratory insufficiency. Biallelic variants in SELENON account for most cases of rigid spine syndrome, however, the underlying genetic cause in some patients remains unexplained. We used exome and genome sequencing to investigate the genetic basis of rigid spine syndrome in patients without a genetic diagnosis. In five patients from four unrelated families, we identified biallelic variants in HMGCS1 (3-hydroxy-3-methylglutaryl-coenzyme A synthase). These included six missense variants and one frameshift variant distributed throughout HMGCS1. All patients presented with spinal rigidity primarily affecting the cervical and dorsolumbar regions, scoliosis, and respiratory insufficiency. Creatine kinase levels were variably elevated. The clinical course worsened with intercurrent disease or certain drugs in some patients; one patient died from respiratory failure following infection. Muscle biopsies revealed irregularities in oxidative enzyme staining with occasional internal nuclei and rimmed vacuoles. HMGCS1 encodes a critical enzyme of the mevalonate pathway and has not yet been associated with disease. Notably, biallelic hypomorphic variants in downstream enzymes including HMGCR and GGPS1 are associated with muscular dystrophy resembling our cohort's presentation. Analyses of recombinant human HMGCS1 protein and four variants (p.S447P, p.Q29L, p.M70T, p.C268S) showed that all mutants maintained their dimerization state. Three of the four mutants exhibited reduced thermal stability, and two mutants showed subtle changes in enzymatic activity compared to the wildtype. Hmgcs1 mutant zebrafish displayed severe early defects, including immobility at 2 days and death by day 3 post-fertilisation and were rescued by HMGCS1 mRNA. We demonstrate that the four variants tested (S447P, Q29L M70T, and C268S) have reduced function compared to wildtype HMGCS1 in zebrafish rescue assays. Additionally, we demonstrate the potential for mevalonic acid supplementation to reduce phenotypic severity in mutant zebrafish. Overall, our analyses suggest that these missense variants in HMGCS1 act through a hypomorphic mechanism. Here, we report an additional component of the mevalonate pathway associated with disease and suggest biallelic variants in HMGCS1 should be considered in patients presenting with an unresolved rigid spine myopathy phenotype. Additionally, we highlight mevalonoic acid supplementation as a potential treatment for patients with HMGCS1-related disease.

Trace element detection in anhydrous minerals by micro-scale quantitative nuclear magnetic resonance spectroscopy

Nominally anhydrous minerals (NAMs) composing Earth’s and planetary rocks incorporate microscopic amounts of volatiles. However, volatile distribution in NAMs and their effect on physical properties of rocks remain controversial. Thus, constraining trace volatile concentrations in NAMs is tantamount to our understanding of the evolution of rocky planets and planetesimals. Here, we present an approach of trace-element quantification using micro-scale Nuclear Magnetic Resonance (NMR) spectroscopy. This approach employs the principle of enhanced mass-sensitivity in NMR microcoils. We were able to demonstrate that this method is in excellent agreement with standard methods across their respective detection capabilities. We show that by simultaneous detection of internal reference nuclei, the quantification sensitivity can be substantially increased, leading to quantifiable trace volatile element amounts of about 50 ng/g measured in a micro-meter sized single anorthitic mineral grain, greatly enhancing detection capabilities of volatiles in geologically important systems.

Pathogenic role of anti-cN1A autoantibodies in sporadic inclusion body myositis

BackgroundSporadic inclusion body myositis (sIBM) is an intractable muscle disease that frequently affects elderly people. Autoantibodies recognising cytosolic 5’-nucleotidase 1A (cN1A) were found in the sera of patients with sIBM....

The clinical features and TCAP mutation spectrum in a Chinese cohort of patients with limb-girdle muscular dystrophy R7.

Limb-girdle muscular dystrophy R7 (LGMDR7) is an autosomal recessive hereditary muscular dystrophy caused by mutations in titin-cap (TCAP). Here, we summarized the clinical characteristics and TCAP mutations in a Chinese cohort of 30 patients with LGMDR7. The onset age of Chinese patients was 19.89 ± 6.70years old, which is later than European and South Asian patients (P < 0.05). Clinically speaking, 20.0% of patients presented with predominant distal weakness, and 73.3% of patients presented with predominant pelvic girdle weakness. Radiological study revealed semitendinosus and magnus adductor were severely involved in Chinese LGMDR7 patients. Rectus femoris, vastus lateralis, vastus intermedius, soleus and tibialis anterior were moderately to severely involved. The most prevalent mutation in this cohort is c.26_33dupAGGTGTCG, while c.165dupG and c.110 + 5G > A are unique in Chinese population as two of the common mutations. Besides, variant c.26_33dupAGGGTGTCG might be a founder mutation in Asian patients. Internal nuclei, lobulated fibers, and scattered rimmed vacuoles were typical morphological changes in Chinese LGMDR7 patients. This is the largest LGMDR7 cohort in the Chinese population and in the world. This article also expands the clinical, pathological, mutational and radiological spectrum of patients with LGMDR7 in China and in the world.

Myalgia in a Patient with Adult-Onset Asthma with Periocular Xanthogranuloma (AAPOX) due to Myotonic Dystrophy type 2 (P6-8.013)

<h3>Objective:</h3> To report a patient with myotonic dystrophy type 2 (DM2) and an adult-onset asthma with periocular xanthogranuloma (AAPOX). <h3>Background:</h3> AAPOX is a rare systemic non-Langerhans histiocytosis, clinically characterized by periocular yellowish plaques, adult-onset asthma, and lymphadenopathy, and pathologically characterized by non-caseating granulomas consisting of foamy histiocytes and Touton giant cells. The etiology of AAPOX is unknown, but recent studies suggested a possible link to IgG4-related disease. Autoimmune diseases occur in up to 30% of myotonic dystrophy type 2 (DM2) patients but concomitant AAPOX and DM2 have never been reported. <h3>Design/Methods:</h3> Case report. <h3>Results:</h3> A 38-year-old man with hyperlipidemia presented with 1.5-year history of progressive bilateral periorbital swelling and periocular yellowish plaques, 1-year history of asthma and exercise intolerance, and 4-month history of rosuvastatin-associated myalgias and difficulty climbing stairs. Periorbital soft tissue biopsy revealed characteristic pathological features of AAPOX. Neurologic examination revealed neither weakness nor clinical myotonia. Family history was significant for bradyarrhythmia requiring pacemaker in his mother and maternal grandfather. The patient’s creatine kinase was elevated at 606 U/L (normal &lt; 308 U/L). HMGCR-IgG was negative. IgG4 level was normal. Electromyography revealed diffuse myotonic discharges and a mild proximal myopathy without fibrillation potentials. A triceps brachii biopsy showed a marked increase of fibers harboring internal nuclei, scattered pyknotic nuclear clumps, and type 1 fiber smallness without granulomas. Genetic testing revealed a heterozygous CCTG repeat expansion &gt; 15,600 base pairs in intron 1 of <i>CNBP</i>, consistent with a diagnosis of DM2. His cardiac evaluation was unrevealing. The patient was treated with prednisone and methotrexate with improvement of his periocular disease. Myalgias persisted despite discontinuation of rosuvastati <h3>Conclusions:</h3> We first report the cooccurrence of AAPOX and DM2. Our finding supports the increased risk of autoimmune diseases in DM2 patients. <b>Disclosure:</b> Dr. Skolka has nothing to disclose. The institution of Shreyasee Amin has received research support from NIH. Dr. Liewluck has nothing to disclose.

Dominantly inherited myosin IIa myopathy caused by aberrant splicing of MYH2

BackgroundMyosin heavy chain (MyHC) isoforms define the three major muscle fiber types in human extremity muscles. Slow beta/cardiac MyHC (MYH7) is expressed in type 1 muscle fibers. MyHC IIa (MYH2) and MyHC IIx (MYH1) are expressed in type 2A and 2B fibers, respectively. Whereas recessive MyHC IIa myopathy has been described in many cases, myopathy caused by dominant MYH2 variants is rare and has been described with clinical manifestations and muscle pathology in only one family and two sporadic cases.MethodsWe investigated three patients from one family with a dominantly inherited myopathy by clinical investigation, whole-genome sequencing, muscle biopsy, and magnetic resonance imaging (MRI).ResultsThree siblings, one woman and two men now 54, 56 and 66 years old, had experienced muscle weakness initially affecting the lower limbs from young adulthood. They have now generalized proximal muscle weakness affecting ambulation, but no ophthalmoplegia. Whole-genome sequencing identified a heterozygous MYH2 variant, segregating with the disease in the three affected individuals: c.5673 + 1G > C. Analysis of cDNA confirmed the predicted splicing defect with skipping of exon 39 and loss of residues 1860–1891 in the distal tail of the MyHC IIa, largely overlapping with the filament assembly region (aa1877–1905). Muscle biopsy in two of the affected individuals showed prominent type 1 muscle fiber predominance with only a few very small, scattered type 2A fibers and no type 2B fibers. The small type 2A fibers were frequently hybrid fibers with either slow MyHC or embryonic MyHC expression. The type 1 fibers showed variation in fiber size, internal nuclei and some structural alterations. There was fatty infiltration, which was also demonstrated by MRI.ConclusionDominantly inherited MyHC IIa myopathy due to a splice defect causing loss of amino acids 1860–1891 in the distal tail of the MyHC IIa protein including part of the assembly competence domain. The myopathy is manifesting with slowly progressive muscle weakness without overt ophthalmoplegia and markedly reduced number and size of type 2 fibers.

Немалиновая миопатия редкой формы (случай из практики)

Introduction Nemaline myopathies (NM) are a group of neuromuscular diseases, the distinctive histological feature of which are nemaline rods in myosymplasts. The purpose of this work is to describe the morphology of a rare form of primary nemaline myopathy that progresses in adulthood. Material and methods The surgical material of the paravertebral muscles of a 51-year-old patient with scoliotic deformity at the level of L4-S1, who was repeatedly operated on to correct spinal deformity due to neurological disorders, was studied. Paraffin sections were stained with hematoxylineosin, according to Masson, using the Ptah method, studied using a 3DHISTECH Pannoramic MIDI II BF scanning microscope to digitize preparations using Whole slide imaging technology in two modes: Single layer mode and Extended focus (3DHISTECH, Hungary). Results In the fragments of the altered muscle tissue, filamentous structures of nemaline bodies in myosymplasts were identified, which were located diffusely-dotted throughout the sarcoplasm or formed clusters of various configurations. There was an increased variability in the diameters of muscle fibers, internal nuclei, myosymplasts altered by contraction and with signs of myophagy, patterns of gradual replacement of muscle fibers by adipocytes, massive fatty degeneration of fibers, and fibrosis of the interstitial space. Intramuscular nerve trunks showed signs of complete involution; fibrous perineurium was preserved, and there were single nerve fibers; neuromuscular spindles were distinguished by an enlarged connective tissue capsule. The vessels of the arterial flow had signs of fibrosis and obliteration of the lumen; the vessels of the venous bed were tortuous. Discussion Due to a large number of genes responsible for NM, genetic search can be difficult and is effective only in 50 % of cases. It has been established that nemaline bodies can be distributed diffusely or form clusters of irregular shape, more often subsarcolemmal and characteristic of small fibers. In the presented clinical case, nemaline bodies were observed over the entire area of the fibers and were characteristic of myosymplasts of various sizes. Conclusion The histopathological study of the paravertebral muscles established the neuromuscular nature of the disease, being nemaline myopathy that progressed in adulthood and had not been diagnosed at previous stages of treatment.

O.11 Identification of a novel heterozygous DYSF variant in a large family with a dominantly-inherited dysferlinopathy

Dysferlinopathy is an autosomal recessive muscular dystrophy, caused by bi-allelic variants in the gene encoding dysferlin (<i>DYSF</i>). Onset typically occurs in the second to third decade and is characterised by slowly progressive skeletal muscle weakness and atrophy of proximal and/or distal muscles of the limb girdles. There are rare cases of symptomatic <i>DYSF</i> variant carriers. Here, we report a large family with a dominantly inherited hyperCKemia and late-onset muscular dystrophy. Genetic analysis identified a co-segregating novel <i>DYSF</i> variant [NM_003494.4: c.6207del, p.(Tyr2070Metfs*4)]. No secondary variants in <i>DYSF</i> or other dystrophy-related genes were identified on whole genome sequencing and analysis of the proband's DNA. Skeletal muscle involvement was milder and later onset than typical dysferlinopathy presentations; these clinical signs manifested in only three individuals, all between the fourth and sixth decades of life. All individuals heterozygous for the c.6207del variant had hyperCKemia. Histological analysis of skeletal muscle biopsies across three generations showed clear dystrophic signs, including inflammatory infiltrate, regenerating myofibres, increased variability in myofibre size, and internal nuclei. Muscle magnetic resonance imaging revealed fatty replacement of muscle in two individuals. Western blot and immunohistochemical analysis of muscle biopsy demonstrated consistent reduction of dysferlin staining. Allele-specific quantitative PCR analysis of <i>DYSF</i> mRNA from patient muscle found that the variant, localised to the extreme C-terminus of dysferlin, does not activate post-transcriptional mRNA decay. We propose that this inheritance pattern may be underappreciated and that other late-onset muscular dystrophy cases with mono-allelic <i>DYSF</i> variants, particularly C-terminal premature truncation variants, may represent dominant forms of disease.

P.79 Late onset oculopharyngeal muscular dystrophy in a POLG1-related progressive external ophthalmoplegia (PEO), a diagnostic challenge

POLG1, a nuclear gene, encodes the catalytic subunit of mitochondrial DNA polymerase γ involved in mtDNA maintenance. Autosomal dominant or recessive inherited phenotypes related to POLG1 mutations display clinical variability, including isolated or syndromic progressive external ophthalmoplegia (PEO). Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset autosomal dominant myopathy characterized by progressive ptosis, dysphagia, and limb weakness. In OPMD patients, the 5’ (GCN)10 repeat region of the PABPN1 gene is abnormally expanded up to 17 repeats. The (GCN)11 enlarged repeat allele is described as a polymorphism or a recessive allele. However, rare cases of patients with a single (GCN)11 heterozygous allele are known to express a late-onset OPMD phenotype. Reporting a patient associating POLG1 compound heterozygous mutations and a PABPN1 (GCN)11 heterozygous expansion with mixed phenotype, we aim to point out the potential clinical overlap and diagnostic challenge linked to these entities. A 74-year-old male patient presented with progressive bilateral ptosis and mild dysphagia at the age of 70. CK and lactate levels were normal. Electrodiagnostic tests demonstrated a mild sensory neuropathy and muscle biopsy showed atrophic and necrotic fibers, increased internal nuclei and twelve COX-negative fibers. Electron microscopy identified electrodense deposits in mitochondria but no intranuclear inclusions. Muscle oxidative phosphorylation analyses demonstrated complexes I and II diminished activities. POLG1 sequencing revealed the previously described c.1760C>T, p.(Pro587Leu) pathogenic variant and the c.233T>A, p.(Met78Lys) novel variant. Segregation study allowed to conclude a trans conformation in the proband. We report a patient presenting with progressive ptosis associated with two potential coexisting etiologies ascertained by polemic evidence. On one hand, biallelic variants were found on his POLG1 gene, associated with features of mitochondrial defects on muscle biopsy. On the other hand, the phenotype also fits with OPMD and is associated with a PABPN1 (GCN)11 heterozygous expansion allele. This peculiar observation illustrates the potential diagnostic challenge that may represent a progressive ptosis, especially in elderly patients. POLG1, a nuclear gene, encodes the catalytic subunit of mitochondrial DNA polymerase γ involved in mtDNA maintenance. Autosomal dominant or recessive inherited phenotypes related to POLG1 mutations display clinical variability, including isolated or syndromic progressive external ophthalmoplegia (PEO). Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset autosomal dominant myopathy characterized by progressive ptosis, dysphagia, and limb weakness. In OPMD patients, the 5’ (GCN)10 repeat region of the PABPN1 gene is abnormally expanded up to 17 repeats. The (GCN)11 enlarged repeat allele is described as a polymorphism or a recessive allele. However, rare cases of patients with a single (GCN)11 heterozygous allele are known to express a late-onset OPMD phenotype. Reporting a patient associating POLG1 compound heterozygous mutations and a PABPN1 (GCN)11 heterozygous expansion with mixed phenotype, we aim to point out the potential clinical overlap and diagnostic challenge linked to these entities. A 74-year-old male patient presented with progressive bilateral ptosis and mild dysphagia at the age of 70. CK and lactate levels were normal. Electrodiagnostic tests demonstrated a mild sensory neuropathy and muscle biopsy showed atrophic and necrotic fibers, increased internal nuclei and twelve COX-negative fibers. Electron microscopy identified electrodense deposits in mitochondria but no intranuclear inclusions. Muscle oxidative phosphorylation analyses demonstrated complexes I and II diminished activities. POLG1 sequencing revealed the previously described c.1760C>T, p.(Pro587Leu) pathogenic variant and the c.233T>A, p.(Met78Lys) novel variant. Segregation study allowed to conclude a trans conformation in the proband. We report a patient presenting with progressive ptosis associated with two potential coexisting etiologies ascertained by polemic evidence. On one hand, biallelic variants were found on his POLG1 gene, associated with features of mitochondrial defects on muscle biopsy. On the other hand, the phenotype also fits with OPMD and is associated with a PABPN1 (GCN)11 heterozygous expansion allele. This peculiar observation illustrates the potential diagnostic challenge that may represent a progressive ptosis, especially in elderly patients.

AFM imaging of the transcriptionally active chromatin in mammalian cells' nuclei

BackgroundNuclear rigidity is traditionally associated with lamina and densely packed heterochromatin. Actively transcribed DNA is thought to be less densely packed. Currently, approaches for direct measurements of the transcriptionally active chromatin rigidity are quite limited. MethodsIsolated nuclei were subjected to mechanical stress at 60 g and analyzed by Atomic Force Microscopy (AFM). ResultsNuclei of the normal fibroblast cells were completely flattened under mechanical stress, whereas nuclei of the cancerous HeLa were extremely resistant. In the deformed HeLa nuclei, AFM revealed a highly-branched landscape assembled of ~400 nm closed-packed globules and their structure was changing in response to external influence. Normal and cancerous cells' isolated nuclei were strikingly different by DNA resistance to applied mechanical stress. Paradoxically, more transcriptionally active and less optically dense chromatin of the nuclei of the cancerous cells demonstrated higher physical rigidity. A high concentration of the transcription inhibitor actinomycin D led to complete flattening of HeLa nuclei, that might be related to the relaxation of supercoiled DNA tending to deformation. At a low concentration of actinomycin D, we observed the intermediary formation of stochastically distributed nanoloops and nanofilaments with different shapes but constant width ~ 180 nm. We related this phenomenon with partial DNA relaxation, while non-relaxed DNA still remained rigid. ConclusionsThe resistance to deformation of nuclear chromatin correlates with fundamental biological processes in the cell nucleus, such as transcription, as assessed by AFM. General significanceA new outlook to studying internal nuclei structure is proposed.

Identification of a novel heterozygous DYSF variant in a large family with a dominantly-inherited dysferlinopathy.

Dysferlinopathy is an autosomal recessive muscular dystrophy, caused by bi-allelic variants in the gene encoding dysferlin (DYSF). Onset typically occurs in the second to third decade and is characterised by slowly progressive skeletal muscle weakness and atrophy of the proximal and/or distal muscles of the four limbs. There are rare cases of symptomatic DYSF variant carriers. Here, we report a large family with a dominantly inherited hyperCKaemia and late-onset muscular dystrophy. Genetic analysis identified a co-segregating novel DYSF variant [NM_003494.4:c.6207del p.(Tyr2070Metfs*4)]. No secondary variants in DYSF or other dystrophy-related genes were identified on whole genome sequencing and analysis of the proband's DNA. Skeletal muscle involvement was milder and later onset than typical dysferlinopathy presentations; these clinical signs manifested in four individuals, all between the fourth and sixth decades of life. All individuals heterozygous for the c.6207del variant had hyperCKaemia. Histological analysis of skeletal muscle biopsies across three generations showed clear dystrophic signs, including inflammatory infiltrates, regenerating myofibres, increased variability in myofibre size and internal nuclei. Muscle magnetic resonance imaging revealed fatty replacement of muscle in two individuals. Western blot and immunohistochemical analysis of muscle biopsy demonstrated consistent reduction of dysferlin staining. Allele-specific quantitative PCR analysis of DYSF mRNA from patient muscle found that the variant, localised to the extreme C-terminus of dysferlin, does not activate post-transcriptional mRNA decay. We propose that this inheritance pattern may be underappreciated and that other late-onset muscular dystrophy cases with mono-allelic DYSF variants, particularly C-terminal premature truncation variants, may represent dominant forms of disease.

Congenital myopathy associated with a novel mutation in MEGF10 gene, myofibrillar alteration and progressive course.

Early-onset myopathy, areflexia, respiratory distress, and dysphagia (EMARDD) is caused by homozygous or compound heterozygous mutation in the MEGF10 gene (OMIM #614399). Phenotypic spectrum of EMARDD is variable, ranging from severe infantile forms in which patients are ventilator-dependent and die in childhood, to milder chronic disorders with a more favorable course (mild variant, mvEMARDD). Here we describe a 22 years old boy, offspring of consanguineous parents, presenting a congenital myopathic phenotype since infancy with elbow contractures and scoliosis. The patient developed a slowly progressive muscle weakness with impaired walking, rhinolalia, dysphagia, and respiratory involvement, which required noninvasive ventilation therapy since the age of 16 years. First muscle biopsy revealed unspecific muscle damage, with fiber size variation, internal nuclei and fibrosis. Myofibrillar alterations were noted at a second muscle biopsy including whorled fibres, cytoplasmic inclusion and minicores. Exome sequencing identified a homozygous mutation in MEGF10 gene, c.2096G > C (p.Cys699Ser), inherited by both parents. This variant, not reported in public databases of mutations, is expected to alter the structure of the protein and is therefore predicted to be probably damaging according to ACMG classification. In conclusion, we found a new likely pathogenic mutation in MEGF10, which is responsible for a progressive form of mvEMARDD with myofibrillar alterations at muscle biopsy. Interestingly, the presence of MEGF10 mutations has not been reported in Italian population. Early diagnosis of MEGF10 myopathy is essential in light of recent results from in vivo testing demonstrating a potential therapeutic effect of SSRIs compounds.

Clinical, genetic, and histological features of centronuclear myopathy in the Netherlands.

Centronuclear myopathy (CNM) is a genetically heterogeneous congenital myopathy characterized by muscle weakness, atrophy, and variable degrees of cardiorespiratory involvement. The clinical severity is largely explained by genotype (DNM2, MTM1, RYR1, BIN1, TTN, and other rarer genetic backgrounds), specific mutation(s), and age of the patient. The histopathological hallmark of CNM is the presence of internal centralized nuclei on muscle biopsy. Information on the phenotypical spectrum, subtype prevalence, and phenotype–genotype correlations is limited. To characterize CNM more comprehensively, we retrospectively assessed a national cohort of 48 CNM patients (mean age = 32 ± 24 years, range 0–80, 54% males) from the Netherlands clinically, histologically, and genetically. All information was extracted from entries in the patient's medical records, between 2000 and 2020. Frequent clinical features in addition to muscle weakness and hypotonia were fatigue and exercise intolerance in more mildly affected cases. Genetic analysis showed variants in four genes (18 DNM2, 14 MTM1, 9 RYR1, and 7 BIN1), including 16 novel variants. In addition to central nuclei, histologic examination revealed a large variability of myopathic features in the different genotypes. The identification and characterization of these patients contribute to trial readiness.

A recurrent RYR1 mutation associated with early-onset hypotonia and benign disease course

The ryanodine receptor RyR1 is the main sarcoplasmic reticulum Ca2+ channel in skeletal muscle and acts as a connecting link between electrical stimulation and Ca2+-dependent muscle contraction. Abnormal RyR1 activity compromises normal muscle function and results in various human disorders including malignant hyperthermia, central core disease, and centronuclear myopathy. However, RYR1 is one of the largest genes of the human genome and accumulates numerous missense variants of uncertain significance (VUS), precluding an efficient molecular diagnosis for many patients and families. Here we describe a recurrent RYR1 mutation previously classified as VUS, and we provide clinical, histological, and genetic data supporting its pathogenicity. The heterozygous c.12083C>T (p.Ser4028Leu) mutation was found in thirteen patients from nine unrelated congenital myopathy families with consistent clinical presentation, and either segregated with the disease in the dominant families or occurred de novo. The affected individuals essentially manifested neonatal or infancy-onset hypotonia, delayed motor milestones, and a benign disease course differing from classical RYR1-related muscle disorders. Muscle biopsies showed unspecific histological and ultrastructural findings, while RYR1-typical cores and internal nuclei were seen only in single patients. In conclusion, our data evidence the causality of the RYR1 c.12083C>T (p.Ser4028Leu) mutation in the development of an atypical congenital myopathy with gradually improving motor function over the first decades of life, and may direct molecular diagnosis for patients with comparable clinical presentation and unspecific histopathological features on the muscle biopsy.

Marked Facial Weakness, Ptosis, and Hanging Jaw: A Case with RYR1 -Related Congenital Centronuclear Myopathy.

Congenital myopathies are an expanding spectrum of neuromuscular disorders with early infantile or childhood onset hypotonia and slowly or nonprogressive skeletal muscle weakness. RYR1 -related myopathies are the most common and frequently diagnosed class of congenital myopathies. Malignant hyperthermia susceptibility and central core disease are autosomal dominant or de novo RYR1 disorder, whereas multiminicore, congenital fiber type disproportion and centronuclear myopathy are autosomal recessive RYR1 disorders. The presence of ptosis, ophthalmoparesis, facial, and proximal muscles weakness, with the presence of dusty cores and multiple internal nuclei on muscle biopsy are clues to the diagnosis. We describe an 18-year-old male, who presented with early infantile onset ptosis, ophthalmoplegia, myopathic facies, hanging lower jaw, and proximal muscle weakness confirmed as an RYR1 -related congenital centronuclear myopathy on genetic analysis and muscle biopsy.

Immunohistochemical analysis of laryngeal muscle of horses clinically affected with recurrent laryngeal neuropathy.

As myosin heavy chain (MyHC) profile of muscle fibres is heavily influenced by neural input, changes in MyHC expression are expected in horses clinically affected with recurrent laryngeal neuropathy (RLN) yet, this has not been thoroughly investigated. To describe the changes in MyHC and fibre diameter in left cricoarytenoideus dorsalis (L-CAD) muscle of horses with clinical signs of RLN. Observational cohort study. Immunohistochemistry was used to assess the MyHC-based fibre-type proportion, size and grouping in the L-CAD of 10 Thoroughbred horses, five clinically affected with RLN and five unaffected controls based on resting endoscopic examination. The Mann-Whitney U test was used to compare the two groups. Compared to controls (of mean age 3.0±1.7years) which only expressed type I, IIA and IIX MyHC, the L-CAD of affected horses (of mean age 2.8±0.8years) had obvious fibre-type grouping, and despite apparent compensatory hypertrophy of a small number of fibres, a decrease in overall fibre diameter (median difference -35.2µm, 95% CI -47.4 to -7.9, P=.02) and diameter of type IIA fibres (median difference -46.8µm, 95% CI -52.1 to -5.0, P=.03) was observed. Anti-fast MyHC (MY32) cross-immunoreacted with embryonic-MyHC. Whereas MY32-positive fibres were identified as type IIX in controls, in affected horses these fibres were less than 50µm diameter with internal nuclei and were MYH3-positive for embryonic myosin indicating depletion of type IIX fibres, yet active regeneration and fibre renewal. Small sample size that did not include subclinical cases. Fibre size and appearance rather than staining colour were relied upon to differentiate embryonic from type IIX MyHC. Horses clinically affected with RLN have overall atrophy of fibres, loss of IIX fibres and expression of embryonic myosin indicating regenerative capacity. Despite hypertrophy of some remaining fibres, the overall decline in the bulk of fibres, including those most fatigue-resistant, may be the critical change that results in failure to maintain arytenoid abduction during exercise although direct comparison to subclinical cases is needed to confirm this.

MRI and tractography techniques to localize the ventral intermediate nucleus and dentatorubrothalamic tract for deep brain stimulation and MR-guided focused ultrasound: a narrative review and update.

The thalamic ventral intermediate nucleus (VIM) can be targeted for treatment of tremor by several procedures, including deep brain stimulation (DBS) and, more recently, MR-guided focused ultrasound (MRgFUS). To date, such targeting has relied predominantly on coordinate-based or atlas-based techniques rather than directly targeting the VIM based on imaging features. While general regional differences of features within the thalamus and some related white matter tracts can be distinguished with conventional imaging techniques, internal nuclei such as the VIM are not discretely visualized. Advanced imaging methods such as quantitative susceptibility mapping (QSM) and fast gray matter acquisition T1 inversion recovery (FGATIR) MRI and high-field MRI pulse sequences that improve the ability to image the VIM region are emerging but have not yet been shown to have reliability and accuracy to serve as the primary method of VIM targeting. Currently, the most promising imaging approach to directly identify the VIM region for clinical purposes is MR diffusion tractography.In this review and update, the capabilities and limitations of conventional and emerging advanced methods for evaluation of internal thalamic anatomy are briefly reviewed. The basic principles of tractography most relevant to VIM targeting are provided for familiarization. Next, the key literature to date addressing applications of DTI and tractography for DBS and MRgFUS is summarized, emphasizing use of direct targeting. This literature includes 1-tract (dentatorubrothalamic tract [DRT]), 2-tract (pyramidal and somatosensory), and 3-tract (DRT, pyramidal, and somatosensory) approaches to VIM region localization through tractography.The authors introduce a 3-tract technique used at their institution, illustrating the oblique curved course of the DRT within the inferior thalamus as well as the orientation and relationship of the white matter tracts in the axial plane. The utility of this 3-tract tractography approach to facilitate VIM localization is illustrated with case examples of variable VIM location, targeting superior to the anterior commissure-posterior commissure plane, and treatment in the setting of pathologic derangement of thalamic anatomy. Finally, concepts demonstrated with these case examples and from the prior literature are synthesized to highlight several potential advantages of tractography for VIM region targeting.

Virtual Exploration of Safe Entry Zones in the Brainstem: Comprehensive Definition and Analysis of the Operative Approach

A detailed and accurate understanding of the intrinsic brainstem anatomy and the interrelationship between its internal tracts and nuclei and external landmarks is of paramount importance for safe and effective brainstem surgery. Using anatomical models can be an important step in increasing such understanding. In the present study, we have shown the applicability of our developed virtual 3-dimensional (3D) model in depicting the safe entry zones (SEZs) to the brainstem. Accurate 3D virtual models of brainstem elements were created using high-resolution magnetic resonance imaging and computed tomography to depict the brainstem SEZs. All the described SEZs to different parts of the brainstem were successfully depicted using our 3D virtual models. The virtual models provide an immersive experience of brainstem anatomy, allowing users to understand the intricacies of the microdissection that is necessary to appropriately work through the brainstem nuclei and tracts toward a particular target. The models provide an unparalleled learning environment to understand the SEZs into the brainstem that can be used for training and research.

Muscle Adaptive Changes in Post-Polio Subjects

Nineteen post-polio subjects (9 men and 10 women) aged 41-65 years were studied by means of muscle strength measurements (Cybex) of knee extension and muscle biopsies of the vastus lateralis for morphometric, histopathological and enzymatic analyses. Data from a reference group of 10 male subjects, age 42-51 years, are also given. Fourteen of the post-polio subjects had experienced a post-polio syndrome-like drop in function. All had had polio at least 25 years earlier. In nine of the 19 subjects, type I fibers accounted for more than 70% of the total. There was a significant negative correlation between muscle strength and the percentage of type I fibers in women. Large cross-section areas of muscle fibers were found, with an average mean fiber area of 8 microns 2 X 10(3). It is assumed that the large muscle fiber areas are due to an extreme use of the remaining muscle fibers in post-polio subjects with low muscle strength. There were significant negative correlations between muscle strength values and mean fiber area in men. Most subjects had single atrophic fibers; groups of atrophic fibers were less common. Internal nuclei and splitting were seen in about half of the subjects. The activity of citrate synthase was low, but normal for glycolytic enzymes.

Design and verification of microelectrode twisting machine

As an interface between external electronic devices and internal neural nuclei, microelectrodes play an important role in many fields, such as animal robots, deep brain stimulation and neural prostheses. Aiming at the problem of high price and complicated fabrication process of microelectrode, a microelectrode twisting machine based on open source electronic prototyping platform (Arduino) and three-dimensional printing technology was proposed, and its microelectrode fabrication performance and neural stimulation performance were verified. The results show that during the fabrication of microelectrodes, the number of positive twisting turns of the electrode wire should generally be set to about 1.8 times of its length, and the number of reverse twisting rings is independent of the length, generally about 5. Moreover, compared with the traditional instrument, the device is not only inexpensive and simple to manufacture, but also has good expandability. It has a positive significance for both the personalization and popularization of microelectrode fabrication and the reduction of experimental cost.