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Firdaus Z, Li X. Unraveling the Genetic Landscape of Neurological Disorders: Insights into Pathogenesis, Techniques for Variant Identification, and Therapeutic Approaches. Int J Mol Sci 2024; 25:2320. [PMID: 38396996 PMCID: PMC10889342 DOI: 10.3390/ijms25042320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
Genetic abnormalities play a crucial role in the development of neurodegenerative disorders (NDDs). Genetic exploration has indeed contributed to unraveling the molecular complexities responsible for the etiology and progression of various NDDs. The intricate nature of rare and common variants in NDDs contributes to a limited understanding of the genetic risk factors associated with them. Advancements in next-generation sequencing have made whole-genome sequencing and whole-exome sequencing possible, allowing the identification of rare variants with substantial effects, and improving the understanding of both Mendelian and complex neurological conditions. The resurgence of gene therapy holds the promise of targeting the etiology of diseases and ensuring a sustained correction. This approach is particularly enticing for neurodegenerative diseases, where traditional pharmacological methods have fallen short. In the context of our exploration of the genetic epidemiology of the three most prevalent NDDs-amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease, our primary goal is to underscore the progress made in the development of next-generation sequencing. This progress aims to enhance our understanding of the disease mechanisms and explore gene-based therapies for NDDs. Throughout this review, we focus on genetic variations, methodologies for their identification, the associated pathophysiology, and the promising potential of gene therapy. Ultimately, our objective is to provide a comprehensive and forward-looking perspective on the emerging research arena of NDDs.
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Affiliation(s)
- Zeba Firdaus
- Department of Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA;
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Xiaogang Li
- Department of Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA;
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
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Zhang YD, Jiang T, Wang SY, Fu XX, Duan R, Wei B, Cao HM, Yan E, Chen SY. The Alzheimer’s disease-associated gene TREML2 modulates inflammation by regulating microglia polarization and NLRP3 inflammasome activation. Neural Regen Res 2023; 18:434-438. [PMID: 35900442 PMCID: PMC9396521 DOI: 10.4103/1673-5374.346468] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Triggering receptor expressed on myeloid cells-like 2 (TREML2) is a newly identified susceptibility gene for Alzheimer’s disease (AD). It encodes a microglial inflammation-associated receptor. To date, the potential role of microglial TREML2 in neuroinflammation in the context of AD remains unclear. In this study, APP/PS1 mice were used to investigate the dynamic changes of TREML2 levels in brain during AD progression. In addition, lipopolysaccharide (LPS) stimulation of primary microglia as well as a lentivirus-mediated TREML2 overexpression and knockdown were employed to explore the role of TREML2 in neuroinflammation in the context of AD. Our results show that TREML2 levels gradually increased in the brains of APP/PS1 mice during disease progression. LPS stimulation of primary microglia led to the release of inflammatory cytokines including interleukin-1β, interleukin-6, and tumor necrosis factor-α in the culture medium. The LPS-induced microglial release of inflammatory cytokines was enhanced by TREML2 overexpression and was attenuated by TREML2 knockdown. LPS increased the levels of microglial M1-type polarization marker inducible nitric oxide synthase. This effect was enhanced by TREML2 overexpression and ameliorated by TREML2 knockdown. Furthermore, the levels of microglial M2-type polarization markers CD206 and ARG1 in the primary microglia were reduced by TREML2 overexpression and elevated by TREML2 knockdown. LPS stimulation increased the levels of NLRP3 in primary microglia. The LPS-induced increase in NLRP3 was further elevated by TREML2 overexpression and alleviated by TREML2 knockdown. In summary, this study provides the first evidence that TREML2 modulates inflammation by regulating microglial polarization and NLRP3 inflammasome activation. These findings reveal the mechanisms by which TREML2 regulates microglial inflammation and suggest that TREML2 inhibition may represent a novel therapeutic strategy for AD.
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Li JQ, Zhong XL, Song JH, Chi S, Xie AM, Tan L, Yu JT. Associations Between TREML2 Gene Variants and Alzheimer's Disease: Biomarkers, Neuroimage, and Cognition. J Alzheimers Dis 2023; 96:1555-1563. [PMID: 37980675 DOI: 10.3233/jad-230936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
BACKGROUND Recent genetic research identified a protective factor against late-onset Alzheimer's disease (AD) in Caucasians, a variant called rs3747742-C in the TREML2 gene. However, the roles of other TREML2 variants in AD have not been fully explored. OBJECTIVE We conducted a focused analysis of 16 TREML2 variants, examining their connection to AD by studying their correlation with cerebrospinal fluid (CSF) proteins, neuroimage, and cognition in the Alzheimer's Disease Neuroimaging Initiative database (ADNI). METHODS A multiple linear regression model was utilized to estimate potential associations between TREML2 genotypes and various endophenotypes in the entire ADNI sample at baseline, with age, gender, years of education, and APOE ɛ4 status included as covariates. To examine changes in clinical outcomes over time, linear mixed-effects models were employed. RESULTS We found that the SNP rs17328707-A was associated with higher ADNI-VS scores, smaller ventricles, and larger middle temporal volume at baseline. The SNP rs6915083-G was linked to lower CSF t-tau and p-tau levels, and higher CSF Aβ levels. The SNP rs9394766-G was associated with a smaller hippocampus and larger ventricles at baseline. In longitudinal cohorts, the rs6915083-G SNP was associated with changes in ADNI-MEM and ADNI-EF scores, as well as the rate of hippocampal and middle temporal atrophy. CONCLUSION Our findings reveal that TREML2 gene variants have different effects on AD. Two variants are protective, while one may be a risk factor. This enhances our understanding of AD genetics and could guide future research and personalized treatments.
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Affiliation(s)
- Jie-Qiong Li
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Xiao-Ling Zhong
- Department of Neurology, Affiliated Qingdao Central Hospital of Qingdao University, Qingdao Cancer Hospital, Qingdao, China
| | - Jing-Hui Song
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Song Chi
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - An-Mu Xie
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Lan Tan
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, Qingdao, Shandong, China
| | - Jin-Tai Yu
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, Qingdao, Shandong, China
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Kühn AL, Frenzel S, Teumer A, Wittfeld K, Garvert L, Weihs A, Homuth G, Prokisch H, Bülow R, Nauck M, Völker U, Völzke H, Grabe HJ, Van der Auwera S. TREML2 Gene Expression and Its Missense Variant rs3747742 Associate with White Matter Hyperintensity Volume and Alzheimer's Disease-Related Brain Atrophy in the General Population. Int J Mol Sci 2022; 23:ijms232213764. [PMID: 36430248 PMCID: PMC9692564 DOI: 10.3390/ijms232213764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/02/2022] [Accepted: 11/04/2022] [Indexed: 11/12/2022] Open
Abstract
Although the common pathology of Alzheimer's disease (AD) and white matter hyperintensities (WMH) is disputed, the gene TREML2 has been implicated in both conditions: its whole-blood gene expression was associated with WMH volume and its missense variant rs3747742 with AD risk. We re-examined those associations within one comprehensive dataset of the general population, additionally searched for cross-relations and illuminated the role of the apolipoprotein E (APOE) ε4 status in the associations. For our linear regression and linear mixed effect models, we used 1949 participants from the Study of Health in Pomerania (Germany). AD was assessed using a continuous pre-symptomatic MRI-based score evaluating a participant's AD-related brain atrophy. In our study, increased whole-blood TREML2 gene expression was significantly associated with reduced WMH volume but not with the AD score. Conversely, rs3747742-C was significantly associated with a reduced AD score but not with WMH volume. The APOE status did not influence the associations. In sum, TREML2 robustly associated with WMH volume and AD-related brain atrophy on different molecular levels. Our results thus underpin TREML2's role in neurodegeneration, might point to its involvement in AD and WMH via different biological mechanisms, and highlight TREML2 as a worthwhile target for disentangling the two pathologies.
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Affiliation(s)
- Annemarie Luise Kühn
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, 17475 Greifswald, Germany
- Correspondence: (A.L.K.); (S.V.d.A.)
| | - Stefan Frenzel
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Alexander Teumer
- Institute for Community Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Katharina Wittfeld
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, 17475 Greifswald, Germany
- German Center for Neurodegenerative Diseases (DZNE), Site Rostock/Greifswald, 17489 Greifswald, Germany
| | - Linda Garvert
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Antoine Weihs
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Georg Homuth
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Technical University Munich, 81675 Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Robin Bülow
- Institute of Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Matthias Nauck
- Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
- German Centre for Cardiovascular Research (DZHK), Partner Site Greifswald, 17475 Greifswald, Germany
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, 17475 Greifswald, Germany
- German Centre for Cardiovascular Research (DZHK), Partner Site Greifswald, 17475 Greifswald, Germany
| | - Henry Völzke
- Institute for Community Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
- German Centre for Cardiovascular Research (DZHK), Partner Site Greifswald, 17475 Greifswald, Germany
| | - Hans Jörgen Grabe
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, 17475 Greifswald, Germany
- German Center for Neurodegenerative Diseases (DZNE), Site Rostock/Greifswald, 17489 Greifswald, Germany
| | - Sandra Van der Auwera
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, 17475 Greifswald, Germany
- German Center for Neurodegenerative Diseases (DZNE), Site Rostock/Greifswald, 17489 Greifswald, Germany
- Correspondence: (A.L.K.); (S.V.d.A.)
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Wang SY, Gong PY, E Y, Zhang YD, Jiang T. The Role of TREML2 in Alzheimer's Disease. J Alzheimers Dis 2021; 76:799-806. [PMID: 32568208 DOI: 10.3233/jad-200406] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Late-onset Alzheimer's disease (AD) accounts for most of all AD casesand is currently considered a complex disorder caused by a combination of environmental and genetic factors. As an important family member of triggering receptor expressed on myeloid cells (TREM), TREM-like transcript 2 gene (TREML2) locates on human chromosome 6p21.1, a newly-identified hot zone for AD susceptibility, and encodes atransmembrane immune receptor. Emerging evidence implied a potential role of TREML2 in the susceptibility and pathogenesis of AD. Here, we review the recent literature about the association of TREML2 variants with AD risk and disease endophenotypes. Moreover, we summarize the latest findings regarding cellular localization and biological functions of TREML2 and speculate its possible role in AD pathogenesis. In addition, we discuss future research directions of TREML2 and AD.
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Affiliation(s)
- Si-Yu Wang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.,Department of Neurology, Nanjing Yuhua Hospital, Nanjing, China
| | - Peng-Yu Gong
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.,Department of Neurology, Nanjing Yuhua Hospital, Nanjing, China
| | - Yan E
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.,Department of Neurology, Nanjing Yuhua Hospital, Nanjing, China
| | - Ying-Dong Zhang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.,Department of Neurology, Nanjing Yuhua Hospital, Nanjing, China.,School of Basic Medicine & Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Teng Jiang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.,Department of Neurology, Nanjing Yuhua Hospital, Nanjing, China
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Seto M, Weiner RL, Dumitrescu L, Hohman TJ. Protective genes and pathways in Alzheimer's disease: moving towards precision interventions. Mol Neurodegener 2021; 16:29. [PMID: 33926499 PMCID: PMC8086309 DOI: 10.1186/s13024-021-00452-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 04/20/2021] [Indexed: 12/29/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive, neurodegenerative disorder that is characterized by neurodegeneration, cognitive impairment, and an eventual inability to perform daily tasks. The etiology of Alzheimer's is complex, with numerous environmental and genetic factors contributing to the disease. Late-onset AD is highly heritable (60 to 80%), and over 40 risk loci for AD have been identified via large genome-wide association studies, most of which are common variants with small effect sizes. Although these discoveries have provided novel insight on biological contributors to AD, disease-modifying treatments remain elusive. Recently, the concepts of resistance to pathology and resilience against the downstream consequences of pathology have been of particular interest in the Alzheimer's field as studies continue to identify individuals who evade the pathology of the disease even into late life and individuals who have all of the neuropathological features of AD but evade downstream neurodegeneration and cognitive impairment. It has been hypothesized that a shift in focus from Alzheimer's risk to resilience presents an opportunity to uncover novel biological mechanisms of AD and to identify promising therapeutic targets for the disease. This review will highlight a selection of genes and variants that have been reported to confer protection from AD within the literature and will also discuss evidence for the biological underpinnings behind their protective effect with a focus on genes involved in lipid metabolism, cellular trafficking, endosomal and lysosomal function, synaptic function, and inflammation. Finally, we offer some recommendations in areas where the field can rapidly advance towards precision interventions that leverage the ideas of protection and resilience for the development of novel therapeutic strategies.
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Affiliation(s)
- Mabel Seto
- Vanderbilt Memory and Alzheimer’s Center, Vanderbilt University Medical Center, 1207 17th Ave S, Nashville, TN 37212 USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN USA
| | - Rebecca L. Weiner
- Vanderbilt Memory and Alzheimer’s Center, Vanderbilt University Medical Center, 1207 17th Ave S, Nashville, TN 37212 USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN USA
| | - Logan Dumitrescu
- Vanderbilt Memory and Alzheimer’s Center, Vanderbilt University Medical Center, 1207 17th Ave S, Nashville, TN 37212 USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN USA
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN USA
| | - Timothy J. Hohman
- Vanderbilt Memory and Alzheimer’s Center, Vanderbilt University Medical Center, 1207 17th Ave S, Nashville, TN 37212 USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN USA
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN USA
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Ennerfelt HE, Lukens JR. The role of innate immunity in Alzheimer's disease. Immunol Rev 2020; 297:225-246. [PMID: 32588460 PMCID: PMC7783860 DOI: 10.1111/imr.12896] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/23/2020] [Accepted: 05/28/2020] [Indexed: 12/12/2022]
Abstract
The amyloid hypothesis has dominated Alzheimer's disease (AD) research for almost 30 years. This hypothesis hinges on the predominant clinical role of the amyloid beta (Aβ) peptide in propagating neurofibrillary tangles (NFTs) and eventual cognitive impairment in AD. Recent research in the AD field has identified the brain-resident macrophages, known as microglia, and their receptors as integral regulators of both the initiation and propagation of inflammation, Aβ accumulation, neuronal loss, and memory decline in AD. Emerging studies have also begun to reveal critical roles for distinct innate immune pathways in AD pathogenesis, which has led to great interest in harnessing the innate immune response as a therapeutic strategy to treat AD. In this review, we will highlight recent advancements in our understanding of innate immunity and inflammation in AD onset and progression. Additionally, there has been mounting evidence suggesting pivotal contributions of environmental factors and lifestyle choices in AD pathogenesis. Therefore, we will also discuss recent findings, suggesting that many of these AD risk factors influence AD progression via modulation of microglia and immune responses.
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Affiliation(s)
- Hannah E. Ennerfelt
- Center for Brain Immunology and Glia (BIG), Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22908, USA
- Cell and Molecular Biology Training Program, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - John R. Lukens
- Center for Brain Immunology and Glia (BIG), Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22908, USA
- Cell and Molecular Biology Training Program, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
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Wang SY, Xue X, Duan R, Gong PY, E Y, Jiang T, Zhang YD. A TREML2 missense variant influences specific hippocampal subfield volumes in cognitively normal elderly subjects. Brain Behav 2020; 10:e01573. [PMID: 32073739 PMCID: PMC7177563 DOI: 10.1002/brb3.1573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 01/22/2020] [Accepted: 02/04/2020] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION Triggering receptor expressed on myeloid cells-like transcript 2 gene (TREML2) is a newly identified AD susceptibility gene. Its missense variant rs3747742-C substantially decreases AD risk in both Caucasians and Han Chinese, but the underlying mechanisms remain elusive. In the present study, to uncover the possible mechanisms by which TREML2 rs3747742-C reduces AD risk, we investigated the possible relation of this variant with AD-related brain structures using a cognitively normal elderly population from Alzheimer's Disease Neuroimaging Initiative (ADNI) database. METHODS In total, 158 cognitively normal elders from ADNI database with complete data for brain structures and TREML2 rs3747742 genotype were included in this study. The association of TREML2 rs3747742 genotype with the structures of three cerebral cortices (entorhinal cortex, middle temporal gyrus, and parahippocampal gyrus), two subcortical regions (amygdala and hippocampus), and three subfields of hippocampus (CA1, CA2 + CA3, and CA4 + dentate gyrus) was investigated. RESULTS A significant difference was noted in the volume of right CA1 subfield among three genotypes of TREML2 rs3747742 (p = .0364). In the multivariate analysis, TREML2 rs3747742-C significantly increased right CA1 subfield volume after adjusting for age, gender, education years, APOE ε4 status, and intracranial volume under the recessive genetic model (Bonferroni corrected p = .003586). CONCLUSION The present study provides the first evidence that TREML2 rs3747742-C carriers have larger volumes of hippocampal CA1 subfield in a cognitively normal elderly population. These findings imply that enhancement of brain reserve may contribute to the protection of TREML2 rs3747742-C in AD susceptibility.
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Affiliation(s)
- Si-Yu Wang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Xiao Xue
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Rui Duan
- School of Basic Medicine & Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Peng-Yu Gong
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Yan E
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Teng Jiang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Ying-Dong Zhang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.,School of Basic Medicine & Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
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