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Ng BW, Kaukonen MK, McClements ME, Shamsnajafabadi H, MacLaren RE, Cehajic-Kapetanovic J. Genetic therapies and potential therapeutic applications of CRISPR activators in the eye. Prog Retin Eye Res 2024; 102:101289. [PMID: 39127142 DOI: 10.1016/j.preteyeres.2024.101289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 08/05/2024] [Accepted: 08/06/2024] [Indexed: 08/12/2024]
Abstract
Conventional gene therapy involving supplementation only treats loss-of-function diseases and is limited by viral packaging sizes, precluding therapy of large genes. The discovery of CRISPR/Cas has led to a paradigm shift in the field of genetic therapy, with the promise of precise gene editing, thus broadening the range of diseases that can be treated. The initial uses of CRISPR/Cas have focused mainly on gene editing or silencing of abnormal variants via utilising Cas endonuclease to trigger the target cell endogenous non-homologous end joining. Subsequently, the technology has evolved to modify the Cas enzyme and even its guide RNA, leading to more efficient editing tools in the form of base and prime editing. Further advancements of this CRISPR/Cas technology itself have expanded its functional repertoire from targeted editing to programmable transactivation, shifting the therapeutic focus to precise endogenous gene activation or upregulation with the potential for epigenetic modifications. In vivo experiments using this platform have demonstrated the potential of CRISPR-activators (CRISPRa) to treat various loss-of-function diseases, as well as in regenerative medicine, highlighting their versatility to overcome limitations associated with conventional strategies. This review summarises the molecular mechanisms of CRISPRa platforms, the current applications of this technology in vivo, and discusses potential solutions to translational hurdles for this therapy, with a focus on ophthalmic diseases.
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Affiliation(s)
- Benjamin Wj Ng
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK; Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Maria K Kaukonen
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK; Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Hoda Shamsnajafabadi
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Robert E MacLaren
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK; Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Jasmina Cehajic-Kapetanovic
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK; Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK.
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Jiang Y, Yi Z, Zheng Y, Ouyang J, Guo D, Li S, Xiao X, Wang P, Sun W, Zhang Q. The Systemic Genotype-Phenotype Characterization of PAX6-Related Eye Disease in 164 Chinese Families. Invest Ophthalmol Vis Sci 2024; 65:46. [PMID: 39212610 PMCID: PMC11364179 DOI: 10.1167/iovs.65.10.46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Accepted: 08/11/2024] [Indexed: 09/04/2024] Open
Abstract
Purpose This study aims to evaluate the genetic and phenotypic characteristics and elucidate the genotype-phenotype correlations of a large Chinese cohort with PAX6-related disorders. Methods Variants detected with exome sequencing were filtered through multistep bioinformatic and co-segregation analyses, and validated by Sanger sequencing. The related clinical data were collected, and cluster analysis and statistical analysis of the PAX6-related phenotypes across different variant groups were carried out. Parental mosaicism was investigated using cloning analysis and Droplet digital PCR. Results A total of 119 pathogenic or likely pathogenic PAX6 variants, including 74 truncation, 31 missense, and 14 others, were identified in 228 patients from 164 unrelated families. The most common phenotypes were foveal hypoplasia (97.8%), nystagmus (92.6%), aniridia (76.7%), cataract (36.8%), and iris hypoplasia (22.4%). Mosaicism ranging from 13.9% to 18.8% was identified in 3 unrelated patients' parents with relatively mild phenotypes. Missense variants in the linker region of the paired domain were associated with high myopia, whereas truncation variants in the homeodomain and proline-serine-threonine-rich domain were associated with hyperopia. Similarly, the degree of iris defects, visual acuity, and associated ocular comorbidity varied among the different types and locations of PAX6 variants. Conclusions Our data indicate that foveal hypoplasia but not aniridia is the most common sign of PAX6-related disorders, contributing to subtle iris changes that might easily be overlooked in clinical practice. Recognition of mosaicism in atypical cases or parents with very mild phenotypes is important in genetic counseling as their offspring are at increased risk of typical aniridia. Recognition of the genotype-phenotype relationship emphasizes involvement of PAX6 regulation in shaping complex ocular phenotypes.
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Affiliation(s)
- Yi Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Zhen Yi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Yuxi Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Jiamin Ouyang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Dongwei Guo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
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3
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Kuchalska K, Wawrocka A, Krawczynski MR. Novel variants in the PAX6 gene related to isolated aniridia. Congenit Anom (Kyoto) 2023. [PMID: 37191119 DOI: 10.1111/cga.12520] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 04/07/2023] [Accepted: 04/25/2023] [Indexed: 05/17/2023]
Abstract
Aniridia, which is a rare congenital defect of the eye, consists of iris hypoplasia or aplasia, and additional ocular abnormalities. It is most commonly caused by autosomal dominant PAX6 gene mutations. However, in about 30% of cases, it is associated with chromosomal rearrangements in the 11p13 region. The aim of this study was to identify the potential PAX6 gene variants, which could cause the isolated aniridia. Eight patients with isolated aniridia were included in this study. MLPA analysis allowed in the past to exclude large structural rearrangements of the PAX6 and adjacent genes like WT1. Blood samples were collected from the patients (and their families in familial cases) and genomic DNA was extracted from peripheral blood leukocytes and buccal cells. The amplification of the 11 exons of the PAX6 gene was performed. Bidirectional Sanger Sequencing was conducted for the identification of the potentially pathogenic variants, and for the segregation analysis of the identified variant in the family. The results were analyzed with the use of CodonCode Aligner software. In three patients, aniridia was sporadic, whereas in another five cases, the eye defect was familial. The potentially pathogenic variants in the PAX6 gene were found in 6 out of 8 patients with aniridia. We identified four known (c.781C > T, c.607C > T, and c.949C > T twice), and two novel variants (c.258_265del and c.495_496insG). Point mutations in the PAX6 gene are the most frequent cause of aniridia. The investigation of the genetic background of the disease is essential for patients to evaluate recurrence risk in the offspring.
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Affiliation(s)
| | - Anna Wawrocka
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
| | - Maciej R Krawczynski
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
- Center of Medical Genetics "Genesis", Poznan, Poland
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Mirjalili Mohanna SZ, Djaksigulova D, Hill AM, Wagner PK, Simpson EM, Leavitt BR. LNP-mediated delivery of CRISPR RNP for wide-spread in vivo genome editing in mouse cornea. J Control Release 2022; 350:401-413. [PMID: 36029893 DOI: 10.1016/j.jconrel.2022.08.042] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 01/02/2023]
Abstract
CRISPR/Cas9-based genome-editing therapies are poised to change the clinical outcome for many diseases with validated therapeutic targets awaiting an appropriate delivery system. Recent advances in lipid nanoparticle (LNP) technology make them an attractive platform for the delivery of various forms of CRISPR/Cas9, including the efficient and transient Cas9/gRNA ribonucleoprotein (RNP) complexes. In this study, we initially tested our novel LNP platform by delivering pre-complexed RNPs and template DNA to cultured mouse cortical neurons, and obtained successful ex vivo genome editing. We then directly injected LNP-packaged RNPs and DNA template into the mouse cornea to evaluate in vivo delivery. For the first time, we demonstrated wide-spread genome editing in the cornea using our LNP-RNPs. The ability of our LNPs to transfect the cornea highlights the potential of our novel delivery platform to be used in CRISPR/Cas9-based genome editing therapies of corneal diseases.
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Affiliation(s)
- Seyedeh Zeinab Mirjalili Mohanna
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC, Canada; Department of Medical Genetics, The University of British Columbia, Vancouver, BC, Canada
| | - Diana Djaksigulova
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC, Canada
| | | | | | - Elizabeth M Simpson
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC, Canada; Department of Medical Genetics, The University of British Columbia, Vancouver, BC, Canada.
| | - Blair R Leavitt
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC, Canada; Department of Medical Genetics, The University of British Columbia, Vancouver, BC, Canada; Incisive Genetics Inc., Vancouver, BC, Canada
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5
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Vasilyeva TA, Marakhonov AV, Kutsev SI, Zinchenko RA. Relative Frequencies of PAX6 Mutational Events in a Russian Cohort of Aniridia Patients in Comparison with the World's Population and the Human Genome. Int J Mol Sci 2022; 23:ijms23126690. [PMID: 35743132 PMCID: PMC9223373 DOI: 10.3390/ijms23126690] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/06/2022] [Accepted: 06/13/2022] [Indexed: 12/10/2022] Open
Abstract
Genome-wide sequencing metadata allows researchers to infer bias in the relative frequencies of mutational events and to predict putative mutagenic models. In addition, much less data could be useful in the evaluation of the mutational frequency spectrum and the prevalent local mutagenic process. Here we analyzed the PAX6 gene locus for mutational spectra obtained in our own and previous studies and compared them with data on other genes as well as the whole human genome. MLPA and Sanger sequencing were used for mutation searching in a cohort of 199 index patients from Russia with aniridia and aniridia-related phenotypes. The relative frequencies of different categories of PAX6 mutations were consistent with those previously reported by other researchers. The ratio between substitutions, small indels, and chromosome deletions in the 11p13 locus was within the interval previously published for 20 disease associated genomic loci, but corresponded to a higher end due to very high frequencies of small indels and chromosome deletions. The ratio between substitutions, small indels, and chromosome deletions for disease associated genes, including the PAX6 gene as well as the share of PAX6 missense mutations, differed considerably from those typical for the whole genome.
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Affiliation(s)
- Tatyana A. Vasilyeva
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (T.A.V.); (S.I.K.); (R.A.Z.)
| | - Andrey V. Marakhonov
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (T.A.V.); (S.I.K.); (R.A.Z.)
- Correspondence: ; Tel.: +7-499-320-60-90
| | - Sergey I. Kutsev
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (T.A.V.); (S.I.K.); (R.A.Z.)
| | - Rena A. Zinchenko
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (T.A.V.); (S.I.K.); (R.A.Z.)
- N.A. Semashko National Research Institute of Public Health, 105064 Moscow, Russia
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6
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Ouyang J, Cai Z, Guo Y, Nie F, Cao M, Duan X. Detection of a novel PAX6 variant in a Chinese family with multiple ocular abnormalities. BMC Ophthalmol 2022; 22:28. [PMID: 35034608 PMCID: PMC8761350 DOI: 10.1186/s12886-022-02256-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 01/05/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aniridia is a congenital, panocular disease that can affect the cornea, anterior chamber angle, iris, lens, retina and optic nerve. PAX6 loss-of-function variants are the most common cause of aniridia, and variants throughout the gene have been linked to a range of ophthalmic abnormalities. Furthermore, particular variants at a given site in PAX6 lead to distinct phenotypes. This study aimed to characterize genetic variants associated with congenital aniridia in a Chinese family. METHODS The proband and family underwent ophthalmologic examinations. DNA was sampled from the peripheral blood of all 6 individuals, and whole-exome sequencing was performed. Sanger sequencing was used to verify the variant in this family members. RESULTS A novel variant (c.114_119delinsAATTTCC: p.Pro39llefsTer17) in the PAX6 gene was identified in subjects II-1, III-1 and III-2, who exhibited complete aniridia and cataracts. The proband and the proband's brother also had glaucoma, high myopia, and foveal hypoplasia. CONCLUSIONS We identified that a novel PAX6 frameshift heterozygous deletion variant is the predominant cause of aniridia in this Chinese family. TRIAL REGISTRATION We did not perform any health-related interventions for the participants.
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Affiliation(s)
- Junyi Ouyang
- Jinan University, Guangzhou, Guangdong, China.,Aier School of Ophthalmology, Central South University, Changsha, Hunan, China.,Aier Glaucoma Research Institute, Changsha Aier Eye Hospital, Changsha, Hunan, China
| | - Ziyan Cai
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Yinjie Guo
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Fen Nie
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Mengdan Cao
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Xuanchu Duan
- Jinan University, Guangzhou, Guangdong, China. .,Aier School of Ophthalmology, Central South University, Changsha, Hunan, China. .,Aier Glaucoma Research Institute, Changsha Aier Eye Hospital, Changsha, Hunan, China.
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7
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Kit V, Cunha DL, Hagag AM, Moosajee M. Longitudinal genotype-phenotype analysis in 86 patients with PAX6-related aniridia. JCI Insight 2021; 6:e148406. [PMID: 34101622 PMCID: PMC8410060 DOI: 10.1172/jci.insight.148406] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/03/2021] [Indexed: 12/30/2022] Open
Abstract
Aniridia is most commonly caused by haploinsufficiency of the PAX6 gene, characterized by variable iris and foveal hypoplasia, nystagmus, cataracts, glaucoma, and aniridia-related keratopathy (ARK). Genotype-phenotype correlations have previously been described; however, detailed longitudinal studies of aniridia are less commonly reported. We identified 86 patients from 62 unrelated families with molecularly confirmed heterozygous PAX6 variants from a UK-based single-center ocular genetics service. They were categorized into mutation groups, and a retrospective review of clinical characteristics (ocular and systemic) from baseline to most recent was recorded. One hundred and seventy-two eyes were evaluated, with a mean follow-up period of 16.3 ± 12.7 years. Nystagmus was recorded in 87.2% of the eyes, and foveal hypoplasia was found in 75%. Cataracts were diagnosed in 70.3%, glaucoma in 20.6%, and ARK in 68.6% of eyes. Prevalence, age of diagnosis and surgical intervention, and need for surgical intervention varied among mutation groups. Overall, the missense mutation subgroup had the mildest phenotype, and surgically naive eyes maintained better visual acuity. Systemic evaluation identified type 2 diabetes in 12.8% of the study group, which is twice the UK prevalence. This is the largest longitudinal study of aniridia in the UK, and as such, it can provide insights into prognostic indicators for patients and guiding clinical management of both ocular and systemic features.
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Affiliation(s)
- Vivienne Kit
- Moorfields Eye Hospital, NHS Foundation Trust, London, United Kingdom.,UCL Institute of Ophthalmology, London, United Kingdom
| | | | - Ahmed M Hagag
- Moorfields Eye Hospital, NHS Foundation Trust, London, United Kingdom.,UCL Institute of Ophthalmology, London, United Kingdom
| | - Mariya Moosajee
- Moorfields Eye Hospital, NHS Foundation Trust, London, United Kingdom.,UCL Institute of Ophthalmology, London, United Kingdom.,Great Ormond Street Hospital for Children, NHS Foundation Trust, London, United Kingdom.,The Francis Crick Institute, London, United Kingdom
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8
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Jin X, Liu W, Qv LH, X WQ, Huang HB. A novel variant in PAX6 as the cause of aniridia in a Chinese family. BMC Ophthalmol 2021; 21:225. [PMID: 34016071 PMCID: PMC8136215 DOI: 10.1186/s12886-021-01848-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 02/05/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Aniridia is a kind of congenital human pan-ocular anomaly, which is related to PAX6 commonly. METHODS The ophthalmic examinations including visual acuity, slit lamp and fundoscopy examination were performed in a Chinese aniridia pedigree. The targeted next-generation sequencing of aniridia genes was used to identify the causative mutation. RESULTS A novel heterozygous PAX6 nonsense mutation c.619A > T (p.K207*) was identified in the Chinese autosomal dominant family with aniridia. Phenotype related to the novel mutation included nystagmus, keratopathy, absence of iris, cataract and foveal hypoplasia. CONCLUSIONS The novel nonsense variation in PAX6 was the cause of aniridia in this family, which expanded the spectrum of the PAX6 mutation.
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Affiliation(s)
- X Jin
- Department of Ophthalmology, Chinese PLA General Hospital, 100853, Beijing, China
| | - W Liu
- Department of Ophthalmology, Hainan Hospital of Chinese PLA General Hospital, 572000, Sanya, Hainan Province, China
| | - L H Qv
- Department of Ophthalmology, the 74th Army Group Hospital, 510318, Guangzhou, China
| | - W Q X
- Department of Ophthalmology, Chinese PLA General Hospital, 100853, Beijing, China
| | - H B Huang
- Department of Ophthalmology, Chinese PLA General Hospital, 100853, Beijing, China.
- Department of Ophthalmology, Hainan Hospital of Chinese PLA General Hospital, 572000, Sanya, Hainan Province, China.
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
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9
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Gopinathan NV, Rajkumar S, Vasavada AR. A rare association of aniridia with conjunctival xerosis in two Indian siblings with PAX6 mutation. Indian J Ophthalmol 2020; 68:2635-2637. [PMID: 33120723 PMCID: PMC7774223 DOI: 10.4103/ijo.ijo_2185_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Nair Vidya Gopinathan
- Department of Pediatric Ophthalmology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat, India
| | - Sankaranarayanan Rajkumar
- Department of Pediatric Ophthalmology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat; Department of Ophthalmic Genetics, Aditya Jyot Foundation for Twinkling Little Eyes, Mumbai, Maharashtra, India
| | - Abhay Raghukant Vasavada
- Department of Pediatric Ophthalmology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat, India
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10
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Cross E, Duncan-Flavell PJ, Howarth RJ, Crooks RO, Thomas NS, Bunyan DJ. Screening of a large PAX6 cohort identified many novel variants and emphasises the importance of the paired and homeobox domains. Eur J Med Genet 2020; 63:103940. [DOI: 10.1016/j.ejmg.2020.103940] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/20/2019] [Accepted: 04/23/2020] [Indexed: 12/21/2022]
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Grant MK, Bobilev AM, Rasys AM, Branson Byers J, Schriever HC, Hekmatyar K, Lauderdale JD. Global and age-related neuroanatomical abnormalities in a Pax6-deficient mouse model of aniridia suggests a role for Pax6 in adult structural neuroplasticity. Brain Res 2020; 1732:146698. [PMID: 32014531 PMCID: PMC10712278 DOI: 10.1016/j.brainres.2020.146698] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 01/14/2020] [Accepted: 01/30/2020] [Indexed: 12/29/2022]
Abstract
PAX6 encodes a highly conserved transcription factor necessary for normal development of the eyes and central nervous system. Heterozygous loss-of-function mutations in PAX6 cause the disorder aniridia in humans and the Small eye trait in mice. Aniridia is a congenital and progressive disorder known for ocular phenotypes; however, recently, consequences of PAX6 haploinsufficiency in the brains of aniridia patients have been identified. These findings span structural and functional abnormalities, including deficits in cognitive and sensory processing. Furthermore, some of these abnormalities are accelerated as aniridia patients age. Although some functional abnormalities may be explained by structural changes, variability of results remain, and the effects of PAX6 heterozygous loss-of-function mutations on neuroanatomy, particularly with regard to aging, have yet to be resolved. Our study used high-resolution magnetic resonance imaging (MRI) and histology to investigate structural consequences of such mutations in the adult brain of our aniridia mouse model, Small eye Neuherberg allele (Pax6SeyNeu/+), at two adult age groups. Using both MRI and histology enables a direct comparison with human studies, while providing higher resolution for detection of more subtle changes. We show volumetric changes in major brain regions of the the Pax6SeyNeu/+ mouse compared to wild-type including genotype- and age-related olfactory bulb differences, age-related cerebellum differences, and genotype-related eye differences. We also show alterations in thickness of major interhemispheric commissures, particularly those anteriorly located within the brain including the optic chiasm, corpus callosum, and anterior commissure. Together, these genotype and age related changes to brain volumes and structures suggest a global decrease in adult brain structural plasticity in our Pax6SeyNeu/+ mice.
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Affiliation(s)
- Madison K Grant
- Department of Cellular Biology, University of Georgia, 250B Coverdell Center, 500 D.W. Brooks Drive, Athens, GA 30602, United States.
| | - Anastasia M Bobilev
- Department of Psychiatry, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, United States; Neuroscience Division of the Biomedical and Health Sciences Institute, The University of Georgia, Athens, GA 30602, United States.
| | - Ashley M Rasys
- Department of Cellular Biology, University of Georgia, 250B Coverdell Center, 500 D.W. Brooks Drive, Athens, GA 30602, United States.
| | - J Branson Byers
- Department of Cellular Biology, University of Georgia, 250B Coverdell Center, 500 D.W. Brooks Drive, Athens, GA 30602, United States.
| | - Hannah C Schriever
- Department of Cellular Biology, University of Georgia, 250B Coverdell Center, 500 D.W. Brooks Drive, Athens, GA 30602, United States.
| | - Khan Hekmatyar
- Bio-imaging Research Center, University of Georgia, Coverdell Center, 500 D.W. Brooks Drive, Athens, GA 30602, United States.
| | - James D Lauderdale
- Department of Cellular Biology, University of Georgia, 250B Coverdell Center, 500 D.W. Brooks Drive, Athens, GA 30602, United States; Neuroscience Division of the Biomedical and Health Sciences Institute, The University of Georgia, Athens, GA 30602, United States.
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12
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Mirjalili Mohanna SZ, Hickmott JW, Lam SL, Chiu NY, Lengyell TC, Tam BM, Moritz OL, Simpson EM. Germline CRISPR/Cas9-Mediated Gene Editing Prevents Vision Loss in a Novel Mouse Model of Aniridia. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 17:478-490. [PMID: 32258211 PMCID: PMC7114625 DOI: 10.1016/j.omtm.2020.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 03/09/2020] [Indexed: 12/18/2022]
Abstract
Aniridia is a rare eye disorder, which is caused by mutations in the paired box 6 (PAX6) gene and results in vision loss due to the lack of a long-term vision-saving therapy. One potential approach to treating aniridia is targeted CRISPR-based genome editing. To enable the Pax6 small eye (Sey) mouse model of aniridia, which carries the same mutation found in patients, for preclinical testing of CRISPR-based therapeutic approaches, we endogenously tagged the Sey allele, allowing for the differential detection of protein from each allele. We optimized a correction strategy in vitro then tested it in vivo in the germline of our new mouse to validate the causality of the Sey mutation. The genomic manipulations were analyzed by PCR, as well as by Sanger and next-generation sequencing. The mice were studied by slit lamp imaging, immunohistochemistry, and western blot analyses. We successfully achieved both in vitro and in vivo germline correction of the Sey mutation, with the former resulting in an average 34.8% ± 4.6% SD correction, and the latter in restoration of 3xFLAG-tagged PAX6 expression and normal eyes. Hence, in this study we have created a novel mouse model for aniridia, demonstrated that germline correction of the Sey mutation alone rescues the mutant phenotype, and developed an allele-distinguishing CRISPR-based strategy for aniridia.
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Affiliation(s)
- Seyedeh Zeinab Mirjalili Mohanna
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC V5Z 4H4, Canada.,Department of Medical Genetics, The University of British Columbia, Vancouver, BC, Canada
| | - Jack W Hickmott
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC V5Z 4H4, Canada.,Department of Medical Genetics, The University of British Columbia, Vancouver, BC, Canada
| | - Siu Ling Lam
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Nina Y Chiu
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC V5Z 4H4, Canada.,Department of Medical Genetics, The University of British Columbia, Vancouver, BC, Canada
| | - Tess C Lengyell
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Beatrice M Tam
- Department of Ophthalmology and Visual Sciences and Centre for Macular Research, The University of British Columbia, Vancouver, BC, Canada
| | - Orson L Moritz
- Department of Ophthalmology and Visual Sciences and Centre for Macular Research, The University of British Columbia, Vancouver, BC, Canada
| | - Elizabeth M Simpson
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, The University of British Columbia, Vancouver, BC V5Z 4H4, Canada.,Department of Medical Genetics, The University of British Columbia, Vancouver, BC, Canada
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13
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Shields LBE, Peppas DS, Rosenberg E. Bilateral aniridia and congenital ureteral valve: Role of genetic testing. Mol Genet Genomic Med 2020; 8:e1183. [PMID: 32056389 PMCID: PMC7196450 DOI: 10.1002/mgg3.1183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/09/2020] [Accepted: 01/30/2020] [Indexed: 02/05/2023] Open
Abstract
Background Congenital aniridia involves total or partial hypoplasia of the iris and is due to a deficiency in PAX6 gene expression. WAGR syndrome is comprised of Wilms tumor, aniridia, genitourinary abnormalities, and intellectual disability. Numerous genitourinary pathologies may be associated with WAGR syndrome, necessitating an evaluation of the genitourinary anatomy. The WT1 is vital for the development of kidneys, ovaries in females, and testes in males. WT1 gene mutations result in a WT1 protein with a decreased ability to bind to DNA, leading to uncontrolled growth, and cell division in the kidney which permits the development of Wilms tumor. A congenital ureteral valve is an exceedingly rare cause of obstructive uropathy. Results A renal and bladder ultrasound demonstrated a renal cyst. A voiding cystourethrogram revealed grade 3 vesicoureteral reflux, and a MAG3 renal scan showed ureteropelvic junction obstruction and hydronephrosis. A ureteral stent was inserted at 3 months of age after which the renal cyst resolved. The patient was urinary tract infection‐free at 27 months of age. Genetic testing confirmed a heterozygous alteration in PAX6 (c.495delG, p.Thr166Leufs*41) and no abnormalities of WT1, excluding WAGR syndrome. Conclusion The genitourinary risks potentially associated with aniridia necessitate prompt genetic analysis to evaluate for WAGR syndrome.
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Affiliation(s)
- Lisa B E Shields
- Norton Neuroscience Institute, Norton Healthcare, Louisville, KY, USA
| | - Dennis S Peppas
- Norton Children's Urology, Norton Healthcare, Louisville, KY, USA
| | - Eran Rosenberg
- Norton Children's Urology, Norton Healthcare, Louisville, KY, USA
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14
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Lima Cunha D, Arno G, Corton M, Moosajee M. The Spectrum of PAX6 Mutations and Genotype-Phenotype Correlations in the Eye. Genes (Basel) 2019; 10:genes10121050. [PMID: 31861090 PMCID: PMC6947179 DOI: 10.3390/genes10121050] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/09/2019] [Accepted: 12/12/2019] [Indexed: 12/13/2022] Open
Abstract
The transcription factor PAX6 is essential in ocular development in vertebrates, being considered the master regulator of the eye. During eye development, it is essential for the correct patterning and formation of the multi-layered optic cup and it is involved in the developing lens and corneal epithelium. In adulthood, it is mostly expressed in cornea, iris, and lens. PAX6 is a dosage-sensitive gene and it is highly regulated by several elements located upstream, downstream, and within the gene. There are more than 500 different mutations described to affect PAX6 and its regulatory regions, the majority of which lead to PAX6 haploinsufficiency, causing several ocular and systemic abnormalities. Aniridia is an autosomal dominant disorder that is marked by the complete or partial absence of the iris, foveal hypoplasia, and nystagmus, and is caused by heterozygous PAX6 mutations. Other ocular abnormalities have also been associated with PAX6 changes, and genotype-phenotype correlations are emerging. This review will cover recent advancements in PAX6 regulation, particularly the role of several enhancers that are known to regulate PAX6 during eye development and disease. We will also present an updated overview of the mutation spectrum, where an increasing number of mutations in the non-coding regions have been reported. Novel genotype-phenotype correlations will also be discussed.
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Affiliation(s)
| | - Gavin Arno
- Institute of Ophthalmology, UCL, 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
| | - Marta Corton
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital—Universidad Autónoma de Madrid (IIS-FJD, UAM), 28040 Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Mariya Moosajee
- Institute of Ophthalmology, UCL, 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
- Correspondence:
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15
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Mirrahimi M, Sabbaghi H, Ahmadieh H, Jahanmard M, Hassanpour K, Suri F. A novel PAX6 mutation causes congenital aniridia with or without retinal detachment. Ophthalmic Genet 2019; 40:146-149. [DOI: 10.1080/13816810.2019.1597374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Mehraban Mirrahimi
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamideh Sabbaghi
- Ophthalmic Epidemiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamid Ahmadieh
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehdi Jahanmard
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Kiana Hassanpour
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Suri
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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16
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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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17
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Pedersen HR, Neitz M, Gilson SJ, Landsend ECS, Utheim ØA, Utheim TP, Baraas RC. The Cone Photoreceptor Mosaic in Aniridia: Within-Family Phenotype-Genotype Discordance. Ophthalmol Retina 2019; 3:523-534. [PMID: 31174676 DOI: 10.1016/j.oret.2019.01.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/30/2019] [Accepted: 01/30/2019] [Indexed: 02/01/2023]
Abstract
PURPOSE Investigate in vivo cone photoreceptor structure in familial aniridia caused by deletion in the PAX6 gene to elucidate the complexity of between-individual variation in retinal phenotype. DESIGN Descriptive case-control study. PARTICIPANTS Eight persons with congenital aniridia (40-66 yrs) from 1 family and 33 normal control participants (14-69 yrs), including 7 unaffected family members (14-53 yrs). METHODS DNA was isolated from saliva samples and used in polymerase chain reaction analysis to amplify and sequence exons and intron or exon junctions of the PAX6 gene. High-resolution retinal images were acquired with OCT and adaptive optics scanning light ophthalmoscopy. Cone density (CD; in cones per square millimeter) and mosaic regularity were estimated along nasal-temporal meridians within the central 0° to 5° eccentricity. Horizontal spectral-domain OCT line scans were segmented to analyze the severity of foveal hypoplasia (FH) and to measure retinal layer thicknesses. MAIN OUTCOMES AND MEASURES Within-family variability in macular retinal layer thicknesses, cone photoreceptor density, and mosaic regularity in aniridia compared with normal control participants. RESULTS DNA sequencing revealed a known PAX6 mutation (IV2-2delA). Those with aniridia showed variable iris phenotype ranging from almost normal appearance to no iris. Four participants with aniridia demonstrated FH grade 2, 2 demonstrated grade 3 FH, and 1 demonstrated grade 4 FH. Visual acuity ranged from 0.20 to 0.86 logarithm of the minimum angle of resolution. Adaptive optics scanning light ophthalmoscopy images were acquired from 5 family members with aniridia. Foveal CD varied between 19 899 and 55 128 cones/mm2 with overlap between the foveal hypoplasia grades. Cone density was 3 standard deviations (SDs) or more less than the normal mean within 0.5°, 2 SDs less than the normal mean at 0.5° to 4°, and more than 1 SD less than the normal mean at 5° retinal eccentricity. CONCLUSIONS The results showed considerable variability in foveal development within a family carrying the same PAX6 mutation. This, together with the structural and functional variability within each grade of foveal hypoplasia, underlines the importance of advancing knowledge about retinal cellular phenotype in aniridia.
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Affiliation(s)
- Hilde R Pedersen
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway
| | - Maureen Neitz
- Department of Ophthalmology, University of Washington, Seattle, Washington
| | - Stuart J Gilson
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway
| | | | | | - Tor Paaske Utheim
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway; Department of Ophthalmology, Oslo University Hospital, Oslo, Norway
| | - Rigmor C Baraas
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway.
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18
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Pedersen HR, Hagen LA, Landsend ECS, Gilson SJ, Utheim ØA, Utheim TP, Neitz M, Baraas RC. Color Vision in Aniridia. Invest Ophthalmol Vis Sci 2019; 59:2142-2152. [PMID: 29801149 PMCID: PMC6110168 DOI: 10.1167/iovs.17-23047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Purpose To assess color vision and its association with retinal structure in persons with congenital aniridia. Methods We included 36 persons with congenital aniridia (10–66 years), and 52 healthy, normal trichromatic controls (10–74 years) in the study. Color vision was assessed with Hardy-Rand-Rittler (HRR) pseudo-isochromatic plates (4th ed., 2002); Cambridge Color Test and a low-vision version of the Color Assessment and Diagnosis test (CAD-LV). Cone-opsin genes were analyzed to confirm normal versus congenital color vision deficiencies. Visual acuity and ocular media opacities were assessed. The central 30° of both eyes were imaged with the Heidelberg Spectralis OCT2 to grade the severity of foveal hypoplasia (FH, normal to complete: 0–4). Results Five participants with aniridia had cone opsin genes conferring deutan color vision deficiency and were excluded from further analysis. Of the 31 with aniridia and normal opsin genes, 11 made two or more red-green (RG) errors on HRR, four of whom also made yellow-blue (YB) errors; one made YB errors only. A total of 19 participants had higher CAD-LV RG thresholds, of which eight also had higher CAD-LV YB thresholds, than normal controls. In aniridia, the thresholds were higher along the RG than the YB axis, and those with a complete FH had significantly higher RG thresholds than those with mild FH (P = 0.038). Additional increase in YB threshold was associated with secondary ocular pathology. Conclusions Arrested foveal formation and associated alterations in retinal processing are likely to be the primary reason for impaired red-green color vision in aniridia.
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Affiliation(s)
- Hilde R Pedersen
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University College of Southeast Norway, Kongsberg, Norway
| | - Lene A Hagen
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University College of Southeast Norway, Kongsberg, Norway
| | | | - Stuart J Gilson
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University College of Southeast Norway, Kongsberg, Norway
| | - Øygunn A Utheim
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway.,Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway
| | - Tor P Utheim
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University College of Southeast Norway, Kongsberg, Norway.,Department of Ophthalmology, Oslo University Hospital, Oslo, Norway.,Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.,Department of Ophthalmology, Drammen Hospital, Drammen, Norway
| | - Maureen Neitz
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Rigmor C Baraas
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University College of Southeast Norway, Kongsberg, Norway
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19
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Tarilonte M, Morín M, Ramos P, Galdós M, Blanco-Kelly F, Villaverde C, Rey-Zamora D, Rebolleda G, Muñoz-Negrete FJ, Tahsin-Swafiri S, Gener B, Moreno-Pelayo MA, Ayuso C, Villamar M, Corton M. Parental Mosaicism in PAX6 Causes Intra-Familial Variability: Implications for Genetic Counseling of Congenital Aniridia and Microphthalmia. Front Genet 2018; 9:479. [PMID: 30386378 PMCID: PMC6199369 DOI: 10.3389/fgene.2018.00479] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 09/26/2018] [Indexed: 11/17/2022] Open
Abstract
Mutations in PAX6 are involved in several developmental eye disorders. These disorders have considerable phenotypic variability, ranging from panocular forms of congenital aniridia and microphthalmia to isolated anomalies of the anterior or posterior segment. Here, we describe 3 families with variable inter-generational ocular expression of aniridia, iris coloboma, or microphthalmia, and an unusual transmission of PAX6 mutations from an unaffected or mildly affected parent; all of which raised suspicion of gonosomal mosaicism. We first identified two previously known nonsense mutations and one novel likely pathogenic missense variant in PAX6 in probands by means of targeted NGS. The subsequent segregation analysis by Sanger sequencing evidenced the presence of highly probable mosaic events in paternal blood samples. Mosaicism was further confirmed by droplet digital PCR analysis in several somatic tissues of mosaic fathers. Quantification of the mutant allele fraction in parental samples showed a marked deviation from 50%, with a range between 12 and 29% depending on cell type. Gonosomal mosaicsm was definitively confirmed in one of the families thanks to the availability of a sperm sample from the mosaic father. Thus, the recurrence risk in this family was estimated to be about one-third. This is the first report confirming parental PAX6 mosaicism as a cause of disease recurrence in aniridia and other related phenotypes. In addition, we demonstrated that post-zygotic mosaicism is a frequent and underestimated pathogenic mechanism in aniridia, explaining intra-familial phenotypic variability in many cases. Our findings may have substantial implications for genetic counseling in congenital aniridia. Thus, we also highlight the importance of comprehensive genetic screening of parents for new sporadic cases with aniridia or related developmental eye disease to more accurately assess recurrence risk. In conclusion, somatic and/or gonosomal mosaicism should be taken into consideration as a genetic factor to explain not only families with unaffected parents despite multiple affected children but also variable expressivity, apparent de novo cases, and even uncharacterized cases of aniridia and related developmental eye disorders, apparently lacking PAX6 mutations.
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Affiliation(s)
- María Tarilonte
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain
| | - Matías Morín
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Patricia Ramos
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Galdós
- Department of Ophthalmology, Cruces University Hospital, Bilbao, Spain
| | - Fiona Blanco-Kelly
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Cristina Villaverde
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Dolores Rey-Zamora
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Gema Rebolleda
- Department of Glaucoma, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Francisco J Muñoz-Negrete
- Department of Glaucoma, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Saoud Tahsin-Swafiri
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Blanca Gener
- Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain.,Department of Genetics, BioCruces Health Research Institute, Cruces University Hospital, Bilbao, Spain
| | - Miguel-Angel Moreno-Pelayo
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Carmen Ayuso
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Manuela Villamar
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Corton
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
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20
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Bai Z, Kong X. Extension of the mutation spectrum of PAX6 from three Chinese congenital aniridia families and identification of male gonadal mosaicism. Mol Genet Genomic Med 2018; 6:1053-1067. [PMID: 30334364 PMCID: PMC6305634 DOI: 10.1002/mgg3.481] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/19/2018] [Accepted: 08/21/2018] [Indexed: 12/29/2022] Open
Abstract
Background Congenital aniridia is a severe autosomal dominant binocular developmental disorder, the primary feature of which is congenital absence or hypoplasia of the iris. PAX6 is the main disease‐causing gene of congenital aniridia; inheritance is autosomal dominant. But the current mutations do not fully explain this disorder. Methods We investigated the mutation profile of genes related in three Chinese families with congenital aniridia through targeted sequencing technology. And we validated the candidate variants by PCR‐based Sanger sequencing. Different degree impairments of islet function were observed in the patients with aniridia by carbohydrate tolerance butter and insulin release tests in our study. Results We identified four novel mutations of PAX6 from three Chinese families with congenital aniridia, which included heterozygous double mutation c.879_880delCA (p.S294Cfs*46) and c.1124C>G (p.P375R) in Family 1 with three patients, heterozygous frameshift mutation c.308delG (p.P103Qfs*21) in Family 2 with one patient, and c.1192delT (p.S398Pfs*126) in Family 3 with two patients. The three frameshift mutations of PAX6 are co‐segregated with the aniridia from controls in the families, but the novel missense mutation is not co‐segregated with the phenotype. The frameshift mutations in Family 1 and Family 2 have effects to truncate the protein, but the frameshift mutation in Family 3 will prolong it. We confirmed the phenomenon of male gonadal mosaicism of PAX6 by the sequencing of two linked novel mutations in Family 1. Most of the patients with isolated aniridia have different degrees of islet damage through related clinical tests. Conclusion It is therefore noteworthy that we found different types of pathogenic mutation, which have effects of truncating or prolonging protein leaded by frameshift mutation. Our results of this study extended the pathogenic mutation spectrum of PAX6 for congenital aniridia and demonstrated the male germline chimerism by molecular experiments.
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Affiliation(s)
- Zhouxian Bai
- Genetic and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiangdong Kong
- Genetic and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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21
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Plaisancié J, Tarilonte M, Ramos P, Jeanton-Scaramouche C, Gaston V, Dollfus H, Aguilera D, Kaplan J, Fares-Taie L, Blanco-Kelly F, Villaverde C, Francannet C, Goldenberg A, Arroyo I, Rozet JM, Ayuso C, Chassaing N, Calvas P, Corton M. Implication of non-coding PAX6 mutations in aniridia. Hum Genet 2018; 137:831-846. [PMID: 30291432 DOI: 10.1007/s00439-018-1940-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/23/2018] [Indexed: 01/14/2023]
Abstract
There is an increasing implication of non-coding regions in pathological processes of genetic origin. This is partly due to the emergence of sophisticated techniques that have transformed research into gene expression by allowing a more global understanding of the genome, both at the genomic, epigenomic and chromatin levels. Here, we implemented the analysis of PAX6, whose coding loss-of-function variants are mainly implied in aniridia, by studying its non-coding regions (untranslated regions, introns and cis-regulatory sequences). In particular, we have taken advantage of the development of high-throughput approaches to screen the upstream and downstream regulatory regions of PAX6 in 47 aniridia patients without identified mutation in the coding sequence. This was made possible through the use of custom targeted resequencing and/or CGH array to analyze the entire PAX6 locus on 11p13. We found candidate variants in 30 of the 47 patients. 9/30 correspond to the well-known described 3' deletions encompassing SIMO and other enhancer elements. In addition, we identified numerous different variants in various non-coding regions, in particular untranslated regions. Among these latter, most of them demonstrated an in vitro functional effect using a minigene strategy, and 12/21 are thus considered as causative mutations or very likely to explain the phenotypes. This new analysis strategy brings molecular diagnosis to more than 90% of our aniridia patients. This study revealed an outstanding mutation pattern in non-coding PAX6 regions confirming that PAX6 remains the major gene for aniridia.
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Affiliation(s)
- Julie Plaisancié
- Service de Génétique Médicale, Pavillon Lefebvre, Hôpital Purpan, CHU Toulouse, Place du Dr Baylac, 31059, Toulouse Cedex 9, France.
- INSERM U1056, Université Toulouse III, Toulouse, France.
| | - M Tarilonte
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz University Hospital-Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - P Ramos
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz University Hospital-Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - C Jeanton-Scaramouche
- Service de Génétique Médicale, Pavillon Lefebvre, Hôpital Purpan, CHU Toulouse, Place du Dr Baylac, 31059, Toulouse Cedex 9, France
| | - V Gaston
- Service de Génétique Médicale, Pavillon Lefebvre, Hôpital Purpan, CHU Toulouse, Place du Dr Baylac, 31059, Toulouse Cedex 9, France
| | - H Dollfus
- Centre de Référence pour les affections rares en génétique ophtalmologique, CARGO, Filière SENSGENE, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - D Aguilera
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz University Hospital-Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - J Kaplan
- Laboratoire de Génétique Ophtalmologique INSERM U1163, Institut Imagine, Paris, France
| | - L Fares-Taie
- Laboratoire de Génétique Ophtalmologique INSERM U1163, Institut Imagine, Paris, France
| | - F Blanco-Kelly
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz University Hospital-Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - C Villaverde
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz University Hospital-Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - C Francannet
- Service de Génétique Médicale, CHU Estaing, Clermont-Ferrand, France
| | - A Goldenberg
- Service de Génétique, CHU de Rouen, Centre Normand de Génomique Médicale et Médecine Personnalisée, Rouen, France
| | - I Arroyo
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
- Department of Genetics, Hospital of Cáceres, Cáceres, Spain
| | - J M Rozet
- Laboratoire de Génétique Ophtalmologique INSERM U1163, Institut Imagine, Paris, France
| | - C Ayuso
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz University Hospital-Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - N Chassaing
- Service de Génétique Médicale, Pavillon Lefebvre, Hôpital Purpan, CHU Toulouse, Place du Dr Baylac, 31059, Toulouse Cedex 9, France
- INSERM U1056, Université Toulouse III, Toulouse, France
| | - P Calvas
- Service de Génétique Médicale, Pavillon Lefebvre, Hôpital Purpan, CHU Toulouse, Place du Dr Baylac, 31059, Toulouse Cedex 9, France
- INSERM U1056, Université Toulouse III, Toulouse, France
| | - M Corton
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz University Hospital-Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
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Epistasis between Pax6 Sey and genetic background reinforces the value of defined hybrid mouse models for therapeutic trials. Gene Ther 2018; 25:524-537. [PMID: 30258099 PMCID: PMC6335240 DOI: 10.1038/s41434-018-0043-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 09/02/2018] [Accepted: 09/05/2018] [Indexed: 12/21/2022]
Abstract
The small eye (Sey) mouse is a model of PAX6-aniridia syndrome (aniridia). Aniridia, a congenital ocular disorder caused by heterozygous loss-of-function mutations in PAX6, needs new vision saving therapies. However, high phenotypic variability in Sey mice makes development of such therapies challenging. We hypothesize that genetic background is a major source of undesirable variability in Sey mice. Here we performed a systematic quantitative examination of anatomical, histological, and molecular phenotypes on the inbred C57BL/6J, hybrid B6129F1, and inbred 129S1/SvImJ backgrounds. The Sey allele significantly reduced eye weight, corneal thickness, PAX6 mRNA and protein levels, and elevated blood glucose levels. Surprisingly, Pax6Sey/Sey brains had significantly elevated Pax6 transcripts compared to Pax6+/+ embryos. Genetic background significantly influenced 12/24 measurements, with inbred strains introducing severe ocular and blood sugar phenotypes not observed in hybrid mice. Additionally, significant interactions (epistasis) between Pax6 genotype and genetic background were detected in measurements of eye weight, cornea epithelial thickness and cell count, retinal mRNA levels, and blood glucose levels. The number of epistatic interactions was reduced in hybrid mice. In conclusion, severe phenotypes in the unnatural inbred strains reinforce the value of more naturalistic F1 hybrid mice for the development of therapies for aniridia and other disorders.
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Phenotype–genotype correlations and emerging pathways in ocular anterior segment dysgenesis. Hum Genet 2018; 138:899-915. [DOI: 10.1007/s00439-018-1935-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 09/10/2018] [Indexed: 12/11/2022]
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Syrimis A, Nicolaou N, Alexandrou A, Papaevripidou I, Nicolaou M, Loukianou E, Sismani C, Malas S, Christophidou-Anastasiadou V, Tanteles GA. Molecular analysis of Cypriot families with aniridia reveals a novel PAX6 mutation. Mol Med Rep 2018; 18:1623-1627. [PMID: 29901133 PMCID: PMC6072148 DOI: 10.3892/mmr.2018.9126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/21/2018] [Indexed: 12/12/2022] Open
Abstract
The present study investigated the clinical and mutational spectrum of aniridia in a cohort of 17 affected individuals from six families from Cyprus. Each proband was initially evaluated for copy number variants at the PAX6 locus and subsequently underwent PAX6 mutation screening. Sequence analysis of FOXC1 and PITX2 was performed in patients who did not carry a PAX6 mutation. The most common clinical features in the group of aniridia patients associated with aniridia were nystagmus, cataracts and glaucoma. PAX6 pathogenic mutations were identified in five out of six families (a diagnostic yield of 84%). Previously reported pathogenic mutations in PAX6 were identified in four families, which comprise p.R203*, p.R240* and p.R317*. In addition, a novel pathogenic variant (p.E220Gfs*23) was identified in a single family. No pathogenic mutations were detected in PAX6, FOXC1 or PITX2 in the only patient with a sporadic form of aniridia‑like phenotype, confirming the genetic heterogeneity associated with this disease. To the best of our knowledge this is the first report on the mutational spectrum of PAX6 in aniridia patients of Cypriot ancestry. Mutational screening of PAX6 serves a crucial role in distinguishing isolated from syndromic forms of aniridia, and it may therefore eliminate the need for renal ultrasound scan surveillance, delineate the phenotype and improve genetic counseling.
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Affiliation(s)
- Andreas Syrimis
- Department of Clinical Genetics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
| | - Nayia Nicolaou
- Department of Clinical Genetics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
| | - Angelos Alexandrou
- Department of Cytogenetics and Genomics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
| | - Ioannis Papaevripidou
- Department of Cytogenetics and Genomics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
| | - Michael Nicolaou
- Department of Clinical Genetics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
| | - Eleni Loukianou
- Department of Ophthalmology, Nicosia General Hospital, 2029 Nicosia, Cyprus
| | - Carolina Sismani
- Department of Cytogenetics and Genomics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
| | - Stavros Malas
- Department of Developmental and Functional Genetics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
| | - Violetta Christophidou-Anastasiadou
- Department of Clinical Genetics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
- Department of Clinical Genetics, Archbishop Makarios III Hospital, 2012 Nicosia, Cyprus
| | - George A. Tanteles
- Department of Clinical Genetics, The Cyprus Institute of Neurology and Genetics, 2370 Nicosia, Cyprus
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Riera M, Wert A, Nieto I, Pomares E. Panel-based whole exome sequencing identifies novel mutations in microphthalmia and anophthalmia patients showing complex Mendelian inheritance patterns. Mol Genet Genomic Med 2017; 5:709-719. [PMID: 29178648 PMCID: PMC5702572 DOI: 10.1002/mgg3.329] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/21/2017] [Accepted: 07/27/2017] [Indexed: 12/15/2022] Open
Abstract
Background Microphthalmia and anophthalmia (MA) are congenital eye abnormalities that show an extremely high clinical and genetic complexity. In this study, we evaluated the implementation of whole exome sequencing (WES) for the genetic analysis of MA patients. This approach was used to investigate three unrelated families in which previous single‐gene analyses failed to identify the molecular cause. Methods A total of 47 genes previously associated with nonsyndromic MA were included in our panel. WES was performed in one affected patient from each family using the AmpliSeqTM Exome technology and the Ion ProtonTM platform. Results A novel heterozygous OTX2 missense mutation was identified in a patient showing bilateral anophthalmia who inherited the variant from a parent who was a carrier, but showed no sign of the condition. We also describe a new PAX6 missense variant in an autosomal‐dominant pedigree affected by mild bilateral microphthalmia showing high intrafamiliar variability, with germline mosaicism determined to be the most plausible molecular cause of the disease. Finally, a heterozygous missense mutation in RBP4 was found to be responsible in an isolated case of bilateral complex microphthalmia. Conclusion This study highlights that panel‐based WES is a reliable and effective strategy for the genetic diagnosis of MA. Furthermore, using this technique, the mutational spectrum of these diseases was broadened, with novel variants identified in each of the OTX2,PAX6, and RBP4 genes. Moreover, we report new cases of reduced penetrance, mosaicism, and variable phenotypic expressivity associated with MA, further demonstrating the heterogeneity of such disorders.
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Affiliation(s)
- Marina Riera
- Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Ana Wert
- Departament d'Oftalmologia Pediàtrica, Estrabisme i Neuroftalmologia, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Isabel Nieto
- Departament de Còrnia, Cataracta i Cirurgia Refractiva, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Esther Pomares
- Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
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Han KH, Lee HJ, Ha IS, Kang HG, Cheong HI. A nonsense PAX6 mutation in a family with congenital aniridia. KOREAN JOURNAL OF PEDIATRICS 2016; 59:S1-S4. [PMID: 28018434 PMCID: PMC5177687 DOI: 10.3345/kjp.2016.59.11.s1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/11/2016] [Accepted: 04/17/2016] [Indexed: 11/27/2022]
Abstract
Congenital aniridia is a rare ocular malformation that presents with severe hypoplasia of the iris and various ocular manifestations. Most cases of congenital aniridia are known to be related to mutations in the paired box gene-6 (PAX6), which is an essential gene in eye development. Herein, we report a familial case of autosomal dominant congenital aniridia with four affected members in 3 consecutive generations and describe the detailed ophthalmologic findings for one of these members. As expected, mutational analysis revealed a nonsense mutation (p.Ser122*) in the PAX6 gene. Thus, our findings reiterate the importance of PAX6 mutations in congenital aniridia.
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Affiliation(s)
- Kyoung Hee Han
- Department of Pediatrics, Jeju National University School of Medicine, Jeju, Korea
| | - Hye Jin Lee
- Department of Ophthalmology, Jeju National University School of Medicine, Jeju, Korea
| | - Il-Soo Ha
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
| | - Hee Gyung Kang
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.; Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.; Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea.; Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea
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27
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Genotype-phenotype correlation of PAX6 gene mutations in aniridia. Hum Genome Var 2016; 3:15052. [PMID: 27081561 PMCID: PMC4760117 DOI: 10.1038/hgv.2015.52] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 09/09/2015] [Accepted: 09/28/2015] [Indexed: 12/27/2022] Open
Abstract
The objective of this study was to investigate the genotype-phenotype correlation of the PAX6 gene in aniridia. We clinically examined 5 families and 16 sporadic patients with aniridia. We performed chromosomal analysis and PCR analysis of the PAX6 gene using patient genomic DNA. Chromosomal analysis demonstrated deletions at 11p13 in one allele in four sporadic patients. Seven nonsense mutations, two frameshifts (two insertions), four splice junction errors and two missense mutations were found, and all were heterozygous. The iris phenotype ranged from total to normal in each patient, and the characteristic phenotypes, including cataract, glaucoma or optic nerve hypoplasia, varied widely even among members of the same family. Foveal hypoplasia was detected in all patients except for one. No obvious genotype-phenotype correlation was identified; however, the aniridia phenotype between the two eyes in each patient was quite similar in all patients. Because PAX6 regulates numerous downstream genes and its expression is regulated by several factors during eye development, the aniridia phenotype may be complex even in family members. However, because PAX6 regulation, resulting from both paternal and maternal alleles associated with PAX6, is considered to be roughly similar in both eyes of each patient, the aniridia phenotype may be similar in both eyes of each patient.
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28
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Madhu V, Dighe AS, Cui Q, Deal DN. Dual Inhibition of Activin/Nodal/TGF-β and BMP Signaling Pathways by SB431542 and Dorsomorphin Induces Neuronal Differentiation of Human Adipose Derived Stem Cells. Stem Cells Int 2015; 2016:1035374. [PMID: 26798350 PMCID: PMC4699250 DOI: 10.1155/2016/1035374] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/03/2015] [Indexed: 12/16/2022] Open
Abstract
Damage to the nervous system can cause devastating diseases or musculoskeletal dysfunctions and transplantation of progenitor stem cells can be an excellent treatment option in this regard. Preclinical studies demonstrate that untreated stem cells, unlike stem cells activated to differentiate into neuronal lineage, do not survive in the neuronal tissues. Conventional methods of inducing neuronal differentiation of stem cells are complex and expensive. We therefore sought to determine if a simple, one-step, and cost effective method, previously reported to induce neuronal differentiation of embryonic stem cells and induced-pluripotent stem cells, can be applied to adult stem cells. Indeed, dual inhibition of activin/nodal/TGF-β and BMP pathways using SB431542 and dorsomorphin, respectively, induced neuronal differentiation of human adipose derived stem cells (hADSCs) as evidenced by formation of neurite extensions, protein expression of neuron-specific gamma enolase, and mRNA expression of neuron-specific transcription factors Sox1 and Pax6 and matured neuronal marker NF200. This process correlated with enhanced phosphorylation of p38, Erk1/2, PI3K, and Akt1/3. Additionally, in vitro subcutaneous implants of SB431542 and dorsomorphin treated hADSCs displayed significantly higher expression of active-axonal-growth-specific marker GAP43. Our data offers novel insights into cell-based therapies for the nervous system repair.
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Affiliation(s)
- Vedavathi Madhu
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Abhijit S. Dighe
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Quanjun Cui
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - D. Nicole Deal
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
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29
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Deml B, Reis LM, Lemyre E, Clark RD, Kariminejad A, Semina EV. Novel mutations in PAX6, OTX2 and NDP in anophthalmia, microphthalmia and coloboma. Eur J Hum Genet 2015; 24:535-41. [PMID: 26130484 PMCID: PMC4929874 DOI: 10.1038/ejhg.2015.155] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/17/2015] [Accepted: 06/03/2015] [Indexed: 12/16/2022] Open
Abstract
Anophthalmia and microphthalmia (A/M) are developmental ocular malformations defined as the complete absence or reduction in size of the eye. A/M is a highly heterogeneous disorder with SOX2 and FOXE3 playing major roles in dominant and recessive pedigrees, respectively; however, the majority of cases lack a genetic etiology. We analyzed 28 probands affected with A/M spectrum (without mutations in SOX2/FOXE3) by whole-exome sequencing. Analysis of 83 known A/M factors identified pathogenic/likely pathogenic variants in PAX6, OTX2 and NDP in three patients. A novel heterozygous likely pathogenic variant in PAX6, c.767T>C, p.(Val256Ala), was identified in two brothers with bilateral microphthalmia, coloboma, primary aphakia, iris hypoplasia, sclerocornea and congenital glaucoma; the unaffected mother appears to be a mosaic carrier. While A/M has been reported as a rare feature, this is the first report of congenital primary aphakia in association with PAX6 and the identified allele represents the first variant in the PAX6 homeodomain to be associated with A/M. A novel pathogenic variant in OTX2, c.651delC, p.(Thr218Hisfs*76), in a patient with syndromic bilateral anophthalmia and a hemizygous pathogenic variant in NDP, c.293 C>T, p.(Pro98Leu), in two brothers with isolated bilateral microphthalmia and sclerocornea were also identified. Pathogenic/likely pathogenic variants were not discovered in the 25 remaining A/M cases. This study underscores the utility of whole-exome sequencing for identification of causative mutations in highly variable ocular phenotypes as well as the extreme genetic heterogeneity of A/M conditions.
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Affiliation(s)
- Brett Deml
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, WI, USA
| | - Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Emmanuelle Lemyre
- Service de Génétique médicale, CHU Ste-Justine, Département de Pédiatrie, Université de Montréal, Montréal, Canada
| | - Robin D Clark
- Division of Medical Genetics, Department of Pediatrics, Loma Linda University Children's Hospital, Loma Linda, CA 92354
| | | | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, WI, USA
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30
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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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31
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Nakayama T, Fisher M, Nakajima K, Odeleye AO, Zimmerman KB, Fish MB, Yaoita Y, Chojnowski JL, Lauderdale JD, Netland PA, Grainger RM. Xenopus pax6 mutants affect eye development and other organ systems, and have phenotypic similarities to human aniridia patients. Dev Biol 2015; 408:328-44. [PMID: 25724657 DOI: 10.1016/j.ydbio.2015.02.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/13/2015] [Accepted: 02/16/2015] [Indexed: 02/06/2023]
Abstract
Mutations in the Pax6 gene cause ocular defects in both vertebrate and invertebrate animal species, and the disease aniridia in humans. Despite extensive experimentation on this gene in multiple species, including humans, we still do not understand the earliest effects on development mediated by this gene. This prompted us to develop pax6 mutant lines in Xenopus tropicalis taking advantage of the utility of the Xenopus system for examining early development and in addition to establish a model for studying the human disease aniridia in an accessible lower vertebrate. We have generated mutants in pax6 by using Transcription Activator-Like Effector Nuclease (TALEN) constructs for gene editing in X. tropicalis. Embryos with putative null mutations show severe eye abnormalities and changes in brain development, as assessed by changes in morphology and gene expression. One gene that we found is downregulated very early in development in these pax6 mutants is myc, a gene involved in pluripotency and progenitor cell maintenance and likely a mediator of some key pax6 functions in the embryo. Changes in gene expression in the developing brain and pancreas reflect other important functions of pax6 during development. In mutations with partial loss of pax6 function eye development is initially relatively normal but froglets show an underdeveloped iris, similar to the classic phenotype (aniridia) seen in human patients with PAX6 mutations. Other eye abnormalities observed in these froglets, including cataracts and corneal defects, are also common in human aniridia. The frog model thus allows us to examine the earliest deficits in eye formation as a result of pax6 lesions, and provides a useful model for understanding the developmental basis for the aniridia phenotype seen in humans.
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Affiliation(s)
- Takuya Nakayama
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Marilyn Fisher
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Keisuke Nakajima
- Division of Embryology and Genetics, Institute for Amphibian Biology, Hiroshima University, Higashihiroshima 739-8526, Japan
| | - Akinleye O Odeleye
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Keith B Zimmerman
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Margaret B Fish
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Yoshio Yaoita
- Division of Embryology and Genetics, Institute for Amphibian Biology, Hiroshima University, Higashihiroshima 739-8526, Japan
| | - Jena L Chojnowski
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - James D Lauderdale
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Peter A Netland
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Robert M Grainger
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA; Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
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32
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Hu P, Meng L, Ma D, Qiao F, Wang Y, Zhou J, Yi L, Xu Z. A novel 11p13 microdeletion encompassing PAX6 in a Chinese Han family with aniridia, ptosis and mental retardation. Mol Cytogenet 2015; 8:3. [PMID: 25628759 PMCID: PMC4307215 DOI: 10.1186/s13039-015-0110-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 01/09/2015] [Indexed: 12/22/2022] Open
Abstract
Purpose To explore possible genetic aberrations in a Chinese family with aniridia, ptosis and mental retardation, and provide genetic evidence for the prenatal diagnosis. Methods 14 exons of PAX6 in the proband were sequenced by the Sanger sequencing technique. Multiplex ligation-dependent probe amplification (MLPA) technique was employed to further explore gene alterations of PAX6. Single nucleotide polymorphisms-array (SNP-array) assay was applied to screen potential pathologic genome-wide copy number variations (CNV). Results There were no detectable pathogenic mutations in the 14 exons of PAX6 in the proband. MLPA indicated a heterozygous deletion encompassing all PAX6 gene regions covered and a partial upstream region. SNP-array assay detected a heterozygous 11p13 microdeletion with a length of 518 kb in the proband, spanning two whole annotated genes, elongation factor protein 4 (ELP4), the paired box gene 6 (PAX6), and partial IMP1 inner-mitochondrial membrane (IMMP1L) gene. SNP-array revealed her affected brother carried the identical deletion. Conclusions The 518 kb heterozygous deletion in 11p13 encompassing PAX6 should be the genetic etiology for the familial aniridia.
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Affiliation(s)
- Ping Hu
- State key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, 123# Tianfei Street, Baixia District Nanjing, 210029 China
| | - Lulu Meng
- State key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, 123# Tianfei Street, Baixia District Nanjing, 210029 China
| | - Dingyuan Ma
- State key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, 123# Tianfei Street, Baixia District Nanjing, 210029 China
| | - Fengchang Qiao
- State key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, 123# Tianfei Street, Baixia District Nanjing, 210029 China
| | - Yan Wang
- State key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, 123# Tianfei Street, Baixia District Nanjing, 210029 China
| | - Jing Zhou
- State key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, 123# Tianfei Street, Baixia District Nanjing, 210029 China
| | - Long Yi
- Department of Pathology, Nanjing University Medical School, Nanjing, China
| | - Zhengfeng Xu
- State key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, 123# Tianfei Street, Baixia District Nanjing, 210029 China
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33
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A novel duplication in the PAX6 gene in a North Indian family with aniridia. Int Ophthalmol 2014; 34:1183-8. [PMID: 25189681 DOI: 10.1007/s10792-013-9882-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Accepted: 11/08/2013] [Indexed: 10/24/2022]
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Douvaras P, Mort RL, Edwards D, Ramaesh K, Dhillon B, Morley SD, Hill RE, West JD. Increased corneal epithelial turnover contributes to abnormal homeostasis in the Pax6(+/-) mouse model of aniridia. PLoS One 2013; 8:e71117. [PMID: 23967157 PMCID: PMC3742784 DOI: 10.1371/journal.pone.0071117] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/24/2013] [Indexed: 01/09/2023] Open
Abstract
We aimed to test previous predictions that limbal epithelial stem cells (LESCs) are quantitatively deficient or qualitatively defective in Pax6+/− mice and decline with age in wild-type (WT) mice. Consistent with previous studies, corneal epithelial stripe patterns coarsened with age in WT mosaics. Mosaic patterns were also coarser in Pax6+/− mosaics than WT at 15 weeks but not at 3 weeks, which excludes a developmental explanation and strengthens the prediction that Pax6+/− mice have a LESC-deficiency. To investigate how Pax6 genotype and age affected corneal homeostasis, we compared corneal epithelial cell turnover and label-retaining cells (LRCs; putative LESCs) in Pax6+/− and WT mice at 15 and 30 weeks. Limbal BrdU-LRC numbers were not reduced in the older WT mice, so this analysis failed to support the predicted age-related decline in slow-cycling LESC numbers in WT corneas. Similarly, limbal BrdU-LRC numbers were not reduced in Pax6+/− heterozygotes but BrdU-LRCs were also present in Pax6+/− corneas. It seems likely that Pax6+/− LRCs are not exclusively stem cells and some may be terminally differentiated CD31-positive blood vessel cells, which invade the Pax6+/− cornea. It was not, therefore, possible to use this approach to test the prediction that Pax6+/− corneas had fewer LESCs than WT. However, short-term BrdU labelling showed that basal to suprabasal movement (leading to cell loss) occurred more rapidly in Pax6+/− than WT mice. This implies that epithelial cell loss is higher in Pax6+/− mice. If increased corneal epithelial cell loss exceeds the cell production capacity it could cause corneal homeostasis to become unstable, resulting in progressive corneal deterioration. Although it remains unclear whether Pax6+/− mice have LESC-deficiency, we suggest that features of corneal deterioration, that are often taken as evidence of LESC-deficiency, might occur in the absence of stem cell deficiency if corneal homeostasis is destabilised by excessive cell loss.
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Affiliation(s)
- Panagiotis Douvaras
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Richard L. Mort
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Dominic Edwards
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Kanna Ramaesh
- Tennent Institute of Ophthalmology, Gartnaval General Hospital, Glasgow, United Kingdom
| | - Baljean Dhillon
- School of Clinical Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Steven D. Morley
- Division of Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Robert E. Hill
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - John D. West
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Palacios IM. Nonsense-mediated mRNA decay: from mechanistic insights to impacts on human health. Brief Funct Genomics 2012; 12:25-36. [PMID: 23148322 DOI: 10.1093/bfgp/els051] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cells are able to recognize and degrade aberrant transcripts in order to self-protect from potentially toxic proteins. Various pathways detect aberrant RNAs in the cytoplasm and are dependent on translation. One of these pathways is the nonsense-mediated RNA decay (NMD). NMD is a surveillance mechanism that degrades transcripts containing nonsense mutations, preventing the translation of possibly harmful truncated proteins. For example, the degradation of a nonsense harming β-globin allele renders normal phenotypes. On the other hand, regulating NMD is also important in those cases when the produced aberrant protein is better than having no protein, as it has been shown for cystic fibrosis. These findings reflect the important role for NMD in human health. In addition, NMD controls the levels of physiologic transcripts, which defines this pathway as a novel gene expression regulator, with huge impact on homeostasis, cell growth and development. While the mechanistic details of NMD are being gradually understood, the physiological role of this RNA surveillance pathway still remains largely unknown. This is a brief and simplified review on various aspects of NMD, such as the nature of the NMD targets, the mechanism of target degradation and the links between NMD and cell growth, animal development and diseases.
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Affiliation(s)
- Isabel M Palacios
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
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Abstract
Aniridia is a rare congenital disorder in which there is a variable degree of hypoplasia or the absence of iris tissue associated with multiple other ocular changes, some present from birth and some arising progressively over time. Most cases are associated with dominantly inherited mutations or deletions of the PAX6 gene. This article will review the clinical manifestations, the molecular basis including genotype-phenotype correlations, diagnostic approaches and management of aniridia.
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Avery P, Vicente-Crespo M, Francis D, Nashchekina O, Alonso CR, Palacios IM. Drosophila Upf1 and Upf2 loss of function inhibits cell growth and causes animal death in a Upf3-independent manner. RNA (NEW YORK, N.Y.) 2011; 17:624-38. [PMID: 21317294 PMCID: PMC3062174 DOI: 10.1261/rna.2404211] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 12/21/2010] [Indexed: 05/29/2023]
Abstract
Nonsense-mediated RNA decay (NMD) is a surveillance mechanism that degrades transcripts containing nonsense mutations, preventing the translation of truncated proteins. NMD also regulates the levels of many endogenous mRNAs. While the mechanism of NMD is gradually understood, its physiological role remains largely unknown. The core NMD genes upf1 and upf2 are essential in several organisms, which may reflect an important developmental role for NMD. Alternatively, the lethality of these mutants might arise from their function in NMD-independent processes. To analyze the developmental importance of NMD, we studied Drosophila mutants of the other core NMD gene, upf3. We compare the resulting upf3 phenotype with those defects observed in upf1 and upf2 loss-of-function mutants, as well as with flies expressing a mutant Upf2 protein unable to bind Upf3. Our results show that Upf3 is an NMD effector in the fly but, unlike Upf1 and Upf2, plays a peripheral role in the degradation of most NMD targets and is not required for development or viability. Furthermore, Upf1 and Upf2 loss-of-function inhibits cell growth and induces apoptosis through a Upf3-independent pathway. Accordingly, disruption of Upf2-Upf1 interaction causes death, while the Upf2-Upf3 complex is dispensable for viability. Our findings suggest that NMD is essential for cell growth and animal development, and that the lethality of upf1 and upf2 mutants is not due to disrupting their roles during NMD-independent processes, but to their function in the degradation of specific mRNAs by the NMD pathway. Furthermore, our results show that Upf3 is not always essential in NMD.
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Affiliation(s)
- Paul Avery
- The Zoology Department, University of Cambridge, Cambridge CB23EJ, United Kingdom
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Vicente-Crespo M, Palacios IM. Nonsense-mediated mRNA decay and development: shoot the messenger to survive? Biochem Soc Trans 2010; 38:1500-5. [PMID: 21118115 PMCID: PMC3432441 DOI: 10.1042/bst0381500] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
NMD (nonsense-mediated mRNA decay) is a surveillance mechanism that degrades transcripts containing nonsense mutations, preventing the translation of potentially harmful truncated proteins. Although the mechanistic details of NMD are gradually being understood, the physiological role of this RNA surveillance pathway still remains largely unknown. The core NMD genes Upf1 (up-frameshift suppressor 1) and Upf2 are essential for animal viability in the fruitfly, mouse and zebrafish. These findings may reflect an important role for NMD during animal development. Alternatively, the lethal phenotypes of upf1 and upf2 mutants might be due to their function in NMD-independent processes. In the present paper, we describe the phenotypes observed when the NMD factors are mutated in various organisms, and discuss findings that might shed light on the function of NMD in cellular growth and development of an organism.
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Affiliation(s)
- Marta Vicente-Crespo
- Division of Biology, University of California San Diego, 9500 Gilman Drive, Bonner Hall 3230, La Jolla, CA 92093-0322, U.S.A
| | - Isabel M. Palacios
- Zoology Department, University of Cambridge, Downing Street, Cambridge CB2 3EJ, U.K
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Atchaneeyasakul LO, Trinavarat A, Dulayajinda D, Kumpornsin K, Thongnoppakhun W, Yenchitsomanus PT, Limwongse C. Novel and De-novo TruncatingPAX6Mutations and Ocular Phenotypes in Thai Aniridia Patients. Ophthalmic Genet 2009; 27:21-7. [PMID: 16543198 DOI: 10.1080/13816810500481667] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To describe the ophthalmic findings and mutation analyses of the PAX6 gene in Thai aniridia patients. METHODS Ten patients from six unrelated families underwent a comprehensive ophthalmic examination. Mutations in the PAX6 gene were screened by single-strand conformational polymorphism (SSCP) and direct DNA sequencing of the SSCP variants. RESULTS Seven patients developed cataracts and six developed glaucoma. Mutation analysis demonstrated four different truncating mutations, two of which were de novo. These included one novel insertion/deletion mutation (c.474del12insGA in exon 5) and three nonsense mutations. R203X and R240X are common recurrent mutations, while Q277X in exon 10 is novel. All mutations resulted in loss of function of the PAX6 protein. CONCLUSION Our data confirm inter- and intrafamilial variable phenotypic manifestations of which the underlying mechanisms may be haploinsufficiency or dominant-negative mutation.
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Affiliation(s)
- La-Ongsri Atchaneeyasakul
- Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkok-noi, Bangkok 10700, Thailand.
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Abstract
Aniridia is a rare panocular disorder affecting the cornea, anterior chamber, iris, lens, retina, macula and optic nerve. It occurs because of mutations in PAX6 on band p13 of chromosome 11. It is associated with a number of syndromes, including Wilm's tumour, bilateral sporadic aniridia, genitourinary abnormalities and mental retardation (WAGR) syndrome. PAX6 mutations result in alterations in corneal cytokeratin expression, cell adhesion and glycoconjugate expression. This, in addition to stem-cell deficiency, results in a fragile cornea and aniridia-associated keratopathy (AAK). It also results in abnormalities in the differentiation of the angle, resulting in glaucoma. Glaucoma may also develop as a result of progressive angle closure from synechiae. There is cataract development, and this is associated with a fragile lens capsule. The iris is deficient. The optic nerve and fovea are hypoplastic, and the retina may be prone to detachment. Aniridia is a profibrotic disorder, and as a result many interventions--including penetrating keratoplasty and filtration surgery--fail. The Boston keratoprosthesis may provide a more effective approach in the management of AAK. Guarded filtration surgery appears to be effective in glaucoma. Despite our increasing understanding of the genetics and pathology of this condition, effective treatment remains elusive.
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Affiliation(s)
- Helena Lee
- Department of Paediatric Ophthalmology, Children's University Hospital, Dublin, Ireland
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SUN DG. A novel PAX6 mutation (c.1286delC) in the patients with hereditary congenital aniridia. YI CHUAN = HEREDITAS 2008; 30:1301-6. [DOI: 10.3724/sp.j.1005.2008.01301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Sánchez-Sánchez F, Mittnacht S. Nonsense-mediated decay: paving the road for genome diversification. Bioessays 2008; 30:926-8. [PMID: 18798540 DOI: 10.1002/bies.20825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The expression of protein-encoding genes is a complex process culminating in the production of mature mRNA and its translation by the ribosomes. The production of a mature mRNA involves an intricate series of processing steps. The majority of eukaryotic protein-encoding genes contain intron sequences that disrupt the protein-encoding frame, and hence have to be removed from immature mRNA prior to translation into protein. The mechanism involved in the selection of correct splice sites is incompletely understood. A considerable body of evidence suggests that the splicing machinery has suboptimal efficiency and fidelity leading to substantial processing inaccuracy. Here we discuss a recently published article that extends observations that cells rely on nonsense-mediated mRNA decay (NMD) to compensate for such suboptimal processing accuracy. Intriguingly these authors provide evidence for a strong selective pressure in favour of premature termination of mRNA translation in the event of intron retention. The analysis presented implies a positive role of NMD in transcript diversification through alternative splicing and suggest that this ancient surveillance mechanism may have co-evolved with intron acquisition born from the need for quality control of splicing patterns.
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Affiliation(s)
- Francisco Sánchez-Sánchez
- Area de Genética, Facultad de Medicina/Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Albacete, Spain.
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Robinson DO, Howarth RJ, Williamson KA, van Heyningen V, Beal SJ, Crolla JA. Genetic analysis of chromosome 11p13 and the PAX6 gene in a series of 125 cases referred with aniridia. Am J Med Genet A 2008; 146A:558-69. [PMID: 18241071 DOI: 10.1002/ajmg.a.32209] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A series of 125 patients referred primarily with aniridia classified as either sporadic (74), familial (24), or in association with WAGR syndrome (14) or other malformations (13) was analysed for mutations, initially by karyotyping and targeted FISH analysis of chromosome 11p13. These methods identified mutations in a significant proportion of patients, 34/125 (27%). Two cases had chromosome rearrangements involving 11p13, 16 cases had visible deletions, and 16 cases had cryptic deletions identified by FISH. The frequency of cryptic deletions in familial aniridia was 27% and in sporadic isolated aniridia was 22%. Of the 14 cases referred with WAGR syndrome, 10 (71%) had chromosomal deletions, 2 cryptic and 8 visible. Of the 13 cases with aniridia and other malformations, 5 (38%) had a chromosomal rearrangement or deletion. In 37 cases with no karyotypic or cryptic chromosome abnormality, sequence analysis of the PAX6 gene was performed. Mutations were identified in 33 cases; 22 with sporadic aniridia, 10 with familial aniridia and 1 with aniridia and other non-WAGR syndrome associated anomalies. Overall, 67 of 71 cases (94%) undergoing full mutation analysis had a mutation in the PAX6 genomic region.
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Affiliation(s)
- David O Robinson
- Wessex Regional Genetics Laboratory, Salisbury District Hospital, Salisbury, Wiltshire, UK.
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Graziano C, D'Elia AV, Mazzanti L, Moscano F, Guidelli Guidi S, Scarano E, Turchetti D, Franzoni E, Romeo G, Damante G, Seri M. A de novo nonsense mutation of PAX6 gene in a patient with aniridia, ataxia, and mental retardation. Am J Med Genet A 2008; 143A:1802-5. [PMID: 17595013 DOI: 10.1002/ajmg.a.31808] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Claudio Graziano
- O. di Genetica Medica, Dipartimento di Medicina Interna, Cardioangiologia ed Epatologia, Università degli Studi di Bologna, Bologna, Italy
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Kim JH, Hwang BS, Lee JH, Cha SC. PAX6 Mutations and Clinical Features of Congenital Aniridia. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2008. [DOI: 10.3341/jkos.2008.49.11.1794] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Jong Ho Kim
- Department of Ophthalmology, Yeungnam University College of Medicine, Daegu, Koera
| | - Bo Sung Hwang
- Department of Ophthalmology, Yeungnam University College of Medicine, Daegu, Koera
| | | | - Soon Cheol Cha
- Department of Ophthalmology, Yeungnam University College of Medicine, Daegu, Koera
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Golzio C, Martinovic-Bouriel J, Thomas S, Mougou-Zrelli S, Grattagliano-Bessieres B, Bonniere M, Delahaye S, Munnich A, Encha-Razavi F, Lyonnet S, Vekemans M, Attie-Bitach T, Etchevers HC. Matthew-Wood syndrome is caused by truncating mutations in the retinol-binding protein receptor gene STRA6. Am J Hum Genet 2007; 80:1179-87. [PMID: 17503335 PMCID: PMC1867105 DOI: 10.1086/518177] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 03/16/2007] [Indexed: 01/01/2023] Open
Abstract
Retinoic acid (RA) is a potent teratogen in all vertebrates when tight homeostatic controls on its endogenous dose, location, or timing are perturbed during early embryogenesis. STRA6 encodes an integral cell-membrane protein that favors RA uptake from soluble retinol-binding protein; its transcription is directly regulated by RA levels. Molecular analysis of STRA6 was undertaken in two human fetuses from consanguineous families we previously described with Matthew-Wood syndrome in a context of severe microphthalmia, pulmonary agenesis, bilateral diaphragmatic eventration, duodenal stenosis, pancreatic malformations, and intrauterine growth retardation. The fetuses had either a homozygous insertion/deletion in exon 2 or a homozygous insertion in exon 7 predicting a premature stop codon in STRA6 transcripts. Five other fetuses presenting at least one of the two major signs of clinical anophthalmia or pulmonary hypoplasia with at least one of the two associated signs of diaphragmatic closure defect or cardiopathy had no STRA6 mutations. These findings suggest a molecular basis for the prenatal manifestations of Matthew-Wood syndrome and suggest that phenotypic overlap with other associations may be due to genetic heterogeneity of elements common to the RA- and fibroblast growth factor-signaling cascades.
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Lise-Schneider B, Calvas P, Roche O, Lambert JC, Dufier JL, Costet-Fighiera C. [Glaucoma with aniridia and isolated congenital glaucoma in siblings: contribution and limits of genetics]. J Fr Ophtalmol 2007; 30:44-8. [PMID: 17287671 DOI: 10.1016/s0181-5512(07)89549-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Congenital glaucoma associated with aniridia and primary congenital glaucoma are regarded as different entities. Indeed, the abnormalities of the angle's structures as well as the genes involved are different. We report the observation of two sisters presenting these two types of glaucoma with particular attention paid to the importance and the difficulty of genetic counseling. OBSERVATIONS Child L, with no particular family history, had presented bilateral aniridia complicated by bilateral glaucoma since birth. In addition to medical and surgical treatment, general and genetic investigations were undertaken that revealed no abnormalities. No microdeletion of the gene PAX6 responsible for the aniridia was found. Consequently, the genetic advice was in favor of a second pregnancy for this couple. At birth, L's sister also presented bilateral congenital glaucoma, which was isolated, without aniridia. New genetic investigations were carried out but no abnormalities in PAX6, nor in FOXC1 or PITX2 involved in the development of the anterior chamber, were found. Moreover, the haplotypes for aniridia locus AN2 inherited by the two sisters were different, proof that this gene could not be responsible for the glaucoma. DISCUSSION At L's birth, the hypothesis retained was that she was a sporadic case whose gene mutation could not be identified (which happens in 50% of sporadic cases). The risk for the second pregnancy was negligible, although not null. The primary congenital glaucoma presented by L's sister remains unexplained in the context of aniridia and the role of the PAX6 gene was eliminated. The study of PITX2 and FOXC1 genes involved in anterior segment dysgenesis proved that they were also not involved. Thus, this observation evokes the responsibility of a gene other than PAX6 in aniridia, which could also have a role in isolated congenital glaucoma. CONCLUSION Analysis of congenital pathologies from a more genetic than clinical point of view seems to progressively break down the barriers established between the various phenotypes of hereditary congenital anomalies. Even if the association of aniridia and primary congenital glaucoma in siblings is reported here for the first time, it does not appear so extraordinary if one considers the complexity of the anterior chamber's development, which involves many genes, most of them still unidentified to date.
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Affiliation(s)
- B Lise-Schneider
- Service d'Ophtalmologie, CHU de Nice, Hôpital Saint Roch, Nice, France
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Analysis of PAX6 gene in a Chinese aniridia family. Chin Med J (Engl) 2006. [DOI: 10.1097/00029330-200608020-00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Kanakubo S, Nomura T, Yamamura KI, Miyazaki JI, Tamai M, Osumi N. Abnormal migration and distribution of neural crest cells in Pax6 heterozygous mutant eye, a model for human eye diseases. Genes Cells 2006; 11:919-33. [PMID: 16866875 DOI: 10.1111/j.1365-2443.2006.00992.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PAX6/Pax6 gene encodes a transcription factor that is crucially required for eye development. Pax6 heterozygous mutant mouse (Pax6(Sey/+)) shows various ocular defects, especially in the anterior segment. It has been well known that the induction of the lens and development of the cornea and retina are dependent on PAX6/Pax6 in a cell-autonomous fashion, although the influence of PAX6/Pax6 on the other tissues derived from the ocular mesenchyme is largely unknown. Using transgenic mouse lines in which neural crest cells are genetically marked by LacZ or EGFP, we revealed the extensive contribution of neural crest derived cells (NCDCs) to the ocular tissues. Furthermore, various eye defects in Pax6(Sey/+) mouse were accompanied by abnormal distribution of NCDCs from early developmental stages to the adult. In Pax6(Sey/+) mouse mice, neural crest cells abnormally migrated into the developing eye in a cell nonautonomous manner at early embryonic stages. These results indicate that normal distribution and integration of NCDCs in ocular tissues depend on a proper dosage of Pax6, and that Pax6(Sey/+) eye anomalies are caused by cell autonomous and nonautonomous defects due to Pax6 haploinsufficiency.
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Affiliation(s)
- Sachiko Kanakubo
- Division of Developmental Neuroscience, Center for Translational and Advanced Animal Research, Tohoku University Graduate School of Medicine, 2-1, Seiryo-machi, Sendai, 980-8575, Japan
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