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AlAbdi L, Rahbeeni Z, Maddirevula S, Helaby R, Abdulwahab F, Khan AO, Riley LG, Alhashem A, Chassaing N, Jamieson RV, Alkuraya FS. A founder variant expands the phenotype of WNT7B-related PDAC syndrome. Clin Genet 2024; 106:66-71. [PMID: 38417950 DOI: 10.1111/cge.14512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/22/2024] [Accepted: 02/15/2024] [Indexed: 03/01/2024]
Abstract
Pulmonary hypoplasia, Diaphragmatic anomalies, Anophthalmia/microphthalmia, and Cardiac defects (PDAC) syndrome is a genetically heterogeneous multiple congenital malformation syndrome. Although pathogenic variants in RARB and STRA6 are established causes of PDAC, many PDAC cases remain unsolved at the molecular level. Recently, we proposed biallelic WNT7B variants as a novel etiology based on several families with typical features of PDAC syndrome albeit with variable expressivity. Here, we report three patients from two families that share a novel founder variant in WNT7B (c.739C > T; Arg247Trp). The phenotypic expression of this variant ranges from typical PDAC features to isolated genitourinary anomalies. Similar to previously reported PDAC-associated WNT7B variants, this variant was found to significantly impair WNT7B signaling activity further corroborating its proposed pathogenicity. This report adds further evidence to WNT7B-related PDAC and expands its variable expressivity.
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Affiliation(s)
- Lama AlAbdi
- Department of Zoology, Collage of Science, King Saud University, Riyadh, Saudi Arabia
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Zuhair Rahbeeni
- Department of Medical Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Sateesh Maddirevula
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Rana Helaby
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Firdous Abdulwahab
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Arif O Khan
- Eye Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA
| | - Lisa G Riley
- Rare Diseases Functional Genomics, Kids Research, The Children's Hospital at Westmead and The Children's Medical Research Institute, Sydney, New South Wales, Australia
- Specialty of Child & Adolescent Health, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Amal Alhashem
- Division of Clinical Genetic and Metabolic Medicine, Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
- Department of Genetic and Metabolic, Sehha Virtual Hospital, Ministry of Health, Riyadh, Saudi Arabia
| | - Nicolas Chassaing
- Centre de Référence des Affections Rares en Génétique Ophtalmologique CARGO, Site Constitutif, Purpan University Hospital, Toulouse, Midi-Pyrénées, France
- Department of Medical Genetics, Purpan University Hospital, Toulouse, Midi-Pyrénées, France
| | - Robyn V Jamieson
- Eye Genetics Research Unit, Children's Medical Research Institute, University of Sydney; The Children's Hospital at Westmead, Sydney Children's Hospitals Network; and Save Sight Institute, Sydney, New South Wales, Australia
- Specialty of Genomic Medicine, Faculty of Medicine and Health and Child and Adolescent Health, University of Sydney, Sydney, New South Wales, Australia
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
- Division of Clinical Genetic and Metabolic Medicine, Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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Leung M, Steinman J, Li D, Lor A, Gruesen A, Sadah A, van Kuijk FJ, Montezuma SR, Kondkar AA, Radhakrishnan R, Lobo GP. The Logistical Backbone of Photoreceptor Cell Function: Complementary Mechanisms of Dietary Vitamin A Receptors and Rhodopsin Transporters. Int J Mol Sci 2024; 25:4278. [PMID: 38673863 PMCID: PMC11050646 DOI: 10.3390/ijms25084278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
In this review, we outline our current understanding of the mechanisms involved in the absorption, storage, and transport of dietary vitamin A to the eye, and the trafficking of rhodopsin protein to the photoreceptor outer segments, which encompasses the logistical backbone required for photoreceptor cell function. Two key mechanisms of this process are emphasized in this manuscript: ocular and systemic vitamin A membrane transporters, and rhodopsin transporters. Understanding the complementary mechanisms responsible for the generation and proper transport of the retinylidene protein to the photoreceptor outer segment will eventually shed light on the importance of genes encoded by these proteins, and their relationship on normal visual function and in the pathophysiology of retinal degenerative diseases.
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Affiliation(s)
- Matthias Leung
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Jeremy Steinman
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Dorothy Li
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Anjelynt Lor
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Andrew Gruesen
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Ahmed Sadah
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Frederik J. van Kuijk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Sandra R. Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Altaf A. Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 12271, Saudi Arabia;
| | - Rakesh Radhakrishnan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Glenn P. Lobo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
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Jackson D, Moosajee M. The Genetic Determinants of Axial Length: From Microphthalmia to High Myopia in Childhood. Annu Rev Genomics Hum Genet 2023; 24:177-202. [PMID: 37624667 DOI: 10.1146/annurev-genom-102722-090617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/27/2023]
Abstract
The axial length of the eye is critical for normal visual function by enabling light to precisely focus on the retina. The mean axial length of the adult human eye is 23.5 mm, but the molecular mechanisms regulating ocular axial length remain poorly understood. Underdevelopment can lead to microphthalmia (defined as a small eye with an axial length of less than 19 mm at 1 year of age or less than 21 mm in adulthood) within the first trimester of pregnancy. However, continued overgrowth can lead to axial high myopia (an enlarged eye with an axial length of 26.5 mm or more) at any age. Both conditions show high genetic and phenotypic heterogeneity associated with significant visual morbidity worldwide. More than 90 genes can contribute to microphthalmia, and several hundred genes are associated with myopia, yet diagnostic yields are low. Crucially, the genetic pathways underpinning the specification of eye size are only now being discovered, with evidence suggesting that shared molecular pathways regulate under- or overgrowth of the eye. Improving our mechanistic understanding of axial length determination will help better inform us of genotype-phenotype correlations in both microphthalmia and myopia, dissect gene-environment interactions in myopia, and develop postnatal therapies that may influence overall eye growth.
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Affiliation(s)
- Daniel Jackson
- Institute of Ophthalmology, University College London, London, United Kingdom;
| | - Mariya Moosajee
- Institute of Ophthalmology, University College London, London, United Kingdom;
- The Francis Crick Institute, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
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Seese SE, Muheisen S, Gath N, Gross JM, Semina EV. Identification of HSPA8 as an interacting partner of MAB21L2 and an important factor in eye development. Dev Dyn 2023; 252:510-526. [PMID: 36576422 PMCID: PMC10947772 DOI: 10.1002/dvdy.560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 11/04/2022] [Accepted: 11/18/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Pathogenic variants in human MAB21L2 result in microphthalmia, anophthalmia, and coloboma. The exact molecular function of MAB21L2 is currently unknown. We conducted a series of yeast two-hybrid (Y2H) experiments to determine protein interactomes of normal human and zebrafish MAB21L2/mab21l2 as well as human disease-associated variant MAB21L2-p.(Arg51Gly) using human adult retina and zebrafish embryo libraries. RESULTS These screens identified klhl31, tnpo1, TNPO2/tnpo2, KLC2/klc2, and SPTBN1/sptbn1 as co-factors of MAB21L2/mab21l2. Several factors, including hspa8 and hspa5, were found to interact with MAB21L2-p.Arg51Gly but not wild-type MAB21L2/mab21l2 in Y2H screens. Further analyses via 1-by-1 Y2H assays, co-immunoprecipitation, and mass spectrometry revealed that both normal and variant MAB21L2 interact with HSPA5 and HSPA8. In situ hybridization detected co-expression of hspa5 and hspa8 with mab21l2 during eye development in zebrafish. Examination of zebrafish mutant hspa8hi138Tg identified reduced hspa8 expression associated with severe ocular developmental defects, including small eye, coloboma, and anterior segment dysgenesis. To investigate the effects of hspa8 deficiency on the mab21l2Arg51_Phe52del allele, corresponding zebrafish double mutants were generated and found to be more severely affected than single mutant lines. CONCLUSION This study identifies heat shock proteins as interacting partners of MAB21L2/mab21l2 and suggests a role for this interaction in vertebrate eye development.
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Affiliation(s)
- Sarah E. Seese
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sanaa Muheisen
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Natalie Gath
- University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Jeffrey M. Gross
- University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Elena V. Semina
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Children’s of Wisconsin, Milwaukee, WI 53226, USA
- Children’s Research Institute, Medical College of Wisconsin, Children’s of Wisconsin, Milwaukee, WI 53226, USA
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An Overview towards Zebrafish Larvae as a Model for Ocular Diseases. Int J Mol Sci 2023; 24:ijms24065387. [PMID: 36982479 PMCID: PMC10048880 DOI: 10.3390/ijms24065387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 03/14/2023] Open
Abstract
Despite the obvious morphological differences in the visual system, zebrafish share a similar architecture and components of the same embryonic origin as humans. The zebrafish retina has the same layered structure and cell types with similar metabolic and phototransduction support as humans, and is functional 72 h after fertilization, allowing tests of visual function to be performed. The zebrafish genomic database supports genetic mapping studies as well as gene editing, both of which are useful in the ophthalmological field. It is possible to model ocular disorders in zebrafish, as well as inherited retinal diseases or congenital or acquired malformations. Several approaches allow the evaluation of local pathological processes derived from systemic disorders, such as chemical exposure to produce retinal hypoxia or glucose exposure to produce hyperglycemia, mimicking retinopathy of prematurity or diabetic retinopathy, respectively. The pathogenesis of ocular infections, autoimmune diseases, or aging can also be assessed in zebrafish larvae, and the preserved cellular and molecular immune mechanisms can be assessed. Finally, the zebrafish model for the study of the pathologies of the visual system complements certain deficiencies in experimental models of mammals since the regeneration of the zebrafish retina is a valuable tool for the study of degenerative processes and the discovery of new drugs and therapies.
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Suzuki M, Tomita M. Genetic Variations of Vitamin A-Absorption and Storage-Related Genes, and Their Potential Contribution to Vitamin A Deficiency Risks Among Different Ethnic Groups. Front Nutr 2022; 9:861619. [PMID: 35571879 PMCID: PMC9096837 DOI: 10.3389/fnut.2022.861619] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/23/2022] [Indexed: 12/01/2022] Open
Abstract
Vitamin A, an essential fat-soluble micronutrient, plays a critical role in the body, by regulating vision, immune responses, and normal development, for instance. Vitamin A deficiency (VAD) is a major cause of xerophthalmia and increases the risk of death from infectious diseases. It is also emerging that prenatal exposure to VAD is associated with disease risks later in life. The overall prevalence of VAD has significantly declined over recent decades; however, the rate of VAD is still high in many low- and mid-income countries and even in high-income countries among specific ethnic/race groups. While VAD occurs when dietary intake is insufficient to meet demands, establishing a strong association between food insecurity and VAD, and vitamin A supplementation is the primary solution to treat VAD, genetic contributions have also been reported to effect serum vitamin A levels. In this review, we discuss genetic variations associated with vitamin A status and vitamin A bioactivity-associated genes, specifically those linked to uptake of the vitamin in the small intestine and its storage in the liver, as well as their potential contribution to vitamin A deficiency risks among different ethnic groups.
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Affiliation(s)
- Masako Suzuki
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, United States
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Wahlin KJ, Cheng J, Jurlina SL, Jones MK, Dash NR, Ogata A, Kibria N, Ray S, Eldred KC, Kim C, Heng JS, Phillips J, Johnston RJ, Gamm DM, Berlinicke C, Zack DJ. CRISPR Generated SIX6 and POU4F2 Reporters Allow Identification of Brain and Optic Transcriptional Differences in Human PSC-Derived Organoids. Front Cell Dev Biol 2021; 9:764725. [PMID: 34869356 PMCID: PMC8635054 DOI: 10.3389/fcell.2021.764725] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/11/2021] [Indexed: 01/29/2023] Open
Abstract
Human pluripotent stem cells (PSCs) represent a powerful tool to investigate human eye development and disease. When grown in 3D, they can self-assemble into laminar organized retinas; however, variation in the size, shape and composition of individual organoids exists. Neither the microenvironment nor the timing of critical growth factors driving retinogenesis are fully understood. To explore early retinal development, we developed a SIX6-GFP reporter that enabled the systematic optimization of conditions that promote optic vesicle formation. We demonstrated that early hypoxic growth conditions enhanced SIX6 expression and promoted eye formation. SIX6 expression was further enhanced by sequential inhibition of Wnt and activation of sonic hedgehog signaling. SIX6 + optic vesicles showed RNA expression profiles that were consistent with a retinal identity; however, ventral diencephalic markers were also present. To demonstrate that optic vesicles lead to bona fide "retina-like" structures we generated a SIX6-GFP/POU4F2-tdTomato dual reporter line that labeled the entire developing retina and retinal ganglion cells, respectively. Additional brain regions, including the hypothalamus and midbrain-hindbrain (MBHB) territories were identified by harvesting SIX6 + /POU4F2- and SIX6- organoids, respectively. Using RNAseq to study transcriptional profiles we demonstrated that SIX6-GFP and POU4F2-tdTomato reporters provided a reliable readout for developing human retina, hypothalamus, and midbrain/hindbrain organoids.
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Affiliation(s)
- Karl J. Wahlin
- Shiley Eye Institute, University of California, San Diego, San Diego, CA, United States,*Correspondence: Karl J. Wahlin,
| | - Jie Cheng
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Shawna L. Jurlina
- Shiley Eye Institute, University of California, San Diego, San Diego, CA, United States
| | - Melissa K. Jones
- Shiley Eye Institute, University of California, San Diego, San Diego, CA, United States
| | - Nicholas R. Dash
- Shiley Eye Institute, University of California, San Diego, San Diego, CA, United States
| | - Anna Ogata
- Shiley Eye Institute, University of California, San Diego, San Diego, CA, United States
| | - Nawal Kibria
- Shiley Eye Institute, University of California, San Diego, San Diego, CA, United States
| | - Sunayan Ray
- Shiley Eye Institute, University of California, San Diego, San Diego, CA, United States
| | - Kiara C. Eldred
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Catherine Kim
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jacob S. Heng
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States,Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, United States,Department of Ophthalmology and Visual Science, Yale School of Medicine, New Haven, CT, United States
| | - Jenny Phillips
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Robert J. Johnston
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - David M. Gamm
- Waisman Center, University of Wisconsin-Madison, Madison, WI, United States,Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States,McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, United States
| | - Cynthia Berlinicke
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Donald J. Zack
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States,Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, United States,Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Alexandre-Moreno S, Bonet-Fernández JM, Atienzar-Aroca R, Aroca-Aguilar JD, Escribano J. Null cyp1b1 Activity in Zebrafish Leads to Variable Craniofacial Defects Associated with Altered Expression of Extracellular Matrix and Lipid Metabolism Genes. Int J Mol Sci 2021; 22:ijms22126430. [PMID: 34208498 PMCID: PMC8234340 DOI: 10.3390/ijms22126430] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 12/13/2022] Open
Abstract
Simple Summary CYP1B1 is a cytochrome P450 monooxygenase involved in oxidative metabolism of different endogenous lipids and drugs. The loss of function (LoF) of this gene underlies many cases of recessive primary congenital glaucoma (PCG), an infrequent disease and a common cause of infantile loss of vision in children. To the best of our knowledge, this is the first study to generate a cyp1b1 knockout zebrafish model. The zebrafish line did not exhibit glaucoma-related phenotypes; however, adult mutant zebrafish presented variable craniofacial alterations, including uni- or bilateral craniofacial alterations with incomplete penetrance and variable expressivity. Transcriptomic analyses of seven-dpf cyp1b1-KO zebrafish revealed differentially expressed genes related to extracellular matrix and cell adhesion, cell growth and proliferation, lipid metabolism and inflammation. Overall, this study provides evidence for the complexity of the phenotypes and molecular pathways associated with cyp1b1 LoF, as well as for the dysregulation of extracellular matrix gene expression as one of the mechanisms underlying cyp1b1 disruption-associated pathogenicity. Abstract CYP1B1 loss of function (LoF) is the main known genetic alteration present in recessive primary congenital glaucoma (PCG), an infrequent disease characterized by delayed embryonic development of the ocular iridocorneal angle; however, the underlying molecular mechanisms are poorly understood. To model CYP1B1 LoF underlying PCG, we developed a cyp1b1 knockout (KO) zebrafish line using CRISPR/Cas9 genome editing. This line carries the c.535_667del frameshift mutation that results in the 72% mRNA reduction with the residual mRNA predicted to produce an inactive truncated protein (p.(His179Glyfs*6)). Microphthalmia and jaw maldevelopment were observed in 23% of F0 somatic mosaic mutant larvae (144 hpf). These early phenotypes were not detected in cyp1b1-KO F3 larvae (144 hpf), but 27% of adult (four months) zebrafish exhibited uni- or bilateral craniofacial alterations, indicating the existence of incomplete penetrance and variable expressivity. These phenotypes increased to 86% in the adult offspring of inbred progenitors with craniofacial defects. No glaucoma-related phenotypes were observed in cyp1b1 mutants. Transcriptomic analyses of the offspring (seven dpf) of cyp1b1-KO progenitors with adult-onset craniofacial defects revealed functionally enriched differentially expressed genes related to extracellular matrix and cell adhesion, cell growth and proliferation, lipid metabolism (retinoids, steroids and fatty acids and oxidation–reduction processes that include several cytochrome P450 genes) and inflammation. In summary, this study shows the complexity of the phenotypes and molecular pathways associated with cyp1b1 LoF, with species dependency, and provides evidence for the dysregulation of extracellular matrix gene expression as one of the mechanisms underlying the pathogenicity associated with cyp1b1 disruption.
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Affiliation(s)
- Susana Alexandre-Moreno
- Área de Genética, Facultad de Medicina de Albacete, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, 02006 Albacete, Spain; (S.A.-M.); (J.-M.B.-F.); (R.A.-A.)
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality (OFTARED), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Juan-Manuel Bonet-Fernández
- Área de Genética, Facultad de Medicina de Albacete, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, 02006 Albacete, Spain; (S.A.-M.); (J.-M.B.-F.); (R.A.-A.)
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality (OFTARED), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Raquel Atienzar-Aroca
- Área de Genética, Facultad de Medicina de Albacete, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, 02006 Albacete, Spain; (S.A.-M.); (J.-M.B.-F.); (R.A.-A.)
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality (OFTARED), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - José-Daniel Aroca-Aguilar
- Área de Genética, Facultad de Medicina de Albacete, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, 02006 Albacete, Spain; (S.A.-M.); (J.-M.B.-F.); (R.A.-A.)
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality (OFTARED), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: (J.-D.A.-A.); (J.E.)
| | - Julio Escribano
- Área de Genética, Facultad de Medicina de Albacete, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, 02006 Albacete, Spain; (S.A.-M.); (J.-M.B.-F.); (R.A.-A.)
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality (OFTARED), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: (J.-D.A.-A.); (J.E.)
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Harding P, Cunha DL, Moosajee M. Animal and cellular models of microphthalmia. THERAPEUTIC ADVANCES IN RARE DISEASE 2021; 2:2633004021997447. [PMID: 37181112 PMCID: PMC10032472 DOI: 10.1177/2633004021997447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/02/2021] [Indexed: 05/16/2023]
Abstract
Microphthalmia is a rare developmental eye disorder affecting 1 in 7000 births. It is defined as a small (axial length ⩾2 standard deviations below the age-adjusted mean) underdeveloped eye, caused by disruption of ocular development through genetic or environmental factors in the first trimester of pregnancy. Clinical phenotypic heterogeneity exists amongst patients with varying levels of severity, and associated ocular and systemic features. Up to 11% of blind children are reported to have microphthalmia, yet currently no treatments are available. By identifying the aetiology of microphthalmia and understanding how the mechanisms of eye development are disrupted, we can gain a better understanding of the pathogenesis. Animal models, mainly mouse, zebrafish and Xenopus, have provided extensive information on the genetic regulation of oculogenesis, and how perturbation of these pathways leads to microphthalmia. However, differences exist between species, hence cellular models, such as patient-derived induced pluripotent stem cell (iPSC) optic vesicles, are now being used to provide greater insights into the human disease process. Progress in 3D cellular modelling techniques has enhanced the ability of researchers to study interactions of different cell types during eye development. Through improved molecular knowledge of microphthalmia, preventative or postnatal therapies may be developed, together with establishing genotype-phenotype correlations in order to provide patients with the appropriate prognosis, multidisciplinary care and informed genetic counselling. This review summarises some key discoveries from animal and cellular models of microphthalmia and discusses how innovative new models can be used to further our understanding in the future. Plain language summary Animal and Cellular Models of the Eye Disorder, Microphthalmia (Small Eye) Microphthalmia, meaning a small, underdeveloped eye, is a rare disorder that children are born with. Genetic changes or variations in the environment during the first 3 months of pregnancy can disrupt early development of the eye, resulting in microphthalmia. Up to 11% of blind children have microphthalmia, yet currently no treatments are available. By understanding the genes necessary for eye development, we can determine how disruption by genetic changes or environmental factors can cause this condition. This helps us understand why microphthalmia occurs, and ensure patients are provided with the appropriate clinical care and genetic counselling advice. Additionally, by understanding the causes of microphthalmia, researchers can develop treatments to prevent or reduce the severity of this condition. Animal models, particularly mice, zebrafish and frogs, which can also develop small eyes due to the same genetic/environmental changes, have helped us understand the genes which are important for eye development and can cause birth eye defects when disrupted. Studying a patient's own cells grown in the laboratory can further help researchers understand how changes in genes affect their function. Both animal and cellular models can be used to develop and test new drugs, which could provide treatment options for patients living with microphthalmia. This review summarises the key discoveries from animal and cellular models of microphthalmia and discusses how innovative new models can be used to further our understanding in the future.
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Affiliation(s)
| | | | - Mariya Moosajee
- UCL Institute of Ophthalmology, 11-43 Bath
Street, London, EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust,
London, UK
- Great Ormond Street Hospital for Children NHS
Foundation Trust, London, UK
- The Francis Crick Institute, London, UK
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10
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Yoon KH, Fox SC, Dicipulo R, Lehmann OJ, Waskiewicz AJ. Ocular coloboma: Genetic variants reveal a dynamic model of eye development. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:590-610. [PMID: 32852110 DOI: 10.1002/ajmg.c.31831] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 12/21/2022]
Abstract
Ocular coloboma is a congenital disorder of the eye where a gap exists in the inferior retina, lens, iris, or optic nerve tissue. With a prevalence of 2-19 per 100,000 live births, coloboma, and microphthalmia, an associated ocular disorder, represent up to 10% of childhood blindness. It manifests due to the failure of choroid fissure closure during eye development, and it is a part of a spectrum of ocular disorders that include microphthalmia and anophthalmia. Use of genetic approaches from classical pedigree analyses to next generation sequencing has identified more than 40 loci that are associated with the causality of ocular coloboma. As we have expanded studies to include singleton cases, hereditability has been very challenging to prove. As such, researchers over the past 20 years, have unraveled the complex interrelationship amongst these 40 genes using vertebrate model organisms. Such research has greatly increased our understanding of eye development. These genes function to regulate initial specification of the eye field, migration of retinal precursors, patterning of the retina, neural crest cell biology, and activity of head mesoderm. This review will discuss the discovery of loci using patient data, their investigations in animal models, and the recent advances stemming from animal models that shed new light in patient diagnosis.
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Affiliation(s)
- Kevin H Yoon
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
| | - Sabrina C Fox
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
| | - Renée Dicipulo
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
| | - Ordan J Lehmann
- Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada.,Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.,Department of Ophthalmology, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew J Waskiewicz
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
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11
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Eintracht J, Corton M, FitzPatrick D, Moosajee M. CUGC for syndromic microphthalmia including next-generation sequencing-based approaches. Eur J Hum Genet 2020; 28:679-690. [PMID: 31896778 PMCID: PMC7171178 DOI: 10.1038/s41431-019-0565-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 11/26/2019] [Accepted: 12/03/2019] [Indexed: 01/29/2023] Open
Affiliation(s)
| | - Marta Corton
- Department of Genetics, IIS-University Hospital Fundación Jiménez Díaz-CIBERER, Madrid, Spain
| | | | - Mariya Moosajee
- UCL Institute of Ophthalmology, London, UK.
- Moorfields Eye Hospital NHS Foundation Trust, London, UK.
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
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12
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von Lintig J, Moon J, Babino D. Molecular components affecting ocular carotenoid and retinoid homeostasis. Prog Retin Eye Res 2020; 80:100864. [PMID: 32339666 DOI: 10.1016/j.preteyeres.2020.100864] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 04/17/2020] [Indexed: 12/15/2022]
Abstract
The photochemistry of vision employs opsins and geometric isomerization of their covalently bound retinylidine chromophores. In different animal classes, these light receptors associate with distinct G proteins that either hyperpolarize or depolarize photoreceptor membranes. Vertebrates also use the acidic form of chromophore, retinoic acid, as the ligand of nuclear hormone receptors that orchestrate eye development. To establish and sustain these processes, animals must acquire carotenoids from the diet, transport them, and metabolize them to chromophore and retinoic acid. The understanding of carotenoid metabolism, however, lagged behind our knowledge about the biology of their receptor molecules. In the past decades, much progress has been made in identifying the genes encoding proteins that mediate the transport and enzymatic transformations of carotenoids and their retinoid metabolites. Comparative analysis in different animal classes revealed how evolutionary tinkering with a limited number of genes evolved different biochemical strategies to supply photoreceptors with chromophore. Mutations in these genes impair carotenoid metabolism and induce various ocular pathologies. This review summarizes this advancement and introduces the involved proteins, including the homeostatic regulation of their activities.
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Affiliation(s)
- Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Jean Moon
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Darwin Babino
- Department of Ophthalmology, School of Medicine, University of Washington, Seattle, WA, USA
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13
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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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14
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Sirbu IO, Chiş AR, Moise AR. Role of carotenoids and retinoids during heart development. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158636. [PMID: 31978553 DOI: 10.1016/j.bbalip.2020.158636] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 02/08/2023]
Abstract
The nutritional requirements of the developing embryo are complex. In the case of dietary vitamin A (retinol, retinyl esters and provitamin A carotenoids), maternal derived nutrients serve as precursors to signaling molecules such as retinoic acid, which is required for embryonic patterning and organogenesis. Despite variations in the composition and levels of maternal vitamin A, embryonic tissues need to generate a precise amount of retinoic acid to avoid congenital malformations. Here, we summarize recent findings regarding the role and metabolism of vitamin A during heart development and we survey the association of genes known to affect retinoid metabolism or signaling with various inherited disorders. A better understanding of the roles of vitamin A in the heart and of the factors that affect retinoid metabolism and signaling can help design strategies to meet nutritional needs and to prevent birth defects and disorders associated with altered retinoid metabolism. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
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Affiliation(s)
- Ioan Ovidiu Sirbu
- Biochemistry Department, Victor Babes University of Medicine and Pharmacy, Eftimie Murgu Nr. 2, 300041 Timisoara, Romania; Timisoara Institute of Complex Systems, V. Lucaciu 18, 300044 Timisoara, Romania.
| | - Aimée Rodica Chiş
- Biochemistry Department, Victor Babes University of Medicine and Pharmacy, Eftimie Murgu Nr. 2, 300041 Timisoara, Romania
| | - Alexander Radu Moise
- Medical Sciences Division, Northern Ontario School of Medicine, Sudbury, ON P3E 2C6, Canada; Department of Chemistry and Biochemistry, Biology and Biomolecular Sciences Program, Laurentian University, Sudbury, ON P3E 2C6, Canada.
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15
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Thompson B, Katsanis N, Apostolopoulos N, Thompson DC, Nebert DW, Vasiliou V. Genetics and functions of the retinoic acid pathway, with special emphasis on the eye. Hum Genomics 2019; 13:61. [PMID: 31796115 PMCID: PMC6892198 DOI: 10.1186/s40246-019-0248-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 11/12/2019] [Indexed: 02/07/2023] Open
Abstract
Retinoic acid (RA) is a potent morphogen required for embryonic development. RA is formed in a multistep process from vitamin A (retinol); RA acts in a paracrine fashion to shape the developing eye and is essential for normal optic vesicle and anterior segment formation. Perturbation in RA-signaling can result in severe ocular developmental diseases—including microphthalmia, anophthalmia, and coloboma. RA-signaling is also essential for embryonic development and life, as indicated by the significant consequences of mutations in genes involved in RA-signaling. The requirement of RA-signaling for normal development is further supported by the manifestation of severe pathologies in animal models of RA deficiency—such as ventral lens rotation, failure of optic cup formation, and embryonic and postnatal lethality. In this review, we summarize RA-signaling, recent advances in our understanding of this pathway in eye development, and the requirement of RA-signaling for embryonic development (e.g., organogenesis and limb bud development) and life.
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Affiliation(s)
- Brian Thompson
- Department of Environmental Health Sciences, Yale School of Public Health, 60 College St, New Haven, CT, 06520, USA
| | - Nicholas Katsanis
- Stanley Manne Research Institute, Lurie Children's Hospital, Chicago, IL, 60611, USA.,Departments of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Nicholas Apostolopoulos
- Department of Environmental Health Sciences, Yale School of Public Health, 60 College St, New Haven, CT, 06520, USA
| | - David C Thompson
- Department of Clinical Pharmacy, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Denver, Aurora, CO, 80045, USA
| | - Daniel W Nebert
- Department of Environmental Health and Center for Environmental Genetics, University Cincinnati Medical Center, Cincinnati, OH, 45267-0056, USA
| | - Vasilis Vasiliou
- Department of Environmental Health Sciences, Yale School of Public Health, 60 College St, New Haven, CT, 06520, USA.
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16
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Carotenoid metabolism at the intestinal barrier. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158580. [PMID: 31794861 DOI: 10.1016/j.bbalip.2019.158580] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/20/2019] [Accepted: 11/21/2019] [Indexed: 12/17/2022]
Abstract
Carotenoids exert a rich variety of physiological functions in mammals and are beneficial for human health. These lipids are acquired from the diet and metabolized to apocarotenoids, including retinoids (vitamin A and its metabolites). The small intestine is a major site for their absorption and bioconversion. From here, carotenoids and their metabolites are distributed within the body in triacylglycerol-rich lipoproteins to support retinoid signaling in peripheral tissues and photoreceptor function in the eyes. In recent years, much progress has been made in identifying carotenoid metabolizing enzymes, transporters, and binding proteins. A diet-responsive regulatory network controls the activity of these components and adapts carotenoid absorption and bioconversion to the bodily requirements of these lipids. Genetic variability in the genes encoding these components alters carotenoid homeostasis and is associated with pathologies. We here summarize the advanced state of knowledge about intestinal carotenoid metabolism and its impact on carotenoid and retinoid homeostasis of other organ systems, including the eyes, liver, and immune system. The implication of the findings for science-based intake recommendations for these essential dietary lipids is discussed. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
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17
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Widjaja-Adhi MAK, Golczak M. The molecular aspects of absorption and metabolism of carotenoids and retinoids in vertebrates. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158571. [PMID: 31770587 DOI: 10.1016/j.bbalip.2019.158571] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/04/2019] [Accepted: 11/07/2019] [Indexed: 02/08/2023]
Abstract
Vitamin A is an essential nutrient necessary for numerous basic physiological functions, including reproduction and development, immune cell differentiation and communication, as well as the perception of light. To evade the dire consequences of vitamin A deficiency, vertebrates have evolved specialized metabolic pathways that enable the absorption, transport, and storage of vitamin A acquired from dietary sources as preformed retinoids or provitamin A carotenoids. This evolutionary advantage requires a complex interplay between numerous specialized retinoid-transport proteins, receptors, and enzymes. Recent advances in molecular and structural biology resulted in a rapid expansion of our understanding of these processes at the molecular level. This progress opened new avenues for the therapeutic manipulation of retinoid homeostasis. In this review, we summarize current research related to the biochemistry of carotenoid and retinoid-processing proteins with special emphasis on the structural aspects of their physiological actions. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
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Affiliation(s)
- Made Airanthi K Widjaja-Adhi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States of America
| | - Marcin Golczak
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States of America; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States of America.
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18
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Han X, Qassim A, An J, Marshall H, Zhou T, Ong JS, Hassall MM, Hysi PG, Foster PJ, Khaw PT, Mackey DA, Gharahkhani P, Khawaja AP, Hewitt AW, Craig JE, MacGregor S. Genome-wide association analysis of 95 549 individuals identifies novel loci and genes influencing optic disc morphology. Hum Mol Genet 2019; 28:3680-3690. [DOI: 10.1093/hmg/ddz193] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 07/30/2019] [Accepted: 08/04/2019] [Indexed: 12/13/2022] Open
Abstract
Abstract
Optic nerve head morphology is affected by several retinal diseases. We measured the vertical optic disc diameter (DD) of the UK Biobank (UKBB) cohort (N = 67 040) and performed the largest genome-wide association study (GWAS) of DD to date. We identified 81 loci (66 novel) for vertical DD. We then replicated the novel loci in International Glaucoma Genetic Consortium (IGGC, N = 22 504) and European Prospective Investigation into Cancer–Norfolk (N = 6005); in general the concordance in effect sizes was very high (correlation in effect size estimates 0.90): 44 of the 66 novel loci were significant at P < 0.05, with 19 remaining significant after Bonferroni correction. We identified another 26 novel loci in the meta-analysis of UKBB and IGGC data. Gene-based analyses identified an additional 57 genes. Human ocular tissue gene expression analysis showed that most of the identified genes are enriched in optic nerve head tissue. Some of the identified loci exhibited pleiotropic effects with vertical cup-to-disc ratio, intraocular pressure, glaucoma and myopia. These results can enhance our understanding of the genetics of optic disc morphology and shed light on the genetic findings for other ophthalmic disorders such as glaucoma and other optic nerve diseases.
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Affiliation(s)
- Xikun Han
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
- School of Medicine, University of Queensland, St Lucia, Brisbane, Australia
| | - Ayub Qassim
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Jiyuan An
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Henry Marshall
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Tiger Zhou
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Jue-Sheng Ong
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Mark M Hassall
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Pirro G Hysi
- Department of Ophthalmology, King’s College London, St. Thomas’ Hospital, London, UK
| | - Paul J Foster
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Peng T Khaw
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - David A Mackey
- Menzies Institute for Medical Research, University of Tasmania, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Puya Gharahkhani
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Anthony P Khawaja
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Australia
- Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Stuart MacGregor
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
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19
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Harding P, Moosajee M. The Molecular Basis of Human Anophthalmia and Microphthalmia. J Dev Biol 2019; 7:jdb7030016. [PMID: 31416264 PMCID: PMC6787759 DOI: 10.3390/jdb7030016] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/08/2019] [Accepted: 08/08/2019] [Indexed: 12/16/2022] Open
Abstract
Human eye development is coordinated through an extensive network of genetic signalling pathways. Disruption of key regulatory genes in the early stages of eye development can result in aborted eye formation, resulting in an absent eye (anophthalmia) or a small underdeveloped eye (microphthalmia) phenotype. Anophthalmia and microphthalmia (AM) are part of the same clinical spectrum and have high genetic heterogeneity, with >90 identified associated genes. By understanding the roles of these genes in development, including their temporal expression, the phenotypic variation associated with AM can be better understood, improving diagnosis and management. This review describes the genetic and structural basis of eye development, focusing on the function of key genes known to be associated with AM. In addition, we highlight some promising avenues of research involving multiomic approaches and disease modelling with induced pluripotent stem cell (iPSC) technology, which will aid in developing novel therapies.
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Affiliation(s)
| | - Mariya Moosajee
- UCL Institute of Ophthalmology, London EC1V 9EL, UK.
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK.
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
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20
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Nedelec B, Rozet JM, Fares Taie L. Genetic architecture of retinoic-acid signaling-associated ocular developmental defects. Hum Genet 2019; 138:937-955. [DOI: 10.1007/s00439-019-02052-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 07/23/2019] [Indexed: 12/14/2022]
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21
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A rare mutation of retinoic acid receptor-β associated with lethal neonatal Matthew-Wood syndrome. Clin Dysmorphol 2019; 28:74-77. [PMID: 30480585 DOI: 10.1097/mcd.0000000000000251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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22
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Williams AL, Bohnsack BL. What's retinoic acid got to do with it? Retinoic acid regulation of the neural crest in craniofacial and ocular development. Genesis 2019; 57:e23308. [PMID: 31157952 DOI: 10.1002/dvg.23308] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/23/2019] [Accepted: 05/05/2019] [Indexed: 12/21/2022]
Abstract
Retinoic acid (RA), the active derivative of vitamin A (retinol), is an essential morphogen signaling molecule and major regulator of embryonic development. The dysregulation of RA levels during embryogenesis has been associated with numerous congenital anomalies, including craniofacial, auditory, and ocular defects. These anomalies result from disruptions in the cranial neural crest, a vertebrate-specific transient population of stem cells that contribute to the formation of diverse cell lineages and embryonic structures during development. In this review, we summarize our current knowledge of the RA-mediated regulation of cranial neural crest induction at the edge of the neural tube and the migration of these cells into the craniofacial region. Further, we discuss the role of RA in the regulation of cranial neural crest cells found within the frontonasal process, periocular mesenchyme, and pharyngeal arches, which eventually form the bones and connective tissues of the head and neck and contribute to structures in the anterior segment of the eye. We then review our understanding of the mechanisms underlying congenital craniofacial and ocular diseases caused by either the genetic or toxic disruption of RA signaling. Finally, we discuss the role of RA in maintaining neural crest-derived structures in postembryonic tissues and the implications of these studies in creating new treatments for degenerative craniofacial and ocular diseases.
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Affiliation(s)
- Antionette L Williams
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
| | - Brenda L Bohnsack
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
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23
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The Oculome Panel Test: Next-Generation Sequencing to Diagnose a Diverse Range of Genetic Developmental Eye Disorders. Ophthalmology 2019; 126:888-907. [PMID: 30653986 DOI: 10.1016/j.ophtha.2018.12.050] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 12/18/2018] [Accepted: 12/21/2018] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To develop a comprehensive next-generation sequencing panel assay that screens genes known to cause developmental eye disorders and inherited eye disease and to evaluate its diagnostic yield in a pediatric cohort with malformations of the globe, anterior segment anomalies, childhood glaucoma, or a combination thereof. DESIGN Evaluation of diagnostic test. PARTICIPANTS Two hundred seventy-seven children, 0 to 16 years of age, diagnosed with nonsyndromic or syndromic developmental eye defects without a genetic diagnosis. METHODS We developed a new oculome panel using a custom-designed Agilent SureSelect QXT target capture method (Agilent Technologies, Santa Clara, CA) to capture and perform parallel high-throughput sequencing analysis of 429 genes associated with eye disorders. Bidirectional Sanger sequencing confirmed suspected pathogenic variants. MAIN OUTCOME MEASURES Collated clinical details and oculome molecular genetic results. RESULTS The oculome design covers 429 known eye disease genes; these are subdivided into 5 overlapping virtual subpanels for anterior segment developmental anomalies including glaucoma (ASDA; 59 genes), microphthalmia-anophthalmia-coloboma (MAC; 86 genes), congenital cataracts and lens-associated conditions (70 genes), retinal dystrophies (RET; 235 genes), and albinism (15 genes), as well as additional genes implicated in optic atrophy and complex strabismus (10 genes). Panel development and testing included analyzing 277 clinical samples and 3 positive control samples using Illumina sequencing platforms; more than 30× read depth was achieved for 99.5% of the targeted 1.77-Mb region. Bioinformatics analysis performed using a pipeline based on Freebayes and ExomeDepth to identify coding sequence and copy number variants, respectively, resulted in a definitive diagnosis in 68 of 277 samples, with variability in diagnostic yield between phenotypic subgroups: MAC, 8.2% (8 of 98 cases solved); ASDA, 24.8% (28 of 113 cases solved); other or syndromic, 37.5% (3 of 8 cases solved); RET, 42.8% (21 of 49 cases solved); and congenital cataracts and lens-associated conditions, 88.9% (8 of 9 cases solved). CONCLUSIONS The oculome test diagnoses a comprehensive range of genetic conditions affecting the development of the eye, potentially replacing protracted and costly multidisciplinary assessments and allowing for faster targeted management. The oculome enabled molecular diagnosis of a significant number of cases in our sample cohort of varied ocular birth defects.
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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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Genetics of anophthalmia and microphthalmia. Part 1: Non-syndromic anophthalmia/microphthalmia. Hum Genet 2019; 138:799-830. [PMID: 30762128 DOI: 10.1007/s00439-019-01977-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/30/2019] [Indexed: 12/22/2022]
Abstract
Eye formation is the result of coordinated induction and differentiation processes during embryogenesis. Disruption of any one of these events has the potential to cause ocular growth and structural defects, such as anophthalmia and microphthalmia (A/M). A/M can be isolated or occur with systemic anomalies, when they may form part of a recognizable syndrome. Their etiology includes genetic and environmental factors; several hundred genes involved in ocular development have been identified in humans or animal models. In humans, around 30 genes have been repeatedly implicated in A/M families, although many other genes have been described in single cases or families, and some genetic syndromes include eye anomalies occasionally as part of a wider phenotype. As a result of this broad genetic heterogeneity, with one or two notable exceptions, each gene explains only a small percentage of cases. Given the overlapping phenotypes, these genes can be most efficiently tested on panels or by whole exome/genome sequencing for the purposes of molecular diagnosis. However, despite whole exome/genome testing more than half of patients currently remain without a molecular diagnosis. The proportion of undiagnosed cases is even higher in those individuals with unilateral or milder phenotypes. Furthermore, even when a strong gene candidate is available for a patient, issues of incomplete penetrance and germinal mosaicism make diagnosis and genetic counseling challenging. In this review, we present the main genes implicated in non-syndromic human A/M phenotypes and, for practical purposes, classify them according to the most frequent or predominant phenotype each is associated with. Our intention is that this will allow clinicians to rank and prioritize their molecular analyses and interpretations according to the phenotypes of their patients.
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Chawla B, Swain W, Williams AL, Bohnsack BL. Retinoic Acid Maintains Function of Neural Crest-Derived Ocular and Craniofacial Structures in Adult Zebrafish. Invest Ophthalmol Vis Sci 2019; 59:1924-1935. [PMID: 29677354 PMCID: PMC5894920 DOI: 10.1167/iovs.17-22845] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Retinoic acid (RA) is required for embryonic formation of the anterior segment of the eye and craniofacial structures. The present study further investigated the role of RA in maintaining the function of these neural crest–derived structures in adult zebrafish. Methods Morphology and histology were analyzed by using live imaging, methylacrylate sections, and TUNEL assay. Functional analysis of vision and aqueous humor outflow were assayed with real-time imaging. Results Both decreased and increased RA signaling altered craniofacial and ocular structures in adult zebrafish. Exogenous treatment with all-trans RA for 5 days resulted in a prognathic jaw, while inhibition of endogenous RA synthesis through treatment with 4-diethylaminobenzaldehyde (DEAB) decreased head height. In adult eyes, RA activity was localized to the retinal pigment epithelium, photoreceptors, outer plexiform layer, inner plexiform layer, iris stroma, and ventral canalicular network. Exogenous RA increased apoptosis in the iris stroma and canalicular network in the ventral iridocorneal angle, resulting in the loss of these structures and decreased aqueous outflow. DEAB, which decreased RA activity throughout the eye, induced widespread apoptosis, resulting in corneal edema, cataracts, retinal atrophy, and loss of iridocorneal angle structures. DEAB-treated fish were blind with no optokinetic response and no aqueous outflow from the anterior chamber. Conclusions Tight control of RA levels is required for normal structure and function of the adult anterior segment. These studies demonstrated that RA plays an important role in maintaining ocular and craniofacial structures in adult zebrafish.
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Affiliation(s)
- Bahaar Chawla
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - William Swain
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Antionette L Williams
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Brenda L Bohnsack
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
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Slavotinek A. Genetics of anophthalmia and microphthalmia. Part 2: Syndromes associated with anophthalmia-microphthalmia. Hum Genet 2018; 138:831-846. [PMID: 30374660 DOI: 10.1007/s00439-018-1949-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 10/20/2018] [Indexed: 12/12/2022]
Abstract
As new genes for A/M are identified in the genomic era, the number of syndromes associated with A/M has greatly expanded. In this review, we provide a brief synopsis of the clinical presentation and molecular genetic etiology of previously characterized pathways involved in A/M, including the Sex-determining region Y-box 2 (SOX2), Orthodenticle Homeobox 2 (OTX2) and Paired box protein-6 (PAX6) genes, and the Stimulated by retinoic acid gene 6 homolog (STRA6), Aldehyde Dehydrogenase 1 Family Member A3 (ALDH1A3), and RA Receptor Beta (RARβ) genes that are involved in retinoic acid synthesis. Less common genetic causes of A/M, including genes involved in BMP signaling [Bone Morphogenetic Protein 4 (BMP4), Bone Morphogenetic Protein 7 (BMP7) and SPARC-related modular calcium-binding protein 1 (SMOC1)], genes involved in the mitochondrial respiratory chain complex [Holocytochrome c-type synthase (HCCS), Cytochrome C Oxidase Subunit 7B (COX7B), and NADH:Ubiquinone Oxidoreductase subunit B11 (NDUFB11)], the BCL-6 corepressor gene (BCOR), Yes-Associated Protein 1 (YAP1) and Transcription Factor AP-2 Alpha (TFAP2α), are more briefly discussed. We also review several recently described genes and pathways associated with A/M, including Smoothened (SMO) that is involved in Sonic hedgehog (SHH) signaling, Structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1) and Solute carrier family 25 member 24 (SLC25A24), emphasizing phenotype-genotype correlations and shared pathways where relevant.
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Affiliation(s)
- Anne Slavotinek
- Division of Genetics, Department of Pediatrics, University of California, San Francisco Room RH384C, 1550 4th St, San Francisco, CA, 94143-2711, USA.
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Mutation of IPO13 causes recessive ocular coloboma, microphthalmia, and cataract. Exp Mol Med 2018; 50:1-11. [PMID: 29700284 PMCID: PMC5938035 DOI: 10.1038/s12276-018-0079-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/22/2018] [Accepted: 02/14/2018] [Indexed: 11/12/2022] Open
Abstract
Ocular coloboma is a developmental structural defect of the eye that often occurs as complex ocular anomalies. However, its genetic etiology remains largely unexplored. Here we report the identification of mutation (c.331C>T, p.R111C) in the IPO13 gene in a consanguineous family with ocular coloboma, microphthalmia, and cataract by a combination of whole-exome sequencing and homozygosity mapping. IPO13 encodes an importin-B family protein and has been proven to be associated with the pathogenesis of coloboma and microphthalmia. We found that Ipo13 was expressed in the cornea, sclera, lens, and retina in mice. Additionally, the mRNA expression level of Ipo13 decreased significantly in the patient compared with its expression in a healthy individual. Morpholino-oligonucleotide-induced knockdown of ipo13 in zebrafish caused dose-dependent microphthalmia and coloboma, which is highly similar to the ocular phenotypes in the patient. Moreover, both visual motor response and optokinetic response were impaired severely. Notably, these ocular phenotypes in ipo13-deficient zebrafish could be rescued remarkably by full-length ipo13 mRNA, suggesting that the phenotypes observed in zebrafish were due to insufficient ipo13 function. Altogether, our findings demonstrate, for the first time, a new role of IPO13 in eye morphogenesis and that loss of function of IPO13 could lead to ocular coloboma, microphthalmia, and cataract in humans and zebrafish. In-depth genomic analysis of the family of a young man with severe visual impairment reveals a new gene involved in eye development. Ocular coloboma encompasses various hereditary disorders in which the eyes form improperly. Many of the underlying genetic factors remain unidentified. Researchers led by Zi-Bing Jin at Wenzhou Medical University in China sequenced the genes of 28-year-old man with a recessive form of ocular coloboma. By comparing these genetic data against equivalent genome sequences from his healthy parents, Jin’s team identified a gene called IPO13 as the culprit. IPO13 has not been linked to human disease before, but the researchers demonstrated that switching off IPO13 expression in zebrafish embryos gave rise to underdeveloped eyes with defects in the iris and cornea. These findings give clinicians another potential indicator for early diagnosis of ocular coloboma.
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Lynch SA, Crushell E, Lambert DM, Byrne N, Gorman K, King MD, Green A, O’Sullivan S, Browne F, Hughes J, Knerr I, Monavari AA, Cotter M, McConnell VPM, Kerr B, Jones SA, Keenan C, Murphy N, Cody D, Ennis S, Turner J, Irvine AD, Casey J. Catalogue of inherited disorders found among the Irish Traveller population. J Med Genet 2018; 55:233-239. [DOI: 10.1136/jmedgenet-2017-104974] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 12/21/2017] [Accepted: 12/22/2017] [Indexed: 01/28/2023]
Abstract
Background Irish Travellers are an endogamous, nomadic, ethnic minority population mostly resident on the island of Ireland with smaller populations in Europe and the USA. High levels of consanguinity result in many rare autosomal recessive disorders. Due to founder effects and endogamy, most recessive disorders are caused by specific homozygous mutations unique to this population. Key clinicians and scientists with experience in managing rare disorders seen in this population have developed a de facto advisory service on differential diagnoses to consider when faced with specific clinical scenarios.Objective(s) To catalogue all known inherited disorders found in the Irish Traveller population.Methods We performed detailed literature and database searches to identify relevant publications and the disease mutations of known genetic disorders found in Irish Travellers.Results We identified 104 genetic disorders: 90 inherited in an autosomal recessive manner; 13 autosomal dominant and one a recurring chromosomal duplication.Conclusion We have collated our experience of inherited disorders found in the Irish Traveller population to make it publically available through this publication to facilitate a targeted genetic approach to diagnostics in this ethnic group.
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Pasutto F, Flinter F, Rauch A, Reis A. Novel STRA6 null mutations in the original family described with Matthew-Wood syndrome. Am J Med Genet A 2017; 176:134-138. [PMID: 29168296 DOI: 10.1002/ajmg.a.38529] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 10/15/2017] [Indexed: 01/31/2023]
Affiliation(s)
- Francesca Pasutto
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Frances Flinter
- Department of Clinical Genetics, Guy's & St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Anita Rauch
- Institute of Medical Genetics, University of Zurich, Schlieren-Zurich, Switzerland
| | - André Reis
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Sadowski S, Chassaing N, Gaj Z, Czichos E, Wilczynski J, Nowakowska D. Both a frameshift and a missense mutation of theSTRA6gene observed in an infant with the Matthew-Wood syndrome. Birth Defects Res 2017; 109:251-253. [DOI: 10.1002/bdra.23465] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/16/2015] [Accepted: 09/28/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Samantha Sadowski
- Obstetrics, Gynecology, and Gynecological Oncology, Medical University of Lodz; Lodz Poland
| | - Nicolas Chassaing
- Service de Génétique Médicale, Pavillon Lefebvre EA-455 UPSIII, Hôpital Purpan CHU Toulouse; France
| | - Zuzanna Gaj
- Department of Perinatology and Gynecology; Polish Mother's Memorial Hospital - Research Institute; Lodz Poland
- Scientific Laboratory of Center of Medical Laboratory Diagnostics, Polish Mother's Memorial Hospital - Research Institute; Lodz Poland
| | - Ewa Czichos
- Department of Pathology; Polish Mother's Memorial Hospital - Research Institute; Lodz Poland
| | - Jan Wilczynski
- Duchess Anna Mazowiecka Public Teaching Hospital; Warsaw Poland
| | - Dorota Nowakowska
- Obstetrics, Gynecology, and Gynecological Oncology, Medical University of Lodz; Lodz Poland
- Department of Perinatology and Gynecology; Polish Mother's Memorial Hospital - Research Institute; Lodz Poland
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Clinical utility gene card for: Non-Syndromic Microphthalmia Including Next-Generation Sequencing-Based Approaches. Eur J Hum Genet 2017; 25:ejhg2016201. [PMID: 28098148 DOI: 10.1038/ejhg.2016.201] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/28/2016] [Accepted: 12/14/2016] [Indexed: 11/08/2022] Open
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Array comparative genomic hybridization and genomic sequencing in the diagnostics of the causes of congenital anomalies. J Appl Genet 2016; 58:185-198. [PMID: 27858254 DOI: 10.1007/s13353-016-0376-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/19/2016] [Accepted: 11/03/2016] [Indexed: 12/17/2022]
Abstract
The aim of this review is to provide the current state of knowledge about the usefulness of modern genetic technologies in uncovering the causality of isolated and multiple congenital anomalies. Array comparative genomic hybridization and next-generation sequencing have revolutionized the clinical approach to patients with these phenotypes. Both technologies enable early diagnosis, especially in clinically challenging newborn populations, and help to uncover genetic defects associated with various phenotypes. The application of both complementary methods could assist in identifying many variants that may simultaneously be involved in the development of a number of isolated or multiple congenital anomalies. Both technologies carry serious variant misinterpretation risks as well. Therefore, the methods of variant classification and accessible variant databases are mentioned. A useful strategy of clinical genetic testing with the application of both methodologies is presented. Finally, future directions and challenges are briefly commented on in this review.
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Plaisancie J, Calvas P, Chassaing N. Genetic Advances in Microphthalmia. J Pediatr Genet 2016; 5:184-188. [PMID: 27895970 DOI: 10.1055/s-0036-1592350] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 01/07/2015] [Indexed: 12/18/2022]
Abstract
Congenital ocular anomalies such as anophthalmia and microphthalmia (AM) are severe craniofacial malformations in human. The etiologies of these ocular globe anomalies are diverse but the genetic origin appears to be a predominant cause. Until recently, genetic diagnosis capability was rather limited in AM patients and only a few genes were available for routine genetic testing. While some issues remain poorly understood, knowledge regarding the molecular basis of AM dramatically improved over the last years with the development of new molecular screening technologies. Thus, the genetic cause is now identifiable in more than 50% of patients with a severe bilateral eye phenotype and in around 30% of all AM patients taken together. Such advances in the knowledge of these genetic bases are important as they improve the quality of care, in terms of diagnosis, prognosis, and genetic counseling delivered to the patients and their families.
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Affiliation(s)
- Julie Plaisancie
- Department of Medical Genetics, Purpan University Hospital, Toulouse, France
| | - Patrick Calvas
- Department of Medical Genetics, Purpan University Hospital, Toulouse, France; U1056 INSERM-FRE 3742 CNRS-Université Toulouse III, Toulouse, France
| | - Nicolas Chassaing
- Department of Medical Genetics, Purpan University Hospital, Toulouse, France; U1056 INSERM-FRE 3742 CNRS-Université Toulouse III, Toulouse, France
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Kelly M, Widjaja-Adhi MAK, Palczewski G, von Lintig J. Transport of vitamin A across blood-tissue barriers is facilitated by STRA6. FASEB J 2016; 30:2985-95. [PMID: 27189978 DOI: 10.1096/fj.201600446r] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/02/2016] [Indexed: 12/31/2022]
Abstract
Vitamin A bound to retinol binding protein 4 (RBP4) constitutes the major transport mode for retinoids in fasting circulation. Emerging evidence suggests that membrane protein, STRA6 (stimulated by retinoic acid 6), is the RBP4 receptor and vitamin A channel; however, the role of STRA6 in vitamin A homeostasis remains to be defined in vivo We subjected Stra6-knockout mice to diets sufficient and insufficient for vitamin A and used heterozygous siblings as controls. We determined vitamin A levels of the eyes, brain, and testis, which highly express Stra6, as well as of tissues with low expression, such as lung and fat. We also studied the consequence of STRA6 deficiency on retinoid-dependent processes in tissues. Furthermore, we examined how STRA6 deficiency affected retinoid homeostasis of the aging mouse. The picture that emerged indicates a critical role for STRA6 in the transport of vitamin A across blood-tissue barriers in the eyes, brain, and testis. Concurrently, fat and lung rely on dietary vitamin A. In testis and brain, Stra6 expression was regulated by vitamin A. In controls, this regulation reduced vitamin A consumption when the dietary supply was limited, sequestering it for the eye. Thus, STRA6 is critical for vitamin A homeostasis and the adaption of this process to the fluctuating supply of the vitamin.-Kelly, M., Widjaja-Adhi, M. A. K., Palczewski, G., von Lintig, J. Transport of vitamin A across blood-tissue barriers is facilitated by STRA6.
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Affiliation(s)
- Mary Kelly
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - M Airanthi K Widjaja-Adhi
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Grzegorz Palczewski
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Johannes von Lintig
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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Chawla B, Schley E, Williams AL, Bohnsack BL. Retinoic Acid and Pitx2 Regulate Early Neural Crest Survival and Migration in Craniofacial and Ocular Development. ACTA ACUST UNITED AC 2016; 107:126-35. [PMID: 27175943 DOI: 10.1002/bdrb.21177] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/21/2016] [Indexed: 12/19/2022]
Affiliation(s)
- Bahaar Chawla
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
| | - Elisa Schley
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
| | - Antionette L Williams
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
| | - Brenda L Bohnsack
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
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Fregeau B, Kim B, Hernández-García A, Jordan V, Cho M, Schnur R, Monaghan K, Juusola J, Rosenfeld J, Bhoj E, Zackai E, Sacharow S, Barañano K, Bosch D, de Vries B, Lindstrom K, Schroeder A, James P, Kulch P, Lalani S, van Haelst M, van Gassen K, van Binsbergen E, Barkovich A, Scott D, Sherr E. De Novo Mutations of RERE Cause a Genetic Syndrome with Features that Overlap Those Associated with Proximal 1p36 Deletions. Am J Hum Genet 2016; 98:963-970. [PMID: 27087320 DOI: 10.1016/j.ajhg.2016.03.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/02/2016] [Indexed: 10/21/2022] Open
Abstract
Deletions of chromosome 1p36 affect approximately 1 in 5,000 newborns and are associated with developmental delay, intellectual disability, and defects involving the brain, eye, ear, heart, and kidney. Arginine-glutamic acid dipeptide repeats (RERE) is located in the proximal 1p36 critical region. RERE is a widely-expressed nuclear receptor coregulator that positively regulates retinoic acid signaling. Animal models suggest that RERE deficiency might contribute to many of the structural and developmental birth defects and medical problems seen in individuals with 1p36 deletion syndrome, although human evidence supporting this role has been lacking. In this report, we describe ten individuals with intellectual disability, developmental delay, and/or autism spectrum disorder who carry rare and putatively damaging changes in RERE. In all cases in which both parental DNA samples were available, these changes were found to be de novo. Associated features that were recurrently seen in these individuals included hypotonia, seizures, behavioral problems, structural CNS anomalies, ophthalmologic anomalies, congenital heart defects, and genitourinary abnormalities. The spectrum of defects documented in these individuals is similar to that of a cohort of 31 individuals with isolated 1p36 deletions that include RERE and are recapitulated in RERE-deficient zebrafish and mice. Taken together, our findings suggest that mutations in RERE cause a genetic syndrome and that haploinsufficiency of RERE might be sufficient to cause many of the phenotypes associated with proximal 1p36 deletions.
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Incomplete penetrance of biallelic ALDH1A3 mutations. Eur J Med Genet 2016; 59:215-8. [PMID: 26873617 DOI: 10.1016/j.ejmg.2016.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 01/31/2016] [Accepted: 02/06/2016] [Indexed: 12/24/2022]
Abstract
The formation of a properly shaped eye is a complex developmental event that requires the coordination of many induction processes and differentiation pathways. Microphthalmia and anophthalmia (MA) represent the most severe defects that can affect the ocular globe during embryonic development. When genetic, these ocular disorders exhibit large genetic heterogeneity and extreme variable expressivity. Around 20 monogenic diseases are known to be associated with MA as main phenotype and the penetrance of mutations is usually full in the patients. Some of these genes encode proteins involved in the vitamin A pathway, tightly regulated during eye development. One of those retinoic acid synthesis genes is ALDH1A3 and biallelic mutations in that gene have been recently found to lead to MA phenotype in patients. Interestingly, we report here the lack of ocular defect in a girl carrying the same homozygous mutation in the ALDH1A3 gene than the affected members of her family. Thus, this report brings new information for the phenotype-genotype correlation of ALDH1A3 mutations and raises important questions, especially in terms of genetic counselling given to the patients and their families. Furthermore, these data contribute to the more general understanding that we have for the complex genetic inheritance of these MA phenotypes.
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Marcadier JL, Mears AJ, Woods EA, Fisher J, Airheart C, Qin W, Beaulieu CL, Dyment DA, Innes AM, Curry CJ. A novel mutation in two Hmong families broadens the range of STRA6-related malformations to include contractures and camptodactyly. Am J Med Genet A 2015; 170A:11-8. [PMID: 26373900 DOI: 10.1002/ajmg.a.37389] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 08/13/2015] [Indexed: 11/06/2022]
Abstract
PDAC (also termed Matthew Wood) syndrome is a rare, autosomal recessive disorder characterized by pulmonary hypoplasia/aplasia, diaphragmatic defects, bilateral anophthalmia, and cardiac malformations. The disorder is caused by mutations in STRA6, an important regulator of vitamin A and retinoic acid metabolism. We describe six cases from four families of Hmong ancestry, seen over a 30 years period in California. These include: (i) consanguineous siblings with a combination of bilateral anophthalmia, diaphragmatic abnormalities, truncus arteriosus, and/or pulmonary agenesis/hypoplasia; (ii) a singleton fetus with bilateral anophthalmia, pulmonary agenesis, cardiac malformation, and renal hypoplasia; (iii) a sibling pair with a combination of antenatal contractures, camptodactyly, fused palpebral fissures, pulmonary agenesis, and/or truncus arteriosus; (iv) a fetus with bilateral anophthalmia, bushy eyebrows, pulmonary agenesis, heart malformation, and abnormal hand positioning. The phenotypic spectrum of PDAC syndrome has until now not included contractures or camptodactyly. Sequencing of STRA6 in unrelated members of families three and four identified a novel, shared homozygous splice site alteration (c.113 + 3_4delAA) that is predicted to be pathogenic. We hypothesize this may represent a unique disease allele in the Hmong. We also provide a focused review of all published PDAC syndrome cases with confirmed or inferred STRA6 mutations, illustrating the phenotypic and molecular variability that characterizes this disorder.
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Affiliation(s)
- Julien L Marcadier
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Alan J Mears
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Jamie Fisher
- Genetic Medicine Central California, Fresno, California
| | - Cory Airheart
- Community Perinatology Medical Group, Fresno, California
| | - Wen Qin
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Chandree L Beaulieu
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - David A Dyment
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - A Micheil Innes
- Department of Medical Genetics and Alberta Children's Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, Alberta, Canada
| | - Cynthia J Curry
- Genetic Medicine Central California, Fresno, California.,Department of Pediatrics, University of California, San Francisco, California
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Vitamin A Transport Mechanism of the Multitransmembrane Cell-Surface Receptor STRA6. MEMBRANES 2015; 5:425-53. [PMID: 26343735 PMCID: PMC4584289 DOI: 10.3390/membranes5030425] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 08/24/2015] [Indexed: 12/18/2022]
Abstract
Vitamin A has biological functions as diverse as sensing light for vision, regulating stem cell differentiation, maintaining epithelial integrity, promoting immune competency, regulating learning and memory, and acting as a key developmental morphogen. Vitamin A derivatives have also been used in treating human diseases. If vitamin A is considered a drug that everyone needs to take to survive, evolution has come up with a natural drug delivery system that combines sustained release with precise and controlled delivery to the cells or tissues that depend on it. This "drug delivery system" is mediated by plasma retinol binding protein (RBP), the principle and specific vitamin A carrier protein in the blood, and STRA6, the cell-surface receptor for RBP that mediates cellular vitamin A uptake. The mechanism by which the RBP receptor absorbs vitamin A from the blood is distinct from other known cellular uptake mechanisms. This review summarizes recent progress in elucidating the fundamental molecular mechanism mediated by the RBP receptor and multiple newly discovered catalytic activities of this receptor, and compares this transport system with retinoid transport independent of RBP/STRA6. How to target this new type of transmembrane receptor using small molecules in treating diseases is also discussed.
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41
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Kelly M, von Lintig J. STRA6: role in cellular retinol uptake and efflux. Hepatobiliary Surg Nutr 2015; 4:229-42. [PMID: 26312242 DOI: 10.3978/j.issn.2304-3881.2015.01.12] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/13/2015] [Indexed: 12/11/2022]
Abstract
Distribution of vitamin A throughout the body is important to maintain retinoid function in peripheral tissues and to ensure optimal vision. A critical step of this process is the transport of vitamin A across cell membranes. Increasing evidence indicates that this process is mediated by a multidomian membrane protein that is encoded by the stimulated by retinoic acid 6 (STRA6) gene. Biochemical studies revealed that STRA6 is a transmembrane pore which transports vitamin A bidirectionally between extra- and intracellular retinoid binding proteins. Vitamin A accumulation in cells is driven by coupling of transport with vitamin A esterification. Loss-of-function studies in zebrafish and mouse models have unraveled the critical importance of STRA6 for vitamin A homeostasis of peripheral tissues. Impairment in vitamin A transport and uptake homeostasis are associated with diseases including type 2 diabetes and a microphthalmic syndrome known as Matthew Wood Syndrome. This review will discuss the advanced state of knowledge about STRA6's biochemistry, biology and association with disease.
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Affiliation(s)
- Mary Kelly
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Johannes von Lintig
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
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42
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Biochemical Basis for Dominant Inheritance, Variable Penetrance, and Maternal Effects in RBP4 Congenital Eye Disease. Cell 2015; 161:634-646. [PMID: 25910211 DOI: 10.1016/j.cell.2015.03.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/30/2015] [Accepted: 02/20/2015] [Indexed: 01/23/2023]
Abstract
Gestational vitamin A (retinol) deficiency poses a risk for ocular birth defects and blindness. We identified missense mutations in RBP4, encoding serum retinol binding protein, in three families with eye malformations of differing severity, including bilateral anophthalmia. The mutant phenotypes exhibit dominant inheritance, but incomplete penetrance. Maternal transmission significantly increases the probability of phenotypic expression. RBP normally delivers retinol from hepatic stores to peripheral tissues, including the placenta and fetal eye. The disease mutations greatly reduce retinol binding to RBP, yet paradoxically increase the affinity of RBP for its cell surface receptor, STRA6. By occupying STRA6 nonproductively, the dominant-negative proteins disrupt vitamin A delivery from wild-type proteins within the fetus, but also, in the case of maternal transmission, at the placenta. These findings establish a previously uncharacterized mode of maternal inheritance, distinct from imprinting and oocyte-derived mRNA, and define a group of hereditary disorders plausibly modulated by dietary vitamin A.
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43
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Reis LM, Semina EV. Conserved genetic pathways associated with microphthalmia, anophthalmia, and coloboma. ACTA ACUST UNITED AC 2015; 105:96-113. [PMID: 26046913 DOI: 10.1002/bdrc.21097] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/13/2015] [Indexed: 12/19/2022]
Abstract
The human eye is a complex organ whose development requires extraordinary coordination of developmental processes. The conservation of ocular developmental steps in vertebrates suggests possible common genetic mechanisms. Genetic diseases involving the eye represent a leading cause of blindness in children and adults. During the last decades, there has been an exponential increase in genetic studies of ocular disorders. In this review, we summarize current success in identification of genes responsible for microphthalmia, anophthalmia, and coloboma (MAC) phenotypes, which are associated with early defects in embryonic eye development. Studies in animal models for the orthologous genes identified overlapping phenotypes for most factors, confirming the conservation of their function in vertebrate development. These animal models allow for further investigation of the mechanisms of MAC, integration of various identified genes into common developmental pathways and finally, provide an avenue for the development and testing of therapeutic interventions.
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Affiliation(s)
- Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Cell Biology Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
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Breen CJ, Martin DS, Ma H, McQuaid K, O'Kennedy R, Findlay JBC. Production of functional human vitamin A transporter/RBP receptor (STRA6) for structure determination. PLoS One 2015; 10:e0122293. [PMID: 25816144 PMCID: PMC4376794 DOI: 10.1371/journal.pone.0122293] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 02/11/2015] [Indexed: 02/06/2023] Open
Abstract
STRA6 is a plasma membrane protein that mediates the transport of vitamin A, or retinol, from plasma retinol binding protein (RBP) into the cell. Mutations in human STRA6 are associated with Matthew-Wood syndrome, which is characterized by severe developmental defects. Despite the obvious importance of this protein to human health, little is known about its structure and mechanism of action. To overcome the difficulties frequently encountered with the production of membrane proteins for structural determination, STRA6 has been expressed in Pichia pastoris as a fusion to green fluorescent protein (GFP), a strategy which has been a critical first step in solving the crystal structures of several membrane proteins. STRA6-GFP was correctly targeted to the cell surface where it bound RBP. Here we report the large-scale expression, purification and characterisation of STRA6-GFP. One litre of culture, corresponding to 175 g cells, yielded about 1.5 mg of pure protein. The interaction between purified STRA6 and its ligand RBP was studied by surface plasmon resonance-based binding analysis. The interaction between STRA6 and RBP was not retinol-dependent and the binding data were consistent with a transient interaction of 1 mole RBP/mole STRA6.
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Affiliation(s)
- Conor J Breen
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
| | - Darren S Martin
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
| | - Hui Ma
- National Centre for Sensor Research, Biomedical Diagnostics Institute, Dublin City University, Dublin, Ireland
| | - Kate McQuaid
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
| | - Richard O'Kennedy
- National Centre for Sensor Research, Biomedical Diagnostics Institute, Dublin City University, Dublin, Ireland
| | - John B C Findlay
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
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Deml B, Kariminejad A, Borujerdi RHR, Muheisen S, Reis LM, Semina EV. Mutations in MAB21L2 result in ocular Coloboma, microcornea and cataracts. PLoS Genet 2015; 11:e1005002. [PMID: 25719200 PMCID: PMC4342166 DOI: 10.1371/journal.pgen.1005002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 01/14/2015] [Indexed: 12/12/2022] Open
Abstract
Ocular coloboma results from abnormal embryonic development and is often associated with additional ocular and systemic features. Coloboma is a highly heterogeneous disorder with many cases remaining unexplained. Whole exome sequencing from two cousins affected with dominant coloboma with microcornea, cataracts, and skeletal dysplasia identified a novel heterozygous allele in MAB21L2, c.151 C>G, p.(Arg51Gly); the mutation was present in all five family members with the disease and appeared de novo in the first affected generation of the three-generational pedigree. MAB21L2 encodes a protein similar to C. elegans mab-21 cell fate-determining factor; the molecular function of MAB21L2 is largely unknown. To further evaluate the role of MAB21L2, zebrafish mutants carrying a p.(Gln48Serfs*5) frameshift truncation (mab21l2Q48Sfs*5) and a p.(Arg51_Phe52del) in-frame deletion (mab21l2R51_F52del) were developed with TALEN technology. Homozygous zebrafish embryos from both lines developed variable lens and coloboma phenotypes: mab21l2Q48Sfs*5 embryos demonstrated severe lens and retinal defects with complete lethality while mab21l2R51_F52del mutants displayed a milder lens phenotype and severe coloboma with a small number of fish surviving to adulthood. Protein studies showed decreased stability for the human p.(Arg51Gly) and zebrafish p.(Arg51_Phe52del) mutant proteins and predicted a complete loss-of-function for the zebrafish p.(Gln48Serfs*5) frameshift truncation. Additionally, in contrast to wild-type human MAB21L2 transcript, mutant p.(Arg51Gly) mRNA failed to efficiently rescue the ocular phenotype when injected into mab21l2Q48Sfs*5 embryos, suggesting this allele is functionally deficient. Histology, immunohistochemistry, and in situ hybridization experiments identified retinal invagination defects, an increase in cell death, abnormal proliferation patterns, and altered expression of several ocular markers in the mab21l2 mutants. These findings support the identification of MAB21L2 as a novel factor involved in human coloboma and highlight the power of genome editing manipulation in model organisms for analysis of the effects of whole exome variation in humans.
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Affiliation(s)
- Brett Deml
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | | | | | - Sanaa Muheisen
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Linda M. Reis
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Elena V. Semina
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail:
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46
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Palczewski K. Chemistry and biology of the initial steps in vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2014; 55:6651-72. [PMID: 25338686 DOI: 10.1167/iovs.14-15502] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Visual transduction is the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain. The first challenge presented by visual transduction is to understand its molecular basis. We know that maintenance of vision is a continuous process requiring the activation and subsequent restoration of a vitamin A-derived chromophore through a series of chemical reactions catalyzed by enzymes in the retina and retinal pigment epithelium (RPE). Diverse biochemical approaches that identified key proteins and reactions were essential to achieve a mechanistic understanding of these visual processes. The three-dimensional arrangements of these enzymes' polypeptide chains provide invaluable insights into their mechanisms of action. A wealth of information has already been obtained by solving high-resolution crystal structures of both rhodopsin and the retinoid isomerase from pigment RPE (RPE65). Rhodopsin, which is activated by photoisomerization of its 11-cis-retinylidene chromophore, is a prototypical member of a large family of membrane-bound proteins called G protein-coupled receptors (GPCRs). RPE65 is a retinoid isomerase critical for regeneration of the chromophore. Electron microscopy (EM) and atomic force microscopy have provided insights into how certain proteins are assembled to form much larger structures such as rod photoreceptor cell outer segment membranes. A second challenge of visual transduction is to use this knowledge to devise therapeutic approaches that can prevent or reverse conditions leading to blindness. Imaging modalities like optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) applied to appropriate animal models as well as human retinal imaging have been employed to characterize blinding diseases, monitor their progression, and evaluate the success of therapeutic agents. Lately two-photon (2-PO) imaging, together with biochemical assays, are revealing functional aspects of vision at a new molecular level. These multidisciplinary approaches combined with suitable animal models and inbred mutant species can be especially helpful in translating provocative cell and tissue culture findings into therapeutic options for further development in animals and eventually in humans. A host of different approaches and techniques is required for substantial progress in understanding fundamental properties of the visual system.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
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Yin J, Morrissey ME, Shine L, Kennedy C, Higgins DG, Kennedy BN. Genes and signaling networks regulated during zebrafish optic vesicle morphogenesis. BMC Genomics 2014; 15:825. [PMID: 25266257 PMCID: PMC4190348 DOI: 10.1186/1471-2164-15-825] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Accepted: 09/24/2014] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The genetic cascades underpinning vertebrate early eye morphogenesis are poorly understood. One gene family essential for eye morphogenesis encodes the retinal homeobox (Rx) transcription factors. Mutations in the human retinal homeobox gene (RAX) can lead to gross morphological phenotypes ranging from microphthalmia to anophthalmia. Zebrafish rx3 null mutants produce a similar striking eyeless phenotype with an associated expanded forebrain. Thus, we used zebrafish rx3-/- mutants as a model to uncover an Rx3-regulated gene network during early eye morphogenesis. RESULTS Rx3-regulated genes were identified using whole transcriptomic sequencing (RNA-seq) of rx3-/- mutants and morphologically wild-type siblings during optic vesicle morphogenesis. A gene co-expression network was then constructed for the Rx3-regulated genes, identifying gene cross-talk during early eye development. Genes highly connected in the network are hub genes, which tend to exhibit higher expression changes between rx3-/- mutants and normal phenotype siblings. Hub genes down-regulated in rx3-/- mutants encompass homeodomain transcription factors and mediators of retinoid-signaling, both associated with eye development and known human eye disorders. In contrast, genes up-regulated in rx3-/- mutants are centered on Wnt signaling pathways, associated with brain development and disorders. The temporal expression pattern of Rx3-regulated genes was further profiled during early development from maternal stage until visual function is fully mature. Rx3-regulated genes exhibited synchronized expression patterns, and a transition of gene expression during the early segmentation stage when Rx3 was highly expressed. Furthermore, most of these deregulated genes are enriched with multiple RAX-binding motif sequences on the gene promoter. CONCLUSIONS Here, we assembled a comprehensive model of Rx3-regulated genes during early eye morphogenesis. Rx3 promotes optic vesicle morphogenesis and represses brain development through a highly correlated and modulated network, exhibiting repression of genes mediating Wnt signaling and concomitant enhanced expression of homeodomain transcription factors and retinoid-signaling genes.
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Affiliation(s)
- Jun Yin
- />UCD Conway Institute, UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4 Ireland
- />Department of Genetics, Yale University School of Medicine, New Haven, CT 06520 USA
| | - Maria E Morrissey
- />UCD Conway Institute, UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4 Ireland
| | - Lisa Shine
- />UCD Conway Institute, UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4 Ireland
| | - Ciarán Kennedy
- />UCD Conway Institute, UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4 Ireland
| | - Desmond G Higgins
- />UCD Conway Institute, UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4 Ireland
| | - Breandán N Kennedy
- />UCD Conway Institute, UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4 Ireland
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Williamson KA, FitzPatrick DR. The genetic architecture of microphthalmia, anophthalmia and coloboma. Eur J Med Genet 2014; 57:369-80. [PMID: 24859618 DOI: 10.1016/j.ejmg.2014.05.002] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 05/14/2014] [Indexed: 10/25/2022]
Abstract
Microphthalmia, anophthalmia and coloboma (MAC) are distinct phenotypes that represent a continuum of structural developmental eye defects. In severe bilateral cases (anophthalmia or severe microphthalmia) the genetic cause is now identifiable in approximately 80 percent of cases, with de novo heterozygous loss-of-function mutations in SOX2 or OTX2 being the most common. The genetic cause of other forms of MAC, in particular isolated coloboma, remains unknown in the majority of cases. This review will focus on MAC phenotypes that are associated with mutation of the genes SOX2, OTX2, PAX6, STRA6, ALDH1A3, RARB, VSX2, RAX, FOXE3, BMP4, BMP7, GDF3, GDF6, ABCB6, ATOH7, C12orf57, TENM3 (ODZ3), and VAX1. Recently reported mutation of the SALL2 and YAP1 genes are discussed in brief. Clinical and genetic features were reviewed in a total of 283 unrelated MAC cases or families that were mutation-positive from these 20 genes. Both the relative frequency of mutations in MAC cohort screens and the level of confidence in the assignment of disease-causing status were evaluated for each gene.
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Affiliation(s)
- Kathleen A Williamson
- Medical Research Council Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - David R FitzPatrick
- Medical Research Council Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK.
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49
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Amengual J, Zhang N, Kemerer M, Maeda T, Palczewski K, Von Lintig J. STRA6 is critical for cellular vitamin A uptake and homeostasis. Hum Mol Genet 2014; 23:5402-17. [PMID: 24852372 DOI: 10.1093/hmg/ddu258] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Vitamin A must be adequately distributed within the body to maintain the functions of retinoids in the periphery and chromophore production in the eyes. Blood transport of the lipophilic vitamin is mediated by the retinol-binding protein, RBP4. Biochemical evidence suggests that cellular uptake of vitamin A from RBP4 is facilitated by a membrane receptor. This receptor, identified as the Stimulated by retinoic acid gene 6 (Stra6) gene product, is highly expressed in epithelia that constitute blood-tissue barriers. Here we established a Stra6 knockout mouse model to analyze the metabolic basis of vitamin A homeostasis in peripheral tissues. These mice were viable when bred on diets replete in vitamin A, but evidenced markedly reduced levels of ocular retinoids. Ophthalmic imaging and histology revealed malformations in the choroid and retinal pigmented epithelium, early cone photoreceptor cell death, and reduced lengths of rod outer segments. Similar to the blood-retina barrier in the RPE, vitamin A transport through the blood-cerebrospinal fluid barrier in the brain's choroid plexus was impaired. Notably, treatment with pharmacological doses of vitamin A restored vitamin A transport across these barriers and rescued the vision of Stra6(-/-) mice. Furthermore, under conditions mimicking vitamin A excess and deficiency, our analyses revealed that STRA6-mediated vitamin A uptake is a regulated process mandatory for ocular vitamin A uptake when RBP4 constitutes the only transport mode in vitamin A deficiency. These findings identifying STRA6 as a bona fide vitamin A transporter have important implications for disease states associated with impaired blood vitamin A homeostasis.
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Affiliation(s)
| | - Ning Zhang
- Department of Pharmacology, School of Medicine
| | | | - Tadao Maeda
- Department of Pharmacology, School of Medicine, Department of Ophthalmology, School of Medicine
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH 44106, USA
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50
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Semerci CN, Kalay E, Yıldırım C, Dinçer T, Olmez A, Toraman B, Koçyiğit A, Bulgu Y, Okur V, Satıroğlu-Tufan L, Akarsu NA. Novel splice-site and missense mutations in the ALDH1A3 gene underlying autosomal recessive anophthalmia/microphthalmia. Br J Ophthalmol 2014; 98:832-40. [PMID: 24568872 DOI: 10.1136/bjophthalmol-2013-304058] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
AIM This study aimed to identify the underlying genetic defect responsible for anophthalmia/microphthalmia. METHODS In total, two Turkish families with a total of nine affected individuals were included in the study. Affymetrix 250 K single nucleotide polymorphism genotyping and homozygosity mapping were used to identify the localisation of the genetic defect in question. Coding region of the ALDH1A3 gene was screened via direct sequencing. cDNA samples were generated from primary fibroblast cell cultures for expression analysis. Reverse transcriptase PCR (RT-PCR) analysis was performed using direct sequencing of the obtained fragments. RESULTS The causative genetic defect was mapped to chromosome 15q26.3. A homozygous G>A substitution (c.666G>A) at the last nucleotide of exon 6 in the ALDH1A3 gene was identified in the first family. Further cDNA sequencing of ALDH1A3 showed that the c.666G>A mutation caused skipping of exon 6, which predicted in-frame loss of 43 amino acids (p.Trp180_Glu222del). A novel missense c.1398C>A mutation in exon 12 of ALDH1A3 that causes the substitution of a conserved asparagine by lysine at amino acid position 466 (p.Asn466Lys) was observed in the second family. No extraocular findings-except for nevus flammeus in one affected individual and a variant of Dandy-Walker malformation in another affected individual-were observed. Autistic-like behaviour and mental retardation were observed in three cases. CONCLUSIONS In conclusion, novel ALDH1A3 mutations identified in the present study confirm the pivotal role of ALDH1A3 in human eye development. Autistic features, previously reported as an associated finding, were considered to be the result of social deprivation and inadequate parenting during early infancy in the presented families.
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Affiliation(s)
- C Nur Semerci
- Department of Medical Genetics, School of Medicine, Pamukkale University, Denizli, Turkey
| | - Ersan Kalay
- Department of Medical Biology, School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Cem Yıldırım
- Department of Ophthalmology, School of Medicine, Pamukkale University, Denizli, Turkey
| | - Tuba Dinçer
- Department of Medical Biology, School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Akgün Olmez
- Department of Pediatric Neurology, Denizli State Hospital of Ministry of Health, Denizli, Turkey
| | - Bayram Toraman
- Department of Medical Biology, School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ali Koçyiğit
- Department of Radiology, School of Medicine, Pamukkale University, Denizli, Turkey
| | - Yunus Bulgu
- Department of Ophthalmology, State Hospital, Şuhut-Afyonkarahisar, Afyon, Turkey
| | - Volkan Okur
- Department of Medical Genetics, School of Medicine, Pamukkale University, Denizli, Turkey
| | - Lale Satıroğlu-Tufan
- Department of Medical Genetics, School of Medicine, Pamukkale University, Denizli, Turkey
| | - Nurten A Akarsu
- Department of Medical Genetics, Gene Mapping Laboratory, School of Medicine, Hacettepe University, Ankara, Turkey
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