1
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Shelkowitz E, Stence NV, Neuberger I, Park KL, Saenz MS, Pao E, Oyama N, Friedman SD, Shaw DWW, Mirzaa GM. Variants in PTEN Are Associated With a Diverse Spectrum of Cortical Dysplasia. Pediatr Neurol 2023; 147:154-162. [PMID: 37619436 DOI: 10.1016/j.pediatrneurol.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 04/12/2023] [Accepted: 06/16/2023] [Indexed: 08/26/2023]
Abstract
BACKGROUND Inactivating mutations in PTEN are among the most common causes of megalencephaly. Activating mutations in other nodes of the PI3K/AKT/MTOR signaling pathway are recognized as a frequent cause of cortical brain malformations. Only recently has PTEN been associated with cortical malformations, and analyses of their prognostic significance have been limited. METHODS Retrospective neuroimaging analysis and detailed chart review were conducted on 20 participants identified with pathogenic or likely pathogenic mutations in PTEN and a cortical brain malformation present on brain magnetic resonance imaging. RESULTS Neuroimaging analysis revealed four main cerebral phenotypes-hemimegalencephaly, focal cortical dysplasia, polymicrogyria (PMG), and a less severe category, termed "macrocephaly with complicated gyral pattern" (MCG). Although a high proportion of participants (90%) had neurodevelopmental findings on presentation, outcomes varied and were favorable in over half of participants. Consistent with prior work, 39% of participants had autism spectrum disorder and 19% of participants with either pure-PMG or pure-MCG phenotypes had epilepsy. Megalencephaly and systemic overgrowth were common, but other systemic features of PTEN-hamartoma tumor syndrome were absent in over one-third of participants. CONCLUSIONS A spectrum of cortical dysplasias is present in individuals with inactivating mutations in PTEN. Future studies are needed to clarify the prognostic significance of each cerebral phenotype, but overall, we conclude that despite a high burden of neurodevelopmental disease, long-term outcomes may be favorable. Germline testing for PTEN mutations should be considered in cases of megalencephaly and cortical brain malformations even in the absence of other findings, including cognitive impairment.
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Affiliation(s)
- Emily Shelkowitz
- Department of Pediatrics, University of Washington, Seattle, Washington.
| | | | - Ilana Neuberger
- Department of Radiology, University of Colorado, Aurora, Colorado
| | - Kristen L Park
- Department of Pediatrics, University of Colorado, Aurora, Colorado
| | | | - Emily Pao
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Nora Oyama
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Seth D Friedman
- Department of Radiology, Seattle Children's Hospital, University of Washington, Seattle, Washington
| | - Dennis W W Shaw
- Department of Radiology, Seattle Children's Hospital, University of Washington, Seattle, Washington
| | - Ghayda M Mirzaa
- Department of Pediatrics, University of Washington, Seattle, Washington; Brotman Baty Institute for Precision Medicine, Seattle, Washington.
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2
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Phosphatase and tensin homolog (PTEN) variants and epilepsy: A multicenter case series. Seizure 2022; 100:82-86. [DOI: 10.1016/j.seizure.2022.06.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 05/25/2022] [Accepted: 06/22/2022] [Indexed: 01/06/2023] Open
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3
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Karalis V, Bateup HS. Current Approaches and Future Directions for the Treatment of mTORopathies. Dev Neurosci 2021; 43:143-158. [PMID: 33910214 PMCID: PMC8440338 DOI: 10.1159/000515672] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/13/2021] [Indexed: 11/19/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is a kinase at the center of an evolutionarily conserved signaling pathway that orchestrates cell growth and metabolism. mTOR responds to an array of intra- and extracellular stimuli and in turn controls multiple cellular anabolic and catabolic processes. Aberrant mTOR activity is associated with numerous diseases, with particularly profound impact on the nervous system. mTOR is found in two protein complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), which are governed by different upstream regulators and have distinct cellular actions. Mutations in genes encoding for mTOR regulators result in a collection of neurodevelopmental disorders known as mTORopathies. While these disorders can affect multiple organs, neuropsychiatric conditions such as epilepsy, intellectual disability, and autism spectrum disorder have a major impact on quality of life. The neuropsychiatric aspects of mTORopathies have been particularly challenging to treat in a clinical setting. Current therapeutic approaches center on rapamycin and its analogs, drugs that are administered systemically to inhibit mTOR activity. While these drugs show some clinical efficacy, adverse side effects, incomplete suppression of mTOR targets, and lack of specificity for mTORC1 or mTORC2 may limit their utility. An increased understanding of the neurobiology of mTOR and the underlying molecular, cellular, and circuit mechanisms of mTOR-related disorders will facilitate the development of improved therapeutics. Animal models of mTORopathies have helped unravel the consequences of mTOR pathway mutations in specific brain cell types and developmental stages, revealing an array of disease-related phenotypes. In this review, we discuss current progress and potential future directions for the therapeutic treatment of mTORopathies with a focus on findings from genetic mouse models.
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Affiliation(s)
- Vasiliki Karalis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Helen S Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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4
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Macken WL, Tischkowitz M, Lachlan KL. PTEN Hamartoma tumor syndrome in childhood: A review of the clinical literature. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2019; 181:591-610. [PMID: 31609537 DOI: 10.1002/ajmg.c.31743] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/28/2019] [Accepted: 09/05/2019] [Indexed: 01/06/2023]
Abstract
PTEN hamartoma tumor syndrome (PHTS) is a highly variable autosomal dominant condition associated with intellectual disability, overgrowth, and tumor predisposition phenotypes, which often overlap. PHTS incorporates a number of historical clinical presentations including Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome, and a macrocephaly-autism/developmental delay syndrome. Many reviews in the literature focus on PHTS as an adult hamartoma and malignancy predisposition condition. Here, we review the current literature with a focus on pediatric presentations. The review starts with a summary of the main conditions encompassed within PHTS. We then discuss PHTS diagnostic criteria, and clinical features. We briefly address rarer PTEN associations, and the possible role of mTOR inhibitors in treatment. We acknowledge the limited understanding of the natural history of childhood-onset PHTS as a cancer predisposition syndrome and present a summary of important management considerations.
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Affiliation(s)
- William L Macken
- Wessex Clinical Genetics Service, University Hospitals Southampton NHS Trust, Southampton, United Kingdom
| | - Marc Tischkowitz
- Department of Clinical Genetics, East Anglian Medical Genetics Service, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom.,Department of Medical Genetics, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Katherine L Lachlan
- Wessex Clinical Genetics Service, University Hospitals Southampton NHS Trust, Southampton, United Kingdom.,Human Genetics and Genomic Medicine, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
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5
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Kim JK, Lee JH. Mechanistic Target of Rapamycin Pathway in Epileptic Disorders. J Korean Neurosurg Soc 2019; 62:272-287. [PMID: 31085953 PMCID: PMC6514310 DOI: 10.3340/jkns.2019.0027] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/12/2019] [Indexed: 12/19/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) pathway coordinates the metabolic activity of eukaryotic cells through environmental signals, including nutrients, energy, growth factors, and oxygen. In the nervous system, the mTOR pathway regulates fundamental biological processes associated with neural development and neurodegeneration. Intriguingly, genes that constitute the mTOR pathway have been found to be germline and somatic mutation from patients with various epileptic disorders. Hyperactivation of the mTOR pathway due to said mutations has garnered increasing attention as culprits of these conditions : somatic mutations, in particular, in epileptic foci have recently been identified as a major genetic cause of intractable focal epilepsy, such as focal cortical dysplasia. Meanwhile, epilepsy models with aberrant activation of the mTOR pathway have helped elucidate the role of the mTOR pathway in epileptogenesis, and evidence from epilepsy models of human mutations recapitulating the features of epileptic patients has indicated that mTOR inhibitors may be of use in treating epilepsy associated with mutations in mTOR pathway genes. Here, we review recent advances in the molecular and genetic understanding of mTOR signaling in epileptic disorders. In particular, we focus on the development of and limitations to therapies targeting the mTOR pathway to treat epileptic seizures. We also discuss future perspectives on mTOR inhibition therapies and special diagnostic methods for intractable epilepsies caused by brain somatic mutations.
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Affiliation(s)
- Jang Keun Kim
- Biomedical Science and Engineering Interdisciplinary Program, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Jeong Ho Lee
- Biomedical Science and Engineering Interdisciplinary Program, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.,Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
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6
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Pulido R. PTEN Inhibition in Human Disease Therapy. Molecules 2018; 23:molecules23020285. [PMID: 29385737 PMCID: PMC6017825 DOI: 10.3390/molecules23020285] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 01/26/2018] [Accepted: 01/28/2018] [Indexed: 12/19/2022] Open
Abstract
The tumor suppressor PTEN is a major homeostatic regulator, by virtue of its lipid phosphatase activity against phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], which downregulates the PI3K/AKT/mTOR prosurvival signaling, as well as by its protein phosphatase activity towards specific protein targets. PTEN catalytic activity is crucial to control cell growth under physiologic and pathologic situations, and it impacts not only in preventing tumor cell survival and proliferation, but also in restraining several cellular regeneration processes, such as those associated with nerve injury recovery, cardiac ischemia, or wound healing. In these conditions, inhibition of PTEN catalysis is being explored as a potentially beneficial therapeutic intervention. Here, an overview of human diseases and conditions in which PTEN inhibition could be beneficial is presented, together with an update on the current status of specific small molecule inhibitors of PTEN enzymatic activity, their use in experimental models, and their limitations as research or therapeutic drugs.
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Affiliation(s)
- Rafael Pulido
- Biomarkers in Cancer Unit, Biocruces Health Research Institute, 48903 Barakaldo, Spain.
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
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7
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Adachi T, Takigawa H, Nomura T, Watanabe Y, Kowa H. Cowden Syndrome with a Novel PTEN Mutation Presenting with Partial Epilepsy Related to Focal Cortical Dysplasia. Intern Med 2018; 57:97-99. [PMID: 29033429 PMCID: PMC5799065 DOI: 10.2169/internalmedicine.9052-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cowden syndrome is a rare autosomal dominant disorder characterized by multiple hamartomas of the ectoderm and brain. A 36-year-old Japanese man presented with right facial seizure during sleep and was admitted to our hospital. He showed cobblestoning over the tongue and palmar pitting but no neurological abnormalities while he was not having a seizure. Brain magnetic resonance imaging showed focal cortical dysplasia in the left frontal lobe. Electroencephalography showed sharp waves over the left frontal lesion. A genetic analysis revealed a novel mutation of PTEN. The administration of carbamazepine ended the seizures. This is the first Japanese case of Cowden syndrome with a novel PTEN gene mutation and cortical dysplasia.
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Affiliation(s)
- Tadashi Adachi
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Japan
| | - Hiroshi Takigawa
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Japan
| | - Takashi Nomura
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Japan
| | - Yasuhiro Watanabe
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Japan
| | - Hisanori Kowa
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Japan
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8
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Balci TB, Davila J, Lewis D, Boafo A, Sell E, Richer J, Nikkel SM, Armour CM, Tomiak E, Lines MA, Sawyer SL. Broad spectrum of neuropsychiatric phenotypes associated with white matter disease in PTEN hamartoma tumor syndrome. Am J Med Genet B Neuropsychiatr Genet 2018; 177:101-109. [PMID: 29152901 DOI: 10.1002/ajmg.b.32610] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/30/2017] [Indexed: 11/11/2022]
Abstract
White matter lesions have been described in patients with PTEN hamartoma tumor syndrome (PHTS). How these lesions correlate with the neurocognitive features associated with PTEN mutations, such as autism spectrum disorder (ASD) or developmental delay, has not been well established. We report nine patients with PTEN mutations and white matter changes on brain magnetic resonance imaging (MRI), eight of whom were referred for reasons other than developmental delay or ASD. Their clinical presentations ranged from asymptomatic macrocephaly with normal development/intellect, to obsessive compulsive disorder, and debilitating neurological disease. To our knowledge, this report constitutes the first detailed description of PTEN-related white matter changes in adult patients and in children with normal development and intelligence. We present a detailed assessment of the neuropsychological phenotype of our patients and discuss the relationship between the wide array of neuropsychiatric features and observed white matter findings in the context of these individuals.
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Affiliation(s)
- Tugce B Balci
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Jorge Davila
- Department of Medical Imaging, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Denice Lewis
- Department of Psychiatry, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Department of Family Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Addo Boafo
- Department of Psychiatry, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Erick Sell
- Division of Neurology, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Julie Richer
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Sarah M Nikkel
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Christine M Armour
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Eva Tomiak
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Matthew A Lines
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.,Division of Metabolics and Newborn Screening, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Sarah L Sawyer
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
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9
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Jeong A, Wong M. Targeting the Mammalian Target of Rapamycin for Epileptic Encephalopathies and Malformations of Cortical Development. J Child Neurol 2018; 33:55-63. [PMID: 29246093 PMCID: PMC5739082 DOI: 10.1177/0883073817696814] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Malformations of cortical development represent a common cause of epileptic encephalopathies and drug-resistant epilepsy in children. As current treatments are often ineffective, new therapeutic targets are needed for epileptic encephalopathies associated with cortical malformations. The mechanistic/mammalian target of rapamycin (mTOR) pathway constitutes a signaling pathway that drives cellular and molecular mechanisms of epileptogenesis in a variety of focal cortical malformations. mTOR inhibitors prevent epilepsy and associated pathogenic mechanisms of epileptogenesis in mouse models of tuberous sclerosis complex and are currently in clinical trials for drug-resistant seizures in these patients. A recent explosion of genetic studies has linked mutations in various genes regulating the mTOR pathway to other cortical malformations, such as focal cortical dysplasia and hemimegalencephaly. Thus, mTOR inhibitors represent promising candidates as novel antiseizure and antiepileptogenic therapies for epilepsy associated with a spectrum of cortical malformations.
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Affiliation(s)
- Anna Jeong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Michael Wong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
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10
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Jeong A, Wong M. mTOR Inhibitors in Children: Current Indications and Future Directions in Neurology. Curr Neurol Neurosci Rep 2017; 16:102. [PMID: 27815691 DOI: 10.1007/s11910-016-0708-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The mammalian/mechanistic target of rapamycin (mTOR) pathway is a key signaling pathway that has been implicated in genetic epilepsy syndromes, neurodegenerative diseases, and conditions associated with autism spectrum disorder and cognitive impairment. The mTOR pathway has become an exciting treatment target for these various disorders, with mTOR inhibitors such as rapamycin being studied for their potential therapeutic applications. In particular, tuberous sclerosis complex (TSC) is a genetic disorder resulting from overactivation of the mTOR pathway, and pharmacologic therapy with mTOR inhibitors has emerged as a viable treatment option for the systemic manifestations of the disease. In this review, we discuss the approved indications for mTOR inhibitors in TSC, the potential future applications of mTOR inhibitors in TSC and other neurological conditions, and the safety considerations applicable to mTOR therapy in the pediatric population.
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Affiliation(s)
- Anna Jeong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, MO, 63110, USA
| | - Michael Wong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, MO, 63110, USA.
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11
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Mirzaa GM, Campbell CD, Solovieff N, Goold C, Jansen LA, Menon S, Timms AE, Conti V, Biag JD, Adams C, Boyle EA, Collins S, Ishak G, Poliachik S, Girisha KM, Yeung KS, Chung BHY, Rahikkala E, Gunter SA, McDaniel SS, Macmurdo CF, Bernstein JA, Martin B, Leary R, Mahan S, Liu S, Weaver M, Doerschner M, Jhangiani S, Muzny DM, Boerwinkle E, Gibbs RA, Lupski JR, Shendure J, Saneto RP, Novotny EJ, Wilson CJ, Sellers WR, Morrissey M, Hevner RF, Ojemann JG, Guerrini R, Murphy LO, Winckler W, Dobyns WB. Association of MTOR Mutations With Developmental Brain Disorders, Including Megalencephaly, Focal Cortical Dysplasia, and Pigmentary Mosaicism. JAMA Neurol 2017; 73:836-845. [PMID: 27159400 DOI: 10.1001/jamaneurol.2016.0363] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
IMPORTANCE Focal cortical dysplasia (FCD), hemimegalencephaly, and megalencephaly constitute a spectrum of malformations of cortical development with shared neuropathologic features. These disorders are associated with significant childhood morbidity and mortality. OBJECTIVE To identify the underlying molecular cause of FCD, hemimegalencephaly, and diffuse megalencephaly. DESIGN, SETTING, AND PARTICIPANTS Patients with FCD, hemimegalencephaly, or megalencephaly (mean age, 11.7 years; range, 2-32 years) were recruited from Pediatric Hospital A. Meyer, the University of Hong Kong, and Seattle Children's Research Institute from June 2012 to June 2014. Whole-exome sequencing (WES) was performed on 8 children with FCD or hemimegalencephaly using standard-depth (50-60X) sequencing in peripheral samples (blood, saliva, or skin) from the affected child and their parents and deep (150-180X) sequencing in affected brain tissue. Targeted sequencing and WES were used to screen 93 children with molecularly unexplained diffuse or focal brain overgrowth. Histopathologic and functional assays of phosphatidylinositol 3-kinase-AKT (serine/threonine kinase)-mammalian target of rapamycin (mTOR) pathway activity in resected brain tissue and cultured neurons were performed to validate mutations. MAIN OUTCOMES AND MEASURES Whole-exome sequencing and targeted sequencing identified variants associated with this spectrum of developmental brain disorders. RESULTS Low-level mosaic mutations of MTOR were identified in brain tissue in 4 children with FCD type 2a with alternative allele fractions ranging from 0.012 to 0.086. Intermediate-level mosaic mutation of MTOR (p.Thr1977Ile) was also identified in 3 unrelated children with diffuse megalencephaly and pigmentary mosaicism in skin. Finally, a constitutional de novo mutation of MTOR (p.Glu1799Lys) was identified in 3 unrelated children with diffuse megalencephaly and intellectual disability. Molecular and functional analysis in 2 children with FCD2a from whom multiple affected brain tissue samples were available revealed a mutation gradient with an epicenter in the most epileptogenic area. When expressed in cultured neurons, all MTOR mutations identified here drive constitutive activation of mTOR complex 1 and enlarged neuronal size. CONCLUSIONS AND RELEVANCE In this study, mutations of MTOR were associated with a spectrum of brain overgrowth phenotypes extending from FCD type 2a to diffuse megalencephaly, distinguished by different mutations and levels of mosaicism. These mutations may be sufficient to cause cellular hypertrophy in cultured neurons and may provide a demonstration of the pattern of mosaicism in brain and substantiate the link between mosaic mutations of MTOR and pigmentary mosaicism in skin.
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Affiliation(s)
- Ghayda M Mirzaa
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, USA.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | | | - Nadia Solovieff
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Carleton Goold
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Laura A Jansen
- Department of Neurology, University of Virginia, Charlottesville, VA, USA
| | - Suchithra Menon
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Andrew E Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Valerio Conti
- Paediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, A. Meyer Children's Hospital, and Department of Neuroscience, Pharmacology and Child Health, University of Florence, Florence, Italy
| | - Jonathan D Biag
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Carissa Adams
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Evan August Boyle
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Sarah Collins
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Gisele Ishak
- Department of Radiology, Seattle Children's Hospital, Seattle, Washington, USA
| | - Sandra Poliachik
- Department of Radiology, Seattle Children's Hospital, Seattle, Washington, USA
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal University, Manipal, Karnataka, India
| | - Kit San Yeung
- Department of Pediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Brian Hon Yin Chung
- Department of Pediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Elisa Rahikkala
- PEDEGO Research Group and Medical Research Center Oulu, University of Oulu and Department of Clinical Genetics, Oulu University Hospital, Finland
| | - Sonya A Gunter
- Department of Neurology, University of Virginia, Charlottesville, VA, USA
| | - Sharon S McDaniel
- Pediatric Neurology and Epilepsy, Kaiser Permanente San Francisco Medical Center, San Francisco, California, USA
| | - Colleen Forsyth Macmurdo
- Division of Medical Genetics, Department of Pediatrics, Stanford University, Stanford, California, USA
| | - Jonathan A Bernstein
- Division of Medical Genetics, Department of Pediatrics, Stanford University, Stanford, California, USA
| | - Beth Martin
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Rebecca Leary
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Scott Mahan
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Shanming Liu
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Molly Weaver
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - Michael Doerschner
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - Shalini Jhangiani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Donna M Muzny
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Eric Boerwinkle
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.,Human Genetics Center, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Russell P Saneto
- Division of Pediatric Neurology, University of Washington, Seattle, Washington, USA.,Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle Washington, USA
| | - Edward J Novotny
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Division of Pediatric Neurology, University of Washington, Seattle, Washington, USA
| | | | | | | | - Robert F Hevner
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Neurosurgery, University of Washington, Seattle, Washington, USA
| | - Jeffrey G Ojemann
- Department of Neurosurgery, University of Washington, Seattle, Washington, USA
| | - Renzo Guerrini
- Paediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, A. Meyer Children's Hospital, and Department of Neuroscience, Pharmacology and Child Health, University of Florence, Florence, Italy.,IRCCS Stella Maris Foundation, Pisa, Italy
| | - Leon O Murphy
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Wendy Winckler
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - William B Dobyns
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, USA.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
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12
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Rapamycin prevents, but does not reverse, aberrant migration in Pten knockout neurons. Neurobiol Dis 2016; 93:12-20. [PMID: 26992888 DOI: 10.1016/j.nbd.2016.03.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 02/08/2016] [Accepted: 03/10/2016] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Phosphatase and tensin homolog (PTEN) is a major negative regulator of the Akt/mammalian target of rapamycin (MTOR) pathway. Mutations in PTEN have been found in a subset of individuals with autism and macrocephaly. Further, focal cortical dysplasia (FCD) has been observed in patients with PTEN mutations prompting us to examine the role of Pten in neuronal migration. The dentate gyrus of Pten(Flox/Flox) mice was injected with Cre- and non-Cre-expressing retroviral particles, which integrate into the dividing genome to birthdate cells. Control and Pten knockout (KO) cell position in the granule cell layer was quantified over time to reveal that Pten KO neurons exhibit an aberrant migratory phenotype beginning at 7.5days-post retroviral injection (DPI). We then assessed whether rapamycin, a mTor inhibitor, could prevent or reverse aberrant migration of granule cells. The preventative group received daily intraperitoneal (IP) injections of rapamycin from 3 to 14 DPI, before discrepancies in cell position have been established, while the reversal group received rapamycin afterward, from 14 to 24 DPI. We found that rapamycin prevented and reversed somal hypertrophy. However, rapamycin prevented, but did not reverse aberrant migration in Pten KO cells. We also find that altered migration occurs through mTorC1 and not mTorC2 activity. Together, these findings suggest a temporal window by which rapamycin can treat aberrant migration, and may have implications for the use of rapamycin to treat PTEN-mutation associated disorders. SIGNIFICANCE STATEMENT Mutations in phosphatase and tensin homolog (PTEN) have been linked to a subset of individuals with autism and macrocephaly, as well as Cowden Syndrome and focal cortical dysplasia. Pten loss leads to neuronal hypertrophy, but the role of Pten in neuronal migration is unclear. Here we have shown that loss of Pten leads to aberrant migration, which can be prevented but not reversed by treatment with rapamycin, a mTor inhibitor. These results are important to consider as clinical trials are developed to examine rapamycin as a therapeutic for autism with PTEN mutations. Our findings show that some abnormalities cannot be reversed, and suggest the potential need for genetic screening and preventative treatment.
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Tilot AK, Frazier TW, Eng C. Balancing Proliferation and Connectivity in PTEN-associated Autism Spectrum Disorder. Neurotherapeutics 2015; 12:609-19. [PMID: 25916396 PMCID: PMC4489960 DOI: 10.1007/s13311-015-0356-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Germline mutations in PTEN, which encodes a widely expressed phosphatase, was mapped to 10q23 and identified as the susceptibility gene for Cowden syndrome, characterized by macrocephaly and high risks of breast, thyroid, and other cancers. The phenotypic spectrum of PTEN mutations expanded to include autism with macrocephaly only 10 years ago. Neurological studies of patients with PTEN-associated autism spectrum disorder (ASD) show increases in cortical white matter and a distinctive cognitive profile, including delayed language development with poor working memory and processing speed. Once a germline PTEN mutation is found, and a diagnosis of phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome made, the clinical outlook broadens to include higher lifetime risks for multiple cancers, beginning in childhood with thyroid cancer. First described as a tumor suppressor, PTEN is a major negative regulator of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) signaling pathway-controlling growth, protein synthesis, and proliferation. This canonical function combines with less well-understood mechanisms to influence synaptic plasticity and neuronal cytoarchitecture. Several excellent mouse models of Pten loss or dysfunction link these neural functions to autism-like behavioral abnormalities, such as altered sociability, repetitive behaviors, and phenotypes like anxiety that are often associated with ASD in humans. These models also show the promise of mTOR inhibitors as therapeutic agents capable of reversing phenotypes ranging from overgrowth to low social behavior. Based on these findings, therapeutic options for patients with PTEN hamartoma tumor syndrome and ASD are coming into view, even as new discoveries in PTEN biology add complexity to our understanding of this master regulator.
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Affiliation(s)
- Amanda K. Tilot
- />Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- />Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44195 USA
| | - Thomas W. Frazier
- />Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- />Center for Autism, Pediatric Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- />Department of Pediatrics, Cleveland Clinic, Cleveland, OH 44195 USA
| | - Charis Eng
- />Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- />Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- />Stanley Shalom Zielony Institute of Nursing Excellence, Cleveland Clinic, Cleveland, OH 44195 USA
- />Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44195 USA
- />Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106 USA
- />Germline High Risk Focus Group, CASE Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106 USA
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Lee BH, Smith T, Paciorkowski AR. Autism spectrum disorder and epilepsy: Disorders with a shared biology. Epilepsy Behav 2015; 47:191-201. [PMID: 25900226 PMCID: PMC4475437 DOI: 10.1016/j.yebeh.2015.03.017] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/06/2015] [Accepted: 03/13/2015] [Indexed: 12/17/2022]
Abstract
There is an increasing recognition of clinical overlap in patients presenting with epilepsy and autism spectrum disorder (ASD), and a great deal of new information regarding the genetic causes of both disorders is available. Several biological pathways appear to be involved in both disease processes, including gene transcription regulation, cellular growth, synaptic channel function, and maintenance of synaptic structure. We review several genetic disorders where ASD and epilepsy frequently co-occur, and we discuss the screening tools available for practicing neurologists and epileptologists to help determine which patients should be referred for formal ASD diagnostic evaluation. Finally, we make recommendations regarding the workflow of genetic diagnostic testing available for children with both ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".
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Affiliation(s)
- Bo Hoon Lee
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY
| | - Tristram Smith
- Division of Neurodevelopmental and Behavioral Pediatrics, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY
| | - Alex R. Paciorkowski
- Departments of Neurology, Pediatrics, and Biomedical Genetics, and the Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY
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Wong M, Roper SN. Genetic animal models of malformations of cortical development and epilepsy. J Neurosci Methods 2015; 260:73-82. [PMID: 25911067 DOI: 10.1016/j.jneumeth.2015.04.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/03/2015] [Accepted: 04/08/2015] [Indexed: 12/31/2022]
Abstract
Malformations of cortical development constitute a variety of pathological brain abnormalities that commonly cause severe, medically-refractory epilepsy, including focal lesions, such as focal cortical dysplasia, heterotopias, and tubers of tuberous sclerosis complex, and diffuse malformations, such as lissencephaly. Although some cortical malformations result from environmental insults during cortical development in utero, genetic factors are increasingly recognized as primary pathogenic factors across the entire spectrum of malformations. Genes implicated in causing different cortical malformations are involved in a variety of physiological functions, but many are focused on regulation of cell proliferation, differentiation, and neuronal migration. Advances in molecular genetic methods have allowed the engineering of increasingly sophisticated animal models of cortical malformations and associated epilepsy. These animal models have identified some common mechanistic themes shared by a number of different cortical malformations, but also revealed the diversity and complexity of cellular and molecular mechanisms that lead to the development of the pathological lesions and resulting epileptogenesis.
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Affiliation(s)
- Michael Wong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Steven N Roper
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610, USA
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