1
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Hernandez RA, Hearn JI, Bhoopalan V, Hamzeh AR, Kwong K, Diamand K, Davies A, Li FJ, Padmanabhan H, Milne R, Ballard F, Spensberger D, Gardiner EE, Miraghazadeh B, Enders A, Cook MC. L-plastin associated syndrome of immune deficiency and hematologic cytopenia. J Allergy Clin Immunol 2024:S0091-6749(24)00458-5. [PMID: 38710235 DOI: 10.1016/j.jaci.2024.05.001] [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: 11/01/2023] [Revised: 04/01/2024] [Accepted: 05/01/2024] [Indexed: 05/08/2024]
Abstract
BACKGROUND LCP1 encodes L-plastin, an actin-bundling protein primarily expressed in hematopoietic cells. In mouse and fish models, LCP1 deficiency has been shown to result in hematologic and immune defects. OBJECTIVE This study aimed to determine the nature of a human inborn error of immunity resulting from a novel genetic variant of LCP1. METHODS We performed genetic, protein, and cellular analysis of PBMCs from a kindred with apparent autosomal dominant immune deficiency. We identified a candidate causal mutation in LCP1, which we evaluated by engineering the orthologous mutation in mice and Jurkat cells. RESULTS A splice-site variant in LCP1 segregated with lymphopenia, neutropenia, and thrombocytopenia. The splicing defect resulted in at least 2 aberrant transcripts, producing an in-frame deletion of 24 nucleotides, and a frameshift deletion of exon 8. Cellular analysis of the kindred revealed a proportionate reduction of T and B cells and a mild expansion of transitional B cells. Similarly, mice carrying the orthologous genetic variant exhibited the same in-frame aberrant transcript, reduced expression Lcp1 and gene dose-dependent leukopenia, mild thrombocytopenia, and lymphopenia, with a significant reduction of T-cell populations. Functional analysis revealed that LCP1c740-1G>A confers a defect in platelet development and function with aberrant spreading on collagen. Immunologic analysis revealed defective actin organization in T cells, reduced migration of PBMCs from patients, splenocytes from mutant mice, and a mutant Jurkat cell line in response to CXCL12; impaired germinal center B-cell expansion after immunization; and reduced cytokinesis during T cell proliferation. CONCLUSIONS We describe a unique human hematopoietic defect affecting neutrophils, lymphocytes, and platelets arising from partial LCP1 deficiency.
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Affiliation(s)
- Raquel A Hernandez
- Division of Immunology and Infectious Diseases, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - James I Hearn
- Division of Genome Sciences and Cancer, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Vijay Bhoopalan
- Division of Genome Sciences and Cancer, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | | | - Kristy Kwong
- Australian Phenomics Facility and John Curtin School of Medical Research, Australian National University, Canberra, Australia; Cambridge Institute of Therapeutic Immunology and Infectious Disease, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Koula Diamand
- Australian Phenomics Facility and John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Ainsley Davies
- Australian Phenomics Facility and John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Fei-Ju Li
- Australian Phenomics Facility and John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Harish Padmanabhan
- Australian Phenomics Facility and John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Rachel Milne
- Australian Phenomics Facility and John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Fiona Ballard
- Division of Immunology and Infectious Diseases, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Dominik Spensberger
- Australian Phenomics Facility and John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Elizabeth E Gardiner
- Division of Genome Sciences and Cancer, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Bahar Miraghazadeh
- Division of Immunology and Infectious Diseases, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Anselm Enders
- Division of Immunology and Infectious Diseases, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Matthew C Cook
- Division of Immunology and Infectious Diseases, John Curtin School of Medical Research, Australian National University, Canberra, Australia; Canberra Clinical Genomics, Canberra, Australia; Cambridge Institute of Therapeutic Immunology and Infectious Disease, Department of Medicine, University of Cambridge, Cambridge, United Kingdom.
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2
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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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3
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Trejo-Reveles V, Owen N, Ching Chan BH, Toms M, Schoenebeck JJ, Moosajee M, Rainger J. Identification of Novel Coloboma Candidate Genes through Conserved Gene Expression Analyses across Four Vertebrate Species. Biomolecules 2023; 13:293. [PMID: 36830662 PMCID: PMC9953556 DOI: 10.3390/biom13020293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/23/2023] [Accepted: 01/28/2023] [Indexed: 02/08/2023] Open
Abstract
Ocular coloboma (OC) is a failure of complete optic fissure closure during embryonic development and presents as a tissue defect along the proximal-distal axis of the ventral eye. It is classed as part of the clinical spectrum of structural eye malformations with microphthalmia and anophthalmia, collectively abbreviated to MAC. Despite deliberate attempts to identify causative variants in MAC, many patients remain without a genetic diagnosis. To reveal potential candidate genes, we utilised transcriptomes experimentally generated from embryonic eye tissues derived from humans, mice, zebrafish, and chicken at stages coincident with optic fissure closure. Our in-silico analyses found 10 genes with optic fissure-specific enriched expression: ALDH1A3, BMPR1B, EMX2, EPHB3, NID1, NTN1, PAX2, SMOC1, TENM3, and VAX1. In situ hybridization revealed that all 10 genes were broadly expressed ventrally in the developing eye but that only PAX2 and NTN1 were expressed in cells at the edges of the optic fissure margin. Of these conserved optic fissure genes, EMX2, NID1, and EPHB3 have not previously been associated with human MAC cases. Targeted genetic manipulation in zebrafish embryos using CRISPR/Cas9 caused the developmental MAC phenotype for emx2 and ephb3. We analysed available whole genome sequencing datasets from MAC patients and identified a range of variants with plausible causality. In combination, our data suggest that expression of genes involved in ventral eye development is conserved across a range of vertebrate species and that EMX2, NID1, and EPHB3 are candidate loci that warrant further functional analysis in the context of MAC and should be considered for sequencing in cohorts of patients with structural eye malformations.
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Affiliation(s)
- Violeta Trejo-Reveles
- Roslin Institute, R(D)SVS, Easter Bush Campus, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Nicholas Owen
- Development, Ageing and Disease, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Ocular Genomics and Therapeutics, The Francis Crick Institute, London NW1 1A, UK
| | - Brian Ho Ching Chan
- Roslin Institute, R(D)SVS, Easter Bush Campus, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Maria Toms
- Development, Ageing and Disease, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Ocular Genomics and Therapeutics, The Francis Crick Institute, London NW1 1A, UK
| | - Jeffrey J. Schoenebeck
- Roslin Institute, R(D)SVS, Easter Bush Campus, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Mariya Moosajee
- Development, Ageing and Disease, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Ocular Genomics and Therapeutics, The Francis Crick Institute, London NW1 1A, UK
- Department of Genetics, Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
| | - Joe Rainger
- Roslin Institute, R(D)SVS, Easter Bush Campus, University of Edinburgh, Edinburgh EH25 9RG, UK
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4
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De Novo ACTG1 Variant Expands the Phenotype and Genotype of Partial Deafness and Baraitser-Winter Syndrome. Int J Mol Sci 2022; 23:ijms23020692. [PMID: 35054877 PMCID: PMC8776155 DOI: 10.3390/ijms23020692] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/02/2022] [Accepted: 01/05/2022] [Indexed: 02/04/2023] Open
Abstract
Actin molecules are fundamental for embryonic structural and functional differentiation; γ-actin is specifically required for the maintenance and function of cytoskeletal structures in the ear, resulting in hearing. Baraitser–Winter Syndrome (B-WS, OMIM #243310, #614583) is a rare, multiple-anomaly genetic disorder caused by mutations in either cytoplasmically expressed actin gene, ACTB (β-actin) or ACTG1 (γ-actin). The resulting actinopathies cause characteristic cerebrofrontofacial and developmental traits, including progressive sensorineural deafness. Both ACTG1-related non-syndromic A20/A26 deafness and B-WS diagnoses are characterized by hypervariable penetrance in phenotype. Here, we identify a 28th patient worldwide carrying a mutated γ-actin ACTG1 allele, with mildly manifested cerebrofrontofacial B-WS traits, hypervariable penetrance of developmental traits and sensorineural hearing loss. This patient also displays brachycephaly and a complete absence of speech faculty, previously unreported for ACTG1-related B-WS or DFNA20/26 deafness, representing phenotypic expansion. The patient’s exome sequence analyses (ES) confirms a de novo ACTG1 variant previously unlinked to the pathology. Additional microarray analysis uncover no further mutational basis for dual molecular diagnosis in our patient. We conclude that γ-actin c.542C > T, p.Ala181Val is a dominant pathogenic variant, associated with mildly manifested facial and cerebral traits typical of B-WS, hypervariable penetrance of developmental traits and sensorineural deafness. We further posit and present argument and evidence suggesting ACTG1-related non-syndromic DFNA20/A26 deafness is a manifestation of undiagnosed ACTG1-related B-WS.
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5
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DFNA20/26 and Other ACTG1-Associated Phenotypes: A Case Report and Review of the Literature. Audiol Res 2021; 11:582-593. [PMID: 34698053 PMCID: PMC8544197 DOI: 10.3390/audiolres11040052] [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: 09/13/2021] [Revised: 10/10/2021] [Accepted: 10/13/2021] [Indexed: 02/08/2023] Open
Abstract
Since the early 2000s, an ever-increasing subset of missense pathogenic variants in the ACTG1 gene has been associated with an autosomal-dominant, progressive, typically post-lingual non-syndromic hearing loss (NSHL) condition designed as DFNA20/26. ACTG1 gene encodes gamma actin, the predominant actin protein in the cytoskeleton of auditory hair cells; its normal expression and function are essential for the stereocilia maintenance. Different gain-of-function pathogenic variants of ACTG1 have been associated with two major phenotypes: DFNA20/26 and Baraitser-Winter syndrome, a multiple congenital anomaly disorder. Here, we report a novel ACTG1 variant [c.625G>A (p. Val209Met)] in an adult patient with moderate-severe NSHL characterized by a downsloping audiogram. The patient, who had a clinical history of slowly progressive NSHL and tinnitus, was referred to our laboratory for the analysis of a large panel of NSHL-associated genes by next generation sequencing. An extensive review of previously reported ACTG1 variants and their associated phenotypes was also performed.
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6
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Cenni C, Mansard L, Blanchet C, Baux D, Vaché C, Baudoin C, Moclyn M, Faugère V, Mondain M, Jeziorski E, Roux AF, Willems M. When Familial Hearing Loss Means Genetic Heterogeneity: A Model Case Report. Diagnostics (Basel) 2021; 11:diagnostics11091636. [PMID: 34573976 PMCID: PMC8465614 DOI: 10.3390/diagnostics11091636] [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: 08/19/2021] [Accepted: 09/04/2021] [Indexed: 11/29/2022] Open
Abstract
We describe a family with both hearing loss (HL) and thrombocytopenia, caused by pathogenic variants in three genes. The proband was a child with neonatal thrombocytopenia, childhood-onset HL, hyper-laxity and severe myopia. The child’s mother (and some of her relatives) presented with moderate thrombocytopenia and adulthood-onset HL. The child’s father (and some of his relatives) presented with adult-onset HL. An HL panel analysis, completed by whole exome sequencing, was performed in this complex family. We identified three pathogenic variants in three different genes: MYH9, MYO7A and ACTG1. The thrombocytopenia in the child and her mother is explained by the MYH9 variant. The post-lingual HL in the paternal branch is explained by the MYO7A variant, absent in the proband, while the congenital HL of the child is explained by a de novo ACTG1 variant. This family, in which HL segregates, illustrates that multiple genetic conditions coexist in individuals and make patient care more complex than expected.
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Affiliation(s)
- Camille Cenni
- Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, CHU Montpellier, Université de Montpellier, 34090 Montpellier, France;
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
| | - Luke Mansard
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
| | - Catherine Blanchet
- Service ORL, CHU Montpellier, Université de Montpellier, 34090 Montpellier, France; (C.B.); (M.M.)
- Centre National de Référence Maladies Rares “Affections Sensorielles Génétiques”, CHU Montpellier, Université de Montpellier, 34090 Montpellier, France
| | - David Baux
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
- INM, Université de Montpellier, INSERM U1298, 34090 Montpellier, France
| | - Christel Vaché
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
- INM, Université de Montpellier, INSERM U1298, 34090 Montpellier, France
| | - Corinne Baudoin
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
| | - Mélodie Moclyn
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
| | - Valérie Faugère
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
| | - Michel Mondain
- Service ORL, CHU Montpellier, Université de Montpellier, 34090 Montpellier, France; (C.B.); (M.M.)
| | - Eric Jeziorski
- Service de Pédiatrie Générale, Infectiologie et Immunologie Clinique, CHU Montpellier, Université de Montpellier, 34090 Montpellier, France;
| | - Anne-Françoise Roux
- Laboratoire de Génétique Moléculaire, CHU Montpellier, Université de Montpellier, 34090 Monpellier, France; (L.M.); (D.B.); (C.V.); (C.B.); (M.M.); (V.F.); (A.-F.R.)
- INM, Université de Montpellier, INSERM U1298, 34090 Montpellier, France
| | - Marjolaine Willems
- Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, CHU Montpellier, Université de Montpellier, 34090 Montpellier, France;
- Correspondence:
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7
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Chan BHC, Moosajee M, Rainger J. Closing the Gap: Mechanisms of Epithelial Fusion During Optic Fissure Closure. Front Cell Dev Biol 2021; 8:620774. [PMID: 33505973 PMCID: PMC7829581 DOI: 10.3389/fcell.2020.620774] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/08/2020] [Indexed: 12/13/2022] Open
Abstract
A key embryonic process that occurs early in ocular development is optic fissure closure (OFC). This fusion process closes the ventral optic fissure and completes the circumferential continuity of the 3-dimensional eye. It is defined by the coming together and fusion of opposing neuroepithelia along the entire proximal-distal axis of the ventral optic cup, involving future neural retina, retinal pigment epithelium (RPE), optic nerve, ciliary body, and iris. Once these have occurred, cells within the fused seam differentiate into components of the functioning visual system. Correct development and progression of OFC, and the continued integrity of the fused margin along this axis, are important for the overall structure of the eye. Failure of OFC results in ocular coloboma-a significant cause of childhood visual impairment that can be associated with several complex ocular phenotypes including microphthalmia and anterior segment dysgenesis. Despite a large number of genes identified, the exact pathways that definitively mediate fusion have not yet been found, reflecting both the biological complexity and genetic heterogeneity of the process. This review will highlight how recent developmental studies have become focused specifically on the epithelial fusion aspects of OFC, applying a range of model organisms (spanning fish, avian, and mammalian species) and utilizing emerging high-resolution live-imaging technologies, transgenic fluorescent models, and unbiased transcriptomic analyses of segmentally-dissected fissure tissue. Key aspects of the fusion process are discussed, including basement membrane dynamics, unique cell behaviors, and the identities and fates of the cells that mediate fusion. These will be set in the context of what is now known, and how these point the way to new avenues of research.
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Affiliation(s)
- Brian Ho Ching Chan
- The Division of Functional Genetics and Development, The Royal Dick School of Veterinary Sciences, The Roslin Institute, The University of Edinburgh, Scotland, United Kingdom
| | - Mariya Moosajee
- University College London Institute of Ophthalmology, London, United Kingdom.,The Francis Crick Institute, London, United Kingdom.,Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.,Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Joe Rainger
- The Division of Functional Genetics and Development, The Royal Dick School of Veterinary Sciences, The Roslin Institute, The University of Edinburgh, Scotland, United Kingdom
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8
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Sun WR, Ramirez S, Spiller KE, Zhao Y, Fuhrmann S. Nf2 fine-tunes proliferation and tissue alignment during closure of the optic fissure in the embryonic mouse eye. Hum Mol Genet 2020; 29:3373-3387. [PMID: 33075808 DOI: 10.1093/hmg/ddaa228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/29/2020] [Accepted: 10/12/2020] [Indexed: 11/14/2022] Open
Abstract
Uveal coloboma represents one of the most common congenital ocular malformations accounting for up to 10% of childhood blindness (~1 in 5000 live birth). Coloboma originates from defective fusion of the optic fissure (OF), a transient gap that forms during eye morphogenesis by asymmetric, ventral invagination. Genetic heterogeneity combined with the activity of developmentally regulated genes suggests multiple mechanisms regulating OF closure. The tumor suppressor and FERM domain protein Neurofibromin 2 (NF2) controls diverse processes in cancer, development and regeneration, via Hippo pathway and cytoskeleton regulation. In humans, NF2 mutations can cause ocular abnormalities, including coloboma, however, its actual role in OF closure is unknown. Using conditional inactivation in the embryonic mouse eye, our data indicate that loss of Nf2 function results in a novel underlying cause for coloboma. In particular, mutant eyes show substantially increased retinal pigmented epithelium (RPE) proliferation in the fissure region with concomitant acquisition of RPE cell fate. Cells lining the OF margin can maintain RPE fate ectopically and fail to transition from neuroepithelial to cuboidal shape. In the dorsal RPE of the optic cup, Nf2 inactivation leads to a robust increase in cell number, with local disorganization of the cytoskeleton components F-actin and pMLC2. We propose that RPE hyperproliferation is the primary cause for the observed defects causing insufficient alignment of the OF margins in Nf2 mutants and failure to fuse properly, resulting in persistent coloboma. Our findings indicate that limiting proliferation particularly in the RPE layer is a critical mechanism during OF closure.
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Affiliation(s)
- Wesley R Sun
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sara Ramirez
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
| | - Kelly E Spiller
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Yan Zhao
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sabine Fuhrmann
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
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9
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Aubert-Mucca M, Pernin-Grandjean J, Marchasson S, Gaston V, Habib C, Meunier I, Sigaudy S, Kaplan J, Roche O, Denis D, Bitoun P, Haye D, Verloes A, Calvas P, Chassaing N, Plaisancié J. Confirmation of FZD5 implication in a cohort of 50 patients with ocular coloboma. Eur J Hum Genet 2020; 29:131-140. [PMID: 32737437 DOI: 10.1038/s41431-020-0695-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 07/01/2020] [Accepted: 07/07/2020] [Indexed: 11/09/2022] Open
Abstract
Defects in optic fissure closure can lead to congenital ocular coloboma. This ocular malformation, often associated with microphthalmia, is described in various clinical forms with different inheritance patterns and genetic heterogeneity. In recent times, the identification of an increased number of genes involved in numerous cellular functions has led to a better understanding in optic fissure closure mechanisms. Nevertheless, most of these genes are also involved in wider eye growth defects such as micro-anophthalmia, questioning the mechanisms controlling both extension and severity of optic fissure closure defects. However, some genes, such as FZD5, have only been so far identified in isolated coloboma. Thus, to estimate the frequency of implication of different ocular genes, we screened a cohort of 50 patients affected by ocular coloboma by using targeted sequencing of 119 genes involved in ocular development. This analysis revealed seven heterozygous (likely) pathogenic variants in RARB, MAB21L2, RBP4, TFAP2A, and FZD5. Surprisingly, three out of the seven variants detected herein were novel disease-causing variants in FZD5 identified in three unrelated families with dominant inheritance. Although molecular diagnosis rate remains relatively low in patients with ocular coloboma (14% (7/50) in this work), these results, however, highlight the importance of genetic screening, especially of FZD5, in such patients. Indeed, in our series, FZD5 variants represent half of the genetic causes, constituting 6% (3/50) of the patients who benefited from a molecular diagnosis. Our findings support the involvement of FZD5 in ocular coloboma and provide clues for screening this gene during current diagnostic procedures.
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Affiliation(s)
- Marion Aubert-Mucca
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France
| | | | | | - Veronique Gaston
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France
| | - Christophe Habib
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France
| | - Isabelle Meunier
- Centre de Référence des Maladies Sensorielles Génétiques, Hôpital Gui de Chauliac, Institut de Neurosciences de Montpellier, INSERM U1051, Université de Montpellier, Montpellier, France
| | - Sabine Sigaudy
- Département de Génétique Médicale, AP-HM, CHU Timone Enfants, Marseille, France
| | - Josseline Kaplan
- Laboratoire de Génétique Ophtalmologique, INSERM U1163 Institut Imagine, Paris, France
| | - Olivier Roche
- Département d'Ophtalmologie, IHU Necker-Enfants-Malades, Université Paris-Descartes, Paris, France
| | - Danièle Denis
- Institut de Neurosciences de la Timone (INT), Centre National de la Recherche Scientifique (CNRS), Aix-Marseille Université (AMU), Marseille, France
| | - Pierre Bitoun
- Département d'Ophtalmologie, SIDVA 91, Juvisy-sur-Orge, France
| | - Damien Haye
- Département de Génétique, Hôpital Robert Debré, Paris, France
| | - Alain Verloes
- Département de Génétique, Hôpital Robert Debré, Paris, France
| | - Patrick Calvas
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France.,INSERM U1056, UDEAR, Equipe 4, Université Toulouse III, Toulouse, France.,Centre de Référence des Affections Rares en Génétique Ophtalmologique CARGO, Site Constitutif, CHU Toulouse, Toulouse, France
| | - Nicolas Chassaing
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France.,INSERM U1056, UDEAR, Equipe 4, Université Toulouse III, Toulouse, France.,Centre de Référence des Affections Rares en Génétique Ophtalmologique CARGO, Site Constitutif, CHU Toulouse, Toulouse, France
| | - Julie Plaisancié
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France. .,INSERM U1056, UDEAR, Equipe 4, Université Toulouse III, Toulouse, France. .,Centre de Référence des Affections Rares en Génétique Ophtalmologique CARGO, Site Constitutif, CHU Toulouse, Toulouse, France.
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10
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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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11
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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: 34] [Impact Index Per Article: 8.5] [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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12
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George A, Cogliati T, Brooks BP. Genetics of syndromic ocular coloboma: CHARGE and COACH syndromes. Exp Eye Res 2020; 193:107940. [PMID: 32032630 DOI: 10.1016/j.exer.2020.107940] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 02/07/2023]
Abstract
Optic fissure closure defects result in uveal coloboma, a potentially blinding condition affecting between 0.5 and 2.6 per 10,000 births that may cause up to 10% of childhood blindness. Uveal coloboma is on a phenotypic continuum with microphthalmia (small eye) and anophthalmia (primordial/no ocular tissue), the so-called MAC spectrum. This review gives a brief overview of the developmental biology behind coloboma and its clinical presentation/spectrum. Special attention will be given to two prominent, syndromic forms of coloboma, namely, CHARGE (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, and Ear anomalies/deafness) and COACH (Cerebellar vermis hypoplasia, Oligophrenia, Ataxia, Coloboma, and Hepatic fibrosis) syndromes. Approaches employed to identify genes involved in optic fissure closure in animal models and recent advances in live imaging of zebrafish eye development are also discussed.
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Affiliation(s)
- Aman George
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health. Bethesda, Maryland, 20892, USA
| | - Tiziana Cogliati
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health. Bethesda, Maryland, 20892, USA
| | - Brian P Brooks
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health. Bethesda, Maryland, 20892, USA.
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13
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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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14
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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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15
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Hardy H, Prendergast JG, Patel A, Dutta S, Trejo-Reveles V, Kroeger H, Yung AR, Goodrich LV, Brooks B, Sowden JC, Rainger J. Detailed analysis of chick optic fissure closure reveals Netrin-1 as an essential mediator of epithelial fusion. eLife 2019; 8:43877. [PMID: 31162046 PMCID: PMC6606025 DOI: 10.7554/elife.43877] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 06/03/2019] [Indexed: 12/13/2022] Open
Abstract
Epithelial fusion underlies many vital organogenic processes during embryogenesis. Disruptions to these cause a significant number of human birth defects, including ocular coloboma. We provide robust spatial-temporal staging and unique anatomical detail of optic fissure closure (OFC) in the embryonic chick, including evidence for roles of apoptosis and epithelial remodelling. We performed complementary transcriptomic profiling and show that Netrin-1 (NTN1) is precisely expressed in the chick fissure margin during fusion but is immediately downregulated after fusion. We further provide a combination of protein localisation and phenotypic evidence in chick, humans, mice and zebrafish that Netrin-1 has an evolutionarily conserved and essential requirement for OFC, and is likely to have an important role in palate fusion. Our data suggest that NTN1 is a strong candidate locus for human coloboma and other multi-system developmental fusion defects, and show that chick OFC is a powerful model for epithelial fusion research. Our bodies are made of many different groups of cells, which are arranged into tissues that perform specific roles. As tissues form in the embryo they must adopt precise three-dimensional structures, depending on their position in the body. In many cases this involves two edges of tissue fusing together to prevent gaps being present in the final structure. In individuals with a condition called ocular coloboma some of the tissues in the eyes fail to merge together correctly, leading to wide gaps that can severely affect vision. There are currently no treatments available for ocular coloboma and in over 70% of patients the cause of the defect is not known. Identifying new genes that control how tissues fuse may help researchers to find what causes this condition and multiple other tissue fusion defects, and establish whether these may be preventable in the future. Much of what is currently known about how tissues fuse has come from studying mice and zebrafish embryos. Although the extensive genetic tools available in these ‘models’ have proved very useful, both offer only a limited time window for observing tissues as they fuse, and the regions involved are very small. Chick embryos, on the other hand, are much larger than mouse or zebrafish embryos and are easier to access from within their eggs. This led Hardy et al. to investigate whether the developing chick eye could be a more useful model for studying the precise details of how tissues merge. Examining chick embryos revealed that tissues in the base of their eyes fuse between five and eight days after the egg had been fertilised, a comparatively long time compared to existing models. Also, many of the genes that Hardy et al. found switched on in chick eyes as the tissues merged had previously been identified as being essential for tissue fusion in humans. However, several new genes were also shown to be involved in the fusing process. For example, Netrin-1 was important for tissues to fuse in the eyes as well as in other regions of the developing embryo. These findings demonstrate that the chick eye is an excellent new model system to study how tissues fuse in animals. Furthermore, the genes identified by Hardy et al. may help researchers to identify the genetic causes of ocular coloboma and other tissue fusion defects in humans.
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Affiliation(s)
- Holly Hardy
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom
| | - James Gd Prendergast
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom
| | - Aara Patel
- Birth Defects Research Centre, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Sunit Dutta
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Violeta Trejo-Reveles
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom
| | - Hannah Kroeger
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom
| | - Andrea R Yung
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Lisa V Goodrich
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Brian Brooks
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Jane C Sowden
- Birth Defects Research Centre, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Joe Rainger
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom
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16
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An update on the genetics of ocular coloboma. Hum Genet 2019; 138:865-880. [PMID: 31073883 DOI: 10.1007/s00439-019-02019-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 04/19/2019] [Indexed: 01/04/2023]
Abstract
Ocular coloboma is an uncommon, but often severe, sight-threatening condition that can be identified from birth. This congenital anomaly is thought to be caused by maldevelopment of optic fissure closure during early eye morphogenesis. It has been causally linked to both inherited (genetic) and environmental influences. In particular, as a consequence of work to identify genetic causes of coloboma, new molecular pathways that control optic fissure closure have now been identified. Many more regulatory mechanisms still await better understanding to inform on the development of potential therapies for patients with this malformation. This review provides an update of known coloboma genes, the pathways they influence and how best to manage the condition. In the age of precision medicine, determining the underlying genetic cause in any given patient is of high importance.
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17
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Weng Y, Luo X, Hou L. Deletion at 12q12 increases the risk of developmental delay and intellectual disability. Ann Hum Genet 2018; 82:482-487. [PMID: 30155906 PMCID: PMC6220791 DOI: 10.1111/ahg.12279] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 06/30/2018] [Accepted: 07/10/2018] [Indexed: 12/17/2022]
Abstract
Single-nucleotide polymorphism (SNP) arrays have been widely used to identify novel genomic imbalances. Many of these genomic imbalances have been confirmed to interact with developmental delays, intellectual disabilities (IDs), and congenital defects. Here, we identify a Chinese girl with a 3.18-Mb deletion at 12q12 (human genome build 19: 43,418,911-46,601,627) who showed postnatal growth delay, low-set ears, small hands and feet, widely spaced nipples, and blue sclerae. Deletions at 12q12 are extremely rare chromosomal imbalances; only four cases involving a deletion of this type have previously been reported. In these five sporadic cases, all of the patients exhibited developmental issues accompanied by different degrees of ID. A review of DECIPHER patient data revealed an additional six cases involving genomic deletion at 12q12. Many of the patients in these cases exhibited developmental delay and ID. When these patients were included, 91% and 73% of individuals with a deletion in this chromosomal region presented with developmental retardation and ID, respectively. Database searches indicated that this copy number variant (CNV) has not been found in normal humans. Therefore, we suggest that a CNV in this region is a risk factor for developmental retardation and ID.
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Affiliation(s)
- Ying Weng
- Department of PaediatricsTongji Hospital, Tongji Medical School, Huazhong University of Science and TechnologyWuhanHubeiChina
| | - Xiaoping Luo
- Department of PaediatricsTongji Hospital, Tongji Medical School, Huazhong University of Science and TechnologyWuhanHubeiChina
| | - Ling Hou
- Department of PaediatricsTongji Hospital, Tongji Medical School, Huazhong University of Science and TechnologyWuhanHubeiChina
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18
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Rainger J, Williamson KA, Soares DC, Truch J, Kurian D, Gillessen‐Kaesbach G, Seawright A, Prendergast J, Halachev M, Wheeler A, McTeir L, Gill AC, van Heyningen V, Davey MG, FitzPatrick DR. A recurrent de novo mutation in ACTG1 causes isolated ocular coloboma. Hum Mutat 2017; 38:942-946. [PMID: 28493397 PMCID: PMC5518294 DOI: 10.1002/humu.23246] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/26/2017] [Accepted: 05/03/2017] [Indexed: 11/17/2022]
Abstract
Ocular coloboma (OC) is a defect in optic fissure closure and is a common cause of severe congenital visual impairment. Bilateral OC is primarily genetically determined and shows marked locus heterogeneity. Whole-exome sequencing (WES) was used to analyze 12 trios (child affected with OC and both unaffected parents). This identified de novo mutations in 10 different genes in eight probands. Three of these genes encoded proteins associated with actin cytoskeleton dynamics: ACTG1, TWF1, and LCP1. Proband-only WES identified a second unrelated individual with isolated OC carrying the same ACTG1 allele, encoding p.(Pro70Leu). Both individuals have normal neurodevelopment with no extra-ocular signs of Baraitser-Winter syndrome. We found this mutant protein to be incapable of incorporation into F-actin. The LCP1 and TWF1 variants each resulted in only minor disturbance of actin interactions, and no further plausibly causative variants were identified in these genes on resequencing 380 unrelated individuals with OC.
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Affiliation(s)
- Joe Rainger
- The Roslin Institute and R(D)SVSUniversity of EdinburghEaster Bush CampusMidlothianUK
| | - Kathleen A Williamson
- MRC Human Genetics Unit, IGMMUniversity of EdinburghWestern General HospitalEdinburghUK
| | - Dinesh C Soares
- MRC Human Genetics Unit, IGMMUniversity of EdinburghWestern General HospitalEdinburghUK
| | - Julia Truch
- MRC Human Genetics Unit, IGMMUniversity of EdinburghWestern General HospitalEdinburghUK
| | - Dominic Kurian
- The Roslin Institute and R(D)SVSUniversity of EdinburghEaster Bush CampusMidlothianUK
| | | | - Anne Seawright
- MRC Human Genetics Unit, IGMMUniversity of EdinburghWestern General HospitalEdinburghUK
| | - James Prendergast
- The Roslin Institute and R(D)SVSUniversity of EdinburghEaster Bush CampusMidlothianUK
| | - Mihail Halachev
- MRC Human Genetics Unit, IGMMUniversity of EdinburghWestern General HospitalEdinburghUK
| | - Ann Wheeler
- MRC Human Genetics Unit, IGMMUniversity of EdinburghWestern General HospitalEdinburghUK
| | - Lynn McTeir
- The Roslin Institute and R(D)SVSUniversity of EdinburghEaster Bush CampusMidlothianUK
| | - Andrew C Gill
- The Roslin Institute and R(D)SVSUniversity of EdinburghEaster Bush CampusMidlothianUK
| | | | - Megan G Davey
- The Roslin Institute and R(D)SVSUniversity of EdinburghEaster Bush CampusMidlothianUK
| | - UK10K
- Wellcome Trust Sanger InstituteGenome CampusHinxtonCambridgeshireUK
| | - David R FitzPatrick
- MRC Human Genetics Unit, IGMMUniversity of EdinburghWestern General HospitalEdinburghUK
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