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Ivanova EL, Mau-Them FT, Riazuddin S, Kahrizi K, Laugel V, Schaefer E, de Saint Martin A, Runge K, Iqbal Z, Spitz MA, Laura M, Drouot N, Gérard B, Deleuze JF, de Brouwer APM, Razzaq A, Dollfus H, Assir MZ, Nitchké P, Hinckelmann MV, Ropers H, Riazuddin S, Najmabadi H, van Bokhoven H, Chelly J. Homozygous Truncating Variants in TBC1D23 Cause Pontocerebellar Hypoplasia and Alter Cortical Development. Am J Hum Genet 2017; 101:428-440. [PMID: 28823707 DOI: 10.1016/j.ajhg.2017.07.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/19/2017] [Indexed: 01/03/2023] Open
Abstract
Pontocerebellar hypoplasia (PCH) is a heterogeneous group of rare recessive disorders with prenatal onset, characterized by hypoplasia of pons and cerebellum. Mutations in a small number of genes have been reported to cause PCH, and the vast majority of PCH cases are explained by mutations in TSEN54, which encodes a subunit of the tRNA splicing endonuclease complex. Here we report three families with homozygous truncating mutations in TBC1D23 who display moderate to severe intellectual disability and microcephaly. MRI data from available affected subjects revealed PCH, small normally proportioned cerebellum, and corpus callosum anomalies. Furthermore, through in utero electroporation, we show that downregulation of TBC1D23 affects cortical neuron positioning. TBC1D23 is a member of the Tre2-Bub2-Cdc16 (TBC) domain-containing RAB-specific GTPase-activating proteins (TBC/RABGAPs). Members of this protein family negatively regulate RAB proteins and modulate the signaling between RABs and other small GTPases, some of which have a crucial role in the trafficking of intracellular vesicles and are involved in neurological disorders. Here, we demonstrate that dense core vesicles and lysosomal trafficking dynamics are affected in fibroblasts harboring TBC1D23 mutation. We propose that mutations in TBC1D23 are responsible for a form of PCH with small, normally proportioned cerebellum and should be screened in individuals with syndromic pontocereballar hypoplasia.
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Affiliation(s)
- Ekaterina L Ivanova
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France; Université de Strasbourg, 67400 Illkirch, France
| | - Frédéric Tran Mau-Them
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaire de Strasbourg, 67000 Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France; Université de Strasbourg, 67400 Illkirch, France
| | - Saima Riazuddin
- Department of Otorhinolaryngology-Head & Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad 44000, Pakistan
| | - Kimia Kahrizi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, 1985713834 Tehran, Iran
| | - Vincent Laugel
- Department of Pediatrics, Strasbourg University Hospital, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, 67000 Strasbourg, France
| | - Elise Schaefer
- Service de Génétique Médicale, Hôpitaux Universitaires de Strasbourg, 67000 Strasbourg, France
| | - Anne de Saint Martin
- Department of Pediatrics, Strasbourg University Hospital, 67000 Strasbourg, France
| | - Karen Runge
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France; Université de Strasbourg, 67400 Illkirch, France
| | - Zafar Iqbal
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Neurology, Oslo University Hospital, 0450 Oslo, Norway
| | - Marie-Aude Spitz
- Department of Pediatrics, Strasbourg University Hospital, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, 67000 Strasbourg, France
| | - Mary Laura
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaire de Strasbourg, 67000 Strasbourg, France
| | - Nathalie Drouot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France; Université de Strasbourg, 67400 Illkirch, France
| | - Bénédicte Gérard
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaire de Strasbourg, 67000 Strasbourg, France
| | | | - Arjan P M de Brouwer
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands
| | - Attia Razzaq
- Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad 44000, Pakistan
| | - Hélène Dollfus
- Service de Génétique Médicale, Hôpitaux Universitaires de Strasbourg, 67000 Strasbourg, France
| | - Muhammad Zaman Assir
- Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad 44000, Pakistan; Allama Iqbal Medical College, University of Health Sciences, 54000 Lahore, Pakistan
| | - Patrick Nitchké
- Institut Imagine, Bioinformatics Platform, Université Paris Descartes, 75015 Paris, France
| | - Maria-Victoria Hinckelmann
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France; Université de Strasbourg, 67400 Illkirch, France
| | - Hilger Ropers
- Max-Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Sheikh Riazuddin
- Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad 44000, Pakistan; Allama Iqbal Medical College, University of Health Sciences, 54000 Lahore, Pakistan
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, 1985713834 Tehran, Iran
| | - Hans van Bokhoven
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands
| | - Jamel Chelly
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaire de Strasbourg, 67000 Strasbourg, France; Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France; Université de Strasbourg, 67400 Illkirch, France; Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, 67000 Strasbourg, France.
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