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Washbourne P. Synapse assembly and neurodevelopmental disorders. Neuropsychopharmacology 2015; 40:4-15. [PMID: 24990427 PMCID: PMC4262893 DOI: 10.1038/npp.2014.163] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 06/23/2014] [Accepted: 06/26/2014] [Indexed: 12/31/2022]
Abstract
In this review we examine the current understanding of how genetic deficits associated with neurodevelopmental disorders may impact synapse assembly. We then go on to discuss how the critical periods for these genetic deficits will shape the nature of future clinical interventions.
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Affiliation(s)
- Philip Washbourne
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA,Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR 97403, USA, Tel: +1 541 346 4138, Fax: +1 541 346 4548, E-mail:
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52
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Kunze A, Tseng P, Godzich C, Murray C, Caputo A, Schweizer FE, Di Carlo D. Engineering cortical neuron polarity with nanomagnets on a chip. ACS NANO 2015; 9:3664-76. [PMID: 25801533 DOI: 10.1021/nn505330w] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Intra- and extracellular signaling play critical roles in cell polarity, ultimately leading to the development of functional cell-cell connections, tissues, and organs. In the brain, pathologically oriented neurons are often the cause for disordered circuits, severely impacting motor function, perception, and memory. Aside from control through gene expression and signaling pathways, it is known that nervous system development can be manipulated by mechanical stimuli (e.g., outgrowth of axons through externally applied forces). The inverse is true as well: intracellular molecular signals can be converted into forces to yield axonal outgrowth. The complete role played by mechanical signals in mediating single-cell polarity, however, remains currently unclear. Here we employ highly parallelized nanomagnets on a chip to exert local mechanical stimuli on cortical neurons, independently of the amount of superparamagnetic nanoparticles taken up by the cells. The chip-based approach was utilized to quantify the effect of nanoparticle-mediated forces on the intracellular cytoskeleton as visualized by the distribution of the microtubule-associated protein tau. While single cortical neurons prefer to assemble tau proteins following poly-L-lysine surface cues, an optimal force range of 4.5-70 pN by the nanomagnets initiated a tau distribution opposed to the pattern cue. In larger cell clusters (groups comprising six or more cells), nanoparticle-mediated forces induced tau repositioning in an observed range of 190-270 pN, and initiation of magnetic field-directed cell displacement was observed at forces above 300 pN. Our findings lay the groundwork for high-resolution mechanical encoding of neural networks in vitro, mechanically driven cell polarization in brain tissues, and neurotherapeutic approaches using functionalized superparamagnetic nanoparticles to potentially restore disordered neural circuits.
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Affiliation(s)
- Anja Kunze
- †Department of Bioengineering, ‡California NanoSystems Institute, and §Department of Neurobiology, University of California, Los Angeles, California 90095, United States
| | - Peter Tseng
- †Department of Bioengineering, ‡California NanoSystems Institute, and §Department of Neurobiology, University of California, Los Angeles, California 90095, United States
| | - Chanya Godzich
- †Department of Bioengineering, ‡California NanoSystems Institute, and §Department of Neurobiology, University of California, Los Angeles, California 90095, United States
| | - Coleman Murray
- †Department of Bioengineering, ‡California NanoSystems Institute, and §Department of Neurobiology, University of California, Los Angeles, California 90095, United States
| | - Anna Caputo
- †Department of Bioengineering, ‡California NanoSystems Institute, and §Department of Neurobiology, University of California, Los Angeles, California 90095, United States
| | - Felix E Schweizer
- †Department of Bioengineering, ‡California NanoSystems Institute, and §Department of Neurobiology, University of California, Los Angeles, California 90095, United States
| | - Dino Di Carlo
- †Department of Bioengineering, ‡California NanoSystems Institute, and §Department of Neurobiology, University of California, Los Angeles, California 90095, United States
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53
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Gerson JE, Castillo-Carranza DL, Kayed R. Advances in therapeutics for neurodegenerative tauopathies: moving toward the specific targeting of the most toxic tau species. ACS Chem Neurosci 2014; 5:752-69. [PMID: 25075869 DOI: 10.1021/cn500143n] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neurodegenerative disease is one of the greatest health concerns today and with no effective treatment in sight, it is crucial that researchers find a safe and successful therapeutic. While neurofibrillary tangles are considered the primary tauopathy hallmark, more evidence continues to come to light to suggest that soluble, intermediate tau aggregates--tau oligomers--are the most toxic species in disease. These intermediate tau species may also be responsible for the spread of pathology, suggesting that oligomeric tau may be the best therapeutic target. Here, we summarize results for the modulation of tau by molecular chaperones, small molecules and aggregation inhibitors, post-translational modifications, immunotherapy, other techniques, and future directions.
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Affiliation(s)
- Julia E. Gerson
- Department
of Neurology, George and Cynthia Mitchell
Center for Alzheimer’s Disease Research, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Diana L. Castillo-Carranza
- Department
of Neurology, George and Cynthia Mitchell
Center for Alzheimer’s Disease Research, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Rakez Kayed
- Department
of Neurology, George and Cynthia Mitchell
Center for Alzheimer’s Disease Research, University of Texas Medical Branch, Galveston, Texas 77555, United States
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54
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Lei P, Ayton S, Moon S, Zhang Q, Volitakis I, Finkelstein DI, Bush AI. Motor and cognitive deficits in aged tau knockout mice in two background strains. Mol Neurodegener 2014; 9:29. [PMID: 25124182 PMCID: PMC4141346 DOI: 10.1186/1750-1326-9-29] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/10/2014] [Indexed: 11/13/2022] Open
Abstract
Background We recently reported that Parkinsonian and dementia phenotypes emerge between 7-12 months of age in tau-/- mice on a Bl6/129sv mixed background. These observations were partially replicated by another group using pure Bl6 background tau-/- mice, but notably they did not observe a cognitive phenotype. A third group using Bl6 background tau-/- mice found cognitive impairment at 20-months of age. Results To reconcile the observations, here we considered the genetic, dietary and environmental variables in both studies, and performed an extended set of behavioral studies on 12-month old tau+/+, tau+/-, and tau-/- mice comparing Bl6/129sv to Bl6 backgrounds. We found that tau-/- in both backgrounds exhibited reduced tyrosine hydroxylase-positive nigral neuron and impaired motor function in all assays used, which was ameliorated by oral treatment with L-DOPA, and not confounded by changes in body weight. Tau-/- in the C57BL6/SV129 background exhibited deficits in the Y-maze cognition task, but the mice on the Bl6 background did not. Conclusions These results validate our previous report on the neurodegenerative phenotypes of aged tau-/- mice, and show that genetic background may impact the extent of cognitive impairment in these mice. Therefore excessive lowering of tau should be avoided in therapeutic strategies for AD.
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Affiliation(s)
| | | | | | | | | | | | - Ashley I Bush
- Oxidation Biology Unit, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia.
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55
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Gheyara AL, Ponnusamy R, Djukic B, Craft RJ, Ho K, Guo W, Finucane MM, Sanchez PE, Mucke L. Tau reduction prevents disease in a mouse model of Dravet syndrome. Ann Neurol 2014; 76:443-56. [PMID: 25042160 PMCID: PMC4338764 DOI: 10.1002/ana.24230] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 07/08/2014] [Accepted: 07/09/2014] [Indexed: 12/12/2022]
Abstract
Objective Reducing levels of the microtubule-associated protein tau has shown promise as a potential treatment strategy for diseases with secondary epileptic features such as Alzheimer disease. We wanted to determine whether tau reduction may also be of benefit in intractable genetic epilepsies. Methods We studied a mouse model of Dravet syndrome, a severe childhood epilepsy caused by mutations in the human SCN1A gene encoding the voltage-gated sodium channel subunit Nav1.1. We genetically deleted 1 or 2 Tau alleles in mice carrying an Nav1.1 truncation mutation (R1407X) that causes Dravet syndrome in humans, and examined their survival, epileptic activity, related hippocampal alterations, and behavioral abnormalities using observation, electroencephalographic recordings, acute slice electrophysiology, immunohistochemistry, and behavioral assays. Results Tau ablation prevented the high mortality of Dravet mice and reduced the frequency of spontaneous and febrile seizures. It reduced interictal epileptic spikes in vivo and drug-induced epileptic activity in brain slices ex vivo. Tau ablation also prevented biochemical changes in the hippocampus indicative of epileptic activity and ameliorated abnormalities in learning and memory, nest building, and open field behaviors in Dravet mice. Deletion of only 1 Tau allele was sufficient to suppress epileptic activity and improve survival and nesting performance. Interpretation Tau reduction may be of therapeutic benefit in Dravet syndrome and other intractable genetic epilepsies. Ann Neurol 2014;76:443–456
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Affiliation(s)
- Ania L Gheyara
- Gladstone Institute of Neurological Disease, University of California, San Francisco, San Francisco, CA; Departments of Pathology, University of California, San Francisco, San Francisco, CA
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56
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Llorens-Martín M, Blazquez-Llorca L, Benavides-Piccione R, Rabano A, Hernandez F, Avila J, DeFelipe J. Selective alterations of neurons and circuits related to early memory loss in Alzheimer's disease. Front Neuroanat 2014; 8:38. [PMID: 24904307 PMCID: PMC4034155 DOI: 10.3389/fnana.2014.00038] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 04/30/2014] [Indexed: 12/17/2022] Open
Abstract
A progressive loss of episodic memory is a well-known clinical symptom that characterizes Alzheimer’s disease (AD). The beginning of this loss of memory has been associated with the very early, pathological accumulation of tau and neuronal degeneration observed in the entorhinal cortex (EC). Tau-related pathology is thought to then spread progressively to the hippocampal formation and other brain areas as the disease progresses. The major cortical afferent source of the hippocampus and dentate gyrus is the EC through the perforant pathway. At least two main circuits participate in the connection between EC and the hippocampus; one originating in layer II and the other in layer III of the EC giving rise to the classical trisynaptic (ECII → dentate gyrus → CA3 → CA1) and monosynaptic (ECIII → CA1) circuits. Thus, the study of the early pathological changes in these circuits is of great interest. In this review, we will discuss mainly the alterations of the granule cell neurons of the dentate gyrus and the atrophy of CA1 pyramidal neurons that occur in AD in relation to the possible differential alterations of these two main circuits.
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Affiliation(s)
- Maria Llorens-Martín
- Consejo Superior de Investigaciones Cientificas-Universidad Autónoma de Madrid, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid Madrid, Spain
| | - Lidia Blazquez-Llorca
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid Madrid, Spain ; Instituto Cajal, Consejo Superior de Investigaciones Cientificas Madrid, Spain
| | - Ruth Benavides-Piccione
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid Madrid, Spain ; Instituto Cajal, Consejo Superior de Investigaciones Cientificas Madrid, Spain ; Centro de Investigación en Red sobre Enfermedades Neurodegenerativas Madrid, Spain
| | - Alberto Rabano
- Departamento de Neuropatología y Banco de Tejidos, Fundación CIEN, Instituto de Salud Carlos III Madrid, Spain
| | - Felix Hernandez
- Consejo Superior de Investigaciones Cientificas-Universidad Autónoma de Madrid, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid Madrid, Spain
| | - Jesus Avila
- Consejo Superior de Investigaciones Cientificas-Universidad Autónoma de Madrid, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid Madrid, Spain ; Centro de Investigación en Red sobre Enfermedades Neurodegenerativas Madrid, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid Madrid, Spain ; Instituto Cajal, Consejo Superior de Investigaciones Cientificas Madrid, Spain ; Centro de Investigación en Red sobre Enfermedades Neurodegenerativas Madrid, Spain
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Khan UA, Liu L, Provenzano FA, Berman DE, Profaci CP, Sloan R, Mayeux R, Duff KE, Small SA. Molecular drivers and cortical spread of lateral entorhinal cortex dysfunction in preclinical Alzheimer's disease. Nat Neurosci 2014; 17:304-11. [PMID: 24362760 PMCID: PMC4044925 DOI: 10.1038/nn.3606] [Citation(s) in RCA: 393] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 11/20/2013] [Indexed: 01/12/2023]
Abstract
The entorhinal cortex has been implicated in the early stages of Alzheimer's disease, which is characterized by changes in the tau protein and in the cleaved fragments of the amyloid precursor protein (APP). We used a high-resolution functional magnetic resonance imaging (fMRI) variant that can map metabolic defects in patients and mouse models to address basic questions about entorhinal cortex pathophysiology. The entorhinal cortex is divided into functionally distinct regions, the medial entorhinal cortex (MEC) and the lateral entorhinal cortex (LEC), and we exploited the high-resolution capabilities of the fMRI variant to ask whether either of them was affected in patients with preclinical Alzheimer's disease. Next, we imaged three mouse models of disease to clarify how tau and APP relate to entorhinal cortex dysfunction and to determine whether the entorhinal cortex can act as a source of dysfunction observed in other cortical areas. We found that the LEC was affected in preclinical disease, that LEC dysfunction could spread to the parietal cortex during preclinical disease and that APP expression potentiated tau toxicity in driving LEC dysfunction, thereby helping to explain regional vulnerability in the disease.
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Affiliation(s)
- Usman A Khan
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York, USA. [3] Program in Neural and Behavioral Science, State University of New York Downstate Medical Center, Brooklyn, New York, USA
| | - Li Liu
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Pathology, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Frank A Provenzano
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Diego E Berman
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Pathology, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Caterina P Profaci
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Pathology, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Richard Sloan
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Richard Mayeux
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Karen E Duff
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Pathology, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Scott A Small
- 1] Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, New York, USA. [2] Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York, USA. [3] Department of Radiology, Columbia University College of Physicians and Surgeons, New York, New York, USA
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Pooler AM, Noble W, Hanger DP. A role for tau at the synapse in Alzheimer's disease pathogenesis. Neuropharmacology 2014; 76 Pt A:1-8. [PMID: 24076336 DOI: 10.1016/j.neuropharm.2013.09.018] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 09/06/2013] [Accepted: 09/07/2013] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease (AD) is characterized by brain deposition of amyloid plaques and tau neurofibrillary tangles along with steady cognitive decline. Although the mechanism by which AD pathogenesis occurs is unclear, accumulating evidence suggests that dysfunction and loss of synaptic connections may be an early event underlying disease progression. Profound synapse degeneration is observed in AD, and the density of these connections strongly correlates with cognitive ability. Initial investigations into AD-related synaptic changes focused on the toxic effects of amyloid. However, recent research suggests an emerging role for tau at the synapse. Even in the absence of tangles, mice overexpressing human tau display significant synaptic degeneration, suggesting that soluble, oligomeric tau is the synaptotoxic species. However, the localization of tau within synapses in both healthy and AD brains indicates that tau might play a role in normal synaptic function, which may be disrupted in disease. Tau is able to impact synaptic activity in several ways: studies show tau interacting directly with post-synaptic signaling complexes, regulating glutamatergic receptor content in dendritic spines, and influencing targeting and function of synaptic mitochondria. Early trials of tau-targeted immunotherapy reduce tau pathology and synapse loss, indicating that the toxic effects of tau may be reversible within a certain time frame. Understanding the role of tau in both normal and degenerating synapses is crucial for the development of therapeutic strategies designed to ameliorate synapse loss and prevent AD pathogenesis. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.
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Affiliation(s)
- Amy M Pooler
- King's College London, Institute of Psychiatry, Department of Neuroscience (PO37), De Crespigny Park, London SE5 8AF, United Kingdom
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59
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Mark/Par-1 Marking the Polarity of Migrating Neurons. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 800:97-111. [DOI: 10.1007/978-94-007-7687-6_6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Abstract
Microtubules (MTs) are essential for neuronal morphogenesis in the developing brain. The MT cytoskeleton provides physical support to shape the fine structure of neuronal processes. MT-based motors play important roles in nucleokinesis, process formation and retraction. Regulation of MT stability downstream of extracellular cues is proposed to be critical for axonogenesis. Axons and dendrites exhibit different patterns of MT organization, underlying the divergent functions of these processes. Centrosomal positioning has drawn the attention of researchers because it is a major clue to understanding neuronal MT organization. In this review, we focus on how recent advances in live imaging have revealed the dynamics of MT organization and centrosome positioning during neural development.
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Affiliation(s)
- Akira Sakakibara
- Department of Anatomy and Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
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61
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Wolfe MS. The role of tau in neurodegenerative diseases and its potential as a therapeutic target. SCIENTIFICA 2012; 2012:796024. [PMID: 24278740 PMCID: PMC3820460 DOI: 10.6064/2012/796024] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 11/05/2012] [Indexed: 06/01/2023]
Abstract
The abnormal deposition of proteins in and around neurons is a common pathological feature of many neurodegenerative diseases. Among these pathological proteins, the microtubule-associated protein tau forms intraneuronal filaments in a spectrum of neurological disorders. The discovery that dominant mutations in the MAPT gene encoding tau are associated with familial frontotemporal dementia strongly supports abnormal tau protein as directly involved in disease pathogenesis. This and other evidence suggest that tau is a worthwhile target for the prevention or treatment of tau-associated neurodegenerative diseases, collectively called tauopathies. However, it is critical to understand the normal biological roles of tau, the specific molecular events that induce tau to become neurotoxic, the biochemical nature of pathogenic tau, the means by which pathogenic tau exerts neurotoxicity, and how tau pathology propagates. Based on known differences between normal and abnormal tau, a number of approaches have been taken toward the discovery of potential therapeutics. Key questions still remain open, such as the nature of the connection between the amyloid- β protein of Alzheimer's disease and tau pathology. Answers to these questions should help better understand the nature of tauopathies and may also reveal new therapeutic targets and strategies.
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Affiliation(s)
- Michael S. Wolfe
- Brigham and Women's Hospital, Harvard Medical School, 77 Avenue Louis Pasteur, H.I.M. 754, Boston, MA 02115, USA
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62
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Copy number variations involving the microtubule-associated protein tau in human diseases. Biochem Soc Trans 2012; 40:672-6. [PMID: 22817714 DOI: 10.1042/bst20120045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mutations of the MAPT (microtubule-associated protein tau) gene are associated with FTLD (frontotemporal lobar degeneration) with tau pathology. These mutations result in a decreased ability of tau to bind MTs (microtubules), an increased production of tau with four MT-binding repeats or enhanced tau aggregation. In two FTLD patients, we recently described CNVs (copy number variations) affecting the MAPT gene, consisting of a partial deletion and a complete duplication of the gene. The partial deletion resulted in a truncated protein lacking the first MT-binding domain, which had a dramatic decrease in the binding to MTs but acquired the ability to bind MAP (microtubule-associated protein) 1-B. In this case, tauopathy probably resulted from both a loss of normal function and a gain of function by which truncated tau would sequester another MAP. In the other FTLD patient, the complete duplication might result in the overexpression of tau, which in the mouse model induces axonopathy and tau aggregates reminiscent of FTLD-tau pathology. Interestingly, the same rearrangement was also described in several children with mental retardation, autism spectrum disorders and dysmorphic features, as well as in a schizophrenic patient. Finally, complete deletions of the MAPT gene have been associated with mental retardation, hypotonia and facial dysmorphism.
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