1
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Reed AE, Peraza J, van den Haak F, Hernandez ER, Gibbs RA, Chinn IK, Lupski JR, Marchi E, Reshef R, Alobeid B, Mace EM, Orange JS. β-Actin G342D as a Cause of NK Cell Deficiency Impairing Lytic Synapse Termination. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2024; 212:962-973. [PMID: 38315012 DOI: 10.4049/jimmunol.2300671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 01/09/2024] [Indexed: 02/07/2024]
Abstract
NK cell deficiency (NKD) occurs when an individual's major clinical immunodeficiency derives from abnormal NK cells and is associated with several genetic etiologies. Three categories of β-actin-related diseases with over 60 ACTB (β-actin) variants have previously been identified, none with a distinct NK cell phenotype. An individual with mild developmental delay, macrothrombocytopenia, and susceptibility to infections, molluscum contagiosum virus, and EBV-associated lymphoma had functional NKD for over a decade. A de novo ACTB variant encoding G342D β-actin was identified and was consistent with the individual's developmental and platelet phenotype. This novel variant also was found to have direct impact in NK cells because its expression in the human NK cell line YTS (YTS-NKD) caused increased cell spreading in lytic immune synapses created on activating surfaces. YTS-NKD cells were able to degranulate and perform cytotoxicity, but they demonstrated defective serial killing because of prolonged conjugation to the killed target cell and thus were effectively unable to terminate lytic synapses. G342D β-actin results in a novel, to our knowledge, mechanism of functional NKD via increased synaptic spreading and defective lytic synapse termination with resulting impaired serial killing, leading to overall reductions in NK cell cytotoxicity.
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Affiliation(s)
- Abigail E Reed
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY
| | - Jackeline Peraza
- Department of Biology, Barnard College of Columbia University, New York, NY
| | - Frederique van den Haak
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY
| | - Evelyn R Hernandez
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX
| | - Ivan K Chinn
- Division of Immunology, Allergy and Retrovirology, Department of Pediatrics, Texas Children's Hospital and Baylor College of Medicine, Houston, TX
| | - James R Lupski
- Department of Molecular and Human Genetics, Human Genome Sequencing Center, Texas Children's Hospital and Baylor College of Medicine, Houston, TX
- Department of Pediatrics, Texas Children's Hospital and Baylor College of Medicine, Houston, TX
| | - Enrica Marchi
- Division of Hematology-Oncology, Department of Medicine, NCI Designated Cancer Center, University of Virginia, Charlottesville, VA
| | - Ran Reshef
- Blood and Marrow Transplantation and Cell Therapy Program, Columbia University Irving Medical Center, New York, NY
| | - Bachir Alobeid
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY
| | - Emily M Mace
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
| | - Jordan S Orange
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
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2
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Ghiselli S, Parmeggiani G, Zambonini G, Cuda D. Hearing Loss in Baraitser-Winter Syndrome: Case Reports and Review of the Literature. J Clin Med 2024; 13:1500. [PMID: 38592426 PMCID: PMC10935159 DOI: 10.3390/jcm13051500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/01/2024] [Accepted: 03/02/2024] [Indexed: 04/10/2024] Open
Abstract
Background: Baraitser-Winter Syndrome (BRWS) is a rare autosomal dominant condition associated with hearing loss (HL). In the literature, two types of this condition are reported, Baraitser-Winter type 1 (BRWS1) and type 2 (BRWS2) produced by specific pathogenetic variants of two different genes, ACTB for BRWS1 and ACTG1 for BRWS2. In addition to syndromic BRWS2, some pathogenic variants in ACTG1 are associated also to another pathologic entity, the "Autosomal dominant non-syndromic hearing loss 20/26". In these syndromes, typical craniofacial features, sensory impairment (vision and hearing) and intellectual disabilities are frequently present. Heart anomalies, renal and gastrointestinal involvement and seizure are also common. Wide inter- and intra-familial variety in the phenotypic spectrum is reported. Some phenotypic aspects of these syndromes are not yet fully described, such as the degree and progression of HL, and better knowledge of them could be useful for correct follow-up and treatment. Methods and Results: In this study, we report two cases of children with HL and diagnosis of BRWS and a review of the current literature on HL in these syndromes.
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Affiliation(s)
- Sara Ghiselli
- Department of Otorhinolaryngology, AUSL Piacenza, 29121 Piacenza, Italy; (G.Z.); (D.C.)
| | | | - Giulia Zambonini
- Department of Otorhinolaryngology, AUSL Piacenza, 29121 Piacenza, Italy; (G.Z.); (D.C.)
| | - Domenico Cuda
- Department of Otorhinolaryngology, AUSL Piacenza, 29121 Piacenza, Italy; (G.Z.); (D.C.)
- Department of Medicine and Surgery, University of Parma, 43121 Parma, Italy
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3
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Binder S, Ramachandran H, Hildebrandt B, Dobner J, Rossi A. Prime-Editing of human ACTB in induced pluripotent stem cells to model human ACTB Loss-of-Function diseases and compensatory mechanisms. Stem Cell Res 2024; 75:103304. [PMID: 38217996 DOI: 10.1016/j.scr.2024.103304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/18/2023] [Accepted: 01/02/2024] [Indexed: 01/15/2024] Open
Abstract
Beta-actin (ACTB) heterozygous loss-of-function mutations are associated with pleiotropic developmental disorders entailing intellectual disability and frequent organ malformations in affected individuals. We generated two CRISPR/Cas9 prime-edited human induced pluripotent stem cell (iPSC) lines, IUFi004-A-1 and IUFi004-A-2, carrying a heterozygous missense mutation in exon 4 of ACTB. Mutant iPSCs exhibited normal cell morphology and genomic integrity, maintained expression of pluripotency markers, and differentiated into the three primary germ layers. The mutants offer a valuable platform for examining the molecular and functional consequences of ACTB haploinsufficiency, developing effective treatments, and exploring mechanisms underlying phenotypic variability and genetic compensation observed in monogenic diseases.
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Affiliation(s)
- Stephanie Binder
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | | | - Barbara Hildebrandt
- Institute of Human Genetics, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Jochen Dobner
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Andrea Rossi
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany.
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4
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Park J, Bird JE. The actin cytoskeleton in hair bundle development and hearing loss. Hear Res 2023; 436:108817. [PMID: 37300948 PMCID: PMC10408727 DOI: 10.1016/j.heares.2023.108817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/18/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
Inner ear hair cells assemble mechanosensitive hair bundles on their apical surface that transduce sounds and accelerations. Each hair bundle is comprised of ∼ 100 individual stereocilia that are arranged into rows of increasing height and width; their specific and precise architecture being necessary for mechanoelectrical transduction (MET). The actin cytoskeleton is fundamental to establishing this architecture, not only by forming the structural scaffold shaping each stereocilium, but also by composing rootlets and the cuticular plate that together provide a stable foundation supporting each stereocilium. In concert with the actin cytoskeleton, a large assortment of actin-binding proteins (ABPs) function to cross-link actin filaments into specific topologies, as well as control actin filament growth, severing, and capping. These processes are individually critical for sensory transduction and are all disrupted in hereditary forms of human hearing loss. In this review, we provide an overview of actin-based structures in the hair bundle and the molecules contributing to their assembly and functional properties. We also highlight recent advances in mechanisms driving stereocilia elongation and how these processes are tuned by MET.
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Affiliation(s)
- Jinho Park
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States.
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5
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Graziani L, Cinnirella G, Ferradini V, Conte C, Bascio FL, Bengala M, Sangiuolo F, Novelli G. A likely pathogenic ACTG1 variant in a child showing partial phenotypic overlap with Baraitser-Winter syndrome. Am J Med Genet A 2023; 191:1565-1569. [PMID: 36810952 DOI: 10.1002/ajmg.a.63157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/16/2022] [Accepted: 02/08/2023] [Indexed: 02/23/2023]
Abstract
Baraitser-Winter syndrome (BRWS) is a rare autosomal dominant disease (AD) caused by heterozygous variants in ACTB (BRWS1) or ACTG1 (BRWS2) genes. BRWS features developmental delay/intellectual disability of variable degree and craniofacial dysmorphisms. Brain abnormalities (especially pachygyria), microcephaly, epilepsy, as well as hearing impairment, cardiovascular and genitourinary abnormalities may be present. We report on a 4-year-old female, who was addressed to our institution because of psychomotor delay associated with microcephaly and dysmorphic features, short stature, mild bilateral sensorineural hearing loss, mild cardiac septal hypertrophy, and abdominal swelling. Clinical exome sequencing detected a c.617G>A p.(Arg206Gln) de novo variant in ACTG1 gene. Such variant has been previously reported in association with a form of AD nonsyndromic sensorineural progressive hearing loss and we classified it as likely pathogenic according to ACMG/AMP criteria, despite our patient's phenotype only partially overlapped BWRS2. Our finding supports the extreme variability of the ACTG1-related disorders, ranging from classical BRWS2 to nuanced clinical expressions not fitting the original description, and occasionally featuring previously undescribed clinical findings.
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Affiliation(s)
- Ludovico Graziani
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Giacomo Cinnirella
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Valentina Ferradini
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Chiara Conte
- Tor Vergata University Hospital, Medical Genetics Unit, Rome, Italy
| | - Federica Lo Bascio
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Mario Bengala
- Tor Vergata University Hospital, Medical Genetics Unit, Rome, Italy
| | - Federica Sangiuolo
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy.,Tor Vergata University Hospital, Medical Genetics Unit, Rome, Italy
| | - Giuseppe Novelli
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy.,Tor Vergata University Hospital, Medical Genetics Unit, Rome, Italy
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6
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Rajan S, Terman JR, Reisler E. MICAL-mediated oxidation of actin and its effects on cytoskeletal and cellular dynamics. Front Cell Dev Biol 2023; 11:1124202. [PMID: 36875759 PMCID: PMC9982024 DOI: 10.3389/fcell.2023.1124202] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/02/2023] [Indexed: 02/19/2023] Open
Abstract
Actin and its dynamic structural remodelings are involved in multiple cellular functions, including maintaining cell shape and integrity, cytokinesis, motility, navigation, and muscle contraction. Many actin-binding proteins regulate the cytoskeleton to facilitate these functions. Recently, actin's post-translational modifications (PTMs) and their importance to actin functions have gained increasing recognition. The MICAL family of proteins has emerged as important actin regulatory oxidation-reduction (Redox) enzymes, influencing actin's properties both in vitro and in vivo. MICALs specifically bind to actin filaments and selectively oxidize actin's methionine residues 44 and 47, which perturbs filaments' structure and leads to their disassembly. This review provides an overview of the MICALs and the impact of MICAL-mediated oxidation on actin's properties, including its assembly and disassembly, effects on other actin-binding proteins, and on cells and tissue systems.
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Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jonathan R. Terman
- Departments of Neuroscience and Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
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7
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Nie K, Huang J, Liu L, Lv H, Chen D, Fan W. Identification of a De Novo Heterozygous Missense ACTB Variant in Baraitser–Winter Cerebrofrontofacial Syndrome. Front Genet 2022; 13:828120. [PMID: 35401677 PMCID: PMC8989421 DOI: 10.3389/fgene.2022.828120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/23/2022] [Indexed: 11/21/2022] Open
Abstract
Baraitser–Winter cerebrofrontofacial syndrome (BWCFF, OMIM: 243310) is a rare autosomal-dominant developmental disorder associated with variants in the genes ACTB or ACTG1. It is characterized by brain malformations, a distinctive facial appearance, ocular coloboma, and intellectual disability. However, the phenotypes of BWCFF are heterogenous, and its molecular pathogenesis has not been fully elucidated. In the present study, we conducted detailed clinical examinations on a Chinese patient with BWCFF and found novel ocular manifestations including pseudoduplication of the optic disc and nystagmus. Targeted gene panel sequencing and Sanger sequencing identified a de novo heterozygous missense c.478A > G (p.Thr160Ala) variant in ACTB. The mRNA and protein expression of ACTB was assessed by quantitative reverse transcription PCR and Western blots. Furthermore, the functional effects of the pathogenic variant were analyzed by protein structure analysis, which indicated that the variant may affect the active site for ATP hydrolysis by the actin ATPase, resulting in abnormal filamentous actin organization in peripheral blood mononuclear cells. This discovery extends the ACTB variant spectrum, which will improve genetic counseling and diagnosis, and may contribute to understanding the pathogenic mechanisms of actin-related diseases.
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Affiliation(s)
- Kailai Nie
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
- Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Junting Huang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Longqian Liu
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Hongbin Lv
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Danian Chen
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
- Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
- *Correspondence: Wei Fan, ; Danian Chen,
| | - Wei Fan
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
- *Correspondence: Wei Fan, ; Danian Chen,
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8
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Sibbin K, Yap P, Nyaga D, Heller R, Evans S, Strachan K, Alburaiky S, Nguyen HMA, Hermann-Le Denmat S, Ganley ARD, O'Sullivan JM, Bloomfield FH. A de novo ACTB gene pathogenic variant in identical twins with phenotypic variation for hydrops and jejunal atresia. Am J Med Genet A 2021; 188:1299-1306. [PMID: 34970864 PMCID: PMC9302691 DOI: 10.1002/ajmg.a.62631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 11/11/2021] [Accepted: 12/11/2021] [Indexed: 11/05/2022]
Abstract
The beta-actin gene (ACTB) encodes a ubiquitous cytoskeletal protein, essential for embryonic development in humans. De novo heterozygous missense variants in the ACTB are implicated in causing Baraitser-Winter cerebrofrontofacial syndrome (BWCFFS; MIM#243310). ACTB pathogenic variants are rarely associated with intestinal malformations. We report on a rare case of monozygotic twins presenting with proximal small bowel atresia and hydrops in one, and apple-peel bowel atresia and laryngeal dysgenesis in the other. The twin with hydrops could not be resuscitated. Intensive and surgical care was provided to the surviving twin. Rapid trio genome sequencing identified a de novo missense variant in ACTB (NM_00101.3:c.1043C>T; p.(Ser348Leu)) that guided the care plan. The identical variant subsequently was identified in the demised twin. To characterize the functional effect, the variant was recreated as a pseudoheterozygote in a haploid wild-type S. cerevisiae strain. There was an obvious growth defect of the yACT1S348L/WT pseudoheterozygote compared to a yACT1WT/WT strain when grown at 22°C but not when grown at 30°C, consistent with the yACT1 S348L variant having a functional defect that is dominant over the wild-type allele. The functional results provide supporting evidence that the Ser348Leu variant is likely to be a pathogenic variant, including being associated with intestinal malformations in BWCFFS, and can demonstrate variable expressivity within monozygotic twins.
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Affiliation(s)
- Kristina Sibbin
- Starship Child Health, Auckland City Hospital, Auckland, New Zealand
| | - Patrick Yap
- Starship Child Health, Auckland City Hospital, Auckland, New Zealand
| | - Denis Nyaga
- Liggins Institute, The University of Auckland, Auckland, New Zealand
| | - Raoul Heller
- Starship Child Health, Auckland City Hospital, Auckland, New Zealand
| | - Stephen Evans
- Starship Child Health, Auckland City Hospital, Auckland, New Zealand
| | - Kate Strachan
- Starship Child Health, Auckland City Hospital, Auckland, New Zealand
| | - Salam Alburaiky
- Starship Child Health, Auckland City Hospital, Auckland, New Zealand
| | - Han M Alex Nguyen
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | | | - Austen R D Ganley
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Justin M O'Sullivan
- Liggins Institute, The University of Auckland, Auckland, New Zealand.,The Maurice Wilkins Centre, The University of Auckland, Auckland, New Zealand.,Australian Parkinsons Mission, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,Brain Research New Zealand, The University of Auckland, Auckland, New Zealand.,MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
| | - Frank H Bloomfield
- Starship Child Health, Auckland City Hospital, Auckland, New Zealand.,Liggins Institute, The University of Auckland, Auckland, New Zealand
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9
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Wu P, Ma J, Zhang T, Ma D. Advances in the genetics of congenital ptosis. Ophthalmic Res 2021; 65:131-139. [PMID: 34969027 DOI: 10.1159/000521575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 12/09/2021] [Indexed: 11/19/2022]
Abstract
Congenital ptosis, a birth defects presents at birth or by 1 year of age, is characterized by the drooping of the upper eyelid. either in isolation (non-syndromic) or with many different systemic disorders (syndromic). The estimated prevalence of ptosis (congenital & acquired) ranges from 0.79 to 1.99 per 10,000 people in different populations, and it is more prevalent in males. The underlying pathogenesis of congenital ptosis are myogenic and neurogenic, related to the development of muscles and nerves. Although most cases are sporadic, there are familial transmission characteristics, including autosomal dominant, recessive mode and X-linkage inheritance patterns. Moreover, some forms are due to chromosomal aberrations and mutations and deletions in mitochondrial DNA. Genes involved in simple congenital ptosis are ZFHX4 and COL25A1. The clinical aspects of various syndromes involving congenital ptosis are partly caused by single gene mutations. However, the pathogenesis of congenital ptosis is not fully understood. We review the reported epidemiology, genetics and clinical features of congenital ptosis and associated syndromes here.
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Affiliation(s)
- Peixuan Wu
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China,
| | - Jing Ma
- ENT Institute, Eye & ENT Hospital, Fudan University, Shanghai, China
- Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai, China
| | - Tianyu Zhang
- ENT Institute, Eye & ENT Hospital, Fudan University, Shanghai, China
- Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Duan Ma
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
- Research Center for Birth Defects, Children's Hospital, Fudan University, Shanghai, China
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10
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Miyoshi T, Belyantseva IA, Kitajiri SI, Miyajima H, Nishio SY, Usami SI, Kim BJ, Choi BY, Omori K, Shroff H, Friedman TB. Human deafness-associated variants alter the dynamics of key molecules in hair cell stereocilia F-actin cores. Hum Genet 2021; 141:363-382. [PMID: 34232383 DOI: 10.1007/s00439-021-02304-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/15/2021] [Indexed: 12/16/2022]
Abstract
Stereocilia protrude up to 100 µm from the apical surface of vertebrate inner ear hair cells and are packed with cross-linked filamentous actin (F-actin). They function as mechanical switches to convert sound vibration into electrochemical neuronal signals transmitted to the brain. Several genes encode molecular components of stereocilia including actin monomers, actin regulatory and bundling proteins, motor proteins and the proteins of the mechanotransduction complex. A stereocilium F-actin core is a dynamic system, which is continuously being remodeled while maintaining an outwardly stable architecture under the regulation of F-actin barbed-end cappers, severing proteins and crosslinkers. The F-actin cores of stereocilia also provide a pathway for motor proteins to transport cargos including components of tip-link densities, scaffolding proteins and actin regulatory proteins. Deficiencies and mutations of stereocilia components that disturb this "dynamic equilibrium" in stereocilia can induce morphological changes and disrupt mechanotransduction causing sensorineural hearing loss, best studied in mouse and zebrafish models. Currently, at least 23 genes, associated with human syndromic and nonsyndromic hearing loss, encode proteins involved in the development and maintenance of stereocilia F-actin cores. However, it is challenging to predict how variants associated with sensorineural hearing loss segregating in families affect protein function. Here, we review the functions of several molecular components of stereocilia F-actin cores and provide new data from our experimental approach to directly evaluate the pathogenicity and functional impact of reported and novel variants of DIAPH1 in autosomal-dominant DFNA1 hearing loss using single-molecule fluorescence microscopy.
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Affiliation(s)
- Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA. .,Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
| | - Shin-Ichiro Kitajiri
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Hiroki Miyajima
- Department of Otolaryngology, Shinshu University School of Medicine, Matsumoto, 390-8621, Japan.,Department of Otolaryngology, Aizawa Hospital, Matsumoto, 390-8510, Japan
| | - Shin-Ya Nishio
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Shin-Ichi Usami
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Bong Jik Kim
- Department of Otolaryngology-Head and Neck Surgery, Chungnam National University College of Medicine, Chungnam National University Sejong Hospital, Sejong, 30099, South Korea.,Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, South Korea
| | - Byung Yoon Choi
- Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Seongnam, 13620, South Korea
| | - Koichi Omori
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Hari Shroff
- Laboratory of High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
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11
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Zhang K, Cox E, Strom S, Xu ZL, Disilvestro A, Usrey K. Prenatal presentation and diagnosis of Baraitser-Winter syndrome using exome sequencing. Am J Med Genet A 2020; 182:2124-2128. [PMID: 32588558 DOI: 10.1002/ajmg.a.61725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 05/08/2020] [Accepted: 05/17/2020] [Indexed: 11/08/2022]
Abstract
Baraitser-Winter cerebrofrontofacial syndrome (BWCFF) is a rare autosomal dominant developmental disorder associated with missense mutations in the genes ACTB or ACTG1. The classic presentation of BWCFF is discerned by the combination of unique craniofacial characteristics including ocular coloboma, intellectual disability, and hypertelorism. Congenital contractures and organ malformations are often present, including structural defects in the brain, heart, renal, and musculoskeletal system. However, there is limited documentation regarding its prenatal presentation that may encourage healthcare providers to be aware of this disorder when presented throughout pregnancy. Herein we describe a case of a pregnancy with large cystic hygroma and omphalocele. Whole exome sequencing (WES) was performed and a de novo, heterozygous, likely pathogenic mutation in ACTB was detected, c.1004G>A (p.Arg335His), conferring a diagnosis of BWCFF.
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Affiliation(s)
- Kermit Zhang
- Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA
| | - Eleina Cox
- Fulgent Genetics, Temple City, California, USA
| | | | | | - Alexis Disilvestro
- Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA.,Maternal Fetal Medicine, Carilion Clinic, Roanoke, Virginia, USA
| | - Kelly Usrey
- Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA.,Maternal Fetal Medicine, Carilion Clinic, Roanoke, Virginia, USA
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12
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Hampshire K, Martin PM, Carlston C, Slavotinek A. Baraitser-Winter cerebrofrontofacial syndrome: Report of two adult siblings. Am J Med Genet A 2020; 182:1923-1932. [PMID: 32506774 DOI: 10.1002/ajmg.a.61637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/21/2020] [Accepted: 04/25/2020] [Indexed: 11/07/2022]
Abstract
Baraitser-Winter cerebrofrontofacial syndrome (BWCS) is a rare, autosomal dominant condition that is characterized by intellectual disability, distinctive craniofacial features, structural brain abnormalities, seizures, microcephaly, hearing loss, and ocular colobomas. The first three cases were described in 1988 by Baraitser and Winter and included two siblings and an unrelated third patient. Subsequently, causative missense variants in the ACTB and ACTG1 genes were identified, with de novo occurrence in patients with the condition. Herein, we describe two adult siblings who were born to unaffected parents and who were diagnosed with BWCS in their fourth and sixth decade of life following exome sequencing performed for intellectual disability. We review the literature reports of adult patients with BWCS to document the clinical features and phenotypic variability that can occur later in life. This is the first molecularly confirmed report of germline mosaicism in BWCS and one of only a few reports to describe two BWCS patients belonging to the same family.
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Affiliation(s)
- Karly Hampshire
- Division of Medical Genetics, Department of Pediatrics, University of California San Francisco, San Francisco, California, USA
| | - Pierre-Marie Martin
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Colleen Carlston
- Division of Medical Genetics, Department of Pediatrics, University of California San Francisco, San Francisco, California, USA
| | - Anne Slavotinek
- Division of Medical Genetics, Department of Pediatrics, University of California San Francisco, San Francisco, California, USA
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Parker F, Baboolal TG, Peckham M. Actin Mutations and Their Role in Disease. Int J Mol Sci 2020; 21:ijms21093371. [PMID: 32397632 PMCID: PMC7247010 DOI: 10.3390/ijms21093371] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/15/2022] Open
Abstract
Actin is a widely expressed protein found in almost all eukaryotic cells. In humans, there are six different genes, which encode specific actin isoforms. Disease-causing mutations have been described for each of these, most of which are missense. Analysis of the position of the resulting mutated residues in the protein reveals mutational hotspots. Many of these occur in regions important for actin polymerization. We briefly discuss the challenges in characterizing the effects of these actin mutations, with a focus on cardiac actin mutations.
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Atzmony L, Ugwu N, Zaki TD, Antaya RJ, Choate KA. Post-zygotic ACTB mutations underlie congenital smooth muscle hamartomas. J Cutan Pathol 2020; 47:681-685. [PMID: 32170967 DOI: 10.1111/cup.13683] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 02/25/2020] [Accepted: 03/10/2020] [Indexed: 01/20/2023]
Abstract
BACKGROUND Congenital smooth muscle hamartomas (CSMHs) are benign lesions that share clinical and histopathological features with Becker nevus, a mosaic disorder associated with post-zygotic ACTB mutations. Given the clinical and histopathological overlap between CSMH and Becker nevus, we hypothesized that post-zygotic mutations in ACTB may underlie CSMH. METHODS Direct sequencing of ACTB gene in affected and unaffected tissue isolated from one case of hemihypertrichosis and hemihypertrophy corresponding to giant segmental CSMH and hemihypertrophy. This was followed by direct sequencing with and without enrichment assay for hotspot ACTB mutations in affected tissue from 12 samples of isolated CSMH from unrelated individuals. RESULTS In total we identified somatic missense ACTB mutations in 9 out of 13 CSMHs (69%). Mutations were either novel or previously reported in Becker nevi and Becker nevus syndrome. CONCLUSIONS CSMHs result from post-zygotic ACTB mutations. This study proves that CSMHs and Becker nevi are nosologically related, and expand the phenotypic spectrum of ACTB mutations.
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Affiliation(s)
- Lihi Atzmony
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Nelson Ugwu
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Theodore D Zaki
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Richard J Antaya
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Keith A Choate
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
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Chacon-Camacho OF, Barragán-Arévalo T, Villarroel CE, Almanza-Monterrubio M, Zenteno JC. Previously undescribed phenotypic findings and novel ACTG1 gene pathogenic variants in Baraitser-Winter cerebrofrontofacial syndrome. Eur J Med Genet 2020; 63:103877. [PMID: 32028042 DOI: 10.1016/j.ejmg.2020.103877] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 11/11/2019] [Accepted: 02/01/2020] [Indexed: 10/25/2022]
Abstract
Baraitser-Winter cerebrofrontofacial syndrome is an autosomal dominant disease characterized by multiple congenital abnormalities and intellectual disability, which is caused by mutations in either the ACTB or ACTG1 genes. In this report, we described novel phenotypic findings in two Mexican patients with the disorder in whom two novel ACTG1 mutations (c.176A > G, p.Gln59Arg; and c.608C > T, p.Thr203Met) were identified.
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Affiliation(s)
- Oscar F Chacon-Camacho
- Department of Genetics, Institute of Ophthalmology "Conde de Valenciana", Mexico City, Mexico; Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla, Estado de México, Mexico
| | | | - Camilo E Villarroel
- Department of Human Genetics, National Institute of Pediatrics, Mexico City, Mexico
| | - Mónica Almanza-Monterrubio
- Department of Human Genetics, National Institute of Pediatrics, Mexico City, Mexico; Department of Strabismus, Institute of Ophthalmology "Conde de Valenciana", Mexico City, Mexico
| | - Juan Carlos Zenteno
- Department of Genetics, Institute of Ophthalmology "Conde de Valenciana", Mexico City, Mexico; Department of Biochemistry, Faculty of Medicine, National Autonomous University of Mexico, Mexico City, Mexico.
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16
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Lupo PJ, Mitchell LE, Jenkins MM. Genome-wide association studies of structural birth defects: A review and commentary. Birth Defects Res 2019; 111:1329-1342. [PMID: 31654503 DOI: 10.1002/bdr2.1606] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 09/21/2019] [Accepted: 10/02/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND While there is strong evidence that genetic risk factors play an important role in the etiologies of structural birth defects, compared to other diseases, there have been relatively few genome-wide association studies (GWAS) of these conditions. We reviewed the current landscape of GWAS conducted for birth defects, noting novel insights, and future directions. METHODS This article reviews the literature with regard to GWAS of structural birth defects. Key defects included in this review include oral clefts, congenital heart defects (CHDs), biliary atresia, pyloric stenosis, hypospadias, craniosynostosis, and clubfoot. Additionally, other issues related to GWAS are considered, including the assessment of polygenic risk scores and issues related to genetic ancestry, as well as utilizing genome-wide single nucleotide polymorphism array data to evaluate gene-environment interactions and Mendelian randomization. RESULTS For some birth defects, including oral clefts and CHDs, several novel susceptibility loci have been identified and replicated through GWAS, including 8q24 for oral clefts, DGKK for hypospadias, and 4p16 for CHDs. Relatively common birth defects for which there are currently no published GWAS include neural tube defects, anotia/microtia, anophthalmia/microphthalmia, gastroschisis, and omphalocele. CONCLUSIONS Overall, GWAS have been successful in identifying several novel susceptibility genes and genomic regions for structural birth defects. These findings have provided new insights into the etiologies of these phenotypes. However, GWAS have been underutilized for understanding the genetic etiologies of several birth defects.
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Affiliation(s)
- Philip J Lupo
- Department of Pediatrics, Section of Hematology-Oncology, Baylor College of Medicine, Houston, Texas
| | - Laura E Mitchell
- Department of Epidemiology, Human Genetics and Environmental Sciences, UTHealth School of Public Health, Houston, Texas
| | - Mary M Jenkins
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia
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Sapir T, Barakat TS, Paredes MF, Lerman-Sagie T, Aronica E, Klonowski W, Nguyen L, Ben Zeev B, Bahi-Buisson N, Leventer R, Rachmian N, Reiner O. Building Bridges Between the Clinic and the Laboratory: A Meeting Review - Brain Malformations: A Roadmap for Future Research. Front Cell Neurosci 2019; 13:434. [PMID: 31611776 PMCID: PMC6776596 DOI: 10.3389/fncel.2019.00434] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 09/09/2019] [Indexed: 01/08/2023] Open
Abstract
In the middle of March 2019, a group of scientists and clinicians (as well as those who wear both hats) gathered in the green campus of the Weizmann Institute of Science to share recent scientific findings, to establish collaborations, and to discuss future directions for better diagnosis, etiology modeling and treatment of brain malformations. One hundred fifty scientists from twenty-two countries took part in this meeting. Thirty-eight talks were presented and as many as twenty-five posters were displayed. This review is aimed at presenting some of the highlights that the audience was exposed to during the three-day meeting.
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Affiliation(s)
- Tamar Sapir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Mercedes F. Paredes
- Department of Neurology and Neuroscience Graduate Division, University of California, San Francisco, San Francisco, CA, United States
| | - Tally Lerman-Sagie
- Pediatric Neurology Unit, Fetal Neurology Clinic, Wolfson Medical Center, Holon and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eleonora Aronica
- Department of (Neuro-)Pathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Zwolle, Netherlands
| | - Wlodzimierz Klonowski
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Laurent Nguyen
- GIGA-Stem Cells, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), C.H.U. Sart Tilman, University of Liège, Liège, Belgium
| | - Bruria Ben Zeev
- Sackler School of Medicine and Pediatric Neurology Unit, Edmond and Lilly Safra Pediatric Hospital, Tel Aviv University, Tel Aviv, Israel
| | - Nadia Bahi-Buisson
- INSERM UMR 1163, Imagine Institute, Paris Descartes University, Paris, France
- Necker Enfants Malades Hospital, Pediatrric Neurology APHP, Paris, France
| | - Richard Leventer
- Department of Neurology, Royal Children’s Hospital, Murdoch Children’s Research Institute, University of Melbourne, Parkville, VIC, Australia
- Department of Pediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Noa Rachmian
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Orly Reiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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Vontell R, Supramaniam VG, Davidson A, Thornton C, Marnerides A, Holder-Espinasse M, Lillis S, Yau S, Jansson M, Hagberg HE, Rutherford MA. Post-mortem Characterisation of a Case With an ACTG1 Variant, Agenesis of the Corpus Callosum and Neuronal Heterotopia. Front Physiol 2019; 10:623. [PMID: 31231230 PMCID: PMC6558385 DOI: 10.3389/fphys.2019.00623] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 05/02/2019] [Indexed: 01/02/2023] Open
Abstract
Cytoplasmic Actin Gamma 1 (ACTG1) gene variant are autosomal dominant and can cause CNS anomalies (Baraitser Winter Malformation Syndrome; BWMS). ACTG1 anomalies in offspring include agenesis of the corpus callosum (ACC) and neuronal heterotopia which are ectopic nodules of nerve cells that failed to migrate appropriately. Subcortical and periventricular neuronal heterotopia have been described previously in association with ACC. In this case report, we investigated a neonatal brain with an ACTG1 gene variant and a phenotype of ACC, and neuronal heterotopia (ACC-H) which was diagnosed on antenatal MR imaging and was consistent with band heterotopia seen on post-mortem brain images. Histologically clusters of neurons were seen in both the subcortical and periventricular white matter (PVWM) brain region that coincided with impaired abnormalities in glial formation. Immunohistochemistry was performed on paraffin-embedded brain tissue blocks from this case with ACTG1 variant and an age-matched control. Using tissue sections from the frontal lobe, we examined the distribution of neuronal cells (HuC/HuD, calretinin, and parvalbumin), growth cone (drebrin), and synaptic proteins (synaptophysin and SNAP-25). Additionally, we investigated how the ACTG1 variant altered astroglia (nestin, GFAP, vimentin); oligodendroglia (OLIG2) and microglia (Iba-1) in the corpus callosum, cortex, caudal ganglionic eminence, and PVWM. As predicted in the ACTG1 variant case, we found a lack of midline radial glia and glutamatergic fibers. We also found disturbances in the cortical region, in glial cells and a lack of extracellular matrix components in the ACTG1 variant. The caudal ganglionic eminence and the PVWM regions in the ACTG1 variant lacked several cellular components that were identified in a control case. Within the neuronal heterotopia, we found evidence of glutamatergic and GABAergic neurons with apparent synaptic connections. The data presented from this case study with BWMS with variants in the ACTG1 gene provides insight as to the composition of neuronal heterotopia, and how disturbances of important migratory signals may dramatically affect ongoing brain development.
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Affiliation(s)
- Regina Vontell
- Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King’s College London, St Thomas’ Hospital, London, United Kingdom
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Veena G. Supramaniam
- Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King’s College London, St Thomas’ Hospital, London, United Kingdom
| | - Alice Davidson
- Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King’s College London, St Thomas’ Hospital, London, United Kingdom
| | - Claire Thornton
- Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King’s College London, St Thomas’ Hospital, London, United Kingdom
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Andreas Marnerides
- Department of Cellular Pathology, Guy’s and St Thomas’ NHS Foundation Trust, St Thomas’ Hospital, London, United Kingdom
| | - Muriel Holder-Espinasse
- Department of Clinical Genetics, Guy’s and St Thomas’ NHS Foundation Trust, Guy’s Hospital, London, United Kingdom
| | - Suzanne Lillis
- Department of Clinical Genetics, Guy’s and St Thomas’ NHS Foundation Trust, Guy’s Hospital, London, United Kingdom
| | - Shu Yau
- Department of Clinical Genetics, Guy’s and St Thomas’ NHS Foundation Trust, Guy’s Hospital, London, United Kingdom
| | - Mattias Jansson
- Department of Clinical Genetics, Guy’s and St Thomas’ NHS Foundation Trust, Guy’s Hospital, London, United Kingdom
| | - Henrik E. Hagberg
- Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King’s College London, St Thomas’ Hospital, London, United Kingdom
- Perinatal Center, Department of Physiology and Neuroscience – Department of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Mary A. Rutherford
- Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King’s College London, St Thomas’ Hospital, London, United Kingdom
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Abstract
PURPOSE Baraitser-Winter cerebrofrontofacial syndrome (BWCFF) is a rare autosomal dominant genetic disorder involving multiple organ systems and primarily characterized by structural brain abnormalities and a distinctive facial appearance. METHODS To study the clinical characteristics, gene types and seizures of BWCFF. The natural history, clinical data and peripheral blood sample were collected in the child and his patients. To screen the β-actin gene (ACTB) of a newly diagnosed child, hoping to find the gene mutation. RESULTS The child had left ptosis, ocular hypertelorism, arched eyebrows, only 30% of the left ear hearing, a slight hypotonia, normal muscle strength, walking instability. The seizures were difficult to control with antiepileptic drugs and presented some degree of psychomotor development delay. Genetic screening showed De Novo in ACTB gene (c.484A> G, p.Thr162Ala). Parents did not detect related gene mutations. CONCLUSIONS Patients with typical facial features and cerebral cortical malformations associated with refractory epilepsy should be highly suspected BWCFF. Patients are advised to carry out genetic screening to confirm the diagnosis.
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Affiliation(s)
- Ying Sun
- a Department of Neurology , Affiliated Hospital of Jining Medical University , Jining City , Shandong Province , China
| | - Xuehua Shen
- a Department of Neurology , Affiliated Hospital of Jining Medical University , Jining City , Shandong Province , China
| | - Qiubo Li
- b Department of Pediatric , Affiliated Hospital of Jining Medical University , Jining City , Shandong Province , China
| | - Qingxia Kong
- a Department of Neurology , Affiliated Hospital of Jining Medical University , Jining City , Shandong Province , China
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20
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Sandestig A, Green A, Jonasson J, Vogt H, Wahlström J, Pepler A, Ellnebo K, Biskup S, Stefanova M. Could Dissimilar Phenotypic Effects of ACTB Missense Mutations Reflect the Actin Conformational Change? Two Novel Mutations and Literature Review. Mol Syndromol 2018; 9:259-265. [PMID: 30733661 DOI: 10.1159/000492267] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2018] [Indexed: 02/03/2023] Open
Abstract
The beta-actin gene encodes 1 of 6 different actin proteins. De novo heterozygous missense mutations in ACTB have been identified in patients with Baraitser-Winter syndrome (BRWS) and also in patients with developmental disorders other than BRWS, such as deafness, dystonia, and neutrophil dysfunction. We describe 2 different novel de novo missense ACTB mutations, c.208C>G (p.Pro70Ala) and c.511C>T (p.Leu171Phe), found by trio exome sequencing analysis of 2 unrelated patients: an 8-year-old boy with a suspected BRWS and a 4-year-old girl with unclear developmental disorder. The mutated residue in the first case is situated in the actin H-loop, which is involved in actin polymerization. The mutated residue in the second case (p.Leu171Phe) is found at the actin barbed end in the W-loop, important for binding to profilin and other actin-binding molecules. While the boy presented with a typical BRWS facial appearance, the girl showed facial features not recognizable as a BRWS gestalt as well as ventricular arrhythmia, cleft palate, thrombocytopenia, and gray matter heterotopia. We reviewed previously published ACTB missense mutations and ascertained that a number of them do not cause typical BRWS. By comparing clinical and molecular data, we speculate that the phenotypic differences found in ACTB missense mutation carriers might supposedly be dependent on the conformational change of ACTB.
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Affiliation(s)
- Anna Sandestig
- Department of Clinical Genetics, Linköping University Hospital, Linköping, Sweden
| | - Anna Green
- Department of Clinical Genetics, Linköping University Hospital, Linköping, Sweden
| | - Jon Jonasson
- Department of Clinical Genetics, Linköping University Hospital, Linköping, Sweden
| | - Hartmut Vogt
- Department of Pediatrics, Linköping University Hospital, Linköping, Sweden
| | - Johan Wahlström
- Department of Pediatrics, Linköping University Hospital, Linköping, Sweden
| | | | - Katarina Ellnebo
- Department of Clinical Genetics, Linköping University Hospital, Linköping, Sweden
| | | | - Margarita Stefanova
- Department of Clinical Genetics, Linköping University Hospital, Linköping, Sweden
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Cuvertino S, Stuart HM, Chandler KE, Roberts NA, Armstrong R, Bernardini L, Bhaskar S, Callewaert B, Clayton-Smith J, Davalillo CH, Deshpande C, Devriendt K, Digilio MC, Dixit A, Edwards M, Friedman JM, Gonzalez-Meneses A, Joss S, Kerr B, Lampe AK, Langlois S, Lennon R, Loget P, Ma DY, McGowan R, Des Medt M, O’Sullivan J, Odent S, Parker MJ, Pebrel-Richard C, Petit F, Stark Z, Stockler-Ipsiroglu S, Tinschert S, Vasudevan P, Villa O, White SM, Zahir FR, Woolf AS, Banka S, Banka S. ACTB Loss-of-Function Mutations Result in a Pleiotropic Developmental Disorder. Am J Hum Genet 2017; 101:1021-1033. [PMID: 29220674 PMCID: PMC5812896 DOI: 10.1016/j.ajhg.2017.11.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 11/13/2017] [Indexed: 10/31/2022] Open
Abstract
ACTB encodes β-actin, an abundant cytoskeletal housekeeping protein. In humans, postulated gain-of-function missense mutations cause Baraitser-Winter syndrome (BRWS), characterized by intellectual disability, cortical malformations, coloboma, sensorineural deafness, and typical facial features. To date, the consequences of loss-of-function ACTB mutations have not been proven conclusively. We describe heterozygous ACTB deletions and nonsense and frameshift mutations in 33 individuals with developmental delay, apparent intellectual disability, increased frequency of internal organ malformations (including those of the heart and the renal tract), growth retardation, and a recognizable facial gestalt (interrupted wavy eyebrows, dense eyelashes, wide nose, wide mouth, and a prominent chin) that is distinct from characteristics of individuals with BRWS. Strikingly, this spectrum overlaps with that of several chromatin-remodeling developmental disorders. In wild-type mouse embryos, β-actin expression was prominent in the kidney, heart, and brain. ACTB mRNA expression levels in lymphoblastic lines and fibroblasts derived from affected individuals were decreased in comparison to those in control cells. Fibroblasts derived from an affected individual and ACTB siRNA knockdown in wild-type fibroblasts showed altered cell shape and migration, consistent with known roles of cytoplasmic β-actin. We also demonstrate that ACTB haploinsufficiency leads to reduced cell proliferation, altered expression of cell-cycle genes, and decreased amounts of nuclear, but not cytoplasmic, β-actin. In conclusion, we show that heterozygous loss-of-function ACTB mutations cause a distinct pleiotropic malformation syndrome with intellectual disability. Our biological studies suggest that a critically reduced amount of this protein alters cell shape, migration, proliferation, and gene expression to the detriment of brain, heart, and kidney development.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Siddharth Banka
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, M13 9PL Manchester, UK; Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester University Foundation NHS Trust, Health Innovation Manchester, M13 9WL Manchester, UK.
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