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Pavone P, Striano P, Cacciaguerra G, Marino SD, Parano E, Pappalardo XG, Falsaperla R, Ruggieri M. Case report: Structural brain abnormalities in TUBA1A-tubulinopathies: a narrative review. Front Pediatr 2023; 11:1210272. [PMID: 37744437 PMCID: PMC10515619 DOI: 10.3389/fped.2023.1210272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/15/2023] [Indexed: 09/26/2023] Open
Abstract
Introduction Tubulin genes have been related to severe neurological complications and the term "tubulinopathy" now refers to a heterogeneous group of disorders involving an extensive family of tubulin genes with TUBA1A being the most common. A review was carried out on the complex and severe brain abnormalities associated with this genetic anomaly. Methods A literature review of the cases of TUBA1A-tubulopathy was performed to investigate the molecular findings linked with cerebral anomalies and to describe the clinical and neuroradiological features related to this genetic disorder. Results Clinical manifestations of TUBA1A-tubulinopathy patients are heterogeneous and severe ranging from craniofacial dysmorphism, notable developmental delay, and intellectual delay to early-onset seizures, neuroradiologically associated with complex abnormalities. TUBA1A-tubulinopathy may display various and complex cortical and subcortical malformations. Discussion A range of clinical manifestations related to different cerebral structures involved may be observed in patients with TUBA1A-tubulinopathy. Genotype-phenotype correlations are discussed here. Individuals with cortical and subcortical anomalies should be screened also for pathogenic variants in TUBA1A.
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Affiliation(s)
- Piero Pavone
- Section of Pediatrics and Child Neuropsychiatry, Department of Child and Experimental Medicine, University of Catania, Catania, Italy
- National Council of Research, Institute for Biomedical Research and Innovation (IRIB), Unit of Catania, Catania, Italy
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genova, Italy
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto “G. Gaslini”, Genova, Italy
| | - Giovanni Cacciaguerra
- Section of Pediatrics and Child Neuropsychiatry, Department of Child and Experimental Medicine, University of Catania, Catania, Italy
| | - Simona Domenica Marino
- Pediatrics and Pediatric Emergency Department, University Hospital, A.U.O “Policlinico-Vittorio Emanuele”, Catania, Italy
| | - Enrico Parano
- National Council of Research, Institute for Biomedical Research and Innovation (IRIB), Unit of Catania, Catania, Italy
| | - Xena Giada Pappalardo
- National Council of Research, Institute for Biomedical Research and Innovation (IRIB), Unit of Catania, Catania, Italy
| | - Raffaele Falsaperla
- Pediatrics and Pediatric Emergency Department, University Hospital, A.U.O “Policlinico-Vittorio Emanuele”, Catania, Italy
| | - Martino Ruggieri
- Section of Pediatrics and Child Neuropsychiatry, Department of Child and Experimental Medicine, University of Catania, Catania, Italy
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Rraku E, Kerstjens-Frederikse WS, Swertz MA, Dijkhuizen T, van Ravenswaaij-Arts CMA, Engwerda A. The phenotypic spectrum of terminal and subterminal 6p deletions based on a social media-derived cohort and literature review. Orphanet J Rare Dis 2023; 18:68. [PMID: 36964621 PMCID: PMC10039519 DOI: 10.1186/s13023-023-02670-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 03/11/2023] [Indexed: 03/26/2023] Open
Abstract
BACKGROUND Terminal 6p deletions are rare, and information on their clinical consequences is scarce, which impedes optimal management and follow-up by clinicians. The parent-driven Chromosome 6 Project collaborates with families of affected children worldwide to better understand the clinical effects of chromosome 6 aberrations and to support clinical guidance. A microarray report is required for participation, and detailed phenotype information is collected directly from parents through a multilingual web-based questionnaire. Information collected from parents is then combined with case data from literature reports. Here, we present our findings on 13 newly identified patients and 46 literature cases with genotypically well-characterised terminal and subterminal 6p deletions. We provide phenotype descriptions for both the whole group and for subgroups based on deletion size and HI gene content. RESULTS The total group shared a common phenotype characterised by ocular anterior segment dysgenesis, vision problems, brain malformations, congenital defects of the cardiac septa and valves, mild to moderate hearing impairment, eye movement abnormalities, hypotonia, mild developmental delay and dysmorphic features. These characteristics were observed in all subgroups where FOXC1 was included in the deletion, confirming a dominant role for this gene. Additional characteristics were seen in individuals with terminal deletions exceeding 4.02 Mb, namely complex heart defects, corpus callosum abnormalities, kidney abnormalities and orofacial clefting. Some of these additional features may be related to the loss of other genes in the terminal 6p region, such as RREB1 for the cardiac phenotypes and TUBB2A and TUBB2B for the cerebral phenotypes. In the newly identified patients, we observed previously unreported features including gastrointestinal problems, neurological abnormalities, balance problems and sleep disturbances. CONCLUSIONS We present an overview of the phenotypic characteristics observed in terminal and subterminal 6p deletions. This reveals a common phenotype that can be highly attributable to haploinsufficiency of FOXC1, with a possible additional effect of other genes in the 6p25 region. We also delineate the developmental abilities of affected individuals and report on previously unrecognised features, showing the added benefit of collecting information directly from parents. Based on our overview, we provide recommendations for clinical surveillance to support clinicians, patients and families.
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Affiliation(s)
- Eleana Rraku
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | | | - Morris A Swertz
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Trijnie Dijkhuizen
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Conny M A van Ravenswaaij-Arts
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
- ATN/Jonx, Groningen, The Netherlands.
| | - Aafke Engwerda
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
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3
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Tantry MSA, Santhakumar K. Insights on the Role of α- and β-Tubulin Isotypes in Early Brain Development. Mol Neurobiol 2023; 60:3803-3823. [PMID: 36943622 DOI: 10.1007/s12035-023-03302-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 03/05/2023] [Indexed: 03/23/2023]
Abstract
Tubulins are the highly conserved subunit of microtubules which involve in various fundamental functions including brain development. Microtubules help in neuronal proliferation, migration, differentiation, cargo transport along the axons, synapse formation, and many more. Tubulin gene family consisting of multiple isotypes, their differential expression and varied post translational modifications create a whole new level of complexity and diversity in accomplishing manifold neuronal functions. The studies on the relation between tubulin genes and brain development opened a new avenue to understand the role of each tubulin isotype in neurodevelopment. Mutations in tubulin genes are reported to cause brain development defects especially cortical malformations, referred as tubulinopathies. There is an increased need to understand the molecular correlation between various tubulin mutations and the associated brain pathology. Recently, mutations in tubulin isotypes (TUBA1A, TUBB, TUBB1, TUBB2A, TUBB2B, TUBB3, and TUBG1) have been linked to cause various neurodevelopmental defects like lissencephaly, microcephaly, cortical dysplasia, polymicrogyria, schizencephaly, subcortical band heterotopia, periventricular heterotopia, corpus callosum agenesis, and cerebellar hypoplasia. This review summarizes on the microtubule dynamics, their role in neurodevelopment, tubulin isotypes, post translational modifications, and the role of tubulin mutations in causing specific neurodevelopmental defects. A comprehensive list containing all the reported tubulin pathogenic variants associated with brain developmental defects has been prepared to give a bird's eye view on the broad range of tubulin functions.
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Affiliation(s)
- M S Ananthakrishna Tantry
- Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur, 603203, India
| | - Kirankumar Santhakumar
- Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur, 603203, India.
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4
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Maillard C, Roux CJ, Charbit-Henrion F, Steffann J, Laquerriere A, Quazza F, Buisson NB. Tubulin mutations in human neurodevelopmental disorders. Semin Cell Dev Biol 2022; 137:87-95. [PMID: 35915025 DOI: 10.1016/j.semcdb.2022.07.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 07/22/2022] [Accepted: 07/22/2022] [Indexed: 10/16/2022]
Abstract
Mutations causing dysfunction of tubulins and microtubule-associated proteins, also known as tubulinopathies, are a group of recently described entities that lead to complex brain malformations. Anatomical and functional consequences of the disruption of tubulins include microcephaly, combined with abnormal corticogenesis due to impaired migration or lamination and abnormal growth cone dynamics of projecting and callosal axons. Key imaging features of tubulinopathies are characterized by three major patterns of malformations of cortical development (MCD): lissencephaly, microlissencephaly, and dysgyria. Additional distinctive MRI features include dysmorphism of the basal ganglia, midline commissural structure hypoplasia or agenesis, and cerebellar and brainstem hypoplasia. Tubulinopathies can be diagnosed as early as 21-24 gestational weeks using imaging and neuropathology, with possible extreme microlissencephaly with an extremely thin cortex, lissencephaly with either thick or thin/intermediate cortex, and dysgyria combined with cerebellar hypoplasia, pons hypoplasia and corpus callosum dysgenesis. More than 100 MCD-associated mutations have been reported in TUBA1A, TUBB2B, or TUBB3 genes, whereas fewer than ten are known in other genes such TUBB2A, TUBB or TUBG1. Although these mutations are scattered along the α- and β-tubulin sequences, recurrent mutations are consistently associated with almost identical cortical dysgenesis. Much of the evidence supports that these mutations alter the dynamic properties and functions of microtubules in several fashions. These include diminishing the abundance of functional tubulin heterodimers, altering GTP binding, altering longitudinal and lateral protofilament interactions, and impairing microtubule interactions with kinesin and/or dynein motors or with MAPs. In this review we discuss the recent advances in our understanding of the effects of mutations of tubulins and microtubule-associated proteins on human brain development and the pathogenesis of malformations of cortical development.
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Affiliation(s)
- Camille Maillard
- Université de Paris, Imagine Institute, Team Genetics and Development of the Cerebral Cortex, F-75015 Paris, France; Université de Paris, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, F-75014 Paris, France
| | - Charles Joris Roux
- Pediatric Radiology, Necker Enfants Malades University Hospital, Université de Paris, Paris, France
| | - Fabienne Charbit-Henrion
- Université de Paris, Sorbonne Paris Cité, Imagine INSERM UMR1163, Service de Génétique Moléculaire, Groupe hospitalier Necker-Enfants Malades, AP-HP, France
| | - Julie Steffann
- Université de Paris, Sorbonne Paris Cité, Imagine INSERM UMR1163, Service de Génétique Moléculaire, Groupe hospitalier Necker-Enfants Malades, AP-HP, France
| | - Annie Laquerriere
- Pathology Laboratory, Rouen University Hospital, Rouen, France; NeoVasc Region-Inserm Team ERI28, Laboratory of Microvascular Endothelium and Neonate Brain Lesions, Institute of Research for Innovation in Biomedicine, University of Rouen, Rouen, France
| | - Floriane Quazza
- Pediatric Neurology, Necker Enfants Malades University Hospital, Université de Paris, Paris, France
| | - Nadia Bahi Buisson
- Université de Paris, Imagine Institute, Team Genetics and Development of the Cerebral Cortex, F-75015 Paris, France; Université de Paris, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, F-75014 Paris, France; Pediatric Neurology, Necker Enfants Malades University Hospital, Université de Paris, Paris, France.
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5
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Dekker J, Diderich KEM, Schot R, Husen SC, Dremmen MHG, Go ATJI, Weerts MJA, van Slegtenhorst MA, Mancini GMS. A novel family illustrating the mild phenotypic spectrum of TUBB2B variants. Eur J Paediatr Neurol 2021; 35:35-39. [PMID: 34592644 DOI: 10.1016/j.ejpn.2021.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/12/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
TUBB2B codes for one of the isotypes of β-tubulin and dominant negative variants in this gene result in distinctive malformations of cortical development (MCD), including dysgyria, dysmorphic basal ganglia and cerebellar anomalies. We present a novel family with a heterozygous missense variant in TUBB2B and an unusually mild phenotype. First, at 21 37 weeks of gestation ultrasonography revealed a fetus with a relatively small head, enlarged lateral ventricles, borderline hypoplastic cerebellum and a thin corpus callosum. The couple opted for pregnancy termination. Exome sequencing on fetal material afterwards identified a heterozygous maternally inherited variant in TUBB2B (NM_178012.4 (TUBB2B):c.530A > T, p.(Asp177Val)), not present in GnomAD and predicted as damaging. The healthy mother had only a language delay in childhood. This inherited TUBB2B variant prompted re-evaluation of the older son of the couple, who presented with a mild delay in motor skills and speech. His MRI revealed mildly enlarged lateral ventricles, a thin corpus callosum, mild cortical dysgyria, and dysmorphic vermis and basal ganglia, a pattern typical of tubulinopathies. This son finally showed the same TUBB2B variant, supporting pathogenicity of the TUBB2B variant. These observations illustrate the wide phenotypic heterogeneity of tubulinopathies, including reduced penetrance and mild expressivity, that require careful evaluation in pre- and postnatal counseling.
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Affiliation(s)
- Jordy Dekker
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Karin E M Diderich
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Rachel Schot
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Sofie C Husen
- Department of Obstetrics and Prenatal Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjolein H G Dremmen
- Department of Radiology and Nuclear Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Attie T J I Go
- Department of Obstetrics and Prenatal Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjolein J A Weerts
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjon A van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands.
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6
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Fenlon LR, Suarez R, Lynton Z, Richards LJ. The evolution, formation and connectivity of the anterior commissure. Semin Cell Dev Biol 2021; 118:50-59. [PMID: 33958283 DOI: 10.1016/j.semcdb.2021.04.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/08/2021] [Accepted: 04/10/2021] [Indexed: 10/21/2022]
Abstract
The anterior commissure is the most ancient of the forebrain interhemispheric connections among all vertebrates. Indeed, it is the predominant pallial commissure in all non-eutherian vertebrates, universally subserving basic functions related to olfaction and survival. A key feature of the anterior commissure is its ability to convey connections from diverse brain areas, such as most of the neocortex in non-eutherian mammals, thereby mediating the bilateral integration of diverse functions. Shared developmental mechanisms between the anterior commissure and more evolutionarily recent commissures, such as the corpus callosum in eutherians, have led to the hypothesis that the former may have been a precursor for additional expansion of commissural circuits. However, differences between the formation of the anterior commissure and other telencephalic commissures suggest that independent developmental mechanisms underlie the emergence of these connections in extant species. Here, we review the developmental mechanisms and connectivity of the anterior commissure across evolutionarily distant species, and highlight its potential functional importance in humans, both in the course of normal neurodevelopment, and as a site of plastic axonal rerouting in the absence or damage of other connections.
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Affiliation(s)
- Laura R Fenlon
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia.
| | - Rodrigo Suarez
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia
| | - Zorana Lynton
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia; The Faculty of Medicine, Brisbane, Australia
| | - Linda J Richards
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia; The School of Biomedical Sciences, Brisbane, Australia.
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7
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Aksel Kiliçarslan Ö, Ataman E, Gürsoy S, Gürbüz G, Ünalp A, Gençpinar P, Olgaç Dündar N, Edizer S, Ülgenalp A, Giray Bozkaya Ö. Investigation of the most common clinical and imaging findings and the role of tubulin genes in the etiology of malformations of cortical development. Turk J Med Sci 2020; 50:1573-1579. [PMID: 32718119 PMCID: PMC7605093 DOI: 10.3906/sag-1901-170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 07/21/2020] [Indexed: 11/03/2022] Open
Abstract
Background and aim The number of reports on the role of tubulin gene mutations (TUBA1A, TUBB2B, and TUBB3) in etiology of malformations of cortical development has peaked in recent years. We aimed to determine tubulin gene defects on a patient population with simple and complex malformations of cortical development, and investigate the relationship between tubulin gene mutations and disease phenotype. Materials and methods We evaluated 47 patients with simple or complex malformations of cortical development, as determined by radiological examination, for demographic features, clinical findings and mutations on TUBA1A, TUBB2B, and TUBB3 genes. Results According to the magnetic resonance imaging findings, 19 patients (40.5%) had simple malformations of cortical development and 28 (59.5%) patients had complex malformations of cortical development. Focal cortical dysplasia was the most common simple malformation, lissencephaly was the most common coexisting cortical malformation, and corpus callosum anomalies were the most common coexisting extracortical neurodevelopmental abnormalities. None of the patients had genetic alterations on TUBA1A, TUBB2B, and TUBB3 genes causing protein dysfunction. On the other hand, the frequencies of some polymorphisms were higher when compared to the literature. Conclusion It is crucial to identify the etiology in patients with malformations of cortical development in order to provide appropriate genetic counseling and prenatal diagnosis. We consider that multicenter studies with higher patient numbers and also including other malformations of cortical development-related genes are required to determine underlying etiological factors of malformations of cortical development patients.
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Affiliation(s)
- Özge Aksel Kiliçarslan
- Department of Medical Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Esra Ataman
- Department of Medical Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Semra Gürsoy
- Department of Pediatric Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Gürkan Gürbüz
- Department of Pediatric Neurology, Dr. Behcet Uz Child Disease and Pediatric Surgery Training and Research Hospital, İzmir, Turkey
| | - Aycan Ünalp
- Department of Pediatric Neurology, Dr. Behcet Uz Child Disease and Pediatric Surgery Training and Research Hospital, İzmir, Turkey
| | - Pinar Gençpinar
- Department of Pediatric Neurology, Tepecik Training and Research Hospital, İzmir,Turkey
| | - Nihal Olgaç Dündar
- Department of Pediatric Neurology, Tepecik Training and Research Hospital, İzmir,Turkey
| | - Selvinaz Edizer
- Department of Pediatric Neurology, Dr. Behcet Uz Child Disease and Pediatric Surgery Training and Research Hospital, İzmir, Turkey
| | - Ayfer Ülgenalp
- Department of Medical Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey,Department of Pediatric Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Özlem Giray Bozkaya
- Department of Medical Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey,Department of Pediatric Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
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8
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Accogli A, Severino M, Riva A, Madia F, Balagura G, Iacomino M, Carlini B, Baldassari S, Giacomini T, Croci C, Pisciotta L, Messana T, Boni A, Russo A, Bilo L, Tonziello R, Coppola A, Filla A, Mecarelli O, Casalone R, Pisani F, Falsaperla R, Marino S, Parisi P, Ferretti A, Elia M, Luchetti A, Milani D, Vanadia F, Silvestri L, Rebessi E, Parente E, Vatti G, Mancardi MM, Nobili L, Capra V, Salpietro V, Striano P, Zara F. Targeted re-sequencing in malformations of cortical development: genotype-phenotype correlations. Seizure 2020; 80:145-152. [DOI: 10.1016/j.seizure.2020.05.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/15/2020] [Accepted: 05/29/2020] [Indexed: 12/25/2022] Open
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9
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Scala M, Bianchi A, Bisulli F, Coppola A, Elia M, Trivisano M, Pruna D, Pippucci T, Canafoglia L, Lattanzi S, Franceschetti S, Nobile C, Gambardella A, Michelucci R, Zara F, Striano P. Advances in genetic testing and optimization of clinical management in children and adults with epilepsy. Expert Rev Neurother 2020; 20:251-269. [PMID: 31941393 DOI: 10.1080/14737175.2020.1713101] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Introduction: Epileptic disorders are a heterogeneous group of medical conditions with epilepsy as the common denominator. Genetic causes, electro-clinical features, and management significantly vary according to the specific condition.Areas covered: Relevant diagnostic advances have been achieved thanks to the advent of Next Generation Sequencing (NGS)-based molecular techniques. These revolutionary tools allow to sequence all coding (whole exome sequencing, WES) and non-coding (whole genome sequencing, WGS) regions of human genome, with a potentially huge impact on patient care and scientific research.Expert opinion: The application of these tests in children and adults with epilepsy has led to the identification of new causative genes, widening the knowledge on the pathophysiology of epilepsy and resulting in therapeutic implications. This review will explore the most recent advancements in genetic testing and provide up-to-date approaches for the choice of the correct test in patients with epilepsy.
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Affiliation(s)
- Marcello Scala
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Amedeo Bianchi
- Division of Neurology, Hospital San Donato Arezzo, Arezzo, Italy
| | - Francesca Bisulli
- IRCCS Istituto Delle Scienze Neurologiche Di Bologna, Bologna, Italy; Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Antonietta Coppola
- Department of Neuroscience and Reproductive and Odontostomatological Sciences, Federico II University, Naples, Italy
| | - Maurizio Elia
- Unit of Neurology and Clinical Neurophysiopathology, IRCCS Oasi Research Institute, Troina, Italy
| | - Marina Trivisano
- Neurology Unit, Department of Neuroscience, IRCCS Bambino Gesù Children's Hospital, Rome, Italy.,Clinic of Nervous System Diseases, University of Foggia, Foggia, Italy
| | - Dario Pruna
- Epilepsy Unit, A. Cao Hospital, Cagliari, Italy
| | - Tommaso Pippucci
- Medical Genetics Unit, Polyclinic Sant' Orsola-Malpighi University Hospital, Bologna, Italy
| | | | - Simona Lattanzi
- Neurological Clinic, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | | | - Carlo Nobile
- CNR-Neuroscience Institute and Department of Biomedical Sciences (C.N.), University of Padua, Padua, Italy
| | - Antonio Gambardella
- Dipartimento Di Scienze Mediche E Chirurgiche, Università Della Magna Graecia, Catanzaro, Istituto Di Scienze Neurologiche CNR Mangone, Cosenza, Italy
| | - Roberto Michelucci
- IRCCS Istituto Delle Scienze Neurologiche Di Bologna, Ospedale Bellaria, Bologna, Italy
| | - Federico Zara
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
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10
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Bittermann E, Abdelhamed Z, Liegel RP, Menke C, Timms A, Beier DR, Stottmann RW. Differential requirements of tubulin genes in mammalian forebrain development. PLoS Genet 2019; 15:e1008243. [PMID: 31386652 PMCID: PMC6697361 DOI: 10.1371/journal.pgen.1008243] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/16/2019] [Accepted: 06/12/2019] [Indexed: 11/24/2022] Open
Abstract
Tubulin genes encode a series of homologous proteins used to construct microtubules which are essential for multiple cellular processes. Neural development is particularly reliant on functional microtubule structures. Tubulin genes comprise a large family of genes with very high sequence similarity between multiple family members. Human genetics has demonstrated that a large spectrum of cortical malformations are associated with de novo heterozygous mutations in tubulin genes. However, the absolute requirement for many of these genes in development and disease has not been previously tested in genetic loss of function models. Here we directly test the requirement for Tuba1a, Tubb2a and Tubb2b in the mouse by deleting each gene individually using CRISPR-Cas9 genome editing. We show that loss of Tubb2a or Tubb2b does not impair survival but does lead to relatively mild cortical malformation phenotypes. In contrast, loss of Tuba1a is perinatal lethal and leads to significant forebrain dysmorphology. We also present a novel mouse ENU allele of Tuba1a with phenotypes similar to the null allele. This demonstrates the requirements for each of the tubulin genes and levels of functional redundancy are quite different throughout the gene family. The ability of the mouse to survive in the absence of some tubulin genes known to cause disease in humans suggests future intervention strategies for these devastating tubulinopathy diseases.
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Affiliation(s)
- Elizabeth Bittermann
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Zakia Abdelhamed
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Anatomy and Embryology, Faculty of Medicine (Girl’s Section), Al-Azhar University, Cairo, Egypt
| | - Ryan P. Liegel
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Chelsea Menke
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Andrew Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, United States of America
| | - David R. Beier
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, United States of America
- Department of Pediatrics, University of Washington Medical School, Seattle, Washington, United States of America
| | - Rolf W. Stottmann
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
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12
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Epilepsy in Tubulinopathy: Personal Series and Literature Review. Cells 2019; 8:cells8070669. [PMID: 31269740 PMCID: PMC6678821 DOI: 10.3390/cells8070669] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 06/25/2019] [Accepted: 06/28/2019] [Indexed: 11/17/2022] Open
Abstract
Mutations in tubulin genes are responsible for a large spectrum of brain malformations secondary to abnormal neuronal migration, organization, differentiation and axon guidance and maintenance. Motor impairment, intellectual disability and epilepsy are the main clinical symptoms. In the present study 15 patients from a personal cohort and 75 from 21 published studies carrying mutations in TUBA1A, TUBB2B and TUBB3 tubulin genes were evaluated with the aim to define a clinical and electrophysiological associated pattern. Epilepsy shows a wide range of severity without a specific pattern. Mutations in TUBA1A (60%) and TUBB2B (74%) and TUBB3 (25%) genes are associated with epilepsy. The accurate analysis of the Electroencephalogram (EEG) pattern in wakefulness and sleep in our series allows us to detect significant abnormalities of the background activity in 100% of patients. The involvement of white matter and of the inter-hemispheric connection structures typically observed in tubulinopathies is evidenced by the high percentage of asynchronisms in the organization of sleep activity recorded. In addition to asymmetries of the background activity, excess of slowing, low amplitude and Magnetic Resonance (MR) imaging confirm the presence of extensive brain malformations involving subcortical and midline structures. In conclusion, epilepsy in tubulinopathies when present has a favorable evolution over time suggesting a not particularly aggressive therapeutic approach.
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13
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Abstract
Mutations causing dysfunction of the tubulins and microtubule-associated proteins, otherwise known as tubulinopathies, are a group of recently described entities, that lead to complex brain malformations. An understanding of the fundamental principles of operation of the cytoskeleton and compounds in particular microtubules, actin, and microtubule-associated proteins, can assist in the interpretation of the imaging findings of tubulinopathies. Somewhat consistent morphological imaging patterns have been described in tubulinopathies such as dysmorphic basal ganglia-the hallmark (found in 75% of cases), callosal dysgenesis, cerebellar hypoplasia/dysplasia, and cortical malformations, most notably lissencephaly. Recognizing the common imaging phenotypes present in tubulinopathies can prove invaluable in directing the genetic workup for a patient with brain malformations.
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14
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Hebebrand M, Hüffmeier U, Trollmann R, Hehr U, Uebe S, Ekici AB, Kraus C, Krumbiegel M, Reis A, Thiel CT, Popp B. The mutational and phenotypic spectrum of TUBA1A-associated tubulinopathy. Orphanet J Rare Dis 2019; 14:38. [PMID: 30744660 PMCID: PMC6371496 DOI: 10.1186/s13023-019-1020-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 02/03/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The TUBA1A-associated tubulinopathy is clinically heterogeneous with brain malformations, microcephaly, developmental delay and epilepsy being the main clinical features. It is an autosomal dominant disorder mostly caused by de novo variants in TUBA1A. RESULTS In three individuals with developmental delay we identified heterozygous de novo missense variants in TUBA1A using exome sequencing. While the c.1307G > A, p.(Gly436Asp) variant was novel, the two variants c.518C > T, p.(Pro173Leu) and c.641G > A, p.(Arg214His) were previously described. We compared the variable phenotype observed in these individuals with a carefully conducted review of the current literature and identified 166 individuals, 146 born and 20 fetuses with a TUBA1A variant. In 107 cases with available clinical information we standardized the reported phenotypes according to the Human Phenotype Ontology. The most commonly reported features were developmental delay (98%), anomalies of the corpus callosum (96%), microcephaly (76%) and lissencephaly (agyria-pachygyria) (70%), although reporting was incomplete in the different studies. We identified a total of 121 specific variants, including 15 recurrent ones. Missense variants cluster in the C-terminal region around the most commonly affected amino acid position Arg402 (13.3%). In a three-dimensional protein model, 38.6% of all disease-causing variants including those in the C-terminal region are predicted to affect the binding of microtubule-associated proteins or motor proteins. Genotype-phenotype analysis for recurrent variants showed an overrepresentation of certain clinical features. However, individuals with these variants are often reported in the same publication. CONCLUSIONS With 166 individuals, we present the most comprehensive phenotypic and genotypic standardized synopsis for clinical interpretation of TUBA1A variants. Despite this considerable number, a detailed genotype-phenotype characterization is limited by large inter-study variability in reporting.
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Affiliation(s)
- Moritz Hebebrand
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
| | - Ulrike Hüffmeier
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
| | - Regina Trollmann
- Department of Pediatrics, Division of Neuropediatrics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Ute Hehr
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Steffen Uebe
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
| | - Arif B Ekici
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
| | - Cornelia Kraus
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
| | - Mandy Krumbiegel
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
| | - André Reis
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
| | - Christian T Thiel
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany.
| | - Bernt Popp
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 10, 91054, Erlangen, Germany
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15
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Wang H, Li S, Li S, Jiang N, Guo J, Zhang W, Zhong M, Xie J. De Novo Mutated TUBB2B Associated Pachygyria Diagnosed by Medical Exome Sequencing and Long-Range PCR. Fetal Pediatr Pathol 2019; 38:63-71. [PMID: 30585108 DOI: 10.1080/15513815.2018.1538273] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
INTRODUCTION A range of cerebrocortical development malformations (MCD) ranging from simplified gyral patterns to the complete loss of gyri and sulci is associated with mutations in a cluster of highly homolog β-tublin genes, such as TUBB2A and TUBB2B. CASE REPORT The fetus had pachygyria, asymmetrical perisylvian polymicrogyria, dysplasia of the lateral sulcus and insula, agenesis of the splenium and partial agenesis of the body corpus callosum, cerebellar superior vermian hypoplasia with agenesis of the inferior vermis. Karyotype and microarray were normal. Trio Medical Exome Sequencing detected a de novo novel heterozygous mutation c.862G > A (p.E288K) in the tubulinpathy genes. Long-range PCR and Sanger sequencing specific for TUBB2A and TUBB2B gene detected a heterozygous variant c.862G > A specific to TUBB2B. CONCLUSION The combination of LR-PCR amplification and medical exome sequencing allows mutational assessment in tubulinopathy genes. Our study expands the spectrum of malformations associated with mutations in the β-tubulin gene TUBB2B.
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Affiliation(s)
- Hui Wang
- a Department of Obstetrics and Gynecology , Nanfang Hospital, Southern Medical University , Guangzhou , China.,b Prenatal Diagnosis Center , Shenzhen Maternity and Child Healthcare Hospital , Shenzhen , China
| | - Shaoyuan Li
- c AmCare Genomics Laboratory , International BioIsland , Guangzhou , Shenzhen , China
| | - Shengli Li
- d Ultrasound Department, Shenzhen Maternity and Child Healthcare Hospital , Shenzhen , China
| | - Niping Jiang
- b Prenatal Diagnosis Center , Shenzhen Maternity and Child Healthcare Hospital , Shenzhen , China
| | - Jimin Guo
- e Medical imaging department, Shenzhen Maternity and Child Healthcare Hospital , Shenzhen , China
| | - Wei Zhang
- c AmCare Genomics Laboratory , International BioIsland , Guangzhou , Shenzhen , China
| | - Mei Zhong
- a Department of Obstetrics and Gynecology , Nanfang Hospital, Southern Medical University , Guangzhou , China
| | - Jiansheng Xie
- b Prenatal Diagnosis Center , Shenzhen Maternity and Child Healthcare Hospital , Shenzhen , China
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16
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Arrigoni F, Romaniello R, Peruzzo D, Poretti A, Bassi MT, Pierpaoli C, Valente EM, Nuovo S, Boltshauser E, Huisman TAGM, Triulzi F, Borgatti R. The spectrum of brainstem malformations associated to mutations of the tubulin genes family: MRI and DTI analysis. Eur Radiol 2018; 29:770-782. [DOI: 10.1007/s00330-018-5610-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/15/2018] [Accepted: 06/15/2018] [Indexed: 02/08/2023]
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17
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Tubulin genes and malformations of cortical development. Eur J Med Genet 2018; 61:744-754. [PMID: 30016746 DOI: 10.1016/j.ejmg.2018.07.012] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 06/03/2018] [Accepted: 07/12/2018] [Indexed: 01/18/2023]
Abstract
A large number of genes encoding for tubulin proteins are expressed in the developing brain. Each is subject to specific spatial and temporal expression patterns. However, most are highly expressed in post-mitotic neurons during stages of neuronal migration and differentiation. The major tubulin subclasses (alpha- and beta-tubulin) share high sequence and structural homology. These globular proteins form heterodimers and subsequently co-assemble into microtubules. Microtubules are dynamic, cytoskeletal polymers which play key roles in cellular processes crucial for cortical development, including neuronal proliferation, migration and cortical laminar organisation. Mutations in seven genes encoding alpha-tubulin (TUBA1A), beta-tubulin (TUBB2A, TUBB2B, TUBB3, TUBB4A, TUBB) and gamma-tubulin (TUBG1) isoforms have been associated with a wide and overlapping range of brain malformations or "Tubulinopathies". The majority of cortical phenotypes include lissencephaly, polymicrogyria, microlissencephaly and simplified gyration. Well-known hallmarks of the tubulinopathies include dysmorphism of the basal ganglia (fusion of the caudate nucleus and putamen with absence of the anterior limb of the internal capsule), midline commissural structures hypoplasia and/or agenesis (anterior commissure, corpus callosum and fornix), hypoplasia of the oculomotor and optic nerves, cerebellar hypoplasia or dysplasia and dysmorphism of the hind-brain structures. The cortical and extra-cortical brain phenotypes observed are largely dependent on the specific tubulin gene affected. In the present review, all the published data on tubulin family gene mutations and the associated cortical phenotypes are summarized. In addition, the most typical neuroimaging patterns of malformations of cortical development associated with tubulin gene mutations detected on the basis of our own experience are described.
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18
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Tubulinopathies continued: refining the phenotypic spectrum associated with variants in TUBG1. Eur J Hum Genet 2018; 26:1132-1142. [PMID: 29706637 PMCID: PMC6057922 DOI: 10.1038/s41431-018-0146-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 03/02/2018] [Accepted: 03/13/2018] [Indexed: 12/30/2022] Open
Abstract
Tubulinopathies are a heterogeneous group of conditions with a wide spectrum of clinical severity resulting from variants in genes of the tubulin superfamily. Variants in TUBG1 have been described in three patients with posterior predominant pachygyria and microcephaly. We here report eight additional patients with four novel heterozygous variants in TUBG1 identified by next-generation sequencing (NGS) analysis. All had severe motor and cognitive impairment and all except one developed seizures in early life. The core imaging features included a pachygyric cortex with posterior to anterior gradient, enlarged lateral ventricles most pronounced over the posterior horns, and variable degrees of reduced white matter volume. Basal ganglia, corpus callosum, brainstem, and cerebellum were often normal, in contrast to patients with variants in other tubulin genes where these structures are frequently malformed. The imaging phenotype associated with variants in TUBG1 is therefore more in line with the phenotype resulting from variants in LIS1 (a.k.a. PAFAH1B1). This difference may, at least in part, be explained by gamma-tubulin’s physiological function in microtubule nucleation, which differs from that of alpha and beta-tubulin.
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19
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Aiken J, Buscaglia G, Bates EA, Moore JK. The α-Tubulin gene TUBA1A in Brain Development: A Key Ingredient in the Neuronal Isotype Blend. J Dev Biol 2017; 5. [PMID: 29057214 PMCID: PMC5648057 DOI: 10.3390/jdb5030008] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Microtubules are dynamic cytoskeletal polymers that mediate numerous, essential functions such as axon and dendrite growth and neuron migration throughout brain development. In recent years, sequencing has revealed dominant mutations that disrupt the tubulin protein building blocks of microtubules. These tubulin mutations lead to a spectrum of devastating brain malformations, complex neurological and physical phenotypes, and even fatality. The most common tubulin gene mutated is the α-tubulin gene TUBA1A, which is the most prevalent α-tubulin gene expressed in post-mitotic neurons. The normal role of TUBA1A during neuronal maturation, and how mutations alter its function to produce the phenotypes observed in patients, remains unclear. This review synthesizes current knowledge of TUBA1A function and expression during brain development, and the brain malformations caused by mutations in TUBA1A.
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Affiliation(s)
- Jayne Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, MS8108, 12801 E 17th Ave, Aurora, CO 80045, USA;
| | - Georgia Buscaglia
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (G.B.); (E.A.B.)
| | - Emily A. Bates
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (G.B.); (E.A.B.)
| | - Jeffrey K. Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, MS8108, 12801 E 17th Ave, Aurora, CO 80045, USA;
- Correspondence: ; Tel.: +1-303-724-6198; Fax: +1-303-724-3420
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20
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Ejaz R, Lionel AC, Blaser S, Walker S, Scherer SW, Babul-Hirji R, Marshall CR, Stavropoulos DJ, Chitayat D. De novo pathogenic variant in TUBB2A presenting with arthrogryposis multiplex congenita, brain abnormalities, and severe developmental delay. Am J Med Genet A 2017; 173:2725-2730. [PMID: 28840640 DOI: 10.1002/ajmg.a.38352] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 05/21/2017] [Accepted: 06/15/2017] [Indexed: 12/29/2022]
Abstract
Disorders of brain formation can occur from pathogenic variants in various alpha and beta tubulin genes. Heterozygous pathogenic variants in the beta tubulin isotype A gene, TUBB2A, have been recently implicated in brain malformations, seizures, and developmental delay. Limited information is known regarding the phenotypic spectrum associated with pathogenic variants in this gene given the rarity of the condition. We report the sixth individual with a de novo heterozygous TUBB2A pathogenic variant, who presented with a severe neurological phenotype along with unique features of arthrogryposis multiplex congenita, optic nerve hypoplasia, dysmorphic facial features, and vocal cord paralysis, thereby expanding the gene-related phenotype.
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Affiliation(s)
- Resham Ejaz
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Anath C Lionel
- The Centre for Applied Genomics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Susan Blaser
- Division of Neuroradiology, Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Susan Walker
- The Centre for Applied Genomics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Stephen W Scherer
- The Centre for Applied Genomics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.,McLaughlin Centre and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Riyana Babul-Hirji
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Christian R Marshall
- The Centre for Applied Genomics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.,Genome Diagnostics, Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Dimitri J Stavropoulos
- Genome Diagnostics, Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - David Chitayat
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.,The Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
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21
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Tubulin-related cerebellar dysplasia: definition of a distinct pattern of cerebellar malformation. Eur Radiol 2017; 27:5080-5092. [DOI: 10.1007/s00330-017-4945-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/08/2017] [Accepted: 06/12/2017] [Indexed: 10/19/2022]
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22
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Calloni SF, Cohen JS, Meoded A, Juusola J, Triulzi FM, Huisman TAGM, Poretti A, Fatemi A. Compound Heterozygous Variants in ROBO1 Cause a Neurodevelopmental Disorder With Absence of Transverse Pontine Fibers and Thinning of the Anterior Commissure and Corpus Callosum. Pediatr Neurol 2017; 70:70-74. [PMID: 28286008 DOI: 10.1016/j.pediatrneurol.2017.01.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/18/2017] [Indexed: 11/19/2022]
Abstract
BACKGROUND Axonal guidance disorders are characterized by white matter tracts with an anomalous course, failure to cross the midline, or presence of anomalous white matter tracts. Diffusion tensor imaging (DTI) is a suitable noninvasive, in vivo neuroimaging tool to study axonal guidance disorders. We describe a novel disorder in a boy with compound heterozygous variants in the ROBO1 gene. PATIENT DESCRIPTION The child was referred at age 13 months because of developmental delay. At age nine years, he had severe intellectual disability and hyperactivity. He was nonverbal and wheelchair dependent because of spastic diplegia and ataxia. Brain magnetic resonance imaging with DTI revealed marked pontine hypoplasia, thinning of the anterior commissure and corpus callosum, and absence of the transverse pontine fibers. In addition, at the level of the pons the corticospinal tracts and medial lemnisci were not clearly separated from each other. Whole exome sequencing revealed compound heterozygous variants in the ROBO1 gene. CONCLUSION This child's neuroimaging phenotype (absence of the transverse pontine fibers and thinning of the anterior commissure and corpus callosum as shown by DTI) is suggestive of an axonal guidance disorder and supports a pathogenic role of the compound heterozygous variants in the ROBO1 gene.
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Affiliation(s)
- Sonia F Calloni
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland; Università degli Studi di Milano, Postgraduation School in Radiodiagnostics, Milan, Italy
| | - Julie S Cohen
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland
| | - Avner Meoded
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland; Pediatric Radiology and Pediatric Neuroradiology, Johns Hopkins All Children's Hospital, St. Petersburg, Florida
| | - Jane Juusola
- Whole Exome Sequencing Program, GeneDx, Gaithersburg, Maryland
| | - Fabio M Triulzi
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Thierry A G M Huisman
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Andrea Poretti
- Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland.
| | - Ali Fatemi
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland; Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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23
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Abstract
The frequency and importance of the evaluation of the posterior fossa have increased significantly over the past 20 years owing to advances in neuroimaging. Conventional and advanced neuroimaging techniques allow detailed evaluation of the complex anatomic structures within the posterior fossa. A wide spectrum of cerebellar and brainstem malformations has been shown. Familiarity with the spectrum of cerebellar and brainstem malformations and their well-defined diagnostic criteria is crucial for optimal therapy, an accurate prognosis, and correct genetic counseling. This article discusses cerebellar and brainstem malformations, with emphasis on neuroimaging findings (including diagnostic criteria), neurologic presentation, systemic involvement, prognosis, and recurrence.
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24
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Rodan LH, El Achkar CM, Berry GT, Poduri A, Prabhu SP, Yang E, Anselm I. De Novo TUBB2A Variant Presenting With Anterior Temporal Pachygyria. J Child Neurol 2017; 32:127-131. [PMID: 27770045 DOI: 10.1177/0883073816672998] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
TUBB2A is a gene that has recently been reported in association with structural brain abnormalities. Only 3 cases have been reported to date with disparate brain morphologic abnormalities, although all patients have presented with developmental delay and infantile-onset epilepsy. We report a fourth patient with a de novo variant in TUBB2A that is predicted to be pathogenic, presenting with developmental delay, spastic diplegia, exaggerated startle, and anterior temporal pachygyria in the absence of epilepsy. This report serves to further delineate the phenotype of the TUBB2A-related disorders. Focal anterior temporal pachygyria may facilitate recognition of additional cases of this tubulinopathy.
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Affiliation(s)
- Lance H Rodan
- 1 Department of Pediatrics, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | | | - Gerard T Berry
- 1 Department of Pediatrics, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Annapurna Poduri
- 2 Department of Neurology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Sanjay P Prabhu
- 3 Department of Radiology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Edward Yang
- 3 Department of Radiology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Irina Anselm
- 2 Department of Neurology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
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25
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Romaniello R, Marelli S, Giorda R, Bedeschi MF, Bonaglia MC, Arrigoni F, Triulzi F, Bassi MT, Borgatti R. Clinical Characterization, Genetics, and Long-Term Follow-up of a Large Cohort of Patients With Agenesis of the Corpus Callosum. J Child Neurol 2017; 32:60-71. [PMID: 27683483 DOI: 10.1177/0883073816664668] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
To gain a better understanding of the clinical and genetic features associated with agenesis of corpus callosum, we enrolled and characterized 162 patients with complete or partial agenesis of corpus callosum. Clinical and genetic protocols allowed us to categorize patients as syndromic subjects, affected by complex extra-brain malformations, and nonsyndromic subjects without any additional anomalies. We observed slight differences in sex ratio (56% males) and agenesis type (52% complete). Syndromic agenesis of corpus callosum subjects were prevalent (69%). We detected associated cerebral malformations in 48% of patients. Neuromotor impairment, cognitive and language disorders, and epilepsy were frequently present, regardless of the agenesis of corpus callosum subtype. Long-term follow-up allowed us to define additional indicators: syndromic agenesis of corpus callosum plus patients showed the most severe clinical features while isolated complete agenesis of corpus callosum patients had the mildest symptoms, although we observed intellectual disability (64%) and epilepsy (15%) in both categories. We achieved a definitive (clinical and/or genetic) diagnosis in 42% of subjects.
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Affiliation(s)
- Romina Romaniello
- 1 Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Susan Marelli
- 1 Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Roberto Giorda
- 2 Laboratory of Molecular Biology, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Maria F Bedeschi
- 3 Medical Genetic Unit, Department of Obstetrics and Pediatrics, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy
| | - Maria C Bonaglia
- 4 Laboratory of Cytogenetics, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Filippo Arrigoni
- 5 Neuroimaging Lab, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Fabio Triulzi
- 5 Neuroimaging Lab, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Maria T Bassi
- 2 Laboratory of Molecular Biology, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Renato Borgatti
- 1 Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
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26
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Abstract
While genetic causes of epilepsy have been hypothesized from the time of Hippocrates, the advent of new genetic technologies has played a tremendous role in elucidating a growing number of specific genetic causes for the epilepsies. This progress has contributed vastly to our recognition of the epilepsies as a diverse group of disorders, the genetic mechanisms of which are heterogeneous. Genotype-phenotype correlation, however, is not always clear. Nonetheless, the developments in genetic diagnosis raise the promise of a future of personalized medicine. Multiple genetic tests are now available, but there is no one test for all possible genetic mutations, and the balance between cost and benefit must be weighed. A genetic diagnosis, however, can provide valuable information regarding comorbidities, prognosis, and even treatment, as well as allow for genetic counseling. In this review, we will discuss the genetic mechanisms of the epilepsies as well as the specifics of particular genetic epilepsy syndromes. We will include an overview of the available genetic testing methods, the application of clinical knowledge into the selection of genetic testing, genotype-phenotype correlations of epileptic disorders, and therapeutic advances as well as a discussion of the importance of genetic counseling.
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Affiliation(s)
- Christelle M El Achkar
- Division of Epilepsy, Department of Neurology, Boston Children's Hospital, and Harvard Medical School, Fegan 9, 300 Longwood Ave, Boston, MA, 02115, USA,
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TUBA1A Mutation Associated With Eye Abnormalities in Addition to Brain Malformation. Pediatr Neurol 2015; 53:442-4. [PMID: 26294046 DOI: 10.1016/j.pediatrneurol.2015.07.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/09/2015] [Accepted: 07/11/2015] [Indexed: 01/10/2023]
Abstract
OBJECTIVE We describe the case of a boy with a TUBA1A mutation presenting with microphthalmia and congenital cataracts in addition to microcephaly and severe brain malformation. METHODS A boy presented in early infancy with microphthalmia, congenital cataracts, and microcephaly. His neurological course included severe hypotonia and drug-resistant epilepsy. Magnetic resonance imaging of the brain revealed a complex malformation that included agenesis of the corpus callosum, severely hypoplastic cerebellar vermis, mildly hypoplastic and dysplastic cerebellar hemispheres, mildly hypoplastic brainstem, mild posterior simplified cerebral gyral pattern, dysplastic basal ganglia and thalami, hypoplastic optic nerves, and absent olfactory bulbs. RESULTS TUBA1A genetic testing was conducted and revealed a previously unreported heterozygous 808G>T missense mutation. Parental genetic testing was negative, indicating that the child's mutation was de novo. CONCLUSION The TUBA1A gene encodes tubulin alpha-1A, a protein with an important role in microtubule function and stability. Human mutations can result in a wide spectrum of brain malformations including lissencephaly, microlissencephaly, cerebellar hypoplasia, agenesis of the corpus callosum, pachygyria and polymicrogyria. Although TUBA1A is expressed in both developing brain and retinal tissue, there are no reported cases of TUBA1A mutations in association with major developmental ophthalmologic abnormalities.
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Tanyalcin I, Al Assaf C, Gheldof A, Stouffs K, Lissens W, Jansen AC. I-PV: a CIRCOS module for interactive protein sequence visualization. Bioinformatics 2015; 32:447-9. [PMID: 26454277 DOI: 10.1093/bioinformatics/btv579] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 10/02/2015] [Indexed: 11/14/2022] Open
Abstract
SUMMARY Today's genome browsers and protein databanks supply vast amounts of information about proteins. The challenge is to concisely bring together this information in an interactive and easy to generate format. AVAILABILITY AND IMPLEMENTATION We have developed an interactive CIRCOS module called i-PV to visualize user supplied protein sequence, conservation and SNV data in a live presentable format. I-PV can be downloaded from http://www.i-pv.org. CONTACT ibrahim.tanyalcin@i-pv.org, itanyalc@vub.ac.be or support@i-pv.org SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Ibrahim Tanyalcin
- Center for Medical Genetics, UZ Brussel, Brussels, Belgium, Neurogenetics Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Carla Al Assaf
- Center for Human Genetics, KU Leuven and University Hospitals Leuven, 3000 Leuven, Belgium
| | | | - Katrien Stouffs
- Center for Medical Genetics, UZ Brussel, Brussels, Belgium, Reproduction, Genetics and Regenerative Medicine, Vrije Universiteit Brussel, Brussels, Belgium and
| | - Willy Lissens
- Center for Medical Genetics, UZ Brussel, Brussels, Belgium, Reproduction, Genetics and Regenerative Medicine, Vrije Universiteit Brussel, Brussels, Belgium and
| | - Anna C Jansen
- Pediatric Neurology Unit, Department of Pediatrics, UZ Brussel, Brussels, Belgium Neurogenetics Research Group, Vrije Universiteit Brussel, Brussels, Belgium
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Goez HR, Scott O, Al-Jabri B, Prowse M, Beaudoin W, Hall S, Mehta V, Amirav I. Decreased Levels of Nasal Nitric Oxide in Children With Midline Neuroanatomical Anomalies: A Possible Connection Between Ciliary Dysfunction and Isolated Nervous System Defects. Pediatr Neurol 2015; 53:324-9. [PMID: 26255753 DOI: 10.1016/j.pediatrneurol.2015.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 07/06/2015] [Accepted: 07/07/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Given the involvement of cilia in midline neurodevelopment, we set to determine whether children with midline neuroanatomical defects have increased prevalence of ciliary dysfunction, using nasal nitric oxide measurement, a screening test for primary ciliary dyskinesia. STUDY DESIGN We measured the nasal nitric oxide levels of 26 children ages 6-17, with congenital midline central nervous system defects, who are otherwise healthy. We evaluated the effect of variables including: age, gender, and anomaly (brain, spinal cord, or combined) on our measurements. We compared our results with the previously established normal range (153.6-509.9 nL/min) and to the cutoff for children with primary ciliary dyskinesia (77 nL/min). RESULTS The overall range for nasal nitric oxide in our cohort was 56.5-334.7 nL/min, with age, gender, and anomaly not having a significant effect. The overall mean, 217.7 nL/min, was significantly lower than the preestablished mean in normal children, 314.51 nL/min (P < 0.01). Four patients (15.4%) had nitric oxide levels below the lower end of normal, with two (7.7%) having values below the cutoff for primary ciliary dyskinesia. CONCLUSIONS This is the first study to report a possible association between ciliary dysfunction and isolated congenital midline neuroanatomical defects, not in the context of any known syndrome. We suggest that genes known to cause isolated central nervous system defects may also be involved in the function of cilia. Longitudinal studies are required to investigate whether, in children with abnormal measurements, nasal nitric oxide levels normalize over time, and whether these children suffer from any respiratory sequelae.
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Affiliation(s)
- Helly Rachel Goez
- Division of Pediatric Neurology, Stollery Children's Hospital, Edmonton, Alberta, Canada.
| | - Ori Scott
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Basma Al-Jabri
- Department of Pediatrics, Glenrose Rehabilitation Hospital, Edmonton, Alberta, Canada
| | - Matthew Prowse
- Department of Pediatrics, Glenrose Rehabilitation Hospital, Edmonton, Alberta, Canada
| | - Wendy Beaudoin
- Division of Pediatric Neurosurgery, Stollery Children's Hospital, Edmonton, Alberta, Canada
| | - Stacey Hall
- Division of Pediatric Neurosurgery, Stollery Children's Hospital, Edmonton, Alberta, Canada
| | - Vivek Mehta
- Division of Pediatric Neurosurgery, Stollery Children's Hospital, Edmonton, Alberta, Canada
| | - Israel Amirav
- Division of Pediatric Respirology, Stollery Children's Hospital, Edmonton, Alberta, Canada
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Kato M. Genotype-phenotype correlation in neuronal migration disorders and cortical dysplasias. Front Neurosci 2015; 9:181. [PMID: 26052266 PMCID: PMC4439546 DOI: 10.3389/fnins.2015.00181] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 05/06/2015] [Indexed: 11/29/2022] Open
Abstract
Neuronal migration disorders are human (or animal) diseases that result from a disruption in the normal movement of neurons from their original birth site to their final destination during early development. As a consequence, the neurons remain somewhere along their migratory route, their location depending on the pathological mechanism and its severity. The neurons form characteristic abnormalities, which are morphologically classified into several types, such as lissencephaly, heterotopia, and cobblestone dysplasia. Polymicrogyria is classified as a group of malformations that appear secondary to post-migration development; however, recent findings of the underlying molecular mechanisms reveal overlapping processes in the neuronal migration and post-migration development stages. Mutations of many genes are involved in neuronal migration disorders, such as LIS1 and DCX in classical lissencephaly spectrum, TUBA1A in microlissencephaly with agenesis of the corpus callosum, and RELN and VLDLR in lissencephaly with cerebellar hypoplasia. ARX is of particular interest from basic and clinical perspectives because it is critically involved in tangential migration of GABAergic interneurons in the forebrain and its mutations cause a variety of phenotypes ranging from hydranencephaly or lissencephaly to early-onset epileptic encephalopathies, including Ohtahara syndrome and infantile spasms or intellectual disability with no brain malformations. The recent advances in gene and genome analysis technologies will enable the genetic basis of neuronal migration disorders to be unraveled, which, in turn, will facilitate genotype-phenotype correlations to be determined.
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Affiliation(s)
- Mitsuhiro Kato
- Department of Pediatrics, Yamagata University Faculty of Medicine Yamagata, Japan
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Jakobsen JN, Santoni-Rugiu E, Sørensen JB. Use of TUBB3 for patient stratification and prognosis in lung cancer. Lung Cancer Manag 2015. [DOI: 10.2217/lmt.15.6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
SUMMARY Microtubules play a crucial role in the eukaryote replicative cell machinery and antimicrotubule drugs such as vinca alkaloids and taxanes are important drugs in the treatment of several solid tumors. TUBB3 has in retrospective studies shown to be of significance with regard to outcome in NSCLC patients treated with anti-microtubule drugs. However, it is still controversial whether or not TUBB3 has a prognostic or a predictive value. This review provides an overview of preclinical and clinical studies that have presented data on the role of TUBB3 in NSCLC.
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Affiliation(s)
- Jan Nyrop Jakobsen
- Department of Oncology, Rigshospitalet, 9 Blegdamsvej, 2100 Copenhagen, Denmark
| | - Eric Santoni-Rugiu
- Department of Pathology, Rigshospitalet, 9 Blegdamsvej, 2100 Copenhagen, Denmark
| | - Jens Benn Sørensen
- Department of Oncology, Rigshospitalet, 9 Blegdamsvej, 2100 Copenhagen, Denmark
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Romaniello R, Arrigoni F, Bassi MT, Borgatti R. Mutations in α- and β-tubulin encoding genes: implications in brain malformations. Brain Dev 2015; 37:273-80. [PMID: 25008804 DOI: 10.1016/j.braindev.2014.06.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/26/2014] [Accepted: 06/02/2014] [Indexed: 12/24/2022]
Abstract
The tubulin gene family is mainly expressed in post-mitotic neurons during cortical development with a specific spatial and temporal expression pattern. Members of this family encode dimeric proteins consisting of two closely related subunits (α and β), representing the major constituents of microtubules. Tubulin genes play a crucial role in the mechanisms of the Central Nervous System development such as neuronal migration and axonal guidance (axon outgrowth and maintenance). Different mutations in α/β-tubulin genes (TUBA1A, TUBA8, TUBB2A, TUBB4A, TUBB2B, TUBB3, and TUBB) might alter the dynamic properties and functions of microtubules in several ways, effecting a reduction in the number of functional tubulin heterodimers and causing alterations in GTP binding and disruptions of the binding of other proteins to microtubules (motor proteins and other microtubule interacting proteins). In recent years an increasing number of brain malformations has been associated with mutations in tubulin genes: malformations of cortical development such as lissencephaly and various grades of gyral disorganization, focal or diffuse polymicrogyria and open or closed-lips schizencephaly as likely consequences of an altered neuronal migration process; abnormalities or agenesis of the midline commissural structures (anterior commissure, corpus callosum and fornix), hypoplasia of the oculomotor and optic nerves, dysmorphisms of the hind-brain as expression of axon guidance disorders. Dysmorphisms of the basal ganglia (fusion between the caudate nucleus and putamen with absence of the anterior limb of the internal capsule) and hippocampi were also observed. A rare form of leukoencephalopathy characterized by hypomyelination with atrophy of the basal ganglia an cerebellum (H-ABC) was also recently described. The present review, describing the structural and functional features of tubulin genes, aims to revise the main cerebral associated malformations and related clinical aspects, suggesting a genotype-phenotype correlation.
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Affiliation(s)
- Romina Romaniello
- Neuropsychiatry and Neurorehabilitation Unit, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Filippo Arrigoni
- Neuroimaging Unit, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Maria Teresa Bassi
- Laboratory of Molecular Biology, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Renato Borgatti
- Neuropsychiatry and Neurorehabilitation Unit, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
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Shimojima K, Narita A, Maegaki Y, Saito A, Furukawa T, Yamamoto T. Whole-exome sequencing identifies a de novo TUBA1A mutation in a patient with sporadic malformations of cortical development: a case report. BMC Res Notes 2014; 7:465. [PMID: 25053001 PMCID: PMC4118784 DOI: 10.1186/1756-0500-7-465] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 07/14/2014] [Indexed: 12/20/2022] Open
Abstract
Background Owing to the number of genetic mutations that contribute to malformations of cortical development, identification of causative mutations in candidate genes is challenging. To overcome these challenges, we performed whole-exome sequencing in this study. Case presentation A Japanese patient presented with microcephaly and severe developmental delay. Brain magnetic resonance imaging showed the presence of colpocephaly associated with lateral ventricle dilatation and the presence of a simplified gyral pattern. Hypoplasia of the corpus callosum and cerebellar vermis were also noted. Because Sanger sequencing is expensive, laborious, and time-consuming, whole-exome sequencing was performed and a de novo missense mutation in TUBA1A (E27Q) was identified. Conclusion The novel mutation identified in this study was located in the genetic region that encodes the N-terminal domain of TUBA1A, a region of TUBA1A with few reported mutations. Retrospective assessment of the clinical and radiological features of this patient―i.e., microcephaly, lissencephaly (pachygyria) with cerebellar hypoplasia, and corpus callosum hypoplasia―indicated that the TUBA1A mutation did not lead to any contradictions. Because rapid and comprehensive mutation analysis by whole-exome sequencing is time- and cost-effective, it might be useful for genetic counseling of patients with sporadic malformations of cortical development.
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Affiliation(s)
| | | | | | | | | | - Toshiyuki Yamamoto
- Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo 162-8666, Japan.
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Liu G, Dwyer T. Microtubule dynamics in axon guidance. Neurosci Bull 2014; 30:569-83. [PMID: 24968808 DOI: 10.1007/s12264-014-1444-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 04/10/2014] [Indexed: 12/18/2022] Open
Abstract
Precise modulation of the cytoskeleton is involved in a variety of cellular processes including cell division, migration, polarity, and adhesion. In developing post-mitotic neurons, extracellular guidance cues not only trigger signaling cascades that act at a distance to indirectly regulate microtubule distribution, and assembly and disassembly in the growth cone, but also directly modulate microtubule stability and dynamics through coupling of guidance receptors with microtubules to control growth-cone turning. Microtubule-associated proteins including classical microtubule-associated proteins and microtubule plus-end tracking proteins are required for modulating microtubule dynamics to influence growth-cone steering. Multiple key signaling components, such as calcium, small GTPases, glycogen synthase kinase-3β, and c-Jun N-terminal kinase, link upstream signal cascades to microtubule stability and dynamics in the growth cone to control axon outgrowth and projection. Understanding the functions and regulation of microtubule dynamics in the growth cone provides new insights into the molecular mechanisms of axon guidance.
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Affiliation(s)
- Guofa Liu
- Department of Biological Sciences, University of Toledo, Toledo, OH, 43606, USA,
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Alcantara D, O'Driscoll M. Congenital microcephaly. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2014; 166C:124-39. [PMID: 24816482 DOI: 10.1002/ajmg.c.31397] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The underlying etiologies of genetic congenital microcephaly are complex and multifactorial. Recently, with the exponential growth in the identification and characterization of novel genetic causes of congenital microcephaly, there has been a consolidation and emergence of certain themes concerning underlying pathomechanisms. These include abnormal mitotic microtubule spindle structure, numerical and structural abnormalities of the centrosome, altered cilia function, impaired DNA repair, DNA Damage Response signaling and DNA replication, along with attenuated cell cycle checkpoint proficiency. Many of these processes are highly interconnected. Interestingly, a defect in a gene whose encoded protein has a canonical function in one of these processes can often have multiple impacts at the cellular level involving several of these pathways. Here, we overview the key pathomechanistic themes underlying profound congenital microcephaly, and emphasize their interconnected nature.
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