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Kang YR, Nam TS, Kim JM, Kang KW, Choi SM, Lee SH, Kim BC, Kim MK. Clinical analysis in patients with SPG11 hereditary spastic paraplegia. Front Neurol 2023; 14:1198728. [PMID: 37396771 PMCID: PMC10310533 DOI: 10.3389/fneur.2023.1198728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 05/26/2023] [Indexed: 07/04/2023] Open
Abstract
Background To analyze the clinical phenotype of hereditary spastic paraplegia (HSP) caused by SPG11 mutations (SPG11-HSP). Methods Among the 17 patients with sporadic HSP who performed whole exome sequencing analysis, six were diagnosed with SPG11-HSP. The clinical and radiologic findings and the results of the electrodiagnostic and neuropsychologic tests were reviewed retrospectively. Results The median age at onset was 16.5 years (range, 13-38 years). Progressive spastic paraparesis was a core feature, and the median spastic paraplegia rating scale score was 24/52 (range, 16-31 points). Additional major symptoms were pseudobulbar dysarthria, intellectual disability, bladder dysfunction, and being overweight. Minor symptoms included upper limbs rigidity and sensory axonopathy. The median body mass index was 26.2 kg/m2 (range, 25.2-32.3 kg/m2). The thin corpus callosum (TCC) was predominant at the rostral body or anterior midbody, and the ears of the lynx sign was seen in all. The follow-up MRI showed the worsening of periventricular white matter (PVWM) signal abnormalities with ventricular widening or the extension of the TCC. Motor evoked potentials (MEP) to the lower limbs showed an absent central motor conduction time (CMCT) in all subjects. The upper limb CMCT was initially absent in three subjects, although it became abnormal in all at the follow-up. The mini-mental state examination median score was 27/30 (range, 26-28) with selective impairment of the attention/calculation domain. The median score of the full-scale intelligence quotient was 48 (range, 42-72) on the Wechsler Adult Intelligence Scale test. Conclusion Attention/calculation deficits and being overweight as well as pseudobulbar dysarthria were common additional symptoms in patients with SPG11-HSP. The rostral body and anterior midbody of the corpus callosum were preferentially thinned, especially in the early stage of the disease. The TCC, PVWM signal changes, and MEP abnormality worsened as the disease progressed.
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Affiliation(s)
- You-Ri Kang
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
| | - Tai-Seung Nam
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Jae-Myung Kim
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
| | - Kyung Wook Kang
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Seong-Min Choi
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Seung-Han Lee
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Byeong C. Kim
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Myeong-Kyu Kim
- Department of Neurology, Chonnam National University Hospital, Gwangju, Republic of Korea
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
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Neurometabolic Dysfunction in SPG11 Hereditary Spastic Paraplegia. Nutrients 2022; 14:nu14224803. [PMID: 36432490 PMCID: PMC9693816 DOI: 10.3390/nu14224803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Pathogenic variants in SPG11 cause the most common autosomal recessive complicated hereditary spastic paraplegia. Besides the prototypical combination of spastic paraplegia with a thin corpus callosum, obesity has increasingly been reported in this multisystem neurodegenerative disease. However, a detailed analysis of the metabolic state is lacking. METHODS In order to characterize metabolic alterations, a cross-sectional analysis was performed comparing SPG11 patients (n = 16) and matched healthy controls (n = 16). We quantified anthropometric parameters, body composition as determined by bioimpedance spectroscopy, and serum metabolic biomarkers, and we measured hypothalamic volume by high-field MRI. RESULTS Compared to healthy controls, SPG11 patients exhibited profound changes in body composition, characterized by increased fat tissue index, decreased lean tissue index, and decreased muscle mass. The presence of lymphedema correlated with increased extracellular fluid. The serum levels of the adipokines leptin, resistin, and progranulin were significantly altered in SPG11 while adiponectin and C1q/TNF-related protein 3 (CTRP-3) were unchanged. MRI volumetry revealed a decreased hypothalamic volume in SPG11 patients. CONCLUSIONS Body composition, adipokine levels, and hypothalamic volume are altered in SPG11. Our data indicate a link between obesity and hypothalamic neurodegeneration in SPG11 and imply that specific metabolic interventions may prevent obesity despite severely impaired mobility in SPG11.
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Shi Y, Wang A, Chen B, Wang X, Niu S, Li W, Li S, Zhang Z. Clinical Features and Genetic Spectrum of Patients With Clinically Suspected Hereditary Progressive Spastic Paraplegia. Front Neurol 2022; 13:872927. [PMID: 35572931 PMCID: PMC9097539 DOI: 10.3389/fneur.2022.872927] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 03/28/2022] [Indexed: 12/27/2022] Open
Abstract
Background and Purpose A variety of hereditary diseases overlap with neurological phenotypes or even share genes with hereditary spastic paraplegia (HSP). The aim of this study was to determine the clinical features and genetic spectrum of patients with clinically suspected HSPs. Methods A total of 52 patients with clinically suspected HSPs were enrolled in this study. All the patients underwent next-generation sequencing (NGS) and triplet repeat primed PCR to screen for the dynamic mutations typical of spinocerebellar ataxia (SCA). Multiplex ligation-dependent probe amplification (MLPA) was further conducted in patients with no causative genetic mutations detected to examine for large deletions and duplications in genes of SPAST, ATL1, REEP1, PGN, and SPG11. Clinical characteristics and findings of brain MRI were analyzed in patients with definite diagnoses. Results The mean age of the patients studied was 36.90 ± 14.57 years. 75% (39/52) of patients manifested a phenotype of complex form of HSPs. A genetic diagnosis was made in 51.9% (27/52) of patients, of whom 40.3% (21/52) of patients had mutations in HSPs genes (SPG4/SPG6/SPG8/SPG11/SPG15/SPG78/SPG5A) and 11.5% (6/52) of patients had mutations in SCAs genes (SCA3/SCA17/SCA28). SPG4 and SPG11 were the most common cause of pure form of HSPs (5/6, 83.3%) and complex form of HSPs (5/15, 33.3%), respectively. Gait disturbance was the most common initial symptom in both the patients with HSPs (15/21) and in patients with SCAs (5/6). Dysarthria and cerebellar ataxia were detected in 28.5% (6/21) and 23.8% (5/21) of patients with HSPs, respectively, and were the most common symptoms in addition to progressive weakness and spasticity of the lower limbs. Cerebellar atrophy was seen on the brain MRI of patients with SPG5A, SCA3, and SCA28. Conclusion Causative genetic mutations were identified in 51.9% of patients with clinically suspected HSPs by NGS and triplet repeat primed PCR. A final diagnosis of HSPs or SCAs was made in 40.3% and 11.5% of patients, respectively. The clinical manifestations and neuroimaging findings overlapped between patients with HSPs and patients with SCAs. Dynamic mutations should be screened in patients with clinically suspected HSPs, especially in those with phenotypes of complex form of HSPs.
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Affiliation(s)
- Yuzhi Shi
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - An Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Bin Chen
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xingao Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Songtao Niu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Wei Li
- China National Clinical Research Center for Neurological Diseases, Beijing, China.,Monogenic Disease Research Center for Neurological Disorders & Precision Medicine Research Center for Neurological Disorders, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Shaowu Li
- Department of Functional Neuroimaging, Beijing Neurosurgical Institute, Beijing, China
| | - Zaiqiang Zhang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
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Molecular Characterization of Portuguese Patients with Hereditary Cerebellar Ataxia. Cells 2022; 11:cells11060981. [PMID: 35326432 PMCID: PMC8946949 DOI: 10.3390/cells11060981] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 01/02/2023] Open
Abstract
Hereditary cerebellar ataxia (HCA) comprises a clinical and genetic heterogeneous group of neurodegenerative disorders characterized by incoordination of movement, speech, and unsteady gait. In this study, we performed whole-exome sequencing (WES) in 19 families with HCA and presumed autosomal recessive (AR) inheritance, to identify the causal genes. A phenotypic classification was performed, considering the main clinical syndromes: spastic ataxia, ataxia and neuropathy, ataxia and oculomotor apraxia (AOA), ataxia and dystonia, and ataxia with cognitive impairment. The most frequent causal genes were associated with spastic ataxia (SACS and KIF1C) and with ataxia and neuropathy or AOA (PNKP). We also identified three families with autosomal dominant (AD) forms arising from de novo variants in KIF1A, CACNA1A, or ATP1A3, reinforcing the importance of differential diagnosis (AR vs. AD forms) in families with only one affected member. Moreover, 10 novel causal-variants were identified, and the detrimental effect of two splice-site variants confirmed through functional assays. Finally, by reviewing the molecular mechanisms, we speculated that regulation of cytoskeleton function might be impaired in spastic ataxia, whereas DNA repair is clearly associated with AOA. In conclusion, our study provided a genetic diagnosis for HCA families and proposed common molecular pathways underlying cerebellar neurodegeneration.
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Güner F, Pozner T, Krach F, Prots I, Loskarn S, Schlötzer-Schrehardt U, Winkler J, Winner B, Regensburger M. Axon-Specific Mitochondrial Pathology in SPG11 Alpha Motor Neurons. Front Neurosci 2021; 15:680572. [PMID: 34326717 PMCID: PMC8314181 DOI: 10.3389/fnins.2021.680572] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 06/14/2021] [Indexed: 11/13/2022] Open
Abstract
Pathogenic variants in SPG11 are the most frequent cause of autosomal recessive complicated hereditary spastic paraplegia (HSP). In addition to spastic paraplegia caused by corticospinal degeneration, most patients are significantly affected by progressive weakness and muscle wasting due to alpha motor neuron (MN) degeneration. Mitochondria play a crucial role in neuronal health, and mitochondrial deficits were reported in other types of HSPs. To investigate whether mitochondrial pathology is present in SPG11, we differentiated MNs from induced pluripotent stem cells derived from SPG11 patients and controls. MN derived from human embryonic stem cells and an isogenic SPG11 knockout line were also included in the study. Morphological analysis of mitochondria in the MN soma versus neurites revealed specific alterations of mitochondrial morphology within SPG11 neurites, but not within the soma. In addition, impaired mitochondrial membrane potential was indicative of mitochondrial dysfunction. Moreover, we reveal neuritic aggregates further supporting neurite pathology in SPG11. Correspondingly, using a microfluidic-based MN culture system, we demonstrate that axonal mitochondrial transport was significantly impaired in SPG11. Overall, our data demonstrate that alterations in morphology, function, and transport of mitochondria are an important feature of axonal dysfunction in SPG11 MNs.
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Affiliation(s)
- Fabian Güner
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tatyana Pozner
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Florian Krach
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Iryna Prots
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sandra Loskarn
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | - Jürgen Winkler
- Department of Molecular Neurology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Center for Rare Diseases Erlangen, University Hospital Erlangen, Erlangen, Germany
| | - Beate Winner
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Center for Rare Diseases Erlangen, University Hospital Erlangen, Erlangen, Germany
| | - Martin Regensburger
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Department of Molecular Neurology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Center for Rare Diseases Erlangen, University Hospital Erlangen, Erlangen, Germany
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Fink JK. Hereditary Myelopathies. ACTA ACUST UNITED AC 2021; 27:185-204. [PMID: 33522742 DOI: 10.1212/con.0000000000000934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE OF REVIEW This article guides clinicians in the clinical recognition and differential diagnosis of hereditary myelopathies. RECENT FINDINGS Rather than a disease, a disease process, or relating to specific cellular vulnerability, the term hereditary myelopathy refers to diverse inherited disorders in which major aspects of the clinical syndrome reflect disturbance of elements within the spinal cord (specifically, the dorsal columns and dorsal root ganglia, corticospinal tracts, and anterior horn cells). It is important to note that the clinical features of almost all hereditary myelopathies reflect not only disturbance of elements within the spinal cord but also disturbance of extraspinal structures (particularly, but not limited to, peripheral nerves and the cerebellum) and that these extraspinal clinical features can be very helpful in recognizing specific myelopathy syndromes. The value of classifying disorders as inherited myelopathies lies primarily in facilitating their clinical recognition and differential diagnosis. It is useful to recognize that many hereditary myelopathies conform to one of four clinical paradigms: (1) spinocerebellar ataxia, (2) motor neuron disorder, (3) leukodystrophy, or (4) distal motor-sensory axonopathy predominantly affecting the central nervous system. Although they are myelopathies, spinal dysraphisms such as spina bifida and myelomeningocele are not included in this context because they are not usually due to single-gene mutation and have low hereditability. SUMMARY This article illustrates clinical paradigms of hereditary myelopathy with clinical examples emphasizing the spectrum, clinical recognition, and differential diagnosis of hereditary myelopathies.
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Rudenskaya GE, Kadnikova VA, Ryzhkova OP. [Common forms of hereditary spastic paraplegias]. Zh Nevrol Psikhiatr Im S S Korsakova 2019; 119:94-104. [PMID: 30874534 DOI: 10.17116/jnevro201911902194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A group of hereditary spastic paraplegias includes about 80 spastic paraplegia genes (SPG): forms with identified (almost 70) or only mapped (about 10) genes. Methods of next generation sequencing (NGS), along with new SPG discovering, modify knowledge about earlier delineated SPG. Clinical and genetic characteristics of common autosomal dominant (SPG4, SPG3, SPG31) and autosomal recessive (SPG11, SPG7, SPG15) forms are presented.
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Affiliation(s)
| | - V A Kadnikova
- Research Centre for Medical Genetics, Moscow, Russia
| | - O P Ryzhkova
- Research Centre for Medical Genetics, Moscow, Russia
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Faber I, Martinez ARM, de Rezende TJR, Martins CR, Martins MP, Lourenço CM, Marques W, Montecchiani C, Orlacchio A, Pedroso JL, Barsottini OGP, Lopes-Cendes Í, França MC. SPG11 mutations cause widespread white matter and basal ganglia abnormalities, but restricted cortical damage. Neuroimage Clin 2018; 19:848-857. [PMID: 29946510 PMCID: PMC6008284 DOI: 10.1016/j.nicl.2018.05.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 05/20/2018] [Accepted: 05/22/2018] [Indexed: 12/12/2022]
Abstract
SPG11 mutations are the major cause of autosomal recessive Hereditary Spastic Paraplegia. The disease has a wide phenotypic variability indicating many regions of the nervous system besides the corticospinal tract are affected. Despite this, anatomical and phenotypic characterization is restricted. In the present study, we investigate the anatomical abnormalities related to SPG11 mutations and how they relate to clinical and cognitive measures. Moreover, we aim to depict how the disease course influences the regions affected, unraveling different susceptibility of specific neuronal populations. We performed clinical and paraclinical studies encompassing neuropsychological, neuroimaging, and neurophysiological tools in a cohort of twenty-five patients and age matched controls. We assessed cortical thickness (FreeSurfer software), deep grey matter volumes (T1-MultiAtlas tool), white matter microstructural damage (DTI-MultiAtlas) and spinal cord morphometry (Spineseg software) on a 3 T MRI scan. Mean age and disease duration were 29 and 13.2 years respectively. Sixty-four percent of the patients were wheelchair bound while 84% were demented. We were able to unfold a diffuse pattern of white matter integrity loss as well as basal ganglia and spinal cord atrophy. Such findings contrasted with a restricted pattern of cortical thinning (motor, limbic and parietal cortices). Electromyography revealed motor neuronopathy affecting 96% of the probands. Correlations with disease duration pointed towards a progressive degeneration of multiple grey matter structures and spinal cord, but not of the white matter. SPG11-related hereditary spastic paraplegia is characterized by selective neuronal vulnerability, in which a precocious and widespread white matter involvement is later followed by a restricted but clearly progressive grey matter degeneration.
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Key Words
- ACE-R, Addenbrooke's Cognitive Examination Revised
- ALS, amyotrophic lateral sclerosis
- CA, cord area
- CE, cord eccentricity
- CMAP, compound muscle action potential
- CST, corticospinal tract
- Complicated hereditary spastic paraplegia
- DTI, diffusion tensor imaging
- FA, fractional anisotropy
- GM, grey matter
- Grey matter
- HSP, hereditary spastic paraplegia
- LH, left hemisphere
- MD, mean diffusivity
- MOCA, Montreal cognitive assessment
- Motor neuron disorder
- NPI, neuropsychiatric inventory
- PNP, sensory-motor polyneuropathy
- PNS, peripheral nervous system
- RH, right hemisphere
- ROI, region of interest
- SC, spinal cord
- SNAP, sensory nerve action potential
- SPG11
- SPRS, Spastic Paraplegia Rating Scale
- STS, cortex adjacent to the superior temporal sulcus
- Spinal cord
- Thinning of the corpus callosum
- WES, whole exome sequencing
- WM, white matter
- White matter
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Affiliation(s)
- Ingrid Faber
- Department of Neurology, University of Campinas (UNICAMP), Campinas, Brazil
| | | | | | | | | | | | - Wilson Marques
- Department of Neurology, University of São Paulo (USP-RP), Ribeirão Preto, Brazil
| | - Celeste Montecchiani
- Laboratorio di Neurogenetica, Centro Europeo di Ricerca sul Cervello (CERC) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Santa Lucia, Rome, Italy
| | - Antonio Orlacchio
- Laboratorio di Neurogenetica, Centro Europeo di Ricerca sul Cervello (CERC) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Santa Lucia, Rome, Italy; Dipartimento di Scienze Chirurgiche e Biomediche, Università di Perugia, Perugia, Italy
| | - Jose Luiz Pedroso
- Department of Neurology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | | | - Íscia Lopes-Cendes
- Department of Medical Genetics, University of Campinas (UNICAMP), Campinas, Brazil
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Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating, uniformly lethal degenerative disorder of motor neurons that overlaps clinically with frontotemporal dementia (FTD). Investigations of the 10% of ALS cases that are transmitted as dominant traits have revealed numerous gene mutations and variants that either cause these disorders or influence their clinical phenotype. The evolving understanding of the genetic architecture of ALS has illuminated broad themes in the molecular pathophysiology of both familial and sporadic ALS and FTD. These central themes encompass disturbances of protein homeostasis, alterations in the biology of RNA binding proteins, and defects in cytoskeletal dynamics, as well as numerous downstream pathophysiological events. Together, these findings from ALS genetics provide new insight into therapies that target genetically distinct subsets of ALS and FTD.
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Affiliation(s)
- Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Robert H Brown
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
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Abstract
PURPOSE OF REVIEW Charcot-Marie-Tooth disease (CMT) and related neuropathies represent a heterogeneous group of hereditary disorders. The present review will discuss the most recent advances in the field. RECENT FINDINGS Knowledge of CMT epidemiology and frequency of the main associated genes is increasing, with an overall prevalence estimated at 10-28/100 000. In the last years, the huge number of newly uncovered genes, thanks to next-generation sequencing techniques, is challenging the current classification of CMT. During the last 18 months other genes have been associated with CMT, such as PMP2, MORC2, NEFH, MME, and DGAT2. For the most common forms of CMT, numerous promising compounds are under study in cellular and animal models, mainly targeting either the protein degradation pathway or the protein overexpression. Consequently, efforts are devoted to develop responsive outcome measures and biomarkers for this overall slowly progressive disorder, with quantitative muscle MRI resulting the most sensitive-to-change measure. SUMMARY This is a rapidly evolving field where better understanding of pathophysiology is paving the way to develop potentially effective treatments, part of which will soon be tested in patients. Intense research is currently devoted to prepare clinical trials and develop responsive outcome measures.
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