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Farcy S, Hachour H, Bahi-Buisson N, Passemard S. Genetic Primary Microcephalies: When Centrosome Dysfunction Dictates Brain and Body Size. Cells 2023; 12:1807. [PMID: 37443841 PMCID: PMC10340463 DOI: 10.3390/cells12131807] [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: 04/06/2023] [Revised: 06/04/2023] [Accepted: 06/13/2023] [Indexed: 07/15/2023] Open
Abstract
Primary microcephalies (PMs) are defects in brain growth that are detectable at or before birth and are responsible for neurodevelopmental disorders. Most are caused by biallelic or, more rarely, dominant mutations in one of the likely hundreds of genes encoding PM proteins, i.e., ubiquitous centrosome or microtubule-associated proteins required for the division of neural progenitor cells in the embryonic brain. Here, we provide an overview of the different types of PMs, i.e., isolated PMs with or without malformations of cortical development and PMs associated with short stature (microcephalic dwarfism) or sensorineural disorders. We present an overview of the genetic, developmental, neurological, and cognitive aspects characterizing the most representative PMs. The analysis of phenotypic similarities and differences among patients has led scientists to elucidate the roles of these PM proteins in humans. Phenotypic similarities indicate possible redundant functions of a few of these proteins, such as ASPM and WDR62, which play roles only in determining brain size and structure. However, the protein pericentrin (PCNT) is equally required for determining brain and body size. Other PM proteins perform both functions, albeit to different degrees. Finally, by comparing phenotypes, we considered the interrelationships among these proteins.
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Affiliation(s)
- Sarah Farcy
- UMR144, Institut Curie, 75005 Paris, France;
- Inserm UMR-S 1163, Institut Imagine, 75015 Paris, France
| | - Hassina Hachour
- Service de Neurologie Pédiatrique, DMU INOV-RDB, APHP, Hôpital Robert Debré, 75019 Paris, France;
| | - Nadia Bahi-Buisson
- Service de Neurologie Pédiatrique, DMU MICADO, APHP, Hôpital Necker Enfants Malades, 75015 Paris, France;
- Université Paris Cité, Inserm UMR-S 1163, Institut Imagine, 75015 Paris, France
| | - Sandrine Passemard
- Service de Neurologie Pédiatrique, DMU INOV-RDB, APHP, Hôpital Robert Debré, 75019 Paris, France;
- Université Paris Cité, Inserm UMR 1141, NeuroDiderot, 75019 Paris, France
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2
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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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3
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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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4
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Further Delineation of Phenotype and Genotype of Primary Microcephaly Syndrome with Cortical Malformations Associated with Mutations in the WDR62 Gene. Genes (Basel) 2021; 12:genes12040594. [PMID: 33921653 PMCID: PMC8072659 DOI: 10.3390/genes12040594] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/12/2021] [Accepted: 04/17/2021] [Indexed: 11/16/2022] Open
Abstract
Type 2 congenital microcephaly (MCPH2) is a brain development disorder characterized by primary microcephaly with or without brain malformations. MCPH2 is caused by mutations in the WDR62 gene. We present three new patients with MCPH2 and compound heterozygous mutations in the WDR62 gene. In all the cases, the parents were healthy and unrelated. All children were clinically diagnosed with congenital microcephaly and retardation of motor and speech development. Sequencing results in the presented patients revealed five new variants in the WDR62 gene (c.4273C>T, c.1711_1712insTA, c.1777_1778delGA, c.1642+2T>G, c.194T>A) and one previously described in the German population (c.2864_2867delACAG). In two of the presented cases, variants in the SMAD4, DKC1, and ATRX genes were also found with unknown effects on the course of the disease. Moreover, in the article we collected and compared the most common clinical symptoms, dysmorphic features, and changes in radiographic examinations of the brain observed in 120 patients with recessive primary microcephaly type 2 caused by mutations in the WDR62 gene.
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5
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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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6
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Naseer MI, Rasool M, Abdulkareem AA, Chaudhary AG, Zaidi SK, Al-Qahtani MH. Novel compound heterozygous mutations in WDR62 gene leading to developmental delay and Primary Microcephaly in Saudi Family. Pak J Med Sci 2019; 35:764-770. [PMID: 31258591 PMCID: PMC6572970 DOI: 10.12669/pjms.35.3.36] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Objective: Primary microcephaly (MCPH) is a rare autosomal recessive disorder characterized by impaired congenital reduction of brain size along with head circumference and intellectual disability. MCPH is a heterogeneous disorder and more than twenty four genes associated with this disease have been identified so far. The objective of this study was to find out the novel genes or mutations leading to the genetic defect in a Saudi family with primary microcephaly. Methods: Whole exome sequencing was carried out to find the novel mutation and the results was further validated using Sanger sequencing analysis. This study was done in the Center of excellence in Genomic Medicine and Research, King Abdulaziz University under KACST project during 2017 and 2018. Results: We report a novel compound heterozygous mutations c.797C>T in exon 7 and c.1102G>A in exon 9 of the WD repeat domain 62 (WDR62) (OMIM 604317) gene in two affected siblings in Saudi family with intellectual disability, speech impediments walking difficulty along with primary microcephaly. Two rare, missense variants were detected in heterozygous state in the WDR62 gene in these two affected individuals from the heterozygous parents. Conclusions: A compound heterozygous mutations c.797C>T in exon 7 and c.1102G> A in exon 9 of the WDR62 gene was identified. WDR62 gene is very important gene and mutation can lead to neuro developmental defects, brain malformations, reduced brain and head size. These results should be taken into consideration during prognostic discussions and mutation spectrum with affected patients and their families in the Saudi population.
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Affiliation(s)
- Muhammad Imran Naseer
- Muhammad Imran Naseer, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, 21589, Jeddah, Kingdom of Saudi Arabia. Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, 21589, Jeddah, Saudi Arabia
| | - Mahmood Rasool
- Mahmood Rasool, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, 21589, Jeddah, Kingdom of Saudi Arabia. Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, 21589, Jeddah, Saudi Arabia
| | - Angham Abdulrahman Abdulkareem
- Angham Abdulrahman Abdulkareem, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, 21589, Jeddah, Kingdom of Saudi Arabia. Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, 21589, Jeddah, Saudi Arabia
| | - Adeel G Chaudhary
- Adeel G. Chaudhary, Center for Innovation in Personalized Medicine, Faculty of Applied Medical Sciences, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, 21589, Jeddah, Kingdom of Saudi Arabia. Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, 21589, Jeddah, Saudi Arabia
| | - Syed Kashif Zaidi
- Syed Kashif Zaidi, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, 21589, Jeddah, Kingdom of Saudi Arabia. Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, 21589, Jeddah, Saudi Arabia
| | - Mohammad H Al-Qahtani
- Mohammad H. Al-Qahtani, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, 21589, Jeddah, Kingdom of Saudi Arabia. Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, 21589, Jeddah, Saudi Arabia
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7
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A novel WDR62 missense mutation in microcephaly with abnormal cortical architecture and review of the literature. J Appl Genet 2019; 60:151-162. [PMID: 30706430 DOI: 10.1007/s13353-019-00486-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 01/05/2019] [Accepted: 01/17/2019] [Indexed: 02/07/2023]
Abstract
Autosomal recessive primary microcephaly (MCPH) is a group of rare neurodevelopmental diseases with severe microcephaly at birth. One type of the disorder, MCPH2, is caused by biallelic mutations in the WDR62 gene, which encodes the WD repeat-containing protein 62. Patients with WDR62 mutation may have a wide range of malformations of cortical development in addition to congenital microcephaly. We describe two patients, a boy and a girl, with severe congenital microcephaly, global developmental delay, epilepsy, and failure to thrive. MRI showed hemispherical asymmetry, diffuse pachygyria, thick gray matter, indistinct gray-white matter junction, and corpus callosum and white matter hypoplasia. Whole exome sequencing revealed the same novel homozygous missense mutation, c.668T>C, p.Phe223Ser in exon 6 of the WDR62 gene. The healthy parents were heterozygous for this mutation. The mutation affects a highly conserved region in one of the WD repeats of the WDR62 protein. Haplotype analysis showed genetic relatedness between the families of the patients. Our findings expand the spectrum of mutations randomly distributed in the WDR62 gene. A review is also provided of the brain malformations described in WDR62 mutations in association with congenital microcephaly.
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Whiting SE, Carson AM, Clark GD, Schwartz DD. Case report of prenatal bilateral cerebellar infarction: implications for social-behavioral functioning. Clin Neuropsychol 2019; 33:890-904. [DOI: 10.1080/13854046.2018.1563631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Sara E. Whiting
- Psychology Section, Department of Pediatrics, Baylor College of Medicine/Texas Children’s Hospital, Houston, TX, USA
| | - Audrey M. Carson
- Psychology Section, Department of Pediatrics, Baylor College of Medicine/Texas Children’s Hospital, Houston, TX, USA
| | - Gary D. Clark
- Department of Neurology, Baylor College of Medicine/Texas Children’s Hospital, Houston, TX, USA
| | - David D. Schwartz
- Psychology Section, Department of Pediatrics, Baylor College of Medicine/Texas Children’s Hospital, Houston, TX, USA
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9
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Yi YG, Lee DW, Kim J, Jang JH, Lee SM, Jang DH. Two Novel Mutations (c.883-4_890del and c.1684C>G) of WDR62 Gene Associated With Autosomal Recessive Primary Microcephaly: A Case Report. Front Pediatr 2019; 7:457. [PMID: 31788460 PMCID: PMC6854001 DOI: 10.3389/fped.2019.00457] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 10/21/2019] [Indexed: 12/11/2022] Open
Abstract
Background: Autosomal recessive primary microcephaly (Microcephaly Primary Hereditary, MCPH) is a rare disorder, affecting 1 in 10,000 children in areas where consanguineous marriages are common. WDR62 gene mutations are the second most common cause of MCPH. Herein, we report a case of primary microcephaly caused by two novel WDR62 mutations, which is, to our knowledge, the first such case report in East Asia. Case presentation: A 6-year-old girl visited our outpatient clinic as a result of microcephaly and delayed development. The patient was born at 36 weeks 4 days through cesarean section. Her birth weight was 1.8 kg (<1st percentile), and she was noted to have microcephaly (head circumference at birth was 28 cm, <-3SD). On examination, delayed speech development and microcephaly with an occipitofrontal head circumference of 43.5 cm (<-3SD) were noted. The patient's gross and fine motor development was normal. Her intelligence quotient was 43 (<0.1 percentile), the same as a 27-month-old child, and her social intelligence quotient was 76.92. Brain imaging revealed simplified gyral patterns of the cerebral cortex; however, laboratory findings, including organic acids, were normal. Multiplex ligation-dependent probe amplification technique for microdeletion syndrome and chromosomal microarray, showed no abnormality. Clinical exome sequencing test revealed two novel heterozygous variants in the WDR62 gene at two different sites: in the boundary of intron 7 and exon 8 (NM_001083961.1: c.883-4_890del) and in exon 13 (NM_001083961.1: c.1684C>G). The patient's parents were identified as heterozygous carriers for each variation. Conclusion: We report on two novel heterozygous mutations in East Asia. Our data expand the understanding of WDR62 mutations.
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Affiliation(s)
- You Gyoung Yi
- Department of Rehabilitation Medicine, National Traffic Injury Rehabilitation Hospital, Seoul, South Korea.,Department of Rehabilitation, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea
| | - Dong-Woo Lee
- Department of Rehabilitation Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Jaewon Kim
- Department of Rehabilitation Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Ja-Hyun Jang
- Department of Laboratory Medicine, Green Cross Laboratories, Yongin-si, South Korea.,Green Cross Genome, Yongin-si, South Korea
| | - Sae-Mi Lee
- Department of Laboratory Medicine, Green Cross Laboratories, Yongin-si, South Korea.,Green Cross Genome, Yongin-si, South Korea
| | - Dae-Hyun Jang
- Department of Rehabilitation Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
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10
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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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11
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Genetics and mechanisms leading to human cortical malformations. Semin Cell Dev Biol 2018; 76:33-75. [DOI: 10.1016/j.semcdb.2017.09.031] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 02/06/2023]
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12
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Nardello R, Fontana A, Antona V, Beninati A, Mangano GD, Stallone MC, Mangano S. A novel mutation of WDR62 gene associated with severe phenotype including infantile spasm, microcephaly, and intellectual disability. Brain Dev 2018; 40:58-64. [PMID: 28756000 DOI: 10.1016/j.braindev.2017.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/23/2017] [Accepted: 07/11/2017] [Indexed: 12/16/2022]
Abstract
The autosomal recessive form of primary microcephaly (MCPH) is a rare disorder characterized by head circumference of at least 3 standard deviation below the mean. The MCPH exhibits genetic heterogeneity with thirteen loci (MCPH1-MCPH13) identified, and associated with variable degree of intellectual disability. It has been reported that WDR62 is the second causative gene of autosomal recessive microcephaly (MCPH2) playing a significant role in spindle formation and the proliferation of neuronal progenitor cells. We report a clinical feature, electroclinical findings, and clinical course of a patient with a severe phenotype of MCPH2 including microcephaly, refractory infantile spasms and intellectual disability. Genetic analysis detected a new homozygous splicing variant c.3335+1G>C in the WD repeat domain 62 (WDR62) gene, inherited from both heterozygous healthy parents, and an additional new heterozygous missense mutation c.1706T>A of G protein-coupled receptor 56 (GPR56) gene inherited from his healthy father. The study seeks to broaden the knowledge of clinical and electroclinical findings of MCPH2 and to contribute to a better characterization of the genotype-phenotype correlation.
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Affiliation(s)
- Rosaria Nardello
- Child Neuropsychiatry Unit, Department of Sciences for Health Promotion and Mother and Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Antonina Fontana
- Child Neuropsychiatry Unit, Department of Sciences for Health Promotion and Mother and Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Vincenzo Antona
- Neonatology and Intensive Care Unit, Department of Sciences for Health Promotion and Mother and Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Annalisa Beninati
- Child Neuropsychiatry Unit, Department of Sciences for Health Promotion and Mother and Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Giuseppe Donato Mangano
- Child Neuropsychiatry Unit, Department of Sciences for Health Promotion and Mother and Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Maria Cristina Stallone
- Child Neuropsychiatry Unit, Department of Sciences for Health Promotion and Mother and Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Salvatore Mangano
- Child Neuropsychiatry Unit, Department of Sciences for Health Promotion and Mother and Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy.
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Shohayeb B, Lim NR, Ho U, Xu Z, Dottori M, Quinn L, Ng DCH. The Role of WD40-Repeat Protein 62 (MCPH2) in Brain Growth: Diverse Molecular and Cellular Mechanisms Required for Cortical Development. Mol Neurobiol 2017; 55:5409-5424. [DOI: 10.1007/s12035-017-0778-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/15/2017] [Indexed: 12/13/2022]
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14
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Disruptions in asymmetric centrosome inheritance and WDR62-Aurora kinase B interactions in primary microcephaly. Sci Rep 2017; 7:43708. [PMID: 28272472 PMCID: PMC5341122 DOI: 10.1038/srep43708] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/26/2017] [Indexed: 12/11/2022] Open
Abstract
Recessive mutations in WD repeat domain 62 (WDR62) cause microcephaly and a wide spectrum of severe brain malformations. Disruption of the mouse ortholog results in microcephaly underlain by reduced proliferation of neocortical progenitors during late neurogenesis, abnormalities in asymmetric centrosome inheritance leading to neuronal migration delays, and altered neuronal differentiation. Spindle pole localization of WDR62 and mitotic progression are defective in patient-derived fibroblasts, which, similar to mouse neocortical progenitors, transiently arrest at prometaphase. Expression of WDR62 is closely correlated with components of the chromosome passenger complex (CPC), a key regulator of mitosis. Wild type WDR62, but not disease-associated mutant forms, interacts with the CPC core enzyme Aurora kinase B and staining of CPC components at centromeres is altered in patient-derived fibroblasts. Our findings demonstrate critical and diverse functions of WDR62 in neocortical development and provide insight into the mechanisms by which its disruption leads to a plethora of structural abnormalities.
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15
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Naseer MI, Rasool M, Sogaty S, Chaudhary RA, Mansour HM, Chaudhary AG, Abuzenadah AM, Al-Qahtani MH. A novel WDR62 mutation causes primary microcephaly in a large consanguineous Saudi family. Ann Saudi Med 2017; 37:148-153. [PMID: 28377545 PMCID: PMC6150548 DOI: 10.5144/0256-4947.2017.148] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Primary microcephaly (MCPH) is a rare developmental defect characterized by impaired cognitive functions, retarded neurodevelopment and reduced brain size. It is genetically heterogeneous and more than 17 genes so far have been identified that are associated with this disease. OBJECTIVE To study the genetic defect in a consanguineous Saudi family with primary microcephaly. DESIGN Cross-sectional clinical genetics study of a Saudi family. SETTING Medical genomics research center. PATIENTS AND METHODS Blood samples collected from six members of a family of healthy consanguineous parents were analyzed by whole exome sequencing to identify the underlying pathogenic mutations in two members of the family (23-year-old female and 7-year-old male) who presented with primary microcephaly, intellectual disability, delayed psychomotor development and walking difficulty, speech impedi-ments and seizures. MAIN OUTCOME MEASURE(S) Detection of mutation in the WD repeat domain 62 (WDR62) gene in a family segregating autosomal recessive primary microcephaly. RESULTS The exome variant analysis identified a novel missense mutation (c.3878C > A) in WDR62 gene in exon 30 resulting in amino acid change from alanine to aspartate (p.Ala1293Asp). Further validation in the affected patients and healthy members of family and 100 unrelated healthy persons as controls confirmed it to be pathogenic. CONCLUSIONS Functional impairment of the WDR62 gene can lead to severe neurodevelopmental de-fects, brain malformations and reduced head size. A missense mutation of exon 30 changed alanine to aspartate in the WDR62 protein leading to the typical MCPH phenotype. LIMITATIONS Mutation was identified in a single family.
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Affiliation(s)
- Muhammad Imran Naseer
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mahmood Rasool
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Sameera Sogaty
- Department of Medical Genetics, King Fahad General Hospital, Jeddah, Saudi Arabia
| | - Rukhaa Adeel Chaudhary
- Faculty of Applied Medical Sciences, Medical Laboratory Technology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Haifa Mansour Mansour
- Faculty of Applied Medical Sciences, Medical Laboratory Technology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Adeel G. Chaudhary
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Adel M. Abuzenadah
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohammad H. Al-Qahtani
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
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Stark AE. The genetic epidemiology of the form of microcephaly ascribed to mutation at the WDR62 locus. ANNALS OF TRANSLATIONAL MEDICINE 2016; 4:281. [PMID: 27570775 DOI: 10.21037/atm.2016.07.08] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The disorder associated with mutation in the WDR62 gene MCPH2 is taken as the prototype of a condition which has a recessive mode of inheritance. The mutant homozygote has relatively lower fitness defined by the selection coefficient. Formulae which relate the incidence of the disorder to the mutation rate and the gene frequency in equilibrium when some degree of inbreeding occurs in the population are given.
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Affiliation(s)
- Alan Edmund Stark
- School of Mathematics and Statistics, F07, University of Sydney, NSW, Australia
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17
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Pervaiz N, Abbasi AA. Molecular evolution of WDR62, a gene that regulates neocorticogenesis. Meta Gene 2016; 9:1-9. [PMID: 27114917 PMCID: PMC4833054 DOI: 10.1016/j.mgene.2016.02.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 02/23/2016] [Indexed: 02/02/2023] Open
Abstract
Human brain evolution is characterized by dramatic expansion in cerebral cortex size. WDR62 (WD repeat domain 62) is one of the important gene in controlling human cortical development. Mutations in WDR62 lead to primary microcephaly, a neurodevelopmental disease characterized by three to four fold reduction in cerebral cortex size of affected individuals. This study analyzes comparative protein evolutionary rate to provide a useful insight into the molecular evolution of WDR62 and hence pinpointed human specific amino acid replacements. Comparative analysis of human WDR62 with two archaic humans (Neanderthals and Denisovans) and modern human populations revealed that five hominin specific amino acid residues (human specific amino acids shared with two archaic humans) might have been accumulated in the common ancestor of extinct archaic humans and modern humans about 550,000–765,000 years ago. Collectively, the data demonstrates an acceleration of WDR62 sequence evolution in hominin lineage and suggests that the ability of WDR62 protein to mediate the neurogenesis has been altered in the course of hominin evolution. We trace the evolutionary history of WDR62 and its putative paralogs. We identify accelerated sequence evolution in human WDR62. We pinpoint eight human specific amino acid sites that reside on the C-terminal. Out of eight, six sites are shared with archaic humans.
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Affiliation(s)
- Nashaiman Pervaiz
- National Center for Bioinformatics, Program of Comparative and Evolutionary Genomics, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Amir Ali Abbasi
- National Center for Bioinformatics, Program of Comparative and Evolutionary Genomics, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
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18
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Refining the phenotype associated with CASC5 mutation. Neurogenetics 2015; 17:71-8. [PMID: 26626498 DOI: 10.1007/s10048-015-0468-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 11/14/2015] [Indexed: 02/03/2023]
Abstract
Autosomal recessive primary microcephaly is a neurodevelopmental disorder characterized by congenitally reduced head circumference by at least two standard deviations (SD) below the mean for age and gender. It is associated with nonprogressive mental retardation of variable degree, minimal neurological deficit with no evidence of architectural anomalies of the brain. So far, 12 genetic loci (MCPH1-12) and corresponding genes have been identified. Most of these encode centrosomal proteins. CASC5 is one the most recently unravelled genes responsible for MCPH with mutations reported in three consanguineous families of Moroccan origin, all of whom harboured the same CASC5 homozygous mutation (c.6125G>A; p.Met2041Ile). Here, we report the identification, by whole exome sequencing, of the same missense mutation in a consanguineous Algerian family. All patients exhibited a similar clinical phenotype, including congenital microcephaly with head circumferences ranging from -3 to -4 standard deviations (SD) after age 5 years, moderate to severe cognitive impairment, short stature (adult height -3 SD), dysmorphic features included a sloping forehead, thick eyebrows, synophris and a low columella. Severe vermis hypoplasia and a large cyst of the posterior fossa were observed in one patient. Close microsatellite markers showed identical alleles in the Algerian the previously and Moroccan patients. This study confirms the involvement of CASC5 in autosomal recessive microcephaly and supports the hypothesis of a founder effect of the c.6125G>A mutation. In addition, this report refines the phenotype of this newly recognized form of primary microcephaly.
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19
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Moffat JJ, Ka M, Jung EM, Kim WY. Genes and brain malformations associated with abnormal neuron positioning. Mol Brain 2015; 8:72. [PMID: 26541977 PMCID: PMC4635534 DOI: 10.1186/s13041-015-0164-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 10/31/2015] [Indexed: 01/05/2023] Open
Abstract
Neuronal positioning is a fundamental process during brain development. Abnormalities in this process cause several types of brain malformations and are linked to neurodevelopmental disorders such as autism, intellectual disability, epilepsy, and schizophrenia. Little is known about the pathogenesis of developmental brain malformations associated with abnormal neuron positioning, which has hindered research into potential treatments. However, recent advances in neurogenetics provide clues to the pathogenesis of aberrant neuronal positioning by identifying causative genes. This may help us form a foundation upon which therapeutic tools can be developed. In this review, we first provide a brief overview of neural development and migration, as they relate to defects in neuronal positioning. We then discuss recent progress in identifying genes and brain malformations associated with aberrant neuronal positioning during human brain development.
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Affiliation(s)
- Jeffrey J Moffat
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, 985960 Nebraska Medical Center, Omaha, NE, 68198-5960, USA.
| | - Minhan Ka
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, 985960 Nebraska Medical Center, Omaha, NE, 68198-5960, USA.
| | - Eui-Man Jung
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, 985960 Nebraska Medical Center, Omaha, NE, 68198-5960, USA.
| | - Woo-Yang Kim
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, 985960 Nebraska Medical Center, Omaha, NE, 68198-5960, USA.
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20
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Carvill GL, Mefford HC. Next-Generation Sequencing in Intellectual Disability. J Pediatr Genet 2015; 4:128-35. [PMID: 27617123 DOI: 10.1055/s-0035-1564439] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/03/2015] [Indexed: 12/19/2022]
Abstract
Next-generation sequencing technologies have revolutionized gene discovery in patients with intellectual disability (ID) and led to an unprecedented expansion in the number of genes implicated in this disorder. We discuss the strategies that have been used to identify these novel genes for both syndromic and nonsyndromic ID and highlight the phenotypic and genetic heterogeneity that underpin this condition. Finally, we discuss the future of defining the genetic etiology of ID, including the role of whole-genome sequencing, mosaicism, and the importance of diagnostic testing in ID.
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Affiliation(s)
- Gemma L Carvill
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, United States
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, United States
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21
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Lim JS, Lee JH. Molecular genetic decoding of malformations of cortical development. ACTA ACUST UNITED AC 2015. [DOI: 10.5734/jgm.2015.12.1.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Jae Seok Lim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
| | - Jeong Ho Lee
- Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
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22
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Rupp V, Rauf S, Naveed I, Windpassinger C, Mir A. A novel single base pair duplication in WDR62 causes primary microcephaly. BMC MEDICAL GENETICS 2014; 15:107. [PMID: 25303973 PMCID: PMC4258795 DOI: 10.1186/s12881-014-0107-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 09/10/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND Primary microcephaly is a disorder of the brain resulting in a reduced head circumference that can come along with intellectual disability but with hardly any other neurological abnormalities. CASE PRESENTATION In this study we report on three Pakistani males from a consanguineous family with 2, 4 and 25 years, diagnosed with autosomal recessive primary microcephaly. By genotyping, Sanger sequencing and using bioinformatical approaches the disease causing mutation was identified and evaluated. CONCLUSION By using a 250K SNP array, we were able to detect an 11Mb large autozygous region in the MCPH2 locus on chromosome 19q13.12. Sequencing of the associated gene, WDR62, revealed the frameshift causing single base pair duplication, c.2527dupG. This mutation is predicted to affect the structural features of WDR62 which in turn changes the conformation and function of the protein. Aspartic acid (D) at position 843 was found to be conserved among various ortholog species. The present findings will be helpful in genetic diagnosis of patients and future studies of WDR62.
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23
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Chavali PL, Pütz M, Gergely F. Small organelle, big responsibility: the role of centrosomes in development and disease. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130468. [PMID: 25047622 PMCID: PMC4113112 DOI: 10.1098/rstb.2013.0468] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The centrosome, a key microtubule organizing centre, is composed of centrioles, embedded in a protein-rich matrix. Centrosomes control the internal spatial organization of somatic cells, and as such contribute to cell division, cell polarity and migration. Upon exiting the cell cycle, most cell types in the human body convert their centrioles into basal bodies, which drive the assembly of primary cilia, involved in sensing and signal transduction at the cell surface. Centrosomal genes are targeted by mutations in numerous human developmental disorders, ranging from diseases exclusively affecting brain development, through global growth failure syndromes to diverse pathologies associated with ciliary malfunction. Despite our much-improved understanding of centrosome function in cellular processes, we know remarkably little of its role in the organismal context, especially in mammals. In this review, we examine how centrosome dysfunction impacts on complex physiological processes and speculate on the challenges we face when applying knowledge generated from in vitro and in vivo model systems to human development.
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Affiliation(s)
- Pavithra L Chavali
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK
| | - Monika Pütz
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK
| | - Fanni Gergely
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK
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24
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Whole-exome sequencing reveals GPIHBP1 mutations in infantile colitis with severe hypertriglyceridemia. J Pediatr Gastroenterol Nutr 2014; 59:17-21. [PMID: 24614124 PMCID: PMC4203304 DOI: 10.1097/mpg.0000000000000363] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Severe congenital hypertriglyceridemia (HTG) is a rare disorder caused by mutations in genes affecting lipoprotein lipase (LPL) activity. Here we report a 5-week-old Hispanic girl with severe HTG (12,031 mg/dL, normal limit 150 mg/dL) who presented with the unusual combination of lower gastrointestinal bleeding and milky plasma. Initial colonoscopy was consistent with colitis, which resolved with reduction of triglycerides. After negative sequencing of the LPL gene, whole-exome sequencing revealed novel compound heterozygous mutations in GPIHBP1. Our study broadens the phenotype of GPIHBP1-associated HTG, reinforces the effectiveness of whole-exome sequencing in Mendelian diagnoses, and implicates triglycerides in gastrointestinal mucosal injury.
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25
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Stutterd CA, Leventer RJ. Polymicrogyria: a common and heterogeneous malformation of cortical development. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2014; 166C:227-39. [PMID: 24888723 DOI: 10.1002/ajmg.c.31399] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Polymicrogyria (PMG) is one of the most common malformations of cortical development. It is characterized by overfolding of the cerebral cortex and abnormal cortical layering. It is a highly heterogeneous malformation with variable clinical and imaging features, pathological findings, and etiologies. It may occur as an isolated cortical malformation, or in association with other malformations within the brain or body as part of a multiple congenital anomaly syndrome. Polymicrogyria shows variable topographic patterns with the bilateral perisylvian pattern being most common. Schizencephaly is a subtype of PMG in which the overfolded cortex lines full-thickness clefts connecting the subarachnoid space with the cerebral ventricles. Both genetic and non-genetic causes of PMG have been identified. Non-genetic causes include congenital cytomegalovirus infection and in utero ischemia. Genetic causes include metabolic conditions such as peroxisomal disorders and the 22q11.2 and 1p36 continguous gene deletion syndromes. Mutations in over 30 genes have been found in association with PMG, especially mutations in the tubulin family of genes. Mutations in the (PI3K)-AKT pathway have been found in association PMG and megalencephaly. Despite recent genetic advances, the mechanisms by which polymicrogyric cortex forms and causes of the majority of cases remain unknown, making diagnostic and prenatal testing and genetic counseling challenging. This review summarizes the clinical, imaging, pathologic, and etiologic features of PMG, highlighting recent genetic advances.
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26
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Poulton CJ, Schot R, Seufert K, Lequin MH, Accogli A, Annunzio GD, Villard L, Philip N, de Coo R, Catsman-Berrevoets C, Grasshoff U, Kattentidt-Mouravieva A, Calf H, de Vreugt-Gronloh E, van Unen L, Verheijen FW, Galjart N, Morris-Rosendahl DJ, Mancini GMS. Severe presentation ofWDR62mutation: Is there a role for modifying genetic factors? Am J Med Genet A 2014; 164A:2161-71. [DOI: 10.1002/ajmg.a.36611] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 04/06/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Cathryn J. Poulton
- Department of Clinical Genetics; Erasmus Medical Center; Rotterdam Germany
| | - Rachel Schot
- Department of Clinical Genetics; Erasmus Medical Center; Rotterdam Germany
| | - Katja Seufert
- Institute of Human Genetics; Albert-Ludwigs University Medical Centre Freiburg; Freiburg Germany
| | | | - Andrea Accogli
- Department of Pediatrics; Gaslini Institute; Genova Italy
| | | | | | - Nicole Philip
- Inserm U910; Aix Marseille University; Marseille France
| | - René de Coo
- Department of Child Neurology; Erasmus Medical Center; Rotterdam Germany
| | | | - Ute Grasshoff
- Institute of Medical Genetics and Applied Genomics; University Hospital Tuebingen; Tuebingen Germany
| | | | - Hans Calf
- ASVZ Zuid West; Rotterdam the Netherlands
| | | | - Leontine van Unen
- Department of Clinical Genetics; Erasmus Medical Center; Rotterdam Germany
| | - Frans W. Verheijen
- Department of Clinical Genetics; Erasmus Medical Center; Rotterdam Germany
| | - Niels Galjart
- Department of Cell Biology; Erasmus Medical Center; Rotterdam the Netherlands
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27
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McDonell LM, Warman Chardon J, Schwartzentruber J, Foster D, Beaulieu CL, Majewski J, Bulman DE, Boycott KM. The utility of exome sequencing for genetic diagnosis in a familial microcephaly epilepsy syndrome. BMC Neurol 2014; 14:22. [PMID: 24479948 PMCID: PMC3916514 DOI: 10.1186/1471-2377-14-22] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/22/2014] [Indexed: 11/30/2022] Open
Abstract
Background Despite remarkable advances in genetic testing, many adults with syndromic epilepsy remain without a molecular diagnosis. The challenge in providing genetic testing for this patient population lies in the extensive genetic heterogeneity associated with epilepsy. Even for the subset of epilepsy patients that present with a defining feature, such as microcephaly, the number of possible genes that would require interrogation by Sanger sequencing is extensive and often prohibitively expensive. Case presentation We report a family of French Canadian descent with four adult children affected with severe intellectual disability, epilepsy and microcephaly born to consanguineous parents and evaluated by the Genetics Service to provide informed genetic counseling to unaffected family members regarding possible recurrence risks. We used whole-exome sequencing (WES) of DNA from one affected sibling as a first-line diagnostic tool and compared the prioritization of variants using two strategies: 1) focusing on genes with homozygous variants; and, 2) focusing on genes associated with microcephaly. Both approaches prioritized the same homozygous novel frameshift mutation (p.Arg608Serfs*26) in WDR62, a gene known to cause autosomal recessive primary microcephaly. Sanger sequencing confirmed the presence of the homozygous mutation in the other three affected siblings. Conclusions WES and subsequent filtering of the rare variants in a single affected family member led to the rapid and cost-effective identification of a novel homozygous frameshift mutation in WDR62, thereby explaining the severe neurodevelopmental disorder in this family and facilitating genetic counseling. Our findings support WES as an effective first-line diagnostic tool in families presenting with rare genetically heterogeneous neurological disorders.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Kym M Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
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28
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Abnormal centrosome and spindle morphology in a patient with autosomal recessive primary microcephaly type 2 due to compound heterozygous WDR62 gene mutation. Orphanet J Rare Dis 2013; 8:178. [PMID: 24228726 PMCID: PMC4225825 DOI: 10.1186/1750-1172-8-178] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 10/10/2013] [Indexed: 11/19/2022] Open
Abstract
Background Autosomal recessive primary microcephaly (MCPH) is a rare neurodevelopmental disease with severe microcephaly at birth due to a pronounced reduction in brain volume and intellectual disability. Biallelic mutations in the WD repeat-containing protein 62 gene WDR62 are the genetic cause of MCPH2. However, the exact underlying pathomechanism of MCPH2 remains to be clarified. Methods/results We characterized the clinical, radiological, and cellular features that add to the human MCPH2 phenotype. Exome sequencing followed by Sanger sequencing in a German family with two affected daughters with primary microcephaly revealed in the index patient the compound heterozygous mutations c.1313G>A (p.R438H) / c.2864-2867delACAG (p.D955Afs*112) of WDR62, the second of which is novel. Radiological examination displayed small frontal lobes, corpus callosum hypoplasia, simplified hippocampal gyration, and cerebellar hypoplasia. We investigated the cellular phenotype in patient-derived lymphoblastoid cells and compared it with that of healthy female controls. WDR62 expression in the patient’s immortalized lymphocytes was deranged, and mitotic spindle defects as well as abnormal centrosomal protein localization were apparent. Conclusion We propose that a disruption of centrosome integrity and/or spindle organization may play an important role in the development of microcephaly in MCPH2.
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29
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Willemsen M, Kleefstra T. Making headway with genetic diagnostics of intellectual disabilities. Clin Genet 2013; 85:101-10. [DOI: 10.1111/cge.12244] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 07/24/2013] [Accepted: 07/24/2013] [Indexed: 01/31/2023]
Affiliation(s)
- M.H. Willemsen
- Department of Human Genetics; Radboud University Medical Centre; Nijmegen The Netherlands
| | - T. Kleefstra
- Department of Human Genetics; Radboud University Medical Centre; Nijmegen The Netherlands
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30
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Cushion TD, Dobyns WB, Mullins JGL, Stoodley N, Chung SK, Fry AE, Hehr U, Gunny R, Aylsworth AS, Prabhakar P, Uyanik G, Rankin J, Rees MI, Pilz DT. Overlapping cortical malformations and mutations in TUBB2B and TUBA1A. ACTA ACUST UNITED AC 2013; 136:536-48. [PMID: 23361065 DOI: 10.1093/brain/aws338] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Polymicrogyria and lissencephaly are causally heterogeneous disorders of cortical brain development, with distinct neuropathological and neuroimaging patterns. They can be associated with additional structural cerebral anomalies, and recurrent phenotypic patterns have led to identification of recognizable syndromes. The lissencephalies are usually single-gene disorders affecting neuronal migration during cerebral cortical development. Polymicrogyria has been associated with genetic and environmental causes and is considered a malformation secondary to abnormal post-migrational development. However, the aetiology in many individuals with these cortical malformations is still unknown. During the past few years, mutations in a number of neuron-specific α- and β-tubulin genes have been identified in both lissencephaly and polymicrogyria, usually associated with additional cerebral anomalies including callosal hypoplasia or agenesis, abnormal basal ganglia and cerebellar hypoplasia. The tubulin proteins form heterodimers that incorporate into microtubules, cytoskeletal structures essential for cell motility and function. In this study, we sequenced the TUBB2B and TUBA1A coding regions in 47 patients with a diagnosis of polymicrogyria and five with an atypical lissencephaly on neuroimaging. We identified four β-tubulin and two α-tubulin mutations in patients with a spectrum of cortical and extra-cortical anomalies. Dysmorphic basal ganglia with an abnormal internal capsule were the most consistent feature. One of the patients with a TUBB2B mutation had a lissencephalic phenotype, similar to that previously associated with a TUBA1A mutation. The remainder had a polymicrogyria-like cortical dysplasia, but the grey matter malformation was not typical of that seen in 'classical' polymicrogyria. We propose that the cortical malformations associated with these genes represent a recognizable tubulinopathy-associated spectrum that ranges from lissencephalic to polymicrogyric cortical dysplasias, suggesting shared pathogenic mechanisms in terms of microtubular function and interaction with microtubule-associated proteins.
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Affiliation(s)
- Thomas D Cushion
- Institute of Life Science, College of Medicine, Swansea University, Swansea SA2 8PP, UK
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31
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A novel WDR62 mutation causes primary microcephaly in a Pakistani family. Mol Biol Rep 2012; 40:591-5. [PMID: 23065275 DOI: 10.1007/s11033-012-2097-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 10/03/2012] [Indexed: 10/27/2022]
Abstract
Autosomal recessive primary microcephaly (MCPH) is a heterogeneous disorder which mainly affects neurodevelopment. Generally, MCPH patients exhibit mild brain structural anomalies and simplified cerebral cortex, but few recently identified genes are associated with severe brain malformations. Here, we report a five generation Pakistani family with three affected individuals presenting primary microcephaly, intellectual disability, schizencephaly and hypoplasia of corpus callosum. The comparison of available clinical information led to candidate gene mapping and sequencing of WD repeat domain 62 (WDR62) gene which is mostly associated with severe brain malformations. A homozygous deletion mutation c.1143delA was detected in exon 9 of WDR62 gene, in all affected individuals, which resulted in frameshift and protein truncation (p.H381PfsX48). This study supports the frequent involvement of WDR62 in patients with gross brain malformations.
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32
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Hanchard NA, Murdock DR, Magoulas PL, Bainbridge M, Muzny D, Wu Y, Wang M, Lupski JR, Gibbs RA, Brown CW. Exploring the utility of whole-exome sequencing as a diagnostic tool in a child with atypical episodic muscle weakness. Clin Genet 2012; 83:457-461. [PMID: 22901280 DOI: 10.1111/j.1399-0004.2012.01951.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 08/03/2012] [Accepted: 08/07/2012] [Indexed: 12/27/2022]
Abstract
The advent of whole-exome next-generation sequencing (WES) has been pivotal for the molecular characterization of Mendelian disease; however, the clinical applicability of WES has remained relatively unexplored. We describe our exploration of WES as a diagnostic tool in a 3½-year old female patient with a 2-year history of episodic muscle weakness and paroxysmal dystonia who presented following a previous extensive but unrevealing diagnostic work-up. WES was performed on the proband and her two parents. Parental exome data was used to filter potential de novo genomic events in the proband and suspected variants were confirmed using di-deoxy sequencing. WES revealed a de novo non-synonymous mutation in exon 21 of the calcium channel gene CACNA1S that has been previously reported in a single patient as a rare cause of atypical hypokalemic periodic paralysis. This was unexpected, as the proband's original differential diagnosis had included hypokalemic periodic paralysis, but clinical and laboratory features were equivocal, and standard clinical molecular testing for hypokalemic periodic paralysis and related disorders was negative. This report highlights the potential diagnostic utility of WES in clinical practice, with implications for the approach to similar diagnostic dilemmas in the future.
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Affiliation(s)
- Neil A Hanchard
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A.,Texas Children's Hospital, 6621 Fannin Street, Houston, Texas, 77030, U.S.A
| | - David R Murdock
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
| | - Pilar L Magoulas
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A.,Texas Children's Hospital, 6621 Fannin Street, Houston, Texas, 77030, U.S.A
| | - Matthew Bainbridge
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
| | - Donna Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
| | - YuanQing Wu
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
| | - Min Wang
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A.,Texas Children's Hospital, 6621 Fannin Street, Houston, Texas, 77030, U.S.A.,Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
| | - Richard A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
| | - Chester W Brown
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A.,Texas Children's Hospital, 6621 Fannin Street, Houston, Texas, 77030, U.S.A.,Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, U.S.A
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Sajid Hussain M, Marriam Bakhtiar S, Farooq M, Anjum I, Janzen E, Reza Toliat M, Eiberg H, Kjaer KW, Tommerup N, Noegel AA, Nürnberg P, Baig SM, Hansen L. Genetic heterogeneity in Pakistani microcephaly families. Clin Genet 2012; 83:446-51. [DOI: 10.1111/j.1399-0004.2012.01932.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 07/04/2012] [Accepted: 07/04/2012] [Indexed: 01/01/2023]
Affiliation(s)
| | | | | | | | - E Janzen
- Cologne Center for Genomics (CCG); University of Cologne; Cologne; Germany
| | - M Reza Toliat
- Cologne Center for Genomics (CCG); University of Cologne; Cologne; Germany
| | - H Eiberg
- Wilhelm Johannsen Centre for Functional Genome Research, Department of Cellular and Molecular Medicine; University of Copenhagen; Copenhagen; Denmark
| | | | | | | | | | - SM Baig
- Human Molecular Genetics Laboratory, Health Biotechnology Division; National Institute for Biotechnology & Genetic Engineering (NIBGE); Faisalabad; Pakistan
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34
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Affiliation(s)
- Jennie E Murray
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, UK
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Gilissen C, Hoischen A, Brunner HG, Veltman JA. Disease gene identification strategies for exome sequencing. Eur J Hum Genet 2012; 20:490-7. [PMID: 22258526 PMCID: PMC3330229 DOI: 10.1038/ejhg.2011.258] [Citation(s) in RCA: 318] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 10/31/2011] [Accepted: 12/07/2011] [Indexed: 12/16/2022] Open
Abstract
Next generation sequencing can be used to search for Mendelian disease genes in an unbiased manner by sequencing the entire protein-coding sequence, known as the exome, or even the entire human genome. Identifying the pathogenic mutation amongst thousands to millions of genomic variants is a major challenge, and novel variant prioritization strategies are required. The choice of these strategies depends on the availability of well-phenotyped patients and family members, the mode of inheritance, the severity of the disease and its population frequency. In this review, we discuss the current strategies for Mendelian disease gene identification by exome resequencing. We conclude that exome strategies are successful and identify new Mendelian disease genes in approximately 60% of the projects. Improvements in bioinformatics as well as in sequencing technology will likely increase the success rate even further. Exome sequencing is likely to become the most commonly used tool for Mendelian disease gene identification for the coming years.
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Affiliation(s)
- Christian Gilissen
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences and Institute for Genetic and Metabolic Disorders, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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