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BACKGROUND AND OBJECTIVES: Charcot-Marie-Tooth disease type 4J (CMT4J) is caused by autosomal recessive variants in the Factor-Induced Gene 4 (FIG4) gene. Recent preclinical work has demonstrated the feasibility of adeno-associated virus serotype 9-FIG4 gene therapy. This study aimed to further characterize the CMT4J phenotype and evaluate feasibility of validated CMT-related outcome measures for future clinical trials. METHODS: This cross-sectional study enrolled children and adults with genetically confirmed CMT4J, with 2 documented disease-causing variants in the FIG4 gene. Patients were recruited through the Inherited Neuropathy Consortium network. Disease severity was assessed using standardized CMT-specific outcome measures and exploratory biomarkers including muscle MRI fat fraction, electrophysiology, and neurofilament light chain levels. Descriptive statistics and correlation analyses were conducted to explore relationships between variables. RESULTS: We recruited a total of 19 patients, including 14 pediatric patients (mean age 10.9 ± 3.9 years) and 5 adults (mean age 40.0 ± 13.9 years). The most frequent symptoms were gross motor delay and distal more than proximal muscle weakness, which were observed in 14 of 19 patients. The most common non-neuromuscular symptoms were cognitive and respiratory deficits, each seen in 8 of 19 patients. We denoted asymmetric weakness in 2 patients and nonuniform slowing of conduction velocities in 6 patients. Charcot-Marie-Tooth Disease Pediatric Scale (CMTPedS), Pediatric Quality of Life Inventory, and Vineland Adaptive Behavior Scale scores were affected in most patients. We observed a significant positive correlation between neurofilament light chain levels and CMTPedS, but the study was underpowered to observe a correlation between CMTPedS and MRI fat fraction. DISCUSSION: We obtained baseline clinical and biomarker data in a broad cohort with CMT4J in pediatric and adult patients. Motor delay, muscle weakness, and respiratory and cognitive difficulties were the most common clinical manifestations of CMT4J. Many patients had nerve conduction studies with nonuniform slowing, and 2 had an asymmetric pattern of muscle weakness. We observed that the neurofilament light chain levels correlated with the CMTPedS in the pediatric population. This study showed feasibility of clinical outcomes including CMTPedS in assessment of disease severity in the pediatric patient population and provided baseline characteristics of exploratory biomarkers, neurofilament light chain levels, and muscle MRI fat fraction. The coronavirus disease 2019 pandemic affected some of the visits, resulting in a reduced number of some of the assessments.
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Doença de Charcot-Marie-Tooth , Humanos , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/fisiopatologia , Criança , Masculino , Feminino , Adulto , Estudos Transversais , Adolescente , Pessoa de Meia-Idade , Proteínas de Neurofilamentos , Imageamento por Ressonância Magnética , Pré-Escolar , Adulto Jovem , Condução Nervosa , Flavoproteínas , Monoéster Fosfórico HidrolasesRESUMO
Dominant mutations in the calcium-permeable ion channel TRPV4 (transient receptor potential vanilloid 4) cause diverse and largely distinct channelopathies, including inherited forms of neuromuscular disease, skeletal dysplasias, and arthropathy. Pathogenic TRPV4 mutations cause gain of ion channel function and toxicity that can be rescued by small molecule TRPV4 antagonists in cellular and animal models, suggesting that TRPV4 antagonism could be therapeutic for patients. Numerous variants in TRPV4 have been detected with targeted and whole exome/genome sequencing, but for the vast majority, their pathogenicity remains unclear. Here, we used a combination of clinical information and experimental structure-function analyses to evaluate 30 TRPV4 variants across various functional protein domains. We report clinical features of seven patients with TRPV4 variants of unknown significance and provide extensive functional characterization of these and an additional 17 variants, including structural position, ion channel function, subcellular localization, expression level, cytotoxicity, and protein-protein interactions. We find that gain-of-function mutations within the TRPV4 intracellular ankyrin repeat domain target charged amino acid residues important for RhoA interaction, whereas ankyrin repeat domain residues outside of the RhoA interface have normal or reduced ion channel activity. We further identify a cluster of gain-of-function variants within the intracellular intrinsically disordered region that may cause toxicity via altered interactions with membrane lipids. In contrast, assessed variants in the transmembrane domain and other regions of the intrinsically disordered region do not cause gain of function and are likely benign. Clinical features associated with gain of function and cytotoxicity include congenital onset of disease, vocal cord weakness, and motor predominant disease, whereas patients with likely benign variants often demonstrated late-onset and sensory-predominant disease. These results provide a framework for assessing additional TRPV4 variants with respect to likely pathogenicity, which will yield critical information to inform patient selection for future clinical trials for TRPV4 channelopathies.
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Recessive SH3TC2 variants cause Charcot-Marie-Tooth disease type 4C (CMT4C). CMT4C is typically a sensorimotor demyelinating polyneuropathy, marked by early onset spinal deformities, but its clinical characteristics and severity are quite variable. Clear relationships between pathogenic variants and the spectrum of disease manifestations are to date lacking. Gene replacement therapy has been shown to ameliorate the phenotype in a mouse model of CMT4C, emphasizing the need for natural history studies to inform clinical trial readiness. Data, including both genetic information and clinical characteristics, were compiled from the longitudinal, prospective dataset of the Inherited Neuropathy Consortium, a member of the Rare Diseases Clinical Research Network (INC-RDCRN). The Charcot Marie Tooth Neuropathy Score (CMTNS), Examination Score (CMTES) and the Rasch-weighted CMTES (CMTES-R) were used to describe symptoms, neurological examinations and neurophysiological characteristics. Standardized response means were calculated at yearly intervals and a mixed model for repeated measures was used to estimate the change in CMTES and CMTES-R over time. Fifty-six individuals (59% female), median age 27 years (range 2-67 years) with homozygous or compound heterozygous variants in SH3TC2 were identified, including 34 unique variants, 14 of which have not previously been published. Twenty-eight participants had longitudinal data available. While there was no significant difference in the CMTES in those with protein truncating versus non-protein truncating variants, there were significant differences in the mean ulnar nerve compound muscle action potential amplitude, the mean radial sensory nerve action potential amplitude, and in the prevalence of scoliosis, suggesting the possibility of a milder phenotype in individuals with one or two non-protein-truncating variants. Overall, the mean value of the CMTES was 13, reflecting moderate clinical severity. There was a high rate of scoliosis (81%), scoliosis surgery (36%), and walking difficulty (94%) among study participants. The CMTES and CMTES-R appeared moderately responsive to change over extended follow-up, demonstrating a standardized response mean of 0.81 standard deviation units or 0.71 standard deviation units, respectively, over 3 years. Our analysis represents the largest cross-sectional and only longitudinal study to date, of the clinical phenotype of both adults and children with CMT4C. With the promise of upcoming genetic treatments, these data will further define the natural history of the disease and inform study design in preparation for clinical trials.
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Escoliose , Animais , Camundongos , Feminino , Masculino , Escoliose/genética , Estudos Longitudinais , Mutação/genética , Estudos Transversais , Estudos Prospectivos , Estudos de Associação GenéticaRESUMO
Mitochondria are essential for the health and viability of both motor and sensory neurons and their axons. Processes that disrupt their normal distribution and transport along axons will likely cause peripheral neuropathies. Similarly, mutations in mtDNA or nuclear encoded genes result in neuropathies that either stand alone or are part of multisystem disorders. This chapter focuses on the more common genetic forms and characteristic clinical phenotypes of "mitochondrial" peripheral neuropathies. We also explain how these various mitochondrial abnormalities cause peripheral neuropathy. In a patient with a neuropathy either due to a mutation in a nuclear or an mtDNA gene, clinical investigations aim to characterize the neuropathy and make an accurate diagnosis. In some patients, this may be relatively straightforward, where a clinical assessment and nerve conduction studies followed by genetic testing is all that is needed. In others, multiple investigations including a muscle biopsy, CNS imaging, CSF analysis, and a wide range of metabolic and genetic tests in blood and muscle may be needed to establish diagnosis.
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Doença de Charcot-Marie-Tooth , Doenças Mitocondriais , Humanos , Doença de Charcot-Marie-Tooth/genética , Doenças Mitocondriais/genética , Mitocôndrias/genética , Axônios/patologia , DNA Mitocondrial , MutaçãoRESUMO
Charcot-Marie-Tooth disease type 1A (CMT1A), caused by duplication of the peripheral myelin protein 22 (PMP22) gene, and CMT1B, caused by mutations in myelin protein zero (MPZ) gene, are the two most common forms of demyelinating CMT (CMT1), and no treatments are available for either. Prior studies of the MpzSer63del mouse model of CMT1B have demonstrated that protein misfolding, endoplasmic reticulum (ER) retention and activation of the unfolded protein response (UPR) contributed to the neuropathy. Heterozygous patients with an arginine to cysteine mutation in MPZ (MPZR98C) develop a severe infantile form of CMT1B which is modelled by MpzR98C/ + mice that also show ER stress and an activated UPR. C3-PMP22 mice are considered to effectively model CMT1A. Altered proteostasis, ER stress and activation of the UPR have been demonstrated in mice carrying Pmp22 mutations. To determine whether enabling the ER stress/UPR and readjusting protein homeostasis would effectively treat these models of CMT1B and CMT1A, we administered Sephin1/IFB-088/icerguestat, a UPR modulator which showed efficacy in the MpzS63del model of CMT1B, to heterozygous MpzR98C and C3-PMP22 mice. Mice were analysed by behavioural, neurophysiological, morphological and biochemical measures. Both MpzR98C/ + and C3-PMP22 mice improved in motor function and neurophysiology. Myelination, as demonstrated by g-ratios and myelin thickness, improved in CMT1B and CMT1A mice and markers of UPR activation returned towards wild-type values. Taken together, our results demonstrate the capability of IFB-088 to treat a second mouse model of CMT1B and a mouse model of CMT1A, the most common form of CMT. Given the recent benefits of IFB-088 treatment in amyotrophic lateral sclerosis and multiple sclerosis animal models, these data demonstrate its potential in managing UPR and ER stress for multiple mutations in CMT1 as well as in other neurodegenerative diseases. (Left panel) the accumulation of overexpressed PMP22 or misfolded mutant P0 in the Schwann cell endoplasmic reticulum (ER) leads to overwhelming of the degradative capacity, activation of ER-stress mechanisms, and myelination impairment. (Right panel) by prolonging eIF2α phosphorylation, IFB-088 reduces the amount of newly synthesized proteins entering the ER, allowing the protein quality control systems to better cope with the unfolded/misfolded protein and allowing myelination to progress.
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Doença de Charcot-Marie-Tooth , Animais , Doença de Charcot-Marie-Tooth/tratamento farmacológico , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/metabolismo , Modelos Animais de Doenças , Fator de Iniciação 2 em Eucariotos/metabolismo , Humanos , Camundongos , Bainha de Mielina/metabolismo , Células de Schwann/metabolismo , Resposta a Proteínas não DobradasRESUMO
The mechanochemical coupling of ATPase hydrolysis and conformational dynamics in kinesin motors facilitates intramolecular interaction cycles between the kinesin motor and neck domains, which are essential for microtubule-based motility. Here, we characterized a charge-inverting KIF1A-E239K mutant that we identified in a family with axonal-type Charcot-Marie-Tooth disease and also in 24 cases in human neuropathies including spastic paraplegia and hereditary sensory and autonomic neuropathy. We show that Glu239 in the ß7 strand is a key residue of the motor domain that regulates the motor-neck interaction. Expression of the KIF1A-E239K mutation has decreased ability to complement Kif1a+/- neurons, and significantly decreases ATPase activity and microtubule gliding velocity. X-ray crystallography shows that this mutation causes an excess positive charge on ß7, which may electrostatically interact with a negative charge on the neck. Quantitative mass spectrometric analysis supports that the mutation hyper-stabilizes the motor-neck interaction at the late ATP hydrolysis stage. Thus, the negative charge of Glu239 dynamically regulates the kinesin motor-neck interaction, promoting release of the neck from the motor domain upon ATP hydrolysis.
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Adenosina Trifosfatases/genética , Cinesinas/genética , Mutação/genética , Neurônios/fisiologia , Idoso , Sequência de Aminoácidos , Axônios/fisiologia , Doença de Charcot-Marie-Tooth , Humanos , Masculino , Microtúbulos/genética , Pessoa de Meia-Idade , Alinhamento de SequênciaRESUMO
Hereditary neuropathies may result from mutations in genes expressed by Schwann cells or neurons that affect selectively the peripheral nervous system (PNS) or may represent a minor or major component of complex inherited diseases that involve also the central nervous system and/or other organs and tissues. The chapter is constantly expanding and reworking, thanks to advances of molecular genetics; next-generation sequencing is identifying a plethora of new genes and is revolutionizing the diagnostic approach. In the past, diagnostic sural nerve biopsies paved the way to the discovery and elucidation of major genes and molecular pathways associated to most frequent hereditary motor-sensory neuropathies. Nowadays, a sural nerve biopsy may prove useful in selected cases for the differential diagnosis of an acquired neuropathy when clinical examination, nerve conduction studies, and molecular tests are not sufficiently informative. Skin biopsy has emerged as a minimally invasive window on the PNS, which may provide biomarkers of progression and clues to the physiopathology and molecular pathology of inherited neuropathies. The aim of our review is to illustrate the pathological features of more frequent and paradigmatic hereditary neuropathies and to highlight their correlations with the roles of the involved genes and functional consequences of related molecular defects.
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Doença de Charcot-Marie-Tooth , Neuropatia Hereditária Motora e Sensorial , Doença de Charcot-Marie-Tooth/genética , Humanos , MutaçãoRESUMO
Mutations in TRPV4 are linked to a group of clinically distinct, but also overlapping axonal neuropathies, including Charcot-Marie-Tooth disease type 2C (CMT2C), scapuloperoneal spinal muscular atrophy, and congenital distal spinal muscular atrophy. The incidence of TRPV4-linked cases ranges from 0 to 7% in overall axonal neuropathy cohorts from European countries and Australia. However, the data from other areas remain largely unknown. In this study, we screened for TRPV4 mutations in a well-characterized USA cohort of 62 unrelated CMT2 patients without mutations in MFN2, GARS, NEFL, and GDAP1. All 15 coding exons of TRPV4 were analyzed by Sanger-sequencing. Clinical features of TRPV4-linked patients were compared with those lacking TRPV4 mutations. We identified two TRPV4 mutations in two patients. A TRPV4-R316C was identified in a patient with family history, while a TRPV4-R269C in an apparently sporadic case. Marked clinical variations were observed in the patients with TRPV4 mutations. Our data suggest that TRPV4-linked CMT2C accounts for a sizable fraction in this USA cohort of CMT2; it has a wide phenotypic spectrum, and vocal cord paralysis, scapular weakness and wasting, skeletal dysplasia, and hearing loss are suggestive signs for TRPV4-linked CMT2C.
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Doença de Charcot-Marie-Tooth/epidemiologia , Atrofia Muscular Espinal/epidemiologia , Mutação , Canais de Cátion TRPV/genética , Adulto , Axônios/patologia , Doenças do Desenvolvimento Ósseo/etiologia , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/fisiopatologia , Éxons/genética , Feminino , Aconselhamento Genético , Perda Auditiva/etiologia , Humanos , Incidência , Masculino , Debilidade Muscular/etiologia , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/fisiopatologia , Mutação de Sentido Incorreto , Linhagem , Fenótipo , Mutação Puntual , Canais de Cátion TRPV/deficiência , Estados Unidos/epidemiologia , Paralisia das Pregas Vocais/etiologiaRESUMO
OBJECTIVE: Charcot-Marie-Tooth (CMT) disease is most commonly caused by duplication of a chromosomal segment surrounding Peripheral Myelin Protein 22, or PMP22 gene, which is classified as CMT1A. Several candidate therapies reduce Pmp22 mRNA levels in CMT1A rodent models, but development of biomarkers for clinical trials in CMT1A is a challenge given its slow progression and difficulty in obtaining nerve samples. Quantitative PCR measurements of PMP22 mRNA in dermal nerves were performed using skin biopsies in human clinical trials for CMT1A, but this approach did not show increased PMP22 mRNA in CMT1A patients compared to controls. One complicating factor is the variable amounts of Schwann cells (SCs) in skin. The objective of the study was to develop a novel method for precise evaluation of PMP22 levels in skin biopsies that can discriminate CMT1A patients from controls. METHODS: We have developed methods to normalize PMP22 transcript levels to SC-specific genes that are not altered by CMT1A status. Several CMT1A-associated genes were assembled into a custom Nanostring panel to enable precise transcript measurements that can be normalized to variable SC content. RESULTS: The digital expression data from Nanostring analysis showed reproducible elevation of PMP22 levels in CMT1A versus control skin biopsies, particularly after normalization to SC-specific genes. INTERPRETATION: This platform should be useful in clinical trials for CMT1A as a biomarker of target engagement that can be used to optimize dosing, and the same normalization framework is applicable to other types of CMT. ANN NEUROL 2019;85:887-898.
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Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/patologia , Proteínas da Mielina/genética , Células de Schwann/patologia , Pele/patologia , Adolescente , Adulto , Idoso , Animais , Biomarcadores/metabolismo , Biópsia , Doença de Charcot-Marie-Tooth/metabolismo , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Proteínas da Mielina/biossíntese , Células de Schwann/metabolismo , Pele/metabolismo , Adulto JovemRESUMO
OBJECTIVE: Genetic modifiers in rare disease have long been suspected to contribute to the considerable variance in disease expression, including Charcot-Marie-Tooth disease type 1A (CMT1A). To address this question, the Inherited Neuropathy Consortium collected a large standardized sample of such rare CMT1A patients over a period of 8 years. CMT1A is caused in most patients by a uniformly sized 1.5 Mb duplication event involving the gene PMP22. METHODS: We genotyped DNA samples from 971 CMT1A patients on Illumina BeadChips. Genome-wide analysis was performed in a subset of 330 of these patients, who expressed the extremes of a hallmark symptom: mild and severe foot dorsiflexion strength impairment. SIPA1L2 (signal-induced proliferation-associated 1 like 2), the top identified candidate modifier gene, was expressed in the peripheral nerve, and our functional studies identified and confirmed interacting proteins using coimmunoprecipitation analysis, mass spectrometry, and immunocytochemistry. Chromatin immunoprecipitation and in vitro siRNA experiments were used to analyze gene regulation. RESULTS: We identified significant association of 4 single nucleotide polymorphisms (rs10910527, rs7536385, rs4649265, rs1547740) in SIPA1L2 with foot dorsiflexion strength (p < 1 × 10-7 ). Coimmunoprecipitation and mass spectroscopy studies identified ß-actin and MYH9 as SIPA1L2 binding partners. Furthermore, we show that SIPA1L2 is part of a myelination-associated coexpressed network regulated by the master transcription factor SOX10. Importantly, in vitro knockdown of SIPA1L2 in Schwannoma cells led to a significant reduction of PMP22 expression, hinting at a potential strategy for drug development. INTERPRETATION: SIPA1L2 is a potential genetic modifier of CMT1A phenotypic expressions and offers a new pathway to therapeutic interventions. ANN NEUROL 2019;85:316-330.
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Doença de Charcot-Marie-Tooth/genética , Pé/fisiopatologia , Proteínas Ativadoras de GTPase/genética , Genes Modificadores/genética , Debilidade Muscular/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Linhagem Celular Tumoral , Doença de Charcot-Marie-Tooth/fisiopatologia , Criança , Pré-Escolar , Feminino , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Redes Reguladoras de Genes , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Debilidade Muscular/fisiopatologia , Proteínas da Mielina/genética , Neurilemoma/genética , Fenótipo , Polimorfismo de Nucleotídeo Único , Ratos , Índice de Gravidade de Doença , Adulto JovemRESUMO
Although mutations in more than 90 genes are known to cause CMT, the underlying genetic cause of CMT remains unknown in more than 50% of affected individuals. The discovery of additional genes that harbor CMT2-causing mutations increasingly depends on sharing sequence data on a global level. In this way-by combining data from seven countries on four continents-we were able to define mutations in ATP1A1, which encodes the alpha1 subunit of the Na+,K+-ATPase, as a cause of autosomal-dominant CMT2. Seven missense changes were identified that segregated within individual pedigrees: c.143T>G (p.Leu48Arg), c.1775T>C (p.Ile592Thr), c.1789G>A (p.Ala597Thr), c.1801_1802delinsTT (p.Asp601Phe), c.1798C>G (p.Pro600Ala), c.1798C>A (p.Pro600Thr), and c.2432A>C (p.Asp811Ala). Immunostaining peripheral nerve axons localized ATP1A1 to the axolemma of myelinated sensory and motor axons and to Schmidt-Lanterman incisures of myelin sheaths. Two-electrode voltage clamp measurements on Xenopus oocytes demonstrated significant reduction in Na+ current activity in some, but not all, ouabain-insensitive ATP1A1 mutants, suggesting a loss-of-function defect of the Na+,K+ pump. Five mutants fall into a remarkably narrow motif within the helical linker region that couples the nucleotide-binding and phosphorylation domains. These findings identify a CMT pathway and a potential target for therapy development in degenerative diseases of peripheral nerve axons.
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Doença de Charcot-Marie-Tooth/genética , Genes Dominantes , Mutação/genética , ATPase Trocadora de Sódio-Potássio/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Sequência de Aminoácidos , Criança , Família , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , ATPase Trocadora de Sódio-Potássio/química , Adulto JovemRESUMO
OBJECTIVE: Charcot-Marie-Tooth type 4J (CMT4J) is a rare autosomal recessive neuropathy caused by mutations in FIG4 that result in loss of FIG4 protein. This study investigates the natural history and mechanisms of segmental demyelination in CMT4J. METHODS: Over the past 9 years, we have enrolled and studied a cohort of 12 CMT4J patients, including 6 novel FIG4 mutations. We evaluated these patients and related mouse models using morphological, electrophysiological, and biochemical approaches. RESULTS: We found sensory motor demyelinating polyneuropathy consistently in all patients. This underlying myelin pathology was associated with nonuniform slowing of conduction velocities, conduction block, and temporal dispersion on nerve conduction studies, which resemble those features in acquired demyelinating peripheral nerve diseases. Segmental demyelination was also confirmed in mice without Fig4 (Fig4-/- ). The demyelination was associated with an increase of Schwann cell dedifferentiation and macrophages in spinal roots where nerve-blood barriers are weak. Schwann cell dedifferentiation was induced by the increasing intracellular Ca2+ . Suppression of Ca2+ level by a chelator reduced dedifferentiation and demyelination of Schwann cells in vitro and in vivo. Interestingly, cell-specific knockout of Fig4 in mouse Schwann cells or neurons failed to cause segmental demyelination. INTERPRETATION: Myelin change in CMT4J recapitulates the features of acquired demyelinating neuropathies. This pathology is not Schwann cell autonomous. Instead, it relates to systemic processes involving interactions of multiple cell types and abnormally elevated intracellular Ca2+ . Injection of a Ca2+ chelator into Fig4-/- mice improved segmental demyelination, thereby providing a therapeutic strategy against demyelination. Ann Neurol 2018;83:756-770.
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Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/patologia , Doenças Desmielinizantes/genética , Flavoproteínas/genética , Mutação , Bainha de Mielina/patologia , Monoéster Fosfórico Hidrolases/genética , Potenciais de Ação/genética , Adolescente , Adulto , Animais , Cálcio/metabolismo , Células Cultivadas , Doença de Charcot-Marie-Tooth/fisiopatologia , Criança , Estudos de Coortes , Doenças Desmielinizantes/tratamento farmacológico , Modelos Animais de Doenças , Feminino , Fibroblastos , Flavoproteínas/metabolismo , Humanos , Macrófagos/patologia , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Fibras Nervosas/patologia , Fibras Nervosas/ultraestrutura , Proteínas do Tecido Nervoso/metabolismo , Condução Nervosa/genética , Monoéster Fosfórico Hidrolases/metabolismo , Nervo Isquiático/metabolismo , Nervo Isquiático/patologiaRESUMO
Recessive mutations in the mitochondrial copper-binding protein SCO2, cytochrome c oxidase (COX) assembly protein, have been reported in several cases with fatal infantile cardioencephalomyopathy with COX deficiency. Significantly expanding the known phenotypic spectrum, we identified compound heterozygous variants in SCO2 in two unrelated patients with axonal polyneuropathy, also known as Charcot-Marie-Tooth disease type 4. Different from previously described cases, our patients developed predominantly motor neuropathy, they survived infancy, and they have not yet developed the cardiomyopathy that causes death in early infancy in reported patients. Both of our patients harbour missense mutations near the conserved copper-binding motif (CXXXC), including the common pathogenic variant E140K and a novel change D135G. In addition, each patient carries a second mutation located at the same loop region, resulting in compound heterozygote changes E140K/P169T and D135G/R171Q. Patient fibroblasts showed reduced levels of SCO2, decreased copper levels and COX deficiency. Given that another Charcot-Marie-Tooth disease gene, ATP7A, is a known copper transporter, our findings further underline the relevance of copper metabolism in Charcot-Marie-Tooth disease.
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Proteínas de Transporte/genética , Doença de Charcot-Marie-Tooth/complicações , Doença de Charcot-Marie-Tooth/genética , Cobre/deficiência , Proteínas Mitocondriais/genética , Mutação/genética , Trifosfato de Adenosina/metabolismo , Adulto , Animais , Axônios/patologia , Proteínas de Transporte/metabolismo , Células Cultivadas , Doença de Charcot-Marie-Tooth/diagnóstico por imagem , Doença de Charcot-Marie-Tooth/patologia , Criança , Análise Mutacional de DNA , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Humanos , Imageamento por Ressonância Magnética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Mitocondriais/metabolismo , Modelos Moleculares , Chaperonas Moleculares , Consumo de Oxigênio/genética , Nervo Isquiático/metabolismo , Nervo Isquiático/patologia , Nervo Isquiático/ultraestruturaRESUMO
INTRODUCTION: Foot deformities are frequent complications in Charcot-Marie-Tooth disease (CMT) patients, often requiring orthopedic surgery. However, there are no prospective, randomized studies on surgical management, and there is variation in the approaches among centers both within and between countries. METHODS: In this study we assessed the frequency of foot deformities and surgery among patients recruited into the Inherited Neuropathies Consortium (INC). We also designed a survey addressed to orthopedic surgeons at INC centers to determine whether surgical approaches to orthopedic complications in CMT are variable. RESULTS: Foot deformities were reported in 71% of CMT patients; 30% of the patients had surgery. Survey questions were answered by 16 surgeons working in different specialized centers. Most of the respondents were foot and ankle surgeons. There was marked variation in surgical management. DISCUSSION: Our findings confirm that the approaches to orthopedic management of CMT are varied. We identify areas that require further research. Muscle Nerve 57: 255-259, 2018.
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Tornozelo/anormalidades , Doença de Charcot-Marie-Tooth/epidemiologia , Doença de Charcot-Marie-Tooth/terapia , Deformidades Congênitas do Pé/etiologia , Deformidades Congênitas do Pé/terapia , Procedimentos Ortopédicos/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Tornozelo/cirurgia , Atitude do Pessoal de Saúde , Doença de Charcot-Marie-Tooth/cirurgia , Criança , Pré-Escolar , Feminino , Deformidades Congênitas do Pé/cirurgia , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Prevalência , Cirurgiões , Inquéritos e Questionários , Adulto JovemRESUMO
INTRODUCTION: This study evaluates carpal tunnel syndrome (CTS) symptom severity, functional status, and outcome of CTS therapies in patients with inherited neuropathies. METHODS: Validated questionnaires were used to compare symptom severity and functional status in patients with and without a diagnosis of CTS and a diagnosis of an inherited neuropathy. RESULTS: 309 patients with inherited neuropathies participated in this study. The CTS symptom severity score (SSS) was found to be the most useful tool in assessing CTS severity in patients with inherited neuropathy. Splint therapy and surgery were associated with significant improvement in carpal tunnel symptoms as measured through the SSS. DISCUSSION: This study provides insight into the assessment of CTS symptom severity and patient-reported outcomes to CTS therapy in individuals with inherited neuropathies. The SSS appears useful for evaluation of CTS symptoms and patient-reported outcomes following CTS interventions in individuals with inherited neuropathies. Muscle Nerve 57: 388-394, 2018.
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Síndrome do Túnel Carpal/diagnóstico , Doença de Charcot-Marie-Tooth/complicações , Nervo Mediano/fisiopatologia , Adulto , Idoso , Síndrome do Túnel Carpal/complicações , Síndrome do Túnel Carpal/fisiopatologia , Doença de Charcot-Marie-Tooth/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Estudos Retrospectivos , Índice de Gravidade de DoençaRESUMO
BACKGROUND: Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common inherited neuropathy, a debilitating disease without known cure. Among patients with CMT1A, disease manifestation, progression and severity are strikingly variable, which poses major challenges for the development of new therapies. Hence, there is a strong need for sensitive outcome measures such as disease and progression biomarkers, which would add powerful tools to monitor therapeutic effects in CMT1A. METHODS: We established a pan-European and American consortium comprising nine clinical centres including 311 patients with CMT1A in total. From all patients, the CMT neuropathy score and secondary outcome measures were obtained and a skin biopsy collected. In order to assess and validate disease severity and progression biomarkers, we performed qPCR on a set of 16 animal model-derived potential biomarkers in skin biopsy mRNA extracts. RESULTS: In 266 patients with CMT1A, a cluster of eight cutaneous transcripts differentiates disease severity with a sensitivity and specificity of 90% and 76.1%, respectively. In an additional cohort of 45 patients with CMT1A, from whom a second skin biopsy was taken after 2-3 years, the cutaneous mRNA expression of GSTT2, CTSA, PPARG, CDA, ENPP1 and NRG1-Iis changing over time and correlates with disease progression. CONCLUSIONS: In summary, we provide evidence that cutaneous transcripts in patients with CMT1A serve as disease severity and progression biomarkers and, if implemented into clinical trials, they could markedly accelerate the development of a therapy for CMT1A.
Assuntos
Doença de Charcot-Marie-Tooth/terapia , Progressão da Doença , Marcadores Genéticos/genética , Pele/patologia , Resultado do Tratamento , Adulto , Idoso , Biópsia , Catepsina A/genética , Doença de Charcot-Marie-Tooth/sangue , Doença de Charcot-Marie-Tooth/genética , Feminino , Glutationa Transferase/genética , Glicoproteínas/genética , Humanos , Masculino , Pessoa de Meia-Idade , Neuregulina-1/genética , Proteínas Nucleares , PPAR gama/genética , Diester Fosfórico Hidrolases/genética , Prognóstico , Pirofosfatases/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Transcrição Gênica/genéticaRESUMO
OBJECTIVE: To describe a second hereditary sensory autonomic neuropathy type VI (HSAN-VI) family harboring 2 novel heterozygous mutations in the dystonin (DST) gene and to evaluate their effect on neurons derived from induced pluripotent stem cells (iPSC). METHODS: The family consisted of 3 affected siblings from nonconsanguineous healthy parents. All members underwent clinical and electrophysiologic evaluation and genetic analysis. Two patients underwent quantitative sensory testing (QST), cardiovascular reflexes, dynamic sweat test, and skin biopsy to evaluate somatic and autonomic cutaneous innervation and to get fibroblast cultures for developing iPSC-derived neurons. RESULTS: Onset occurred in the first decade, with painless and progressive mutilating distal ulcerations leading to amputation and joint deformity. Sensation to pain, touch, and vibration was reduced. Autonomic disturbances included hypohidrosis, pupillary abnormalities, and gastrointestinal and sexual dysfunction. Nerve conduction studies showed a severe axonal sensory neuropathy. QST and autonomic functional studies were abnormal. Skin biopsy revealed a lack of sensory and autonomic nerve fibers. Genetic analysis revealed 2 pathogenic mutations in the DST gene affecting exclusively the DST neuronal isoform-a2. Neurons derived from iPSC showed absence or very low levels of DST protein and short and dystrophic neuritis or no projections at all. CONCLUSIONS: Unlike the previous HSAN-VI family, our description indicates that DST mutations may be associated with a nonlethal and nonsyndromic phenotype. Neuronal loss affects large and small sensory nerve fibers as well as autonomic ones. Induced-PSC findings suggest that dystonin defect might alter proper development of the peripheral nerves. Dystonin-a2 plays a major role in the HSAN-VI phenotype.
Assuntos
Distonina/genética , Neuropatias Hereditárias Sensoriais e Autônomas/genética , Neuropatias Hereditárias Sensoriais e Autônomas/fisiopatologia , Mutação , Adulto , Distonina/metabolismo , Neuropatias Hereditárias Sensoriais e Autônomas/patologia , Heterozigoto , Humanos , Células-Tronco Pluripotentes Induzidas/patologia , Células-Tronco Pluripotentes Induzidas/fisiologia , Masculino , Pessoa de Meia-Idade , Neurônios/patologia , Neurônios/fisiologia , RNA Mensageiro/metabolismo , IrmãosRESUMO
OBJECTIVES: To analyse and describe the clinical and genetic spectrum of Charcot-Marie-Tooth disease (CMT) caused by mutations in the neurofilament light polypeptide gene (NEFL). METHODS: Combined analysis of newly identified patients with NEFL-related CMT and all previously reported cases from the literature. RESULTS: Five new unrelated patients with CMT carrying the NEFL mutations P8R and N98S and the novel variant L311P were identified. Combined data from these cases and 62 kindreds from the literature revealed four common mutations (P8R, P22S, N98S and E396K) and three mutational hotspots accounting for 37 (55%) and 50 (75%) kindreds, respectively. Eight patients had de novo mutations. Loss of large-myelinated fibres was a uniform feature in a total of 21 sural nerve biopsies and 'onion bulb' formations and/or thin myelin sheaths were observed in 14 (67%) of them. The neurophysiological phenotype was broad but most patients with E90K and N98S had upper limb motor conduction velocities <38 m/s. Age of onset was ≤3 years in 25 cases. Pyramidal tract signs were described in 13 patients and 7 patients were initially diagnosed with or tested for inherited ataxia. Patients with E90K and N98S frequently presented before age 3 years and developed hearing loss or other neurological features including ataxia and/or cerebellar atrophy on brain MRI. CONCLUSIONS: NEFL-related CMT is clinically and genetically heterogeneous. Based on this study, however, we propose mutational hotspots and relevant clinical-genetic associations that may be helpful in the evaluation of NEFL sequence variants and the differential diagnosis with other forms of CMT.
Assuntos
Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/patologia , Mutação/genética , Proteínas de Neurofilamentos/genética , Axônios/patologia , Ataxia Cerebelar/genética , Ataxia Cerebelar/patologia , Genótipo , Humanos , Linhagem , Fenótipo , Nervo Sural/patologiaRESUMO
INTRODUCTION: Charcot-Marie-Tooth disease type 1C (CMT1C) is a rare, dominantly inherited neuropathy caused by mutations in the lipopolysaccharide-induced tumor necrosis factor (LITAF) or small integral membrane protein of the lysosome/late endosome (SIMPLE) gene. METHODS: We present a case series comprised of 10 patients in whom CMT1C is caused by a Gly112Ser substitution in the encoded protein. We focus on clinical presentation, electrodiagnostic analyses, and our findings in the context of previously described cases. RESULTS: The Gly112Ser mutation causing CMT1C is a mild form of CMT, as patients walked on time, had less weakness than those with Charcot-Marie-Tooth disease type 1A (CMT1A), had a CMT neuropathy score (CMTNS) indicative of mild disease, and had faster ulnar and median motor nerve conduction velocities compared to those with CMT1A. DISCUSSION: The G112S mutation in LITAF seems to be clinically indistinguishable from a mild presentation of CMT1A. Muscle Nerve 56: 1092-1095, 2017.