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Zhang X, Wang D, Dongye M, Zhu Y, Chen C, Wang R, Long E, Liu Z, Wu X, Lin D, Chen J, Lin Z, Wang J, Li W, Li Y, Li D, Lin H. Loss-of-function mutations in FREM2 disrupt eye morphogenesis. Exp Eye Res 2019; 181:302-312. [PMID: 30802441 DOI: 10.1016/j.exer.2019.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/30/2019] [Accepted: 02/17/2019] [Indexed: 10/27/2022]
Abstract
Cryptophthalmos is a rare congenital disorder characterized by ocular dysplasia with eyelid malformation. Complete cryptophthalmos is characterized by the presence of continuous skin from the forehead over the eyes and onto the cheek, along with complete fusion of the eyelids. In the present study, we characterized the clinical manifestations of three patients with isolated bilateral cryptophthalmos. These patients shared the same c.6499C > T missense mutation in the FRAS1-related extracellular matrix protein 2 (FREM2) gene, while each individual presented an additional nonsense mutation in the same gene (Patient #1, c.2206C > T; Patient #2, c.5309G > A; and Patient #3, c.4063C > T). Then, we used CRISPR/Cas9 to generate mice carrying Frem2R725X/R2156W compound heterozygous mutations, and showed that these mice recapitulated the human isolated cryptophthalmos phenotype. We detected FREM2 expression in the outer plexiform layer of the retina for the first time in the cryptophthalmic eyes, and the levels were comparable to the wild-type mice. Moreover, a set of different expressed genes that may contribute secondarily to the phenotypes were identified by performing RNA sequencing (RNA-seq) of the fetal Frem2 mutant mice. Our findings extend the spectrum of FREM2 mutations, and provide insights into opportunities for the prenatal diagnosis of isolated cryptophthalmos. Furthermore, our work highlights the importance of the FREM2 protein during the development of eyelids and the anterior segment of the eyeballs, establishes a suitable animal model for studying epithelial reopening during eyelid development and serves as a valuable reference for further mechanistic studies of the pathogenesis of isolated cryptophthalmos.
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Affiliation(s)
- Xiayin Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Dongni Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Meimei Dongye
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Yi Zhu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Chuan Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Ruixin Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Erping Long
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Zhenzhen Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Xiaohang Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Duoru Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Jingjing Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Zhuoling Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Jinghui Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Wangting Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Yang Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing, 100730, China
| | - Dongmei Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing, 100730, China
| | - Haotian Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China.
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Verma AS, Fitzpatrick DR. Anophthalmia and microphthalmia. Orphanet J Rare Dis 2007; 2:47. [PMID: 18039390 PMCID: PMC2246098 DOI: 10.1186/1750-1172-2-47] [Citation(s) in RCA: 243] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Accepted: 11/26/2007] [Indexed: 12/03/2022] Open
Abstract
Anophthalmia and microphthalmia describe, respectively, the absence of an eye and the presence of a small eye within the orbit. The combined birth prevalence of these conditions is up to 30 per 100,000 population, with microphthalmia reported in up to 11% of blind children. High-resolution cranial imaging, post-mortem examination and genetic studies suggest that these conditions represent a phenotypic continuum. Both anophthalmia and microphthalmia may occur in isolation or as part of a syndrome, as in one-third of cases. Anophthalmia/microphthalmia have complex aetiology with chromosomal, monogenic and environmental causes identified. Chromosomal duplications, deletions and translocations are implicated. Of monogenic causes only SOX2 has been identified as a major causative gene. Other linked genes include PAX6, OTX2, CHX10 and RAX. SOX2 and PAX6 mutations may act through causing lens induction failure. FOXE3 mutations, associated with lens agenesis, have been observed in a few microphthalmic patients. OTX2, CHX10 and RAX have retinal expression and may result in anophthalmia/microphthalmia through failure of retinal differentiation. Environmental factors also play a contributory role. The strongest evidence appears to be with gestational-acquired infections, but may also include maternal vitamin A deficiency, exposure to X-rays, solvent misuse and thalidomide exposure. Diagnosis can be made pre- and post-natally using a combination of clinical features, imaging (ultrasonography and CT/MR scanning) and genetic analysis. Genetic counselling can be challenging due to the extensive range of genes responsible and wide variation in phenotypic expression. Appropriate counselling is indicated if the mode of inheritance can be identified. Differential diagnoses include cryptophthalmos, cyclopia and synophthalmia, and congenital cystic eye. Patients are often managed within multi-disciplinary teams consisting of ophthalmologists, paediatricians and/or clinical geneticists, especially for syndromic cases. Treatment is directed towards maximising existing vision and improving cosmesis through simultaneous stimulation of both soft tissue and bony orbital growth. Mild to moderate microphthalmia is managed conservatively with conformers. Severe microphthalmia and anophthalmia rely upon additional remodelling strategies of endo-orbital volume replacement (with implants, expanders and dermis-fat grafts) and soft tissue reconstruction. The potential for visual development in microphthalmic patients is dependent upon retinal development and other ocular characteristics.
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Lowry RB, Kohut R, Sibbald B, Rouleau J. Anophthalmia and microphthalmia in the Alberta Congenital Anomalies Surveillance System. Can J Ophthalmol 2005; 40:38-44. [PMID: 15825528 DOI: 10.1016/s0008-4182(05)80115-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND A higher than expected rate of anophthalmia/microphthalmia (A/M) for 1999 was noted in both the Alberta Congenital Anomalies Surveillance System (ACASS) and the Canadian Congenital Anomalies Surveillance System (CCASS). Since this increase was at variance with the previous 19 years, we performed a review to determine whether the increase was true and, if so, the possible explanation. METHODS We reviewed the records of the cases of A/M in the ACASS together with the accompanying attachments (e.g., consultant, autopsy and chromosome reports) for 1991-2001. In addition, we contacted all 91 registered ophthalmologists in Alberta. Letters were also written to the Edmonton and Calgary offices of the Canadian National Institute for the Blind (CNIB). RESULTS Sixty cases of A/M were ascertained over the study period. Of the 88 active ophthalmologists in the province, 21 (24%) replied, but no new cases were ascertained from this source. No replies were received from the CNIB. We constructed five categories of clinical phenotypes for the 60 cases: 20 had a chromosomal etiology, 13 had a recognized syndrome or association, 16 had extraocular malformations, 5 had other eye anomalies, and 6 had A/M only. Pregnancy terminations were not included. The higher rate in 1999 was mainly due to cases with a chromosomal etiology or a recognized syndrome or association. There was no indication that a teratogen was causing a cluster of A/M cases, as our annual rates were comparable to those for other jurisdictions not only in Canada but also in other countries. INTERPRETATION Our review confirmed that the rate of A/M in Alberta in 1999 was high but that the increase was mainly due to five cases of trisomy 13 together with one case associated with a syndrome (Meckel-Gruber). Our findings provide reassurance that there was no environmental cause of clustering of anophthalmia or microphthalmia. This review demonstrates the importance of ongoing population-based surveillance in providing baseline birth prevalence rates for evaluating trends and clusters.
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Affiliation(s)
- R Brian Lowry
- Alberta Congenital Anomalies Surveillance System, Health Surveillance, Alberta Health and Wellness, Calgary, Alta.
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Hornby SJ, Ward SJ, Gilbert CE, Dandona L, Foster A, Jones RB. Environmental risk factors in congenital malformations of the eye. ANNALS OF TROPICAL PAEDIATRICS 2002; 22:67-77. [PMID: 11926054 DOI: 10.1179/027249302125000193] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Developmental eye defects such as coloboma are a significant cause of visual morbidity in children, and are more common in India than elsewhere. The possible role of environmental factors in the aetiology of these conditions was investigated by studying birth order, symptoms of vitamin A deficiency (night blindness), drug use and maternal illness in pregnancy, rubella antibodies and exposure to agricultural chemicals. Through hospital records and community-based rehabilitation programmes in Andhra Pradesh, children with colobomata were recruited from schools for the blind. Eighty-three mothers of affected children were interviewed. The results showed that 43% of parents were consanguineous, that 19% had a positive family history and that the frequency of coloboma was highest in second-born children. Eleven (16%) mothers had a history of night blindness while pregnant with the affected child; seven (8%) took medication during the 1st trimester, abortifacients in two cases; three reported fever in the 1st trimester; and 11 (13%) reported exposure to agricultural chemicals.
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Affiliation(s)
- Stella J Hornby
- Department of Epidemiology & International Eye Health, Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
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Goujard J. Clusters of birth defects: emergency and management. A review of some publications. Eur J Epidemiol 1999; 15:853-62. [PMID: 10608366 DOI: 10.1023/a:1007530216916] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Published reports of clusters of congenital anomalies, traditionally defined as an aggregation in time and/or space of malformed cases, are interesting to analyse in terms of emergence, management and initiator of a public health decision. Through some examples of clusters for which a suspected source has been suggested, for those having identified important causal relationship or for those where the cluster appeared without any explanation, the paper shows the different steps that were taken after the initial 'alarm' and the time spent between the alarm and a final conclusion. If basic keys such as accurate field investigation, reliable estimation of the expected number and etiological evaluation, are the rule, the handling should remain flexible to take into account the particularity of each cluster. Among the clusters of congenital anomalies published in the last 20 years, very few of them were clearly explained.
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Affiliation(s)
- J Goujard
- INSERM Unité 149 and Registre des Malformations Congénitales de Paris, France.
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