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1.
Am J Hum Genet ; 2021 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-33861953

RESUMEN

JAG2 encodes the Notch ligand Jagged2. The conserved Notch signaling pathway contributes to the development and homeostasis of multiple tissues, including skeletal muscle. We studied an international cohort of 23 individuals with genetically unsolved muscular dystrophy from 13 unrelated families. Whole-exome sequencing identified rare homozygous or compound heterozygous JAG2 variants in all 13 families. The identified bi-allelic variants include 10 missense variants that disrupt highly conserved amino acids, a nonsense variant, two frameshift variants, an in-frame deletion, and a microdeletion encompassing JAG2. Onset of muscle weakness occurred from infancy to young adulthood. Serum creatine kinase (CK) levels were normal or mildly elevated. Muscle histology was primarily dystrophic. MRI of the lower extremities revealed a distinct, slightly asymmetric pattern of muscle involvement with cores of preserved and affected muscles in quadriceps and tibialis anterior, in some cases resembling patterns seen in POGLUT1-associated muscular dystrophy. Transcriptome analysis of muscle tissue from two participants suggested misregulation of genes involved in myogenesis, including PAX7. In complementary studies, Jag2 downregulation in murine myoblasts led to downregulation of multiple components of the Notch pathway, including Megf10. Investigations in Drosophila suggested an interaction between Serrate and Drpr, the fly orthologs of JAG1/JAG2 and MEGF10, respectively. In silico analysis predicted that many Jagged2 missense variants are associated with structural changes and protein misfolding. In summary, we describe a muscular dystrophy associated with pathogenic variants in JAG2 and evidence suggests a disease mechanism related to Notch pathway dysfunction.

2.
Brain ; 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33855352

RESUMEN

Abnormal gut motility is a feature of several mitochondrial encephalomyopathies, and mutations in genes such as TYMP and POLG, have been linked to these rare diseases. The human genome encodes three DNA ligases, of which only one, ligase III (LIG3), has a mitochondrial splice variant and is crucial for mitochondrial health. We investigated the effect of reduced LIG3 activity and resulting mitochondrial dysfunction in seven patients from three independent families, who showed the common occurrence of gut dysmotility and neurological manifestations reminiscent of mitochondrial neurogastrointestinal encephalomyopathy. DNA from these patients was subjected to whole exome sequencing. In all patients, compound heterozygous variants in a new disease gene, LIG3, were identified. All variants were predicted to have a damaging effect on the protein. The LIG3 gene encodes the only mitochondrial DNA (mtDNA) ligase and therefore plays a pivotal role in mtDNA repair and replication. In vitro assays in patient-derived cells showed a decrease in LIG3 protein levels and ligase activity. We demonstrated that the LIG3 gene defects affect mtDNA maintenance, leading to mtDNA depletion without the accumulation of multiple deletions as observed in other mitochondrial disorders. This mitochondrial dysfunction is likely to cause the phenotypes observed in these patients. The most prominent and consistent clinical signs were severe gut dysmotility and neurological abnormalities, including leukoencephalopathy, epilepsy, migraine, stroke-like episodes, and neurogenic bladder. A decrease in the number of myenteric neurons, and increased fibrosis and elastin levels were the most prominent changes in the gut. Cytochrome c oxidase (COX) deficient fibres in skeletal muscle were also observed. Disruption of lig3 in zebrafish reproduced the brain alterations and impaired gut transit in vivo. In conclusion, we identified variants in the LIG3 gene that result in a mitochondrial disease characterized by predominant gut dysmotility, encephalopathy, and neuromuscular abnormalities. Bonora et al. identify a new mitochondrial recessive disorder caused by biallelic variants in the LIG3 gene encoding DNA ligase III, which is responsible for mitochondrial DNA repair. Clinical signs include gut dysmotility and neurological features such as leucoencephalopathy, epilepsy and stroke-like episodes.

3.
J Hum Genet ; 2021 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-33744911

RESUMEN

Heat shock protein family B member 8, encoded by HSPB8, is an essential component of the chaperone-assisted selective autophagy complex, which maintains muscle function by degrading damaged proteins in the cells. Mutations in HSPB8 have been reported to cause Charcot-Marie-Tooth type 2L, distal hereditary motor neuropathy IIa, and rimmed vacuolar myopathies (RVM). In this study, we identified a novel heterozygous frameshift variant c.525_529del in HSPB8 in a large Japanese family with RVM, using whole exome sequencing. Three affected individuals had severe respiratory failure, which has not been addressed by previous studies. Muscle atrophy in the paraspinal muscles was also a clinical feature of the individuals affected with RVM in this study. The frameshift mutation was located in the last coding exon, and the mutated protein was predicted to harbor an isoleucine-leucine-valine (ILV) sequence, which corresponds to the IXI/V (isoleucine, X amino acids, and isoleucine or valine) motif. The IXI/V motif is essential for assembly into larger oligomers in other small heat shock proteins and all frameshift mutants of HSPB8 were predicted to share the ILV sequence in the C-terminal extension. The in silico prediction tools showed low protein solubility and increased aggregation propensity for the region around the ILV sequence. The IXI/V motif might be associated with the pathogenesis of HSPB8-related RVM.

4.
Intern Med ; 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33642484

RESUMEN

We herein report a case of seronegative immune-mediated necrotizing myopathy (IMNM) concurrent with anti-Kv1.4 and anti-titin antibodies. A 72-year-old Japanese woman presented with a 29-year history of fluctuating high serum creatine kinase (CK) levels followed by intermittent ptosis and respiratory muscle weakness. This case highlights the fact that marked respiratory muscle weakness requiring intubation can be seen in an ambulant patient with IMNM. Marked respiratory muscle weakness, rhabdomyolysis-like acute elevation of CK levels, and anti-striational muscle antibodies may be a characteristic constellation of findings in a distinct subgroup of patients with inflammatory myopathy with myasthenia gravis or similar symptoms.

5.
J Hum Genet ; 2021 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-33712684

RESUMEN

Megaconial congenital muscular dystrophy (CMD)(OMIM #602541), related to CHKB mutation, is a rare autosomal recessive disorder. To date, only 35 confirmed patients are recorded. We present a detailed description of the clinical, histopathological, imaging, and genetic findings of five children from four Indian families. The children had moderate-to-severe autistic behavior, hand stereotypies, and global developmental delay mimicking atypical Rett syndrome. In addition, generalized hypotonia was a common initial finding. The progression of muscle weakness was variable, with two patients having a milder phenotype and three having a severe form. Interestingly, the majority did not attain sphincter control. Only patient 1 had classical ichthyotic skin changes. Muscle biopsy in two patients showed a myopathic pattern with characteristic peripherally placed enlarged mitochondria on modified Gomori trichrome stain and electron microscopy. Genetic analysis in these patients identified three novel null mutations in CHKB [c.1027dupA (p.Ser343LysfsTer86);c.224 + 1G > T (5' splice site); c.1123C > T (p.Gln375Ter)] and one reported missense mutation, c.581G > A (p.Arg194Gln), all in the homozygous state. Megaconial CMD, although rare, forms an important group with a complex phenotypic presentation and accounted for 5.5% of our genetically confirmed CMD patients. Atypical Rett syndrome-like presentation may be a clue towards CHKB-related disorder.

7.
Rinsho Shinkeigaku ; 2021 Mar 25.
Artículo en Japonés | MEDLINE | ID: mdl-33762492

RESUMEN

A 62-year-old Japanese man with swollen fingers and walking difficulty due to myalgia and muscle weakness in proximal limb muscles was admitted to our hospital. Serum creatine kinase was remarkably increased (7,380 U/l) and rapidly progressing interstitial pneumonia developed. Muscle biopsy showed necrotic and regenerating fibers without mononuclear infiltration and fibrosis. Anti-Th/To antibodies were detected in the serum, and anti-Th/To antibody-positive systemic sclerosis was diagnosed. Anti-Th/To antibody-positive sclerosis-associated myopathy has not yet been reported in the literature. The present case suggests that anti-Th/To antibody-positive systemic sclerosis can be accompanied by immune-mediated necrotizing myopathy and be effectively treated with immunotherapy comprising corticosteroids, tacrolimus and immunoglobulin.

8.
Rinsho Shinkeigaku ; 2021 Mar 25.
Artículo en Japonés | MEDLINE | ID: mdl-33762494

RESUMEN

We report a 47-year-old woman who presented with progressive myalgia, weakness in the proximal limbs, and dysphagia for a month and a half. No skin rash was observed on admission. Examination of MRI data suggested inflammatory changes in the proximal limbs and trunk muscles. Biopsy specimens from the left biceps muscle showed no perifascicular atrophy, but immunohistochemical staining revealed the presence of myxovirus resistance protein A (MxA) in myofibers, strongly suggesting dermatomyositis (DM). In addition, her serum was positive for anti-nuclear matrix protein 2 (anti-NXP-2) antibody, which is reportedly useful as a marker of DM without skin lesions. Her symptoms gradually improved upon intravenous methylprednisolone pulse therapy in conjunction with oral prednisolone, oral tacrolimus, and intravenous immunoglobulin therapy. Our findings suggest that in cases where inflammatory muscle disease is suspected, anti-NXP-2 antibody analyses should be considered for precise diagnosis, even if there are no dermatological symptoms.

9.
Rinsho Shinkeigaku ; 2021 Mar 25.
Artículo en Japonés | MEDLINE | ID: mdl-33762497

RESUMEN

A 71-year-old woman was admitted to our hospital with type2 respiratory failure. Her daily life activities had been normal, although she had noticed mild truncal weakness in her sixties. Her parents were consanguineous, and her sister had suffered similar symptoms. Although Pompe disease was suspected on the basis of the clinical course and CT findings of selective muscular atrophy in the paraspinal, thigh flexor and sartorius muscle, acid alpha-glucosidase activity was normal. The serum creatine kinase level was not elevated, and muscle biopsy showed no specific change. Genetic analysis revealed a novel homozygous variant c.227T>C (p.Phe76Ser) in the SELENON gene, and she was suspected to have selenoprotein-related myopathy, which is reported to develop in childhood. Selenoprotein-related myopathy should be considered as a differential diagnosis in aged patients presenting with respiratory failure of unknown origin.

10.
Artículo en Inglés | MEDLINE | ID: mdl-33727065

RESUMEN

BACKGROUND: Type I interferonopathies are a recently established subgroup of autoinflammatory diseases caused by mutations in genes associated with proteasome degradation or cytoplasmic RNA and DNA sensing pathways. OBJECTIVE: This study aimed to unveil the molecular pathogenesis of a patient with novel type I interferonopathy, for which no known genetic mutations have been identified. METHODS: We performed the whole exome sequencing (WES) of a 1-month-old boy with novel type I interferonopathy. We also investigated proteasome activities using patient-derived B lymphoblastoid cell lines (LCLs) and normal LCLs transduced with the mutant gene. RESULTS: WES identified a de novo proteasome 20S subunit beta 9 (PSMB9) p.G156D mutation in the patient who developed fever, a chilblain-like skin rash, myositis, and severe pulmonary hypertension due to the hyperactivation of interferon-alpha. Patient-derived LCLs revealed reduced proteasome activities, and exogenous transduction of mutant PSMB9 p.G156D into normal LCLs significantly suppressed proteasome activities, and the endogenous PSMB9 protein was lost along with the reduction of other immunoproteasome subunits, PSMB8 and PSMB10 proteins. He responded to the administration of a Janus kinase (JAK) inhibitor, tofacitinib, and he was successfully withdrawn from veno-arterial extracorporeal membranous oxygenation. At 7 months of age, he received an unrelated cord blood transplantation. At 2 years post transplantation, he no longer required tofacitinib and experienced no disease recurrence. CONCLUSION: We present the case of a patient with a novel type I interferonopathy caused by a de novo PSMB9 p.G156D mutation which suppressed the wild-type PSMB9 protein expression. JAK inhibitor and stem cell transplantation could be curative therapies in patients with severe interferonopathies.

11.
Brain Nerve ; 73(2): 147-159, 2021 Feb.
Artículo en Japonés | MEDLINE | ID: mdl-33561829

RESUMEN

In the field of neurology, idiopathic inflammatory myopathy has been classified into four sub-categories, namely, dermatomyositis, anti-synthetase syndrome, inclusion body myositis, and immune-mediated necrotizing myopathy (IMNM), based upon histological and serological findings. Among them, IMNM has features similar to muscular dystrophy, and it may thus be difficult to differentiate between these two conditions, not only clinically but also pathologically, especially in chronic cases and pediatric patients. This is partly because the main pathological feature of both IMNM and muscular dystrophy is myofiber necrosis and regeneration. Furthermore, IMNM patients with anti-SRP antibodies tend to have more prominent muscle atrophy, especially in the shoulder girdle, which mimics the muscle involvement pattern in facioscapulohumeral muscular dystrophy. Some IMNM patients with anti-HMGCR antibodies have onset in their childhood or even in infancy, and may be misdiagnosed with muscular dystrophy. On the other hand, some muscular dystrophies have been reported to show more prominent lymphocyte infiltration than others, which may also mislead muscle pathologists. Nevertheless, these conditions can be distinguished using the relevant histological evaluations, including muscle immunohistochemistry for the MHC and C5b-9 antigens, in addition to appropriate clinical and laboratory examinations including muscle MRI and autoantibody testing.


Asunto(s)
Enfermedades Musculares , Distrofias Musculares , Miositis por Cuerpos de Inclusión , Miositis , Autoanticuerpos , Niño , Humanos , Músculo Esquelético , Distrofias Musculares/diagnóstico , Miositis/diagnóstico
12.
BMC Nephrol ; 22(1): 74, 2021 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-33639890

RESUMEN

BACKGROUND: Lately, monoclonal gammopathy of renal significance (MGRS) has been defined as a group of renal disorders that are strongly associated with monoclonal protein, including amyloid immunoglobulin light chain (AL) amyloidosis. Amyloid myopathy is rare (1.5% of all patients with amyloidosis) and the prognosis is poor. Furthermore, only approximately 20% of patients with amyloid myopathy are reported to have renal involvement, indicating a lack of data in the literature. CASE PRESENTATION: Here, we report a rare case of MGRS-related AL amyloidosis complicated by amyloid myopathy that presented with muscle weakness in the upper and lower limbs, neck and fingers, and nephrotic syndrome. Blood, urine, and bone marrow examination revealed monoclonal gammopathy of undetermined significance (MGUS) (Bence Jones protein-lambda). Muscle biopsy of the vastus lateralis muscle demonstrated amyloid proteins in the sarcolemma and in the blood vessel walls on Congo red staining, suggesting amyloid myopathy, and tiny inclusions in fibers on modified Gomori trichrome stain. Although we thought they were reminiscent of nemaline bodies, we could not confirm the nature of this structure. Renal biopsy demonstrated amyloid proteins in the mesangial region, part of the capillary walls, and the blood vessel walls on direct fast scarlet staining. As these amyloid proteins were positive for p-component staining and negative for amyloid A staining, ß2-microglobulin, and pre-albumin, and as lambda light chains were positive in the mesangial region, we diagnosed the patient with MGRS-related AL amyloidosis. Although he was treated with melphalan and dexamethasone, his symptoms did not improve. CONCLUSIONS: AL amyloidosis involving the kidneys and muscles has a poor prognosis, and a delayed diagnosis of amyloid myopathy is common because of its rarity and frequent misdiagnosis, which increases organ function deterioration. Therefore, early detection, therapeutic intervention, and careful follow-up are crucial.

13.
Intern Med ; 2021 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-33612671

RESUMEN

Cardiac involvement has recently been the focus of sporadic late-onset nemaline myopathy (SLONM). However, right ventricular failure and pulmonary hypertension, in addition to repetitive cardiac arrest, are noteworthy characteristics of SLONM. We herein report a 66-year-old woman with SLONM whose main symptoms were cardiac arrest, right ventricular failure, and pulmonary hypertension. Despite permanent pacemaker replacement, cardiac arrest occurred repetitively, and even with continuous positive airway pressure, right ventricular failure and pulmonary hypertension persisted. The patient was finally diagnosed with SLONM by a muscle biopsy. Our case suggests the possibility of cardiovascular involvement in SLONM, especially right ventricular failure and pulmonary hypertension.

15.
Neurology ; 96(12): e1595-e1607, 2021 03 23.
Artículo en Inglés | MEDLINE | ID: mdl-33597289

RESUMEN

OBJECTIVE: To assess long-term (2 years) effects of bimagrumab in participants with sporadic inclusion body myositis (sIBM). METHODS: Participants (aged 36-85 years) who completed the core study (RESILIENT [Efficacy and Safety of Bimagrumab/BYM338 at 52 Weeks on Physical Function, Muscle Strength, Mobility in sIBM Patients]) were invited to join an extension study. Individuals continued on the same treatment as in the core study (10 mg/kg, 3 mg/kg, 1 mg/kg bimagrumab or matching placebo administered as IV infusions every 4 weeks). The co-primary outcome measures were 6-minute walk distance (6MWD) and safety. RESULTS: Between November 2015 and February 2017, 211 participants entered double-blind placebo-controlled period of the extension study. Mean change in 6MWD from baseline was highly variable across treatment groups, but indicated progressive deterioration from weeks 24-104 in all treatment groups. Overall, 91.0% (n = 142) of participants in the pooled bimagrumab group and 89.1% (n = 49) in the placebo group had ≥1 treatment-emergent adverse event (AE). Falls were slightly higher in the bimagrumab 3 mg/kg group vs 10 mg/kg, 1 mg/kg, and placebo groups (69.2% [n = 36 of 52] vs 56.6% [n = 30 of 53], 58.8% [n = 30 of 51], and 61.8% [n = 34 of 55], respectively). The most frequently reported AEs in the pooled bimagrumab group were diarrhea 14.7% (n = 23), involuntary muscle contractions 9.6% (n = 15), and rash 5.1% (n = 8). Incidence of serious AEs was comparable between the pooled bimagrumab and the placebo group (18.6% [n = 29] vs 14.5% [n = 8], respectively). CONCLUSION: Extended treatment with bimagrumab up to 2 years produced a good safety profile and was well-tolerated, but did not provide clinical benefits in terms of improvement in mobility. The extension study was terminated early due to core study not meeting its primary endpoint. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov identifier NCT02573467. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with sIBM, long-term treatment with bimagrumab was safe, well-tolerated, and did not provide meaningful functional benefit. The study is rated Class IV because of the open-label design of extension treatment period 2.

16.
Rinsho Shinkeigaku ; 61(1): 47-50, 2021 Jan 29.
Artículo en Japonés | MEDLINE | ID: mdl-33328421

RESUMEN

A 69-year-old woman was admitted to our hospital because of limb weakness. She was diagnosed to have chronic renal failure due to diabetes mellitus and had suffered from pericardial effusion at 67 years of age. She started taking colchicine 18 months before admission and thereafter gradually developed muscle weakness in her limbs and had become bedridden at the time of admission. The withdrawal of colchicine improved her limb weakness, and therefore we diagnosed her to have colchicine myopathy. Her muscle strength did not completely recover even after six months from cessation of colchicine. It was suggested that renal failure and muscle disuse had prevented the full recovery of her muscles in addition to the long-term use of colchicine. Typical colchicine myopathy improves rapidly, but the long-term use of colchicine is considered to cause muscle weakness. Although the CK level was elevated, the elevated CK and myopathy had been overlooked because the CK baseline was low due to the patient's small amount of muscle mass. Moreover, the estimated GFR was recorded to be higher than her actual renal function due to her small amount of muscle mass, therefore the risk of colchicine myopathy in this case remained unrecognized.

18.
Neurobiol Aging ; 100: 120.e1-120.e6, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33339634

RESUMEN

Mutations in the valosin-containing protein (VCP) gene are known to cause various neurodegenerative disorders. Here, we report 8 Japanese patients [6 men, 2 women; median age at onset: 49.5 (range, 35-58) years] from 5 unrelated families with VCP missense mutations. Although 7 of 8 patients were diagnosed with either inclusion body myopathy or amyotrophic lateral sclerosis, 1 patient showed demyelinating polyneuropathy, which was confirmed by longitudinal nerve conduction studies. Sural nerve biopsy of the patient revealed intranuclear ubiquitin staining in Schwann cells. Three known pathogenic VCP mutations (p.Arg191Gln, p.Arg155Cys, and p.Ile126Phe) were detected. A novel mutation, c.293 A>T (p.Asp98Val), was also identified in a patient with amyotrophic lateral sclerosis and frontotemporal dementia. This mutation was predicted to be "deleterious" or "disease causing" using in silico mutation analyses. In conclusion, demyelinating polyneuropathy may be a novel phenotype caused by VCP mutations. The p.Asp98Val mutation was found to be a novel pathogenic mutation of VCP proteinopathy. We believe our cases represent a wide clinical spectrum of VCP mutations.

19.
Neuropathology ; 2020 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-33300189

RESUMEN

We report clinicopathological findings of a patient with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes/Leigh syndrome (MELAS/LS) associated with a novel m.3482A>G mutation in MT-ND1. A 41-year-old woman had experienced multiple stroke-like episodes since age 16. She developed akinetic mutism two months before admission to our hospital. Neurological examination revealed akinetic mutism, bilateral deafness, and muscular atrophy. Cerebrospinal fluid tests revealed elevated pyruvate and lactate levels. Fluid-attenuated inversion recovery images on magnetic resonance imaging showed hyperintense areas in the right frontal and both sides of temporal and occipital lobes, both sides of the striatum, and the midbrain. Muscle biopsy revealed strongly succinate dehydrogenase-reactive blood vessels. L-arginine therapy improved her consciousness and prevented further stroke-like episodes. However, she died from aspiration pneumonia. Postmortem autopsy revealed scattered infarct-like lesions with cavitation in the cerebral cortex and necrotic lesions in the striatum and midbrain. The patient was pathologically confirmed as having MELAS/LS based on two characteristic clinicopathological findings: presenting MELAS/LS overlap phenotype and effectiveness of L-arginine treatment.

20.
Neurology ; 2020 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-33277422

RESUMEN

OBJECTIVE: To identify the characteristic pathologic features of dermatomyositis (DM) associated with anti-Mi-2 autoantibodies (anti-Mi-2 DM). METHODS: We reviewed 188 muscle biopsies from patients (1) pathologically diagnosed with DM through the sarcoplasmic expression for the myxovirus resistant protein A (MxA+) and (2) serologically positive for 1 of 5 DM-specific autoantibodies (DMSA) (anti-Mi-2, n = 30; other DMSA, n = 152) or negative for all 5 DMSAs (n = 6). We then compared the histopathologic and immunohistochemical features of anti-Mi-2 DM to non-Mi-2 DM and antisynthetase syndrome (ASS) patients (n = 212) using t-test, Fisher's exact test, and a logistic regression model. RESULTS: Anti-Mi-2 DM patients showed significantly higher severity scores in muscle fiber and inflammatory domains than non-Mi-2 DM patients. The presence of perifascicular necrosis, increased perimysial alkaline phosphatase activity, and sarcolemmal membrane attack complex deposition was more frequent in anti-Mi-2 DM patients (p < 0.01). Following Bonferroni correction, there were no significant differences in the percentages of the features mentioned above between the anti-Mi-2 DM and ASS (p > 0.01). CONCLUSION: Perifascicular necrosis and perimysial pathology, features previously reported in ASS, are common in anti-Mi-2 DM patients. Our findings not only assist in differentiating anti-Mi-2 DM from other DM subtypes but also suggest the possibility of an overlapping mechanism between anti-Mi-2 DM and ASS. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that the muscle biopsies of DM patients with anti-Mi-2 autoantibodies are more likely to demonstrate higher severity scores in muscle fiber and inflammatory domains.

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