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Zhang J, Ban T, Zhou L, Ji H, Yan H, Shi Z, Cao B, Jiang Y, Wang J, Wu Y. Epilepsy in children with leukodystrophies. J Neurol 2020; 267:2612-2618. [DOI: 10.1007/s00415-020-09889-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 05/03/2020] [Accepted: 05/05/2020] [Indexed: 01/06/2023]
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Mutations in RARS cause a hypomyelination disorder akin to Pelizaeus-Merzbacher disease. Eur J Hum Genet 2017; 25:1134-1141. [PMID: 28905880 DOI: 10.1038/ejhg.2017.119] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 06/18/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a rare Mendelian disorder characterised by central nervous system hypomyelination. PMD typically manifests in infancy or early childhood and is caused by mutations in proteolipid protein-1 (PLP1). However, variants in several other genes including gap junction protein gamma 2 (GJC2) can also cause a similar phenotype and are referred to PMD-like disease (PMLD). Whole-exome sequencing in two siblings presenting with clinical symptoms of PMD revealed a homozygous variant in the arginyl-tRNA synthetase (RARS) gene: NM_002887.3: c.[5A>G] p.(Asp2Gly). Subsequent screening of a PMD cohort without a genetic diagnosis identified an unrelated individual with novel compound heterozygous variants including a missense variant c.[1367C>T] p.(Ser456Leu) and a de novo deletion c.[1846_1847delTA] p.(Tyr616Leufs*6). Protein levels of RARS and the multi-tRNA synthetase complex into which it assembles were found to be significantly reduced by 80 and 90% by western blotting and Blue native-PAGE respectively using patient fibroblast extracts. As RARS is involved in protein synthesis whereby it attaches arginine to its cognate tRNA, patient cells were studied to determine their ability to proliferate with limiting amounts of this essential amino acid. Patient fibroblasts cultured in medium with limited arginine at 30 °C and 40 °C, showed a significant decrease in fibroblast proliferation (P<0.001) compared to control cells, suggestive of inefficiency of protein synthesis in the patient cells. Our functional studies provide further evidence that RARS is a PMD-causing gene.
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Gait abnormalities and progressive myelin degeneration in a new murine model of Pelizaeus-Merzbacher disease with tandem genomic duplication. J Neurosci 2013; 33:11788-99. [PMID: 23864668 DOI: 10.1523/jneurosci.1336-13.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a hypomyelinating leukodystrophy caused by mutations of the proteolipid protein 1 gene (PLP1), which is located on the X chromosome and encodes the most abundant protein of myelin in the central nervous sytem. Approximately 60% of PMD cases result from genomic duplications of a region of the X chromosome that includes the entire PLP1 gene. The duplications are typically in a head-to-tail arrangement, and they vary in size and gene content. Although rodent models with extra copies of Plp1 have been developed, none contains an actual genomic rearrangement that resembles those found in PMD patients. We used mutagenic insertion chromosome engineering resources to generate the Plp1dup mouse model by introducing an X chromosome duplication in the mouse genome that contains Plp1 and five neighboring genes that are also commonly duplicated in PMD patients. The Plp1dup mice display progressive gait abnormalities compared with wild-type littermates. The single duplication leads to increased transcript levels of Plp1 and four of the five other duplicated genes over wild-type levels in the brain beginning the second postnatal week. The Plp1dup mice also display altered transcript levels of other important myelin proteins leading to a progressive degeneration of myelin. Our results show that a single duplication of the Plp1 gene leads to a phenotype similar to the pattern seen in human PMD patients with duplications.
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Lee E, Yum MS, Choi HW, Yoo HW, You SJ, Lee EH, Ko TS. Magnetic resonance imaging and spectroscopic analysis in 5 cases of Pelizaeus-Merzbacher disease: metabolic abnormalities as diagnostic tools. KOREAN JOURNAL OF PEDIATRICS 2012; 55:397-402. [PMID: 23133488 PMCID: PMC3488617 DOI: 10.3345/kjp.2012.55.10.397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 02/14/2012] [Accepted: 04/16/2012] [Indexed: 11/28/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is a rare, X-linked recessive disorder characterized by dysmyelination in the central nervous system. PMD results from deletion, mutation, or duplication of the proteolipid protein gene (PLP1) located at Xq22, leading to the failure of axon myelination by oligodendrocytes in the central nervous system. PMD may be suspected when there are clinical manifestations such as nystagmus, developmental delays, and spasticity, and genetic analysis can confirm the diagnosis. Further diagnostic manifestations of the disease include a lack of myelination on brain magnetic resonance (MR) imaging and aberrant N-acetyl aspartate (NAA) and choline concentrations that reflect axonal and myelination abnormalities on phroton MR spectroscopy. We report 5 cases of PMD (in 1 girl and 4 boys). PLP1 duplication was detected in 2 patients. Brain MR analyses and MR spectroscopy were performed for all the patients. The brain MR images showed white matter abnormalities typical of PMD, and the MR spectroscopic images showed diverse patterns of NAA, creatinine, and choline concentrations. We propose that MR spectroscopic analysis of metabolic alterations can aid the PMD diagnosis and can contribute to a better understanding of the pathogenesis of the disease.
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Affiliation(s)
- Eun Lee
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
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Liégeois FJ, Morgan AT. Neural bases of childhood speech disorders: lateralization and plasticity for speech functions during development. Neurosci Biobehav Rev 2011; 36:439-58. [PMID: 21827785 DOI: 10.1016/j.neubiorev.2011.07.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 07/07/2011] [Accepted: 07/23/2011] [Indexed: 11/27/2022]
Abstract
Current models of speech production in adults emphasize the crucial role played by the left perisylvian cortex, primary and pre-motor cortices, the basal ganglia, and the cerebellum for normal speech production. Whether similar brain-behaviour relationships and leftward cortical dominance are found in childhood remains unclear. Here we reviewed recent evidence linking motor speech disorders (apraxia of speech and dysarthria) and brain abnormalities in children and adolescents with developmental, progressive, or childhood-acquired conditions. We found no evidence that unilateral damage can result in apraxia of speech, or that left hemisphere lesions are more likely to result in dysarthria than lesion to the right. The few studies reporting on childhood apraxia of speech converged towards morphological, structural, metabolic or epileptic anomalies affecting the basal ganglia, perisylvian and rolandic cortices bilaterally. Persistent dysarthria, similarly, was commonly reported in individuals with syndromes and conditions affecting these same structures bilaterally. In conclusion, for the first time we provide evidence that longterm and severe childhood speech disorders result predominantly from bilateral disruption of the neural networks involved in speech production.
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Affiliation(s)
- Frédérique J Liégeois
- Developmental Cognitive Neuroscience Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK.
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Yiu EM, Farrell SA, Soman T. Classic Pelizaeus-Merzbacher disease in a girl with an unbalanced chromosomal translocation and functional duplication of PLP1. Mov Disord 2010; 24:2171-2. [PMID: 19705472 DOI: 10.1002/mds.22734] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Fattal-Valevski A, DiMaio MS, Hisama FM, Hobson GM, Davis-Williams A, Garbern JY, Mahoney MJ, Kolodny EH, Pastores GM. Variable expression of a novel PLP1 mutation in members of a family with Pelizaeus-Merzbacher disease. J Child Neurol 2009; 24:618-24. [PMID: 19151366 DOI: 10.1177/0883073808327833] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pelizaeus-Merzbacher disease is a rare X-linked disorder caused by mutations of the proteolipid protein 1 gene that encodes a structural component of myelin. It is characterized by progressive psychomotor delay, nystagmus, spastic quadriplegia, and cerebellar ataxia. Variable clinical expression was seen in 5 members of a family bearing a novel missense mutation in proteolipid protein 1, c.619T>C. Symptomatic patients included a 6-year-old girl, her younger brother, and their maternal uncle, a 29-year-old college graduate initially diagnosed with cerebral palsy; their brain magnetic resonance imaging studies showed diffuse dysmyelination. The mother had a history of delayed walking, achieved independently by age 3; she and the maternal grandmother were asymptomatic on presentation. Review of clinical information and family history led to consideration of Pelizaeus-Merzbacher disease. Subsequent identification of the causal mutation enabled preimplantation genetic diagnosis and the birth of an unaffected child.
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Affiliation(s)
- Aviva Fattal-Valevski
- Institute for Child Development and Pediatric Neurology Unit, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Kim SJ, Yoon JS, Baek HJ, Suh SI, Bae SY, Cho HJ, Ki CS. Identification of proteolipid protein 1 gene duplication by multiplex ligation-dependent probe amplification: first report of genetically confirmed family of Pelizaeus-Merzbacher disease in Korea. J Korean Med Sci 2008; 23:328-31. [PMID: 18437021 PMCID: PMC2526427 DOI: 10.3346/jkms.2008.23.2.328] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive disorder with a prototype of a dysmyelinating leukodystrophy that is caused by a mutation in the proteolipid protein 1 (PLP1) gene on the long arm of the X chromosome in band Xq22. This mutation results in abnormal expression or production of PLP. We here present a Korean boy with spastic quadriplegia, horizontal nystagmus, saccadic gaze, intentional tremor, head titubation, ataxia, and developmental delay. The brain magnetic resonance imaging (MRI) showed abnormally high signal intensities in the white matter tract, including a subcortical U fiber on the T2-weighted and fluid attenuated inversion recovery (FLAIR) image. The chromosomal analysis was normal; however, duplication of the PLP1 gene in chromosome Xq22 was detected when the multiplex ligation-dependent probe amplification (MLPA) method was used. We also investigated the pedigree for a genetic study related to PMD. This case suggests that the duplication mutation of the PLP1 gene in patients with PMD results in a mild clinical form of the disorder that mimics the spastic quadriplegia of cerebral palsy.
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Affiliation(s)
- Sei Joo Kim
- Department of Physical Medicine and Rehabilitation, College of Medicine, Korea University, Seoul, Korea
| | - Joon Shik Yoon
- Department of Physical Medicine and Rehabilitation, College of Medicine, Korea University, Seoul, Korea
| | - Hye Jin Baek
- Department of Physical Medicine and Rehabilitation, College of Medicine, Korea University, Seoul, Korea
| | - Sang Il Suh
- Department of Diagnostic Radiology, College of Medicine, Korea University, Seoul, Korea
| | - Sook Young Bae
- Department of Laboratory Medicine,College of Medicine, Korea University, Seoul, Korea
| | - Hyun-Jung Cho
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Tanaka M, Hamano SI, Sakata H, Adachi N, Kaga K, Osaka H, Kurosawa K. Discrepancy between auditory brainstem responses, auditory steady-state responses, and auditory behavior in two patients with Pelizaeus-Merzbacher disease. Auris Nasus Larynx 2007; 35:404-7. [PMID: 18029128 DOI: 10.1016/j.anl.2007.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 08/16/2007] [Accepted: 09/14/2007] [Indexed: 11/16/2022]
Abstract
We reported two cases of Pelizaeus-Merzbacher disease. Both cases visited our hospital manifesting horizontal nystagmoid movements present from birth, and delayed motor development. Magnetic resonance imaging of the brain showed diffuse dysmyelination of the cerebral white matter, and auditory brainstem response showed waves I and II but absence of all subsequent components. Conditioned orientation reflex (COR) audiometry showed poor reactions in an infantile case whose development was severely retarded, and who spoke no meaningful words. Auditory steady-state response (ASSR) was a helpful tool for identifying her auditory ability; thereafter, her communication skills improved naturally. The other case was mildly developmentally retarded, and the results of COR audiometry and ASSR were considered the same level. The discrepancy between results of these hearing tests may arise under the influence of developmental level of the case.
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Affiliation(s)
- Manabu Tanaka
- Division of Neurology, Saitama Children's Medical Center, Saitama, Japan.
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Harsan LA, Poulet P, Guignard B, Parizel N, Skoff RP, Ghandour MS. Astrocytic hypertrophy in dysmyelination influences the diffusion anisotropy of white matter. J Neurosci Res 2007; 85:935-44. [PMID: 17278151 DOI: 10.1002/jnr.21201] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effect of a proteolipid protein (PLP) mutation on the developing white matter anisotropy was examined by diffusion tensor magnetic resonance imaging (DT-MRI) in a noninvasive study of a mouse model of Pelizaeus-Merzbacher disease (PMD). The jimpy PLP mutation in mice produces an irreversible dysmyelination in jimpy males, whereas heterozygous females exhibit a transient hypomyelination, as assessed by a longitudinal study of the same mice during development. Modifications of the different individual DT-MRI parameters were highlighted by specific changes in tissue structures caused by the mutation that includes the hypomyelination, axonal abnormalities, and recovery. Astrocytic hypertrophy is a striking cellular event in dysmyelinated jimpy brain, where most axons or bundles of fibers are entirely wrapped by astrocyte cytoplasmic processes, so its influences on DT-MRI parameters in dysmyelination were examined for the first time. DT-MRI data of the jimpy brain were compared with those obtained from dysmyelination of (oligo-TTK) transgenic mice, induced by oligodendrocyte killing, which have a mild astrocyte hypertrophy (Jalabi et al., 2005), and from recovering jimpy females, which have reduced astrocyte hypertrophy. The unique morphological feature of astrocytes in jimpy males coupled with an increase in the water channel protein aquaporin 4 (AQP4) was found to facilitate the directional water diffusion in the white matter. In addition to the major changes of DT-MRI parameters in the two dysmyelinated mice caused by the myelin loss and axonal modifications, the amplified magnitude of radial and axial diffusions in jimpy males was attributed principally to the strongly pronounced astrocyte hypertrophy.
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Affiliation(s)
- Laura A Harsan
- UMR 7004 CNRS/ULP, Institut de Physique Biologique, Strasbourg, France
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McGuire LM, Williams LS, Walsh LE, DeMyer WE, Golomb MR. The impact of Pelizaeus-Merzbacher disease on the family. Pediatr Neurol 2007; 36:101-5. [PMID: 17275661 DOI: 10.1016/j.pediatrneurol.2006.09.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 08/03/2006] [Accepted: 09/26/2006] [Indexed: 10/23/2022]
Abstract
The impact of Pelizaeus-Merzbacher disease on families and caregivers of affected children has not been well-studied. Parents, relatives, and caregivers from 18 families with 20 affected children with Pelizaeus-Merzbacher disease were asked to complete the Children's Health Questionnaire-Parent Form 50, an instrument used to assess health-related quality of life in children and family impact of illness. Mean and standard deviation (S.D.) of subscale scores were calculated and compared with previously published norms. Agreement between mothers and fathers was calculated using Cronbach's test. Mean scale scores in this cohort were lower than previously published norms for the following categories: physical function (25.9 vs 96.1, >2 S.D.); family activity (55.6 vs 89.7, >1 S.D.); and parental time impact (66.2 vs 87.8, >1 S.D.). However, family cohesion (73.3 vs 72.3, <1 S.D.), self-esteem (71.1 vs 79.8, <1 S.D.), behavior (78.9 vs 75.6, <1 S.D.), and mental health scale scores (74.2 vs 78.5, <1 S.D.) were similar to previously published norms. Parental agreement was poor, with 5 of 8 parent pairs (63%) differing in their responses (<0.7) Although impact on caregiver time and limitation of physical function and family activities is high, parents and caregivers in the cohort appear to remain cohesive and view their children's psychosocial health as similar to normal children.
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Affiliation(s)
- Lisa M McGuire
- Division of Pediatric Neurology, Department of Neurology, Indiana University School of Medicine, and the Roudebush Veterans' Affairs Medical Center Health Services Research and Development Service, Indianapolis, Indiana 46202, USA
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Blumkin L, Lev D, Watemberg N, Lerman-Sagie T. Hypomyelinating leukoencephalopathy with paroxysmal tonic upgaze and absence of psychomotor development. Mov Disord 2007; 22:226-30. [PMID: 17149740 DOI: 10.1002/mds.21277] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hypomyelinating leukoencephalopathies are characterized by a substantial and permanent deficit in myelin deposition in the brain. Although our knowledge and understanding of the etiology of white matter diseases has progressively increased, many cases with this disorder remain undiagnosed, despite extensive evaluations. Recently, new disease entities have been defined by combining magnetic resonance imaging pattern recognition and clinical features. We describe a 1-year-old Ashkenazi Jewish girl with a hypomyelinating leukoencephalopathy, who presented in the neonatal period with episodes of sustained paroxysmal tonic upward gaze, roving eye movements, pendular nystagmus, and severe hypotonia, with the later appearance of pyramidal and extrapyramidal signs and no development. In addition, she has dysmorphic signs. This clinical picture is not consistent with any of the previously described hypomyelinating leukoencephalopathies and may represent a new entity.
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Affiliation(s)
- Lubov Blumkin
- Pediatric Neurology Unit, Wolfson Medical Center, Holon, affiliated to Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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Astle WF, Papp A, Huang PT, Ingram A. Refractive laser surgery in children with coexisting medical and ocular pathology. J Cataract Refract Surg 2006; 32:103-8. [PMID: 16516787 DOI: 10.1016/j.jcrs.2005.11.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Accepted: 02/17/2005] [Indexed: 11/25/2022]
Abstract
PURPOSE To report the visual, refractive, and functional outcomes of photorefractive keratectomy (PRK) and of laser-assisted subepithelial keratectomy in a group of children with significant refractive error and underlying medical conditions or ocular pathology who were noncompliant with traditional management. SETTING Nonhospital surgical facility and a hospital clinic. METHODS This case series comprised 5 individual cases of anisometropic amblyopia and/or high myopia. Underlying medical and ocular conditions were as follows: upper eyelid hemangioma with oblique myopic astigmatism, Pelizaeus-Merzbacher leukodystrophy with nystagmus, Klippel-Trenaunay-Weber syndrome with glaucoma, incontinentia pigmenti with unilateral optic nerve atrophy, and Goldenhar syndrome with unilateral optic nerve hypoplasia. Photorefractive keratectomy or LASEK was performed in 6 eyes of 5 patients. Age range at the time of surgery was 1.0 to 7.0 years. All procedures were performed under general anesthesia. RESULTS Best corrected visual acuity improved by 2 lines in 2 patients and 1 line in 2 patients by 6 months after surgery. Stereopsis and/or fusional status improved in 3 patients. Amblyopia treatment compliance improved in 1 patient. Alignment improved without strabismus surgery in 2 cases. A functional vision survey demonstrated a positive effect on the ability of all 5 children to function in their environment. CONCLUSION During the period of visual cortical plasticity, refractive surgery, by eliminating the refractive component of amblyopia and by promoting fusional ability, provides considerable improvement in children, even those with underlying medical conditions associated with ocular pathology.
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Affiliation(s)
- William F Astle
- Alberta Children's Hospital, University of Calgary, Division of Ophthalmology, Canada
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