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Fellows BJ, Tolezano GC, Pires SF, Ruegg MSG, Knapp KM, Krepischi ACV, Bicknell LS. A novel KNL1 intronic splicing variant likely destabilizes the KMN complex, causing primary microcephaly. Am J Med Genet A 2024; 194:e63468. [PMID: 37937525 DOI: 10.1002/ajmg.a.63468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 11/09/2023]
Abstract
Primary microcephaly (MCPH) is an autosomal recessive disorder characterized by head circumference of at least two standard deviations below the mean. Biallelic variants in the kinetochore gene KNL1 is a known cause of MCPH4. KNL1 is the central component of the KNL1-MIS12-NSL1 (KMN) network, which acts as the signaling hub of the kinetochore and is required for correct chromosomal segregation during mitosis. We identified biallelic KNL1 variants in two siblings from a non-consanguineous family with microcephaly and intellectual disability. The two siblings carry a frameshift variant predicted to prematurely truncate the transcript and undergo nonsense mediated decay, and an intronic single nucleotide variant (SNV) predicted to disrupt splicing. An in vitro splicing assay and qPCR from blood-derived RNA confirmed that the intronic variant skips exon 23, significantly reducing levels of the canonical transcript. Protein modeling confirmed that absence of exon 23, an inframe exon, would disrupt a key interaction within the KMN network and likely destabilize the kinetochore signaling hub, disrupting mitosis. Therefore, this splicing variant is pathogenic and, in trans with a frameshift variant, causes the MCPH phenotype associated with KLN1. This finding furthers the association of splicing variants as a common pathogenic variant class for KNL1.
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Affiliation(s)
- Bridget J Fellows
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Giovanna Cantini Tolezano
- Human Genome and Stem Cell Research Center, Institute of Biosciences, University of São Paulo, São Paulo, SP, Brazil
| | - Sara Ferreira Pires
- Human Genome and Stem Cell Research Center, Institute of Biosciences, University of São Paulo, São Paulo, SP, Brazil
| | - Mischa S G Ruegg
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Karen M Knapp
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | | | - Louise S Bicknell
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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2
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Ribeiro JH, Altinisik N, Rajan N, Verslegers M, Baatout S, Gopalakrishnan J, Quintens R. DNA damage and repair: underlying mechanisms leading to microcephaly. Front Cell Dev Biol 2023; 11:1268565. [PMID: 37881689 PMCID: PMC10597653 DOI: 10.3389/fcell.2023.1268565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/25/2023] [Indexed: 10/27/2023] Open
Abstract
DNA-damaging agents and endogenous DNA damage constantly harm genome integrity. Under genotoxic stress conditions, the DNA damage response (DDR) machinery is crucial in repairing lesions and preventing mutations in the basic structure of the DNA. Different repair pathways are implicated in the resolution of such lesions. For instance, the non-homologous DNA end joining and homologous recombination pathways are central cellular mechanisms by which eukaryotic cells maintain genome integrity. However, defects in these pathways are often associated with neurological disorders, indicating the pivotal role of DDR in normal brain development. Moreover, the brain is the most sensitive organ affected by DNA-damaging agents compared to other tissues during the prenatal period. The accumulation of lesions is believed to induce cell death, reduce proliferation and premature differentiation of neural stem and progenitor cells, and reduce brain size (microcephaly). Microcephaly is mainly caused by genetic mutations, especially genes encoding proteins involved in centrosomes and DNA repair pathways. However, it can also be induced by exposure to ionizing radiation and intrauterine infections such as the Zika virus. This review explains mammalian cortical development and the major DNA repair pathways that may lead to microcephaly when impaired. Next, we discuss the mechanisms and possible exposures leading to DNA damage and p53 hyperactivation culminating in microcephaly.
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Affiliation(s)
- Jessica Honorato Ribeiro
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
- Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Nazlican Altinisik
- Laboratory for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, University Hospital, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Nicholas Rajan
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Mieke Verslegers
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
- Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Jay Gopalakrishnan
- Laboratory for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, University Hospital, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Roel Quintens
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
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3
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Zhao Y, Yang J, Lu D, Zhu Y, Liao K, Tian Y, Yin R. The Loss-Function of KNL1 Causes Oligospermia and Asthenospermia in Mice by Affecting the Assembly and Separation of the Spindle through Flow Cytometry and Immunofluorescence. SENSORS (BASEL, SWITZERLAND) 2023; 23:2571. [PMID: 36904774 PMCID: PMC10007211 DOI: 10.3390/s23052571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 02/13/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
KNL1 (kinetochore scaffold 1) has attracted much attention as one of the assembly elements of the outer kinetochore, and the functions of its different domains have been gradually revealed, most of which are associated with cancers, but few links have been made between KNL1 and male fertility. Here, we first linked KNL1 to male reproductive health and the loss-function of KNL1 resulted in oligospermia and asthenospermia in mice (an 86.5% decrease in total sperm number and an 82.4% increase in static sperm number, respectively) through CASA (computer-aided sperm analysis). Moreover, we introduced an ingenious method to pinpoint the abnormal stage in the spermatogenic cycle using flow cytometry combined with immunofluorescence. Results showed that 49.5% haploid sperm was reduced and 53.2% diploid sperm was increased after the function of KNL1 was lost. Spermatocytes arrest was identified at the meiotic prophase I of spermatogenesis, which was induced by the abnormal assembly and separation of the spindle. In conclusion, we established an association between KNL1 and male fertility, providing a guide for future genetic counseling regarding oligospermia and asthenospermia, and a powerful method for further exploring spermatogenic dysfunction by utilizing flow cytometry and immunofluorescence.
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Affiliation(s)
- Yuwei Zhao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200000, China
| | - Jingmin Yang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200000, China
- Shanghai WeHealth BioMedical Technology Co., Ltd., Shanghai 201318, China
- NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing Population and Family Planning Science and Technology Research Institute, Chongqing 404100, China
| | - Daru Lu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200000, China
- NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing Population and Family Planning Science and Technology Research Institute, Chongqing 404100, China
| | - Yijian Zhu
- NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing Population and Family Planning Science and Technology Research Institute, Chongqing 404100, China
| | - Kai Liao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200000, China
| | - Yafei Tian
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200000, China
- Shanghai WeHealth BioMedical Technology Co., Ltd., Shanghai 201318, China
| | - Rui Yin
- NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing Population and Family Planning Science and Technology Research Institute, Chongqing 404100, China
- Reproductive Medicine Research Center, Medical Research Institute, Southwest University, Chongqing 400715, China
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4
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Asif M, Abdullah U, Nürnberg P, Tinschert S, Hussain MS. Congenital Microcephaly: A Debate on Diagnostic Challenges and Etiological Paradigm of the Shift from Isolated/Non-Syndromic to Syndromic Microcephaly. Cells 2023; 12:cells12040642. [PMID: 36831309 PMCID: PMC9954724 DOI: 10.3390/cells12040642] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
Congenital microcephaly (CM) exhibits broad clinical and genetic heterogeneity and is thus categorized into several subtypes. However, the recent bloom of disease-gene discoveries has revealed more overlaps than differences in the underlying genetic architecture for these clinical sub-categories, complicating the differential diagnosis. Moreover, the mechanism of the paradigm shift from a brain-restricted to a multi-organ phenotype is only vaguely understood. This review article highlights the critical factors considered while defining CM subtypes. It also presents possible arguments on long-standing questions of the brain-specific nature of CM caused by a dysfunction of the ubiquitously expressed proteins. We argue that brain-specific splicing events and organ-restricted protein expression may contribute in part to disparate clinical manifestations. We also highlight the role of genetic modifiers and de novo variants in the multi-organ phenotype of CM and emphasize their consideration in molecular characterization. This review thus attempts to expand our understanding of the phenotypic and etiological variability in CM and invites the development of more comprehensive guidelines.
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Affiliation(s)
- Maria Asif
- Cologne Center for Genomics (CCG), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
| | - Uzma Abdullah
- University Institute of Biochemistry and Biotechnology (UIBB), PMAS-Arid Agriculture University, Rawalpindi, Rawalpindi 46300, Pakistan
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
| | - Sigrid Tinschert
- Zentrum Medizinische Genetik, Medizinische Universität, 6020 Innsbruck, Austria
| | - Muhammad Sajid Hussain
- Cologne Center for Genomics (CCG), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
- Correspondence:
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5
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Zaqout S, Kaindl AM. Autosomal Recessive Primary Microcephaly: Not Just a Small Brain. Front Cell Dev Biol 2022; 9:784700. [PMID: 35111754 PMCID: PMC8802810 DOI: 10.3389/fcell.2021.784700] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/01/2021] [Indexed: 02/06/2023] Open
Abstract
Microcephaly or reduced head circumference results from a multitude of abnormal developmental processes affecting brain growth and/or leading to brain atrophy. Autosomal recessive primary microcephaly (MCPH) is the prototype of isolated primary (congenital) microcephaly, affecting predominantly the cerebral cortex. For MCPH, an accelerating number of mutated genes emerge annually, and they are involved in crucial steps of neurogenesis. In this review article, we provide a deeper look into the microcephalic MCPH brain. We explore cytoarchitecture focusing on the cerebral cortex and discuss diverse processes occurring at the level of neural progenitors, early generated and mature neurons, and glial cells. We aim to thereby give an overview of current knowledge in MCPH phenotype and normal brain growth.
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Affiliation(s)
- Sami Zaqout
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
- Biomedical and Pharmaceutical Research Unit, QU Health, Qatar University, Doha, Qatar
| | - Angela M. Kaindl
- Institute of Cell and Neurobiology, Charité—Universitätsmedizin Berlin, Berlin, Germany
- Center for Chronically Sick Children (Sozialpädiatrisches Zentrum, SPZ), Charité—Universitätsmedizin Berlin, Berlin, Germany
- Department of Pediatric Neurology, Charité—Universitätsmedizin Berlin, Berlin, Germany
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6
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Abstract
In this review, Phan et al. discuss the different models that have been proposed to explain how centrosome dysfunction impairs cortical development, and review the evidence supporting a unified model in which centrosome defects reduce cell proliferation in the developing cortex by prolonging mitosis and activating a mitotic surveillance pathway. Last, they also extend their discussion to centrosome-independent microcephaly mutations, such as those involved in DNA replication and repair Primary microcephaly is a brain growth disorder characterized by a severe reduction of brain size and thinning of the cerebral cortex. Many primary microcephaly mutations occur in genes that encode centrosome proteins, highlighting an important role for centrosomes in cortical development. Centrosomes are microtubule organizing centers that participate in several processes, including controlling polarity, catalyzing spindle assembly in mitosis, and building primary cilia. Understanding which of these processes are altered and how these disruptions contribute to microcephaly pathogenesis is a central unresolved question. In this review, we revisit the different models that have been proposed to explain how centrosome dysfunction impairs cortical development. We review the evidence supporting a unified model in which centrosome defects reduce cell proliferation in the developing cortex by prolonging mitosis and activating a mitotic surveillance pathway. Finally, we also extend our discussion to centrosome-independent microcephaly mutations, such as those involved in DNA replication and repair.
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7
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Duerinckx S, Désir J, Perazzolo C, Badoer C, Jacquemin V, Soblet J, Maystadt I, Tunca Y, Blaumeiser B, Ceulemans B, Courtens W, Debray F, Destree A, Devriendt K, Jansen A, Keymolen K, Lederer D, Loeys B, Meuwissen M, Moortgat S, Mortier G, Nassogne M, Sekhara T, Van Coster R, Van Den Ende J, Van der Aa N, Van Esch H, Vanakker O, Verhelst H, Vilain C, Weckhuysen S, Passemard S, Verloes A, Aeby A, Deconinck N, Van Bogaert P, Pirson I, Abramowicz M. Phenotypes and genotypes in non-consanguineous and consanguineous primary microcephaly: High incidence of epilepsy. Mol Genet Genomic Med 2021; 9:e1768. [PMID: 34402213 PMCID: PMC8457702 DOI: 10.1002/mgg3.1768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 05/06/2021] [Accepted: 07/03/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Primary microcephaly (PM) is defined as a significant reduction in occipitofrontal circumference (OFC) of prenatal onset. Clinical and genetic heterogeneity of PM represents a diagnostic challenge. METHODS We performed detailed phenotypic and genomic analyses in a large cohort (n = 169) of patients referred for PM and could establish a molecular diagnosis in 38 patients. RESULTS Pathogenic variants in ASPM and WDR62 were the most frequent causes in non-consanguineous patients in our cohort. In consanguineous patients, microarray and targeted gene panel analyses reached a diagnostic yield of 67%, which contrasts with a much lower rate in non-consanguineous patients (9%). Our series includes 11 novel pathogenic variants and we identify novel candidate genes including IGF2BP3 and DNAH2. We confirm the progression of microcephaly over time in affected children. Epilepsy was an important associated feature in our PM cohort, affecting 34% of patients with a molecular confirmation of the PM diagnosis, with various degrees of severity and seizure types. CONCLUSION Our findings will help to prioritize genomic investigations, accelerate molecular diagnoses, and improve the management of PM patients.
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Affiliation(s)
- Sarah Duerinckx
- Institut de Recherche Interdisciplinaire en Biologie Humaine et moléculaireUniversité Libre de BruxellesBrusselsBelgium
| | - Julie Désir
- Centre de Génétique HumaineInstitut de Pathologie et de GénétiqueGosseliesBelgium
| | - Camille Perazzolo
- Institut de Recherche Interdisciplinaire en Biologie Humaine et moléculaireUniversité Libre de BruxellesBrusselsBelgium
| | - Cindy Badoer
- Department of GeneticsHôpital ErasmeULB Center of Human GeneticsUniversité Libre de BruxellesBrusselsBelgium
| | - Valérie Jacquemin
- Institut de Recherche Interdisciplinaire en Biologie Humaine et moléculaireUniversité Libre de BruxellesBrusselsBelgium
| | - Julie Soblet
- Department of GeneticsHôpital ErasmeULB Center of Human GeneticsUniversité Libre de BruxellesBrusselsBelgium
- Hôpital Universitaire des Enfants Reine Fabiola (HUDERF)Université Libre de BruxellesBrusselsBelgium
| | - Isabelle Maystadt
- Centre de Génétique HumaineInstitut de Pathologie et de GénétiqueGosseliesBelgium
| | - Yusuf Tunca
- Department of Medical GeneticsGülhane Faculty of Medicine & Gülhane Training and Research HospitalUniversity of Health Sciences TurkeyAnkaraTurkey
| | | | | | | | | | - Anne Destree
- Centre de Génétique HumaineInstitut de Pathologie et de GénétiqueGosseliesBelgium
| | | | - Anna Jansen
- Universitair Ziekenhuis Brussel (UZ Brussel)Centrum Medische GeneticaUniversiteit Brussel (VUB)BrusselsBelgium
| | - Kathelijn Keymolen
- Universitair Ziekenhuis Brussel (UZ Brussel)Centrum Medische GeneticaUniversiteit Brussel (VUB)BrusselsBelgium
| | - Damien Lederer
- Centre de Génétique HumaineInstitut de Pathologie et de GénétiqueGosseliesBelgium
| | - Bart Loeys
- University and University Hospital of AntwerpAntwerpBelgium
| | | | - Stéphanie Moortgat
- Centre de Génétique HumaineInstitut de Pathologie et de GénétiqueGosseliesBelgium
| | - Geert Mortier
- University and University Hospital of AntwerpAntwerpBelgium
| | | | | | | | | | | | - Hilde Van Esch
- Center for Human GeneticsUniversity Hospitals LeuvenLeuvenBelgium
| | | | | | - Catheline Vilain
- Department of GeneticsHôpital ErasmeULB Center of Human GeneticsUniversité Libre de BruxellesBrusselsBelgium
- Hôpital Universitaire des Enfants Reine Fabiola (HUDERF)Université Libre de BruxellesBrusselsBelgium
| | | | | | - Alain Verloes
- Department of GeneticsAPHPRobert Debré University HospitalParisFrance
| | - Alec Aeby
- Hôpital Universitaire des Enfants Reine Fabiola (HUDERF)Université Libre de BruxellesBrusselsBelgium
| | - Nicolas Deconinck
- Hôpital Universitaire des Enfants Reine Fabiola (HUDERF)Université Libre de BruxellesBrusselsBelgium
| | | | - Isabelle Pirson
- Institut de Recherche Interdisciplinaire en Biologie Humaine et moléculaireUniversité Libre de BruxellesBrusselsBelgium
| | - Marc Abramowicz
- Institut de Recherche Interdisciplinaire en Biologie Humaine et moléculaireUniversité Libre de BruxellesBrusselsBelgium
- Department of Genetic Medicine and DevelopmentUniversity of GenevaGenèveSwitzerland
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8
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Garrity M, Kavus H, Rojas-Vasquez M, Valenzuela I, Larson A, Reed S, Bellus G, Mignot C, Munnich A, Isidor B, Chung WK. Neurodevelopmental phenotypes in individuals with pathogenic variants in CHAMP1. Cold Spring Harb Mol Case Stud 2021; 7:a006092. [PMID: 34021018 PMCID: PMC8327885 DOI: 10.1101/mcs.a006092] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/10/2021] [Indexed: 02/06/2023] Open
Abstract
De novo pathogenic variants in CHAMP1 (chromosome alignment maintaining phosphoprotein 1), which encodes kinetochore-microtubule associated protein on 13q34, cause a rare neurodevelopmental disorder. We enrolled 14 individuals with pathogenic variants in CHAMP1 that were documented by exome sequencing or gene panel sequencing. Medical history interviews, seizure surveys, Vineland Adapted Behavior Scales Second Edition, and other behavioral surveys were completed by primary caregivers of available participants in Simons Searchlight. Clinicians extracted clinical data from the medical record for two participants. We report on clinical features of 14 individuals (ages 2-26) with de novo predicted loss-of-function variants in CHAMP1 and compare them with previously reported cases (total n = 32). At least two individuals have the same de novo variant: p.(Ser181Cysfs*5), p.(Trp348*), p.(Arg398*), p.(Arg497*), or p.(Tyr709*). Common phenotypes include intellectual disability/developmental delay, language impairment, congenital and acquired microcephaly, behavioral problems including autism spectrum disorder, seizures, hypotonia, gastrointestinal issues of reflux and constipation, and ophthalmologic issues. Other rarely observed phenotypes include leukemia, failure to thrive, and high pain tolerance. Pathogenic variants in CHAMP1 are associated with a variable clinical phenotype of developmental delay/intellectual disability and seizures.
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Affiliation(s)
- Madison Garrity
- Columbia University School of Dental Medicine, New York, New York 10032, USA
| | - Haluk Kavus
- Department of Pediatrics, Columbia University Medical Center, New York, New York 10032, USA
| | - Marta Rojas-Vasquez
- Department of Pediatric Hematology-Oncology, Stollery Children's Hospital, Edmonton, Alberta T6G 2B7, Canada
| | - Irene Valenzuela
- Department of Clinical and Molecular Genetics, Hospital Vall d'Hebron, 08035 Barcelona, Spain
| | - Austin Larson
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Aurora, Colorado 80045, USA
| | - Sara Reed
- Clinical Genetics and Genomic Medicine, Geisinger Health System, Danville, Pennsylvania 17821, USA
| | - Gary Bellus
- Clinical Genetics and Genomic Medicine, Geisinger Health System, Danville, Pennsylvania 17821, USA
| | - Cyril Mignot
- APHP-Sorbonne Université, Département de Génétique, Hôpital Trousseau et Groupe Hospitalier Pitié-Salpêtrière, 75013 Paris, France
| | - Arnold Munnich
- Imagine Institute, INSERM UMR 1163, Université de Paris; Fédération de Génétique Médicale, Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - Bertrand Isidor
- Service de Génétique Médicale, CHU Nantes, 44093 Nantes Cedex 1, France
- L'Institut du Thorax, INSERM, CNRS, Université de Nantes, 44007 Nantes, France
| | - Wendy K Chung
- Department of Pediatrics, Columbia University Medical Center, New York, New York 10032, USA
- Department of Medicine, Columbia University Medical Center, New York, New York 10032, USA
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9
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Jean F, Stuart A, Tarailo-Graovac M. Dissecting the Genetic and Etiological Causes of Primary Microcephaly. Front Neurol 2020; 11:570830. [PMID: 33178111 PMCID: PMC7593518 DOI: 10.3389/fneur.2020.570830] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 09/09/2020] [Indexed: 12/20/2022] Open
Abstract
Autosomal recessive primary microcephaly (MCPH; “small head syndrome”) is a rare, heterogeneous disease arising from the decreased production of neurons during brain development. As of August 2020, the Online Mendelian Inheritance in Man (OMIM) database lists 25 genes (involved in molecular processes such as centriole biogenesis, microtubule dynamics, spindle positioning, DNA repair, transcriptional regulation, Wnt signaling, and cell cycle checkpoints) that are implicated in causing MCPH. Many of these 25 genes were only discovered in the last 10 years following advances in exome and genome sequencing that have improved our ability to identify disease-causing variants. Despite these advances, many patients still lack a genetic diagnosis. This demonstrates a need to understand in greater detail the molecular mechanisms and genetics underlying MCPH. Here, we briefly review the molecular functions of each MCPH gene and how their loss disrupts the neurogenesis program, ultimately demonstrating that microcephaly arises from cell cycle dysregulation. We also explore the current issues in the genetic basis and clinical presentation of MCPH as additional avenues of improving gene/variant prioritization. Ultimately, we illustrate that the detailed exploration of the etiology and inheritance of MCPH improves the predictive power in identifying previously unknown MCPH candidates and diagnosing microcephalic patients.
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Affiliation(s)
- Francesca Jean
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Amanda Stuart
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Maja Tarailo-Graovac
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
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10
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The Mitotic Apparatus and Kinetochores in Microcephaly and Neurodevelopmental Diseases. Cells 2019; 9:cells9010049. [PMID: 31878213 PMCID: PMC7016623 DOI: 10.3390/cells9010049] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/18/2019] [Accepted: 12/21/2019] [Indexed: 12/15/2022] Open
Abstract
Regulators of mitotic division, when dysfunctional or expressed in a deregulated manner (over- or underexpressed) in somatic cells, cause chromosome instability, which is a predisposing condition to cancer that is associated with unrestricted proliferation. Genes encoding mitotic regulators are growingly implicated in neurodevelopmental diseases. Here, we briefly summarize existing knowledge on how microcephaly-related mitotic genes operate in the control of chromosome segregation during mitosis in somatic cells, with a special focus on the role of kinetochore factors. Then, we review evidence implicating mitotic apparatus- and kinetochore-resident factors in the origin of congenital microcephaly. We discuss data emerging from these works, which suggest a critical role of correct mitotic division in controlling neuronal cell proliferation and shaping the architecture of the central nervous system.
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11
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Omer Javed A, Li Y, Muffat J, Su KC, Cohen MA, Lungjangwa T, Aubourg P, Cheeseman IM, Jaenisch R. Microcephaly Modeling of Kinetochore Mutation Reveals a Brain-Specific Phenotype. Cell Rep 2019; 25:368-382.e5. [PMID: 30304678 PMCID: PMC6392048 DOI: 10.1016/j.celrep.2018.09.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 08/01/2018] [Accepted: 09/11/2018] [Indexed: 11/28/2022] Open
Abstract
Most genes mutated in microcephaly patients are expressed ubiquitously, and yet the brain is the only major organ compromised in most patients. Why the phenotype remains brain specific is poorly understood. In this study, we used in vitro differentiation of human embryonic stem cells to monitor the effect of a point mutation in kinetochore null protein 1 (KNL1;CASC5), identified in microcephaly patients, during in vitro brain development. We found that neural progenitors bearing a patient mutation showed reduced KNL1 levels, aneuploidy, and an abrogated spindle assembly checkpoint. By contrast, no reduction of KNL1 levels or abnormalities was observed in fibroblasts and neural crest cells. We established that the KNL1 patient mutation generates an exonic splicing silencer site, which mainly affects neural progenitors because of their higher levels of splicing proteins. Our results provide insight into the brain-specific phenomenon, consistent with microcephaly being the only major phenotype of patients bearing KNL1 mutation. Using 3D neural spheroids, Javed et al. investigate a mutation in KNL1 that causes microcephaly. Their study shows that, despite ubiquitous mutant KNL1 expression, KNL1 mRNA processing is affected only in neural precursors due to difference in splicing protein levels, offering insights into why the phenotype remains brain specific in patients.
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Affiliation(s)
- Attya Omer Javed
- Université Paris-Saclay, ED 569, 5 Rue Jean-Baptiste Clément, 92290 Châtenay-Malabry, France; Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Yun Li
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M4G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Julien Muffat
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Kuan-Chung Su
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Malkiel A Cohen
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Tenzin Lungjangwa
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Patrick Aubourg
- Université Paris-Saclay, ED 569, 5 Rue Jean-Baptiste Clément, 92290 Châtenay-Malabry, France; INSERM U1169, CHU Bicêtre Paris Sud, Le Kremlin-Bicêtre, France
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, MIT, 31 Ames Street, Cambridge, MA 02139, USA
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, MIT, 31 Ames Street, Cambridge, MA 02139, USA.
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12
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Duerinckx S, Jacquemin V, Drunat S, Vial Y, Passemard S, Perazzolo C, Massart A, Soblet J, Racapé J, Desmyter L, Badoer C, Papadimitriou S, Le Borgne YA, Lefort A, Libert F, De Maertelaer V, Rooman M, Costagliola S, Verloes A, Lenaerts T, Pirson I, Abramowicz M. Digenic inheritance of human primary microcephaly delineates centrosomal and non-centrosomal pathways. Hum Mutat 2019; 41:512-524. [PMID: 31696992 PMCID: PMC7496698 DOI: 10.1002/humu.23948] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 11/01/2019] [Accepted: 11/03/2019] [Indexed: 12/30/2022]
Abstract
Primary microcephaly (PM) is characterized by a small head since birth and is vastly heterogeneous both genetically and phenotypically. While most cases are monogenic, genetic interactions between Aspm and Wdr62 have recently been described in a mouse model of PM. Here, we used two complementary, holistic in vivo approaches: high throughput DNA sequencing of multiple PM genes in human patients with PM, and genome‐edited zebrafish modeling for the digenic inheritance of PM. Exomes of patients with PM showed a significant burden of variants in 75 PM genes, that persisted after removing monogenic causes of PM (e.g., biallelic pathogenic variants in CEP152). This observation was replicated in an independent cohort of patients with PM, where a PM gene panel showed in addition that the burden was carried by six centrosomal genes. Allelic frequencies were consistent with digenic inheritance. In zebrafish, non‐centrosomal gene casc5 −/− produced a severe PM phenotype, that was not modified by centrosomal genes aspm or wdr62 invalidation. A digenic, quadriallelic PM phenotype was produced by aspm and wdr62. Our observations provide strong evidence for digenic inheritance of human PM, involving centrosomal genes. Absence of genetic interaction between casc5 and aspm or wdr62 further delineates centrosomal and non‐centrosomal pathways in PM.
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Affiliation(s)
- Sarah Duerinckx
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium.,Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles-Vrije Universiteit Brussel, Brussels, Belgium
| | - Valérie Jacquemin
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Séverine Drunat
- Department of Genetics, Robert Debré University Hospital, APHP, Paris, France.,INSERM UMR 1141, Université de Paris Diderot, Paris, France
| | - Yoann Vial
- Department of Genetics, Robert Debré University Hospital, APHP, Paris, France.,INSERM UMR 1141, Université de Paris Diderot, Paris, France
| | - Sandrine Passemard
- Department of Genetics, Robert Debré University Hospital, APHP, Paris, France.,INSERM UMR 1141, Université de Paris Diderot, Paris, France
| | - Camille Perazzolo
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Annick Massart
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Julie Soblet
- Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles-Vrije Universiteit Brussel, Brussels, Belgium.,Department of Genetics, ULB Center of Human Genetics, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium.,Department of Genetics, ULB Center of Human Genetics, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Judith Racapé
- Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium
| | - Laurence Desmyter
- Department of Genetics, ULB Center of Human Genetics, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Cindy Badoer
- Department of Genetics, ULB Center of Human Genetics, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Sofia Papadimitriou
- Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles-Vrije Universiteit Brussel, Brussels, Belgium.,Machine Learning Group, Université Libre de Bruxelles, Brussels, Belgium.,Artificial Intelligence Lab, Vrije Universiteit Brussel, Brussels, Belgium
| | - Yann-Aël Le Borgne
- Machine Learning Group, Université Libre de Bruxelles, Brussels, Belgium
| | - Anne Lefort
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Frédérick Libert
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Viviane De Maertelaer
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Marianne Rooman
- Computational Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium
| | - Sabine Costagliola
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Alain Verloes
- Department of Genetics, Robert Debré University Hospital, APHP, Paris, France.,INSERM UMR 1141, Université de Paris Diderot, Paris, France
| | - Tom Lenaerts
- Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles-Vrije Universiteit Brussel, Brussels, Belgium.,Machine Learning Group, Université Libre de Bruxelles, Brussels, Belgium.,Artificial Intelligence Lab, Vrije Universiteit Brussel, Brussels, Belgium
| | - Isabelle Pirson
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Marc Abramowicz
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium.,Present Address: Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
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13
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Shi L, Qalieh A, Lam MM, Keil JM, Kwan KY. Robust elimination of genome-damaged cells safeguards against brain somatic aneuploidy following Knl1 deletion. Nat Commun 2019; 10:2588. [PMID: 31197172 PMCID: PMC6565622 DOI: 10.1038/s41467-019-10411-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 04/30/2019] [Indexed: 01/12/2023] Open
Abstract
The brain is a genomic mosaic shaped by cellular responses to genome damage. Here, we manipulate somatic genome stability by conditional Knl1 deletion from embryonic mouse brain. KNL1 mutations cause microcephaly and KNL1 mediates the spindle assembly checkpoint, a safeguard against chromosome missegregation and aneuploidy. We find that following Knl1 deletion, segregation errors in mitotic neural progenitor cells give rise to DNA damage on the missegregated chromosomes. This triggers rapid p53 activation and robust apoptotic and microglial phagocytic responses that extensively eliminate cells with somatic genome damage, thus causing microcephaly. By leaving only karyotypically normal progenitors to continue dividing, these mechanisms provide a second safeguard against brain somatic aneuploidy. Without Knl1 or p53-dependent safeguards, genome-damaged cells are not cleared, alleviating microcephaly, but paradoxically leading to total pre-weaning lethality. Thus, mitotic genome damage activates robust responses to eliminate somatic mutant cells, which if left unpurged, can impact brain and organismal fitness.
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Affiliation(s)
- Lei Shi
- Molecular & Behavioral Neuroscience Institute (MBNI), University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Adel Qalieh
- Molecular & Behavioral Neuroscience Institute (MBNI), University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Mandy M Lam
- Molecular & Behavioral Neuroscience Institute (MBNI), University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jason M Keil
- Molecular & Behavioral Neuroscience Institute (MBNI), University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
- Medical Scientist Training Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kenneth Y Kwan
- Molecular & Behavioral Neuroscience Institute (MBNI), University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA.
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14
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Gharbaran R, Somenarain L. Putative Cellular and Molecular Roles of Zika Virus in Fetal and Pediatric Neuropathologies. Pediatr Dev Pathol 2019; 22:5-21. [PMID: 30149771 DOI: 10.1177/1093526618790742] [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: 12/13/2022]
Abstract
Although the World Health Organization declared an end to the recent Zika virus (ZIKV) outbreak and its association with adverse fetal and pediatric outcome, on November 18, 2016, the virus still remains a severe public health threat. Laboratory experiments thus far supported the suspicions that ZIKV is a teratogenic agent. Evidence indicated that ZIKV infection cripples the host cells' innate immune responses, allowing productive replication and potential dissemination of the virus. In addition, studies suggest potential transplacental passage of the virus and subsequent selective targeting of neural progenitor cells (NPCs). Depletion of NPCs by ZIKV is associated with restricted brain growth. And while microcephaly can result from infection at any gestational stages, the risk is greater during the first trimester. Although a number of recent studies revealed some of specific molecular and cellular roles of ZIKV proteins of this mosquito-borne flavivirus, the mechanisms by which it produces it suspected pathophysiological effects are not completely understood. Thus, this review highlights the cellular and molecular evidence that implicate ZIKV in fetal and pediatric neuropathologies.
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Affiliation(s)
- Rajendra Gharbaran
- 1 Department of Biological Sciences, Bronx Community College, The City University of New York, Bronx, New York
| | - Latchman Somenarain
- 1 Department of Biological Sciences, Bronx Community College, The City University of New York, Bronx, New York
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15
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Comprehensive review on the molecular genetics of autosomal recessive primary microcephaly (MCPH). Genet Res (Camb) 2018; 100:e7. [PMID: 30086807 DOI: 10.1017/s0016672318000046] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Primary microcephaly (MCPH) is an autosomal recessive sporadic neurodevelopmental ailment with a trivial head size characteristic that is below 3-4 standard deviations. MCPH is the smaller upshot of an architecturally normal brain; a significant decrease in size is seen in the cerebral cortex. At birth MCPH presents with non-progressive mental retardation, while secondary microcephaly (onset after birth) presents with and without other syndromic features. MCPH is a neurogenic mitotic syndrome nevertheless pretentious patients demonstrate normal neuronal migration, neuronal apoptosis and neural function. Eighteen MCPH loci (MCPH1-MCPH18) have been mapped to date from various populations around the world and contain the following genes: Microcephalin, WDR62, CDK5RAP2, CASC5, ASPM, CENPJ, STIL, CEP135, CEP152, ZNF335, PHC1, CDK6, CENPE, SASS6, MFSD2A, ANKLE2, CIT and WDFY3, clarifying our understanding about the molecular basis of microcephaly genetic disorder. It has previously been reported that phenotype disease is caused by MCB gene mutations and the causes of this phenotype are disarrangement of positions and organization of chromosomes during the cell cycle as a result of mutated DNA, centriole duplication, neurogenesis, neuronal migration, microtubule dynamics, transcriptional control and the cell cycle checkpoint having some invisible centrosomal process that can manage the number of neurons that are produced by neuronal precursor cells. Furthermore, researchers inform us about the clinical management of families that are suffering from MCPH. Establishment of both molecular understanding and genetic advocating may help to decrease the rate of this ailment. This current review study examines newly identified genes along with previously identified genes involved in autosomal recessive MCPH.
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16
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Takimoto M. D40/KNL1/CASC5 and autosomal recessive primary microcephaly. Congenit Anom (Kyoto) 2017; 57:191-196. [PMID: 28901661 DOI: 10.1111/cga.12252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/04/2017] [Accepted: 09/09/2017] [Indexed: 12/30/2022]
Abstract
Autosomal recessive primary microcephaly (MCPH) is a very rare neuro-developmental disease with brain size reduction. More than a dozen loci encoding proteins of diverse function have been shown to be responsible for MCPH1-13. Mutations in the D40/KNL1/CASC5 gene, which was initially characterized as a gene involved in chromosomal translocation in leukemia and as a member of the cancer/testis gene family, was later found to encode a kinetochore protein essential for mitotic cell division and to cause MCPH4. Although our previous studies showed that this gene is required for cell growth and division in vitro and in animal experiments, the revelation that mutations in this gene caused microcephaly provides in vivo evidence of a critical role in brain growth. In this review, we describe mutated gene targets responsible for MCPH1-13 and summarize clinical studies of, and molecular and biological aspects of the gene and encoded protein responsible for MCPH4.
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Affiliation(s)
- Masato Takimoto
- Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
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17
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de Wolf B, Kops GJPL. Kinetochore Malfunction in Human Pathologies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1002:69-91. [DOI: 10.1007/978-3-319-57127-0_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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18
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Regional selection of the brain size regulating gene CASC5 provides new insight into human brain evolution. Hum Genet 2016; 136:193-204. [PMID: 27878434 DOI: 10.1007/s00439-016-1748-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 11/15/2016] [Indexed: 12/25/2022]
Abstract
Human evolution is marked by a continued enlargement of the brain. Previous studies on human brain evolution focused on identifying sequence divergences of brain size regulating genes between humans and nonhuman primates. However, the evolutionary pattern of the brain size regulating genes during recent human evolution is largely unknown. We conducted a comprehensive analysis of the brain size regulating gene CASC5 and found that in recent human evolution, CASC5 has accumulated many modern human specific amino acid changes, including two fixed changes and six polymorphic changes. Among human populations, 4 of the 6 amino acid polymorphic sites have high frequencies of derived alleles in East Asians, but are rare in Europeans and Africans. We proved that this between-population allelic divergence was caused by regional Darwinian positive selection in East Asians. Further analysis of brain image data of Han Chinese showed significant associations of the amino acid polymorphic sites with gray matter volume. Hence, CASC5 may contribute to the morphological and structural changes of the human brain during recent evolution. The observed between-population divergence of CASC5 variants was driven by natural selection that tends to favor a larger gray matter volume in East Asians.
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19
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Wang R, Khan A, Han S, Zhang X. Molecular analysis of 23 Pakistani families with autosomal recessive primary microcephaly using targeted next-generation sequencing. J Hum Genet 2016; 62:299-304. [DOI: 10.1038/jhg.2016.128] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 09/26/2016] [Accepted: 09/26/2016] [Indexed: 12/19/2022]
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20
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Zarate YA, Kaylor JA, Bosanko K, Lau S, Vargas J, Gao H. First clinical report of an infant with microcephaly and CASC5 mutations. Am J Med Genet A 2016; 170:2215-8. [PMID: 27149178 DOI: 10.1002/ajmg.a.37726] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/18/2016] [Indexed: 11/05/2022]
Affiliation(s)
- Yuri A Zarate
- Section of Genetics and Metabolism, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Julie A Kaylor
- Molecular Genetic Pathology, Arkansas Children's Hospital, Little Rock, Arkansas
| | - Katherine Bosanko
- Section of Genetics and Metabolism, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Sarah Lau
- Fulgent Diagnostics, Temple City, California
| | - Jose Vargas
- Fulgent Diagnostics, Temple City, California
| | - Hanlin Gao
- Fulgent Diagnostics, Temple City, California
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