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Ren X, Huang L, Cheng S, Wang J, Li N. Novel pathogenic variants of SLC38A8 gene and literature review. Eur J Ophthalmol 2024:11206721241242155. [PMID: 38515398 DOI: 10.1177/11206721241242155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
PURPOSE This study aimed to analyze the clinical and genetic characteristics of 6 Chinese patients with foveal hypoplasia (FH) caused by the variants of solute carrier family 38 member 8 (SLC38A8), and to describe the genotype and phenotype of SLC38A8 variants from previous literature. METHODS All subjects underwent comprehensive ophthalmic examinations. Optical coherence tomography (OCT) was performed to evaluate the structural grade of FH. Pathogenic variants of SLC38A8 gene were identified using panel-based next-generation sequencing and direct Sanger sequencing techniques. Further, all previously reported cases of SLC38A8 variants were re-analyzed together with the novel ones identified in this study. RESULTS Nystagmus and FH were present in 6 patients with variants of SLC38A8 gene, accompanied by a normal anterior segment. Grade 4 FH was identified in 4 patients. A total of 12 variants of SLC38A8 gene were identified, including 9 novel variants. Systematical analysis revealed that half of the variants (30/60) were missense, the majority of which (23/30) were distributed in the transmembrane (TM) domains. Grade 4 FH was detected in the majority of patients (66%, 23/35). There was no statistical difference in the clinical features between the subgroups of patients with 0, 1 and 2 missense variants. CONCLUSION Severe arrest of foveal development was identified in patients with variants of SLC38A8. This study provides a brief summary of the clinical and genetic characteristics of the pathogenic SLC38A8 variants, which is helpful in the differentiation diagnosis of FH.
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Affiliation(s)
- Xiaofang Ren
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, No.56 Nanlishi Road, Xicheng District, Beijing, 100040, China
| | - Lijuan Huang
- Department of Ophthalmology, The Second Affiliated Hospital, Fujian Medical University, Quanzhou, 362000, China
| | - Shan Cheng
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Jing Wang
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Ningdong Li
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, No.56 Nanlishi Road, Xicheng District, Beijing, 100040, China
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, National Clinical Research Center for Eye Diseases, Shanghai, China
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Shoji MK, Khodeiry MM, Sengillo JD, Mendoza C. Expanding the mutational spectrum of FHONDA syndrome. Ophthalmic Genet 2023; 44:602-605. [PMID: 36748941 DOI: 10.1080/13816810.2023.2175873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/09/2023] [Accepted: 01/29/2023] [Indexed: 02/08/2023]
Abstract
AIM The aim of the study is to present a rare case of Foveal Hypoplasia, Optic Nerve Decussation defects, and Anterior segment dysgenesis (FHONDA) confirmed by genetic testing with two separate pathogenic mutations in the SLC38A8 gene. MATERIALS AND METHODS This was a case report. RESULTS A 3-month-old female presented to a neuro-ophthalmology clinic with nystagmus. Her past medical and family history was unremarkable. Her examination demonstrated horizontal pendular nystagmus and small optic nerves with foveal hypoplasia bilaterally. Neuroimaging was unremarkable. She underwent an examination under anesthesia and electroretinogram (ERG). Her anterior segment examination was normal, and dilated fundus examination demonstrated foveal hypoplasia with diffuse pigment granularity. The ERG was normal. Genetic testing revealed two mutations in the SLC38A8 gene, p.Glu233Lys:c.697 G>A (pathogenic) and p.Asp283Ala:c.848A>C (likely pathogenic) with positive parental segregation analysis. Therefore, she was diagnosed with FHONDA. CONCLUSIONS To our knowledge, this is the first report of a patient with FHONDA who is compound heterozygous for these two SLC38A8 mutations, which represents an expansion of the known mutational spectrum associated with this syndrome. Moreover, it may provide guidance into genetic counseling for patients and parents with these mutations.
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Affiliation(s)
- Marissa K Shoji
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA
| | | | - Jesse D Sengillo
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA
| | - Carlos Mendoza
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA
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3
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Kuht HJ, Maconachie GDE, Han J, Kessel L, van Genderen MM, McLean RJ, Hisaund M, Tu Z, Hertle RW, Gronskov K, Bai D, Wei A, Li W, Jiao Y, Smirnov V, Choi JH, Tobin MD, Sheth V, Purohit R, Dawar B, Girach A, Strul S, May L, Chen FK, Heath Jeffery RC, Aamir A, Sano R, Jin J, Brooks BP, Kohl S, Arveiler B, Montoliu L, Engle EC, Proudlock FA, Nishad G, Pani P, Varma G, Gottlob I, Thomas MG. Genotypic and Phenotypic Spectrum of Foveal Hypoplasia: A Multicenter Study. Ophthalmology 2022; 129:708-718. [PMID: 35157951 PMCID: PMC9341240 DOI: 10.1016/j.ophtha.2022.02.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 01/01/2023] Open
Abstract
PURPOSE To characterize the genotypic and phenotypic spectrum of foveal hypoplasia (FH). DESIGN Multicenter, observational study. PARTICIPANTS A total of 907 patients with a confirmed molecular diagnosis of albinism, PAX6, SLC38A8, FRMD7, AHR, or achromatopsia from 12 centers in 9 countries (n = 523) or extracted from publicly available datasets from previously reported literature (n = 384). METHODS Individuals with a confirmed molecular diagnosis and availability of foveal OCT scans were identified from 12 centers or from the literature between January 2011 and March 2021. A genetic diagnosis was confirmed by sequence analysis. Grading of FH was derived from OCT scans. MAIN OUTCOME MEASURES Grade of FH, presence or absence of photoreceptor specialization (PRS+ vs. PRS-), molecular diagnosis, and visual acuity (VA). RESULTS The most common genetic etiology for typical FH in our cohort was albinism (67.5%), followed by PAX6 (21.8%), SLC38A8 (6.8%), and FRMD7 (3.5%) variants. AHR variants were rare (0.4%). Atypical FH was seen in 67.4% of achromatopsia cases. Atypical FH in achromatopsia had significantly worse VA than typical FH (P < 0.0001). There was a significant difference in the spectrum of FH grades based on the molecular diagnosis (chi-square = 60.4, P < 0.0001). All SLC38A8 cases were PRS- (P = 0.003), whereas all FRMD7 cases were PRS+ (P < 0.0001). Analysis of albinism subtypes revealed a significant difference in the grade of FH (chi-square = 31.4, P < 0.0001) and VA (P = 0.0003) between oculocutaneous albinism (OCA) compared with ocular albinism (OA) and Hermansky-Pudlak syndrome (HPS). Ocular albinism and HPS demonstrated higher grades of FH and worse VA than OCA. There was a significant difference (P < 0.0001) in VA between FRMD7 variants compared with other diagnoses associated with FH. CONCLUSIONS We characterized the phenotypic and genotypic spectrum of FH. Atypical FH is associated with a worse prognosis than all other forms of FH. In typical FH, our data suggest that arrested retinal development occurs earlier in SLC38A8, OA, HPS, and AHR variants and later in FRMD7 variants. The defined time period of foveal developmental arrest for OCA and PAX6 variants seems to demonstrate more variability. Our findings provide mechanistic insight into disorders associated with FH and have significant prognostic and diagnostic value.
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Affiliation(s)
- Helen J Kuht
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom; Foveal Development Investigators Group
| | - Gail D E Maconachie
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom; Academic Unit of Ophthalmology and Orthoptics, University of Sheffield, Sheffield, United Kingdom; Foveal Development Investigators Group
| | - Jinu Han
- Institute of Vision Research, Department of Ophthalmology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea; Foveal Development Investigators Group
| | - Line Kessel
- Department of Ophthalmology, Rigshospitalet, Denmark; Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark; Foveal Development Investigators Group
| | - Maria M van Genderen
- Department of Ophthalmology, University Medical Centre Utrecht, Utrecht, The Netherlands; Bartiméus Diagnostic Centre for Complex Visual Disorders, Zeist, The Netherlands; Foveal Development Investigators Group
| | - Rebecca J McLean
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Michael Hisaund
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Zhanhan Tu
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom; Foveal Development Investigators Group
| | - Richard W Hertle
- Department of Ophthalmology, The Rebecca D. Considine Research Institute and The Children's Vision Center, Akron Children's Hospital, Akron, Ohio; Department of Surgery, The Northeastern Ohio Medical University, Rootstown, Ohio; Foveal Development Investigators Group
| | - Karen Gronskov
- Department of Clinical Genetics, Rigshospitalet-Kennedy Center, Glostrup, Denmark; Foveal Development Investigators Group
| | - Dayong Bai
- Department of Ophthalmology, Beijing Children's Hospital, National Center for Children's Health, Capital Medical University, Beijing, China; Foveal Development Investigators Group
| | - Aihua Wei
- Department of Dermatology, Beijing Tongren Hospital, Capital Medical University, Beijing, China; Foveal Development Investigators Group
| | - Wei Li
- Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute; Rare Disease Center, National Center for Children's Health; MOE Key Laboratory of Major Diseases in Children, Beijing Children's Hospital, Capital Medical University, Beijing, China; Foveal Development Investigators Group
| | - Yonghong Jiao
- Beijing Tongren Eye Centre, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Lab, Beijing, China; Foveal Development Investigators Group
| | - Vasily Smirnov
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris, France; Exploration de la Vision et Neuro-Ophtalmologie, CHU de Lille, Lille, France; Foveal Development Investigators Group
| | - Jae-Hwan Choi
- Department of Neurology, Pusan National University School of Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, South Korea; Foveal Development Investigators Group
| | - Martin D Tobin
- Department of Health Sciences, University of Leicester, Leicester, United Kingdom; Foveal Development Investigators Group
| | - Viral Sheth
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom; Academic Unit of Ophthalmology and Orthoptics, University of Sheffield, Sheffield, United Kingdom
| | - Ravi Purohit
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Basu Dawar
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Ayesha Girach
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Sasha Strul
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota; Foveal Development Investigators Group
| | - Laura May
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota; Foveal Development Investigators Group
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Crawley, Australia; Foveal Development Investigators Group
| | - Rachael C Heath Jeffery
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Crawley, Australia; Foveal Development Investigators Group
| | - Abdullah Aamir
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Ronaldo Sano
- Retina and Vitreous Sector of Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil; Foveal Development Investigators Group
| | - Jing Jin
- Sidney Kimmel Medical College of Thomas Jefferson University, Nemours Children's Health, Philadelphia, Pennsylvania; Nemours Children's Health, Wilmington, Delaware
| | - Brian P Brooks
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland; Foveal Development Investigators Group
| | - Susanne Kohl
- Centre for Ophthalmology, Institute for Ophthalmic Research, University Tübingen, Tübingen, Germany; Foveal Development Investigators Group
| | - Benoit Arveiler
- Rare Diseases, Genetics and Metabolism, INSERM U1211, University of Bordeaux, Bordeaux, France; Molecular Genetics Laboratory, Bordeaux University Hospital, Bordeaux, France; Foveal Development Investigators Group
| | - Lluis Montoliu
- National Centre for Biotechnology (CNB-CSIC) and CIBERER-ISCIII, Madrid, Spain; Foveal Development Investigators Group
| | - Elizabeth C Engle
- Departments of Neurology and Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; Howard Hughes Medical Institute, Chevy Chase, Maryland; Foveal Development Investigators Group
| | - Frank A Proudlock
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Garima Nishad
- International Institute of Information Technology, Hyderabad, India
| | - Prateek Pani
- International Institute of Information Technology, Hyderabad, India
| | - Girish Varma
- International Institute of Information Technology, Hyderabad, India; Foveal Development Investigators Group
| | - Irene Gottlob
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom; Foveal Development Investigators Group; Cooper Neurological Institute, Cooper Medical School of Rowan University, Camden, New Jersey
| | - Mervyn G Thomas
- The University of Leicester Ulverscroft Eye Unit, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom; Foveal Development Investigators Group.
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4
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Hayashi T, Kondo H, Matsushita I, Mizobuchi K, Baba A, Iida K, Kubo H, Nakano T. Homozygous single nucleotide duplication of SLC38A8 in autosomal recessive foveal hypoplasia: The first Japanese case report. Doc Ophthalmol 2021; 143:323-330. [PMID: 34037952 DOI: 10.1007/s10633-021-09842-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/13/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE To characterize the clinical and genetic features of a Japanese male patient with foveal hypoplasia caused by a homozygous single nucleotide duplication in the SLC38A8 gene. METHODS We performed a comprehensive ophthalmic examination including full-field electroretinography (FF-ERG) and pattern-reversal visual evoked potentials (PR-VEPs). Whole-exome sequencing (WES) was performed to identify the disease-causing variant; Sanger sequencing was used for confirmation. RESULTS In the WES analysis, a homozygous single nucleotide duplication (c.995dupG; p.Trp333MetfsTer35) was identified in SLC38A8 of the patient. His unaffected mother carried the variant heterozygously. The patient exhibited hyperopia, congenital nystagmus, low visual acuity, and grade 4 foveal hypoplasia. Slit-lamp examination revealed mild posterior embryotoxon and goniodysgenesis. Fundus examination revealed the absence of foveal hyperpigmentation and foveal avascularity, but there were no retinal degenerative lesions. In the FF-ERG, the amplitudes of rod ERG, standard-flash, and bright-flash ERG were within the normal range; cone-mediated responses also showed nearly normal amplitudes. The PR-VEP findings revealed delayed P100 latencies and decreased amplitudes of the P100 components, but no chiasmal misrouting. CONCLUSIONS This report is the first report on the clinical and genetic characteristics of SLC38A8-associated foveal hypoplasia in the Japanese population. This is also the first report of normal rod- and cone-mediated responses in a patient with this disorder.
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Affiliation(s)
- Takaaki Hayashi
- Department of Ophthalmology, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan. .,Department of Ophthalmology, Katsushika Medical Center, The Jikei University School of Medicine, 6-41-2 Aoto, Katsushika-ku, Tokyo, 125-8506, Japan.
| | - Hiroyuki Kondo
- Department of Ophthalmology, University of Occupational and Environmental Health, Kitakyushu, Fukuoka, 807-8555, Japan
| | - Itsuka Matsushita
- Department of Ophthalmology, University of Occupational and Environmental Health, Kitakyushu, Fukuoka, 807-8555, Japan
| | - Kei Mizobuchi
- Department of Ophthalmology, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Akinori Baba
- Department of Ophthalmology, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Kie Iida
- Department of Ophthalmology, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Hiroyuki Kubo
- Department of Ophthalmology, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Tadashi Nakano
- Department of Ophthalmology, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
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5
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Schiff ER, Tailor VK, Chan HW, Theodorou M, Webster AR, Moosajee M. Novel Biallelic Variants and Phenotypic Features in Patients with SLC38A8-Related Foveal Hypoplasia. Int J Mol Sci 2021; 22:ijms22031130. [PMID: 33498813 PMCID: PMC7866073 DOI: 10.3390/ijms22031130] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/17/2021] [Accepted: 01/21/2021] [Indexed: 12/19/2022] Open
Abstract
Biallelic pathogenic variants in solute carrier family 38 member 8, SLC38A8, cause a pan-ocular autosomal recessive condition known as foveal hypoplasia 2, FVH2, characterised by foveal hypoplasia, nystagmus and optic nerve chiasmal misrouting. Patients are often clinically diagnosed with ocular albinism, but foveal hypoplasia can occur in several other ocular disorders. Here we describe nine patients from seven families who had molecularly confirmed biallelic recessive variants in SLC38A8 identified through whole genome sequencing or targeted gene panel testing. We identified four novel sequence variants (p.(Tyr88*), p.(Trp145*), p.(Glu233Gly) and c.632+1G>A). All patients presented with foveal hypoplasia, nystagmus and reduced visual acuity; however, one patient did not exhibit any signs of chiasmal misrouting, and three patients had features of anterior segment dysgenesis. We highlight these findings in the context of 30 other families reported to date. This study reinforces the importance of obtaining a molecular diagnosis in patients whose phenotype overlap with other inherited ocular conditions, in order to support genetic counselling, clinical prognosis and family planning. We expand the spectrum of SLC38A8 mutations which will be relevant for treatment through future genetic-based therapies.
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Affiliation(s)
- Elena R. Schiff
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK; (E.R.S.); (V.K.T.); (H.W.C.); (M.T.); (A.R.W.)
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Vijay K. Tailor
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK; (E.R.S.); (V.K.T.); (H.W.C.); (M.T.); (A.R.W.)
- Department of Experimental Psychology, University College London, London WC1H 0AP, UK
| | - Hwei Wuen Chan
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK; (E.R.S.); (V.K.T.); (H.W.C.); (M.T.); (A.R.W.)
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Department of Ophthalmology, National University Hospital, Singapore S118177, Singapore
| | - Maria Theodorou
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK; (E.R.S.); (V.K.T.); (H.W.C.); (M.T.); (A.R.W.)
| | - Andrew R. Webster
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK; (E.R.S.); (V.K.T.); (H.W.C.); (M.T.); (A.R.W.)
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Mariya Moosajee
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK; (E.R.S.); (V.K.T.); (H.W.C.); (M.T.); (A.R.W.)
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
- The Francis Crick Institute, London NW1 1AT, UK
- Correspondence:
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6
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Weiner C, Hecht I, Rotenstreich Y, Guttman S, Or L, Morad Y, Shapira G, Shomron N, Pras E. The pathogenicity of SLC38A8 in five families with foveal hypoplasia and congenital nystagmus. Exp Eye Res 2020; 193:107958. [PMID: 32032626 DOI: 10.1016/j.exer.2020.107958] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 01/16/2020] [Accepted: 02/03/2020] [Indexed: 11/30/2022]
Abstract
PURPOSE A recently described subtype of foveal hypoplasia with congenital nystagmus and optic-nerve-decussation defects was found to be associated with mutations in the SLC38A8 gene. The aim of this study is to advance the clinical and molecular knowledge of SLC38A8 gene mutations. METHODS Five Israeli families with congenital foveal hypoplasia were studied, two of Karait Jewish origins and three of Indian Jewish origins. Subjects underwent a comprehensive ophthalmic examination including retinal photography and ocular coherence tomography. Molecular analysis including whole exome sequencing and screening of the SLC38A8 gene for specific disease-causing variants was performed. RESULTS Eight affected individuals were identified, all had congenital nystagmus and all but one had hypoplastic foveal pits. Anterior segment dysgenesis was observed in only one patient, one had evidence of developmental delay and another displayed early age-related macular degeneration (AMD). Molecular analysis revealed a recently described homozygous mutation, c.95T > G; p.Ile32Ser, in two families of Jewish Indian descent, and the same mutation in two families of Karaite Jewish descent. In a patient with only one pathogenic mutation (c.95T > G; p.Ile32Ser), a possible partial clinical expression of the disorder was seen. One patient of Jewish Indian descent was found to be compound heterozygous for c.95T > G; p.Ile32Ser and a novel mutation c.490_491delCT; p.L164Vfs*41. CONCLUSIONS In five unrelated families with congenital nystagmus and foveal hypoplasia, mutations in the SLC38A8 gene were identified. Possible partial expression in a heterozygous patient was observed and novel potential disease-related phenotypes were identified including early-onset AMD and developmental delay. A novel mutation was also identified and a similar mutation in both Indian and Karaite Jewish ethnicities could be suggestive for common ancestry.
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Affiliation(s)
- Chen Weiner
- Matlow's Ophthalmo-genetic Laboratory, Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Idan Hecht
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Ophthalmology, Shamir Medical Center, (formerly Assaf Harofeh Medical Center), Zerifin, Israel
| | - Ygal Rotenstreich
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Electrophysiology Clinic and Retinal Research Laboratory, Goldschleger Eye Institute, Sheba Medical Center, Israel
| | - Sharon Guttman
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Ophthalmology, Shamir Medical Center, (formerly Assaf Harofeh Medical Center), Zerifin, Israel
| | - Lior Or
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Ophthalmology, Shamir Medical Center, (formerly Assaf Harofeh Medical Center), Zerifin, Israel
| | - Yair Morad
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Ophthalmology, Shamir Medical Center, (formerly Assaf Harofeh Medical Center), Zerifin, Israel
| | - Guy Shapira
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Noam Shomron
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel; Edmond J. Safra Center of Bioinformatics, Tel Aviv University, Tel Aviv, Israel
| | - Eran Pras
- Matlow's Ophthalmo-genetic Laboratory, Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Ophthalmology, Shamir Medical Center, (formerly Assaf Harofeh Medical Center), Zerifin, Israel
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7
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Toral MA, Velez G, Boudreault K, Schaefer KA, Xu Y, Saffra N, Bassuk AG, Tsang SH, Mahajan VB. Structural modeling of a novel SLC38A8 mutation that causes foveal hypoplasia. Mol Genet Genomic Med 2017; 5:202-209. [PMID: 28546991 PMCID: PMC5441399 DOI: 10.1002/mgg3.266] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 11/07/2016] [Accepted: 11/13/2016] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Foveal hypoplasia (FH) in the absence of albinism, aniridia, microphthalmia, or achromatopsia is exceedingly rare, and the molecular basis for the disorder remains unknown. FH is characterized by the absence of both the retinal foveal pit and avascular zone, but with preserved retinal architecture. SLC38A8 encodes a sodium-coupled neutral amino acid transporter with a preference for glutamate as a substrate. SLC38A8 has been linked to FH. Here, we describe a novel mutation to SLC38A8 which causes FH, and report the novel use of OCT-angiography to improve the precision of FH diagnosis. More so, we used computational modeling to explore possible functional effects of known SLC38A8 mutations. METHODS Fundus autofluorescence, SD-OCT, and OCT-angiography were used to make the clinical diagnosis. Whole-exome sequencing led to the identification of a novel disease-causing variant in SLC38A8. Computational modeling approaches were used to visualize known SLC38A8 mutations, as well as to predict mutation effects on transporter structure and function. RESULTS We identified a novel point mutation in SLC38A8 that causes FH. A conclusive diagnosis was made using OCT-angiography, which more clearly revealed retinal vasculature penetrating into the foveal region. Structural modeling of the channel showed the mutation was near previously published mutations, clustered on an extracellular loop. Our modeling also predicted that the mutation destabilizes the protein by altering the electrostatic potential within the channel pore. CONCLUSION Our results demonstrate a novel use for OCT-angiography in confirming FH, and also uncover genotype-phenotype correlations of FH-linked SLC38A8 mutations.
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Affiliation(s)
- Marcus A Toral
- Omics LaboratoryUniversity of IowaIowa CityIowa.,Department of Ophthalmology and Visual SciencesUniversity of IowaIowa CityIowa.,Medical Scientist Training ProgramUniversity of IowaIowa CityIowa
| | - Gabriel Velez
- Omics LaboratoryUniversity of IowaIowa CityIowa.,Department of Ophthalmology and Visual SciencesUniversity of IowaIowa CityIowa.,Medical Scientist Training ProgramUniversity of IowaIowa CityIowa
| | | | - Kellie A Schaefer
- Omics LaboratoryUniversity of IowaIowa CityIowa.,Department of Ophthalmology and Visual SciencesUniversity of IowaIowa CityIowa
| | - Yu Xu
- Department of OphthalmologyUniversity of MontrealMontrealQuebecCanada
| | - Norman Saffra
- Department of OphthalmologyMaimonides Medical CenterBrooklynNew York
| | | | - Stephen H Tsang
- The Barbara & Donald Jonas Laboratory of Regenerative Medicine and Bernard & Shirlee Brown Glaucoma LaboratoryDepartments of Ophthalmology, Pathology & Cell BiologyCollege of Physicians & SurgeonsColumbia UniversityNew York CityNew York.,Edward S. Harkness Eye InstituteNew York-Presbyterian HospitalNew York CityNew York
| | - Vinit B Mahajan
- Omics LaboratoryUniversity of IowaIowa CityIowa.,Department of Ophthalmology and Visual SciencesUniversity of IowaIowa CityIowa
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