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Ohuchi H, Sato K, Habuta M, Fujita H, Bando T. Congenital eye anomalies: More mosaic than thought? Congenit Anom (Kyoto) 2019; 59:56-73. [PMID: 30039880 DOI: 10.1111/cga.12304] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 07/16/2018] [Accepted: 07/17/2018] [Indexed: 12/13/2022]
Abstract
The eye is a sensory organ that primarily captures light and provides the sense of sight, as well as delivering non-visual light information involving biological rhythms and neurophysiological activities to the brain. Since the early 1990s, rapid advances in molecular biology have enabled the identification of developmental genes, genes responsible for human congenital diseases, and relevant genes of mutant animals with various anomalies. In this review, we first look at the development of the eye, and we highlight seminal reports regarding archetypal gene defects underlying three developmental ocular disorders in humans: (1) holoprosencephaly (HPE), with cyclopia being exhibited in the most severe cases; (2) microphthalmia, anophthalmia, and coloboma (MAC) phenotypes; and (3) anterior segment dysgenesis (ASDG), known as Peters anomaly and its related disorders. The recently developed methods, such as next-generation sequencing and genome editing techniques, have aided the discovery of gene mutations in congenital eye diseases and gene functions in normal eye development. Finally, we discuss Pax6-genome edited mosaic eyes and propose that somatic mosaicism in developmental gene mutations should be considered a causal factor for variable phenotypes, sporadic cases, and de novo mutations in human developmental disorders.
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Affiliation(s)
- Hideyo Ohuchi
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Keita Sato
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Munenori Habuta
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Hirofumi Fujita
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Tetsuya Bando
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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Abarca Barriga HH, Caballero N, Trubnykova M, Castro-Mujica MDC, La Serna-Infantes JE, Vásquez F, Hennekam RC. A novel ASPH variant extends the phenotype of Shawaf-Traboulsi syndrome. Am J Med Genet A 2018; 176:2494-2500. [PMID: 30194805 DOI: 10.1002/ajmg.a.40508] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/14/2018] [Accepted: 07/17/2018] [Indexed: 11/10/2022]
Abstract
Shawaf-Traboulsi syndrome (or Traboulsi syndrome; MIM 601552) is an infrequently reported entity characterized by a typical face (long face, large nose, convex nasal ridge, underdeveloped malae, crowded teeth, retrognathia), skeletal signs (long and slender fingers, sometimes pectus deformation and hypermobile joints), and ectopia lentis with conjunctival blebs, shallow anterior chamber and iridocorneal adhesions. The entity is caused by homozygous variants in ASPH. Here, we report on a boy with the clinical diagnosis of Shawaf-Traboulsi syndrome, in whom exome sequencing allowed identification of a novel variant in ASPH. We compare the findings in the present patient to those of earlier reported patients; furthermore add new signs for this entity.
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Affiliation(s)
- Hugo H Abarca Barriga
- Department of Genetic & Inborn Errors of Metabolism, Instituto Nacional de Salud del Niño, Lima, Peru.,Human Medicine Faculty, Universidad Ricardo Palma, Lima, Peru
| | | | - Milana Trubnykova
- Department of Genetic & Inborn Errors of Metabolism, Instituto Nacional de Salud del Niño, Lima, Peru
| | | | | | - Flor Vásquez
- Department of Genetic & Inborn Errors of Metabolism, Instituto Nacional de Salud del Niño, Lima, Peru
| | - Raoul C Hennekam
- Department of Pediatrics and Translational Genetics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Cheng MH, Tam CN, Choy KW, Tsang WH, Tsang SL, Pang CP, Song YQ, Sham MH. A γA-Crystallin Mouse Mutant Secc with Small Eye, Cataract and Closed Eyelid. PLoS One 2016; 11:e0160691. [PMID: 27513760 PMCID: PMC4981419 DOI: 10.1371/journal.pone.0160691] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 07/23/2016] [Indexed: 11/18/2022] Open
Abstract
Cataract is the most common cause of visual loss in humans. A spontaneously occurred, autosomal dominant mouse mutant Secc, which displayed combined features of small eye, cataract and closed eyelid was discovered in our laboratory. In this study, we identified the mutation and characterized the cataract phenotype of this novel Secc mutant. The Secc mutant mice have eyelids that remain half-closed throughout their life. The mutant lens has a significant reduction in size and with opaque spots clustered in the centre. Histological analysis showed that in the core region of the mutant lens, the fiber cells were disorganized and clefts and vacuoles were observed. The cataract phenotype was evident from new born stage. We identified the Secc mutation by linkage analysis using whole genome microsatellite markers and SNP markers. The Secc locus was mapped at chromosome 1 flanked by SNPs rs3158129 and rs13475900. Based on the chromosomal position, the candidate cataract locus γ-crystallin gene cluster (Cryg) was investigated by sequencing. A single base deletion (299delG) in exon 3 of Cryga which led to a frame-shift of amino acid sequence from position 91 was identified. As a result of this mutation, the sequences of the 3rd and 4th Greek-key motifs of the γA-crystallin are replaced with an unrelated C-terminal peptide of 75 residues long. Coincidentally, the point mutation generated a HindIII restriction site, allowing the identification of the CrygaSecc mutant allele by RFLP. Western blot analysis of 3-week old lenses showed that the expression of γ-crystallins was reduced in the CrygaSecc mutant. Furthermore, in cell transfection assays using CrygaSecc mutant cDNA expression constructs in 293T, COS-7 and human lens epithelial B3 cell lines, the mutant γA-crystallins were enriched in the insoluble fractions and appeared as insoluble aggregates in the transfected cells. In conclusion, we have demonstrated that the Secc mutation leads to the generation of CrygaSecc proteins with reduced solubility and prone to form aggregates within lens cells. Accumulation of mutant proteins in the lens fibers would lead to cataract formation in the Secc mutant.
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Affiliation(s)
- Man Hei Cheng
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Chung Nga Tam
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Kwong Wai Choy
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Wai Hung Tsang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Sze Lan Tsang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Chi Pui Pang
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - You Qiang Song
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Centre for Reproduction Development and Growth, Li Ka Shing Faculty of Medicine, Pokfulam, Hong Kong SAR, China
| | - Mai Har Sham
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Centre for Reproduction Development and Growth, Li Ka Shing Faculty of Medicine, Pokfulam, Hong Kong SAR, China
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Wang TH, Hsiong CH, Ho HT, Shih TY, Yen SJ, Wang HH, Wu JY, Kuo BPC, Chen YT, Ho ST, Hu OYP. Genetic polymorphisms of metabolic enzymes and the pharmacokinetics of indapamide in Taiwanese subjects. AAPS JOURNAL 2013; 16:206-13. [PMID: 24357089 DOI: 10.1208/s12248-013-9535-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 09/18/2013] [Indexed: 11/30/2022]
Abstract
To understand the genetic makeup and impact on pharmacokinetics (PK) in the Taiwanese population, we analyzed the pharmacogenetic (PG) profile and demonstrated its effects on enzyme metabolism using indapamide as an example. A multiplex mass spectrometry method was used to examine the single nucleotide polymorphism (SNP) profile of eight major phases I and II metabolic enzymes in 1,038 Taiwanese subjects. A PG/PK study was conducted in 24 healthy subjects to investigate the possible effects of 28 SNPs on drug biotransformation. Among the genetic profile analyzed, eight SNPs from CYP2A6, CYP2C19, CYP2D6, CYP2E1, CYP3A5, and UGT2B7 showed higher variant frequencies than those previously reported in Caucasians or Africans. For instance, we observed 14.7% frequency of the SNP rs5031016 (I471T) from CYP2A6 in Taiwanese, whereas 0% variation was reported in Caucasians and Africans. The PG/PK study of indapamide demonstrated that the polymorphic SNPs CYP2C9 rs4918758 and CYP2C19 rs4244285 appeared to confer lowered enzyme activity, as indicated by increased C max (25% ∼ 64%), increased area under the plasma level-time curves (30~76%), increased area under the time infinity (43% ∼ 80%), and lower apparent clearance values than PK for wild-type indapamide. Our results reinforce the biochemical support of CYP2C19 in indapamide metabolism and identify a possible new participating enzyme CYP2C9. The PG/PK approach contributed toward understanding the genetic makeup of different ethnic groups and associations of enzymes in drug metabolism. It could be used to identify two genetic markers that enable to differentiate subjects with varied PK outcomes of indapamide.
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Affiliation(s)
- Teng-Hsu Wang
- School of Pharmacy, National Defense Medical Center, P.O. Box 90048-512, Taipei, Taiwan, Republic of China
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Asai-Coakwell M, French CR, Berry KM, Ye M, Koss R, Somerville M, Mueller R, van Heyningen V, Waskiewicz AJ, Lehmann OJ. GDF6, a novel locus for a spectrum of ocular developmental anomalies. Am J Hum Genet 2007; 80:306-15. [PMID: 17236135 PMCID: PMC1785352 DOI: 10.1086/511280] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Accepted: 11/28/2006] [Indexed: 01/19/2023] Open
Abstract
Colobomata represent visually impairing ocular closure defects that are associated with a diverse range of developmental anomalies. Characterization of a chromosome 8q21.2-q22.1 segmental deletion in a patient with chorioretinal coloboma revealed elements of nonallelic homologous recombination and nonhomologous end joining. This genomic architecture extends the range of chromosomal rearrangements associated with human disease and indicates that a broader spectrum of human chromosomal rearrangements may use coupled homologous and nonhomologous mechanisms. We also demonstrate that the segmental deletion encompasses GDF6, encoding a member of the bone-morphogenetic protein family, and that inhibition of gdf6a in a model organism accurately recapitulates the proband's phenotype. The spectrum of disorders generated by morpholino inhibition and the more severe defects (microphthalmia and anophthalmia) observed at higher doses illustrate the key role of GDF6 in ocular development. These results underscore the value of integrated clinical and molecular investigation of patients with chromosomal anomalies.
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Affiliation(s)
- Mika Asai-Coakwell
- Department of Ophthalmology and Medical Genetics, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
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Abstract
PURPOSE OF REVIEW To integrate knowledge on the embryologic and molecular basis of optic fissure closure with clinical observations in patients with uveal coloboma. RECENT FINDINGS Closure of the optic fissure has been well characterized and many genetic alterations have been associated with coloboma; however, molecular mechanisms leading to coloboma remain largely unknown. In the past decade, we have gained better understanding of genes critical to eye development; however, mutations in these genes have been found in few individuals with coloboma. CHD7 mutations have been identified in patients with CHARGE syndrome (coloboma, heart defects, choanal atresia, retarded growth, genital anomalies, and ear anomalies or deafness). Animal models are bringing us closer to a molecular understanding of optic fissure closure. SUMMARY Optic fissure closure requires precise orchestration in timing and apposition of two poles of the optic cup. The relative roles of genetics and environment on this process remain elusive. While most cases of coloboma are sporadic, autosomal dominant, autosomal recessive, and X-linked inheritance patterns have been described. Genetically, colobomata demonstrate pleiotropy, heterogeneity, variable expressivity, and reduced penetrance. Coloboma is a complex disorder with a variable prognosis and requires regular examination to optimize visual acuity and to monitor for potential complications.
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Affiliation(s)
- Lan Chang
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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