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Amorim AM, Ramada AB, Lopes AC, Duarte Silva E, Lemos J, Ribeiro JC. Vestibulo-ocular reflex dynamics with head-impulses discriminates Usher patients type 1 and 2. Sci Rep 2024; 14:3701. [PMID: 38355682 PMCID: PMC10867007 DOI: 10.1038/s41598-024-54270-y] [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: 10/04/2023] [Accepted: 02/10/2024] [Indexed: 02/16/2024] Open
Abstract
Usher Syndrome classification takes into account the absence of vestibular function but its correlation with genotype is not well characterized. We intend to investigate whether video Head Impulse Test (vHIT) is useful in screening and to differentiate Usher Syndrome types. 29 Usher patients (USH) with a genetically confirmed diagnosis and 30 healthy controls were studied with vHIT and dizziness handicap inventory questionnaire (DHI). Statistical significant differences between USH1, USH2 and controls were found in the vestibulo-ocular-reflex (VOR) gain of all SCCs, with USH1 patients consistently presenting smaller gains. VOR gain of the right lateral SCC could discriminate controls from USH1, and USH2 from USH1 with an overall diagnostic accuracy of 90%. USH1 DHI correlated with VOR (ρ = - 0,971, p = 0.001). Occurrence rate of covert and overt lateral semicircular canals refixation saccades (RS) was significantly different between groups, being higher in USH1 patients (p < 0.001). USH1 peak velocity of covert and overt saccades was higher for lateral semicircular canals (p < 0.05 and p = 0.001) compared with USH2 and controls. Covert saccades occurrence rate for horizontal SCCs could discriminate USH1 from USH2 patients and controls with a diagnostic accuracy of 85%. vHIT is a fast and non-invasive instrument which allowed us to screen and distinguish Usher patients from controls with a high precision. Importantly, its use allowed further discrimination between USH1 from USH2 groups. Moreover, VOR gain seems to correlate with vertigo-related quality of life in more severe phenotypes.
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Affiliation(s)
- Ana Margarida Amorim
- Department of Otorhinolaryngology, Coimbra University Hospital Centre, Praceta Mota Pinto, 3000-135, Coimbra, Portugal.
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
| | - Ana Beatriz Ramada
- Department of Otorhinolaryngology, Coimbra University Hospital Centre, Praceta Mota Pinto, 3000-135, Coimbra, Portugal
| | - Ana Cristina Lopes
- Department of Otorhinolaryngology, Coimbra University Hospital Centre, Praceta Mota Pinto, 3000-135, Coimbra, Portugal
| | | | - João Lemos
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
- Department of Neurology, Coimbra University Hospital Centre, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - João Carlos Ribeiro
- Department of Otorhinolaryngology, Coimbra University Hospital Centre, Praceta Mota Pinto, 3000-135, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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Guimaraes TACD, Arram E, Shakarchi AF, Georgiou M, Michaelides M. Inherited causes of combined vision and hearing loss: clinical features and molecular genetics. Br J Ophthalmol 2023; 107:1403-1414. [PMID: 36162969 DOI: 10.1136/bjo-2022-321790] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 09/07/2022] [Indexed: 11/04/2022]
Abstract
Combined vision and hearing loss, also known as dual sensory impairment, can occur in several genetic conditions, including ciliopathies such as Usher and Bardet-Biedl syndrome, mitochondrial DNA disorders and systemic diseases, such as CHARGE, Stickler, Waardenburg, Alport and Alstrom syndrome. The retinal phenotype may point to the diagnosis of such disorders. Herein, we aim to provide a comprehensive review of the molecular genetics and clinical features of the most common non-chromosomal inherited disorders to cause dual sensory impairment.
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Affiliation(s)
| | - Elizabeth Arram
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Ahmed F Shakarchi
- Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Michalis Georgiou
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
- Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Michel Michaelides
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
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3
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Bullock G, Johnson GS, Pattridge SG, Mhlanga-Mutangadura T, Guo J, Cook J, Campbell RS, Vite CH, Katz ML. A Homozygous MAN2B1 Missense Mutation in a Doberman Pinscher Dog with Neurodegeneration, Cytoplasmic Vacuoles, Autofluorescent Storage Granules, and an α-Mannosidase Deficiency. Genes (Basel) 2023; 14:1746. [PMID: 37761886 PMCID: PMC10531151 DOI: 10.3390/genes14091746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 08/28/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023] Open
Abstract
A 7-month-old Doberman Pinscher dog presented with progressive neurological signs and brain atrophy suggestive of a hereditary neurodegenerative disorder. The dog was euthanized due to the progression of disease signs. Microscopic examination of tissues collected at the time of euthanasia revealed massive accumulations of vacuolar inclusions in cells throughout the central nervous system, suggestive of a lysosomal storage disorder. A whole genome sequence generated with DNA from the affected dog contained a likely causal, homozygous missense variant in MAN2B1 that predicted an Asp104Gly amino acid substitution that was unique among whole genome sequences from over 4000 dogs. A lack of detectable α-mannosidase enzyme activity confirmed a diagnosis of a-mannosidosis. In addition to the vacuolar inclusions characteristic of α-mannosidosis, the dog exhibited accumulations of autofluorescent intracellular inclusions in some of the same tissues. The autofluorescence was similar to that which occurs in a group of lysosomal storage disorders called neuronal ceroid lipofuscinoses (NCLs). As in many of the NCLs, some of the storage bodies immunostained strongly for mitochondrial ATP synthase subunit c protein. This protein is not a substrate for α-mannosidase, so its accumulation and the development of storage body autofluorescence were likely due to a generalized impairment of lysosomal function secondary to the accumulation of α-mannosidase substrates. Thus, it appears that storage body autofluorescence and subunit c accumulation are not unique to the NCLs. Consistent with generalized lysosomal impairment, the affected dog exhibited accumulations of intracellular inclusions with varied and complex ultrastructural features characteristic of autophagolysosomes. Impaired autophagic flux may be a general feature of this class of disorders that contributes to disease pathology and could be a target for therapeutic intervention. In addition to storage body accumulation, glial activation indicative of neuroinflammation was observed in the brain and spinal cord of the proband.
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Affiliation(s)
- Garrett Bullock
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA; (G.B.); (G.S.J.); (S.G.P.); (T.M.-M.); (J.G.)
| | - Gary S. Johnson
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA; (G.B.); (G.S.J.); (S.G.P.); (T.M.-M.); (J.G.)
| | - Savannah G. Pattridge
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA; (G.B.); (G.S.J.); (S.G.P.); (T.M.-M.); (J.G.)
| | - Tendai Mhlanga-Mutangadura
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA; (G.B.); (G.S.J.); (S.G.P.); (T.M.-M.); (J.G.)
| | - Juyuan Guo
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA; (G.B.); (G.S.J.); (S.G.P.); (T.M.-M.); (J.G.)
| | - James Cook
- Specialists in Companion Animal Neurology, Clearwater, FL 33765, USA;
| | - Rebecca S. Campbell
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (R.S.C.); (C.H.V.)
| | - Charles H. Vite
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (R.S.C.); (C.H.V.)
| | - Martin L. Katz
- Neurodegenerative Diseases Research Laboratory, Department of Ophthalmology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
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Stephenson KAJ, Whelan L, Zhu J, Dockery A, Wynne NC, Cairns RM, Kirk C, Turner J, Duignan ES, O'Byrne JJ, Silvestri G, Kenna PF, Farrar GJ, Keegan DJ. Usher Syndrome on the Island of Ireland: A Genotype-Phenotype Review. Invest Ophthalmol Vis Sci 2023; 64:23. [PMID: 37466950 PMCID: PMC10362925 DOI: 10.1167/iovs.64.10.23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023] Open
Abstract
Purpose Usher syndrome (USH) is a genetically heterogeneous group of autosomal recessive (AR) syndromic inherited retinal degenerations (IRDs) representing 50% of deaf-blindness. All subtypes include retinitis pigmentosa, sensorineural hearing loss, and vestibular abnormalities. Thorough phenotyping may facilitate genetic diagnosis and intervention. Here we report the clinical/genetic features of an Irish USH cohort. Methods USH patients were selected from the Irish IRD registry (Target 5000). Patients were examined clinically (deep-phenotyping) and genetically using a 254 IRD-associated gene target capture sequencing panel, USH2A exon, and whole genome sequencing. Results The study identified 145 patients (24.1% USH1 [n = 35], 73.8% USH2 [n = 107], 1.4% USH3 [n = 2], and 0.7% USH4 [n = 1]). A genetic diagnosis was reached in 82.1%, the majority (80.7%) being MYO7A or USH2A genotypes. Mean visual acuity and visual field (VF) were 0.47 ± 0.58 LogMAR and 31.3° ± 32.8°, respectively, at a mean age of 43 years. Legal blindness criteria were met in 40.7%. Cataract was present in 77.4%. ADGRV1 genotypes had the most VF loss, whereas USH2A patients had greater myopia and CDH23 had the most astigmatism. Variants absent from gnomAD non-Finnish Europeans and ClinVar represented more than 20% of the variants identified and were detected in ADGRV1, ARSG, CDH23, MYO7A, and USH2A. Conclusions USH is a genetically diverse group of AR IRDs that have a profound impact on affected individuals and their families. The prevalence and phenotype/genotype characteristics of USH in Ireland have, as yet, gone unreported. Understanding the genotype of Irish USH patients may guide clinical and genetic characterization facilitating access to existing/novel therapeutics.
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Affiliation(s)
- Kirk A J Stephenson
- Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Laura Whelan
- The School of Genetics & Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Julia Zhu
- Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Adrian Dockery
- Next Generation Sequencing Laboratory, Pathology Department, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Niamh C Wynne
- The Research Foundation, Royal Victoria Eye & Ear Hospital, Dublin, Ireland
| | - Rebecca M Cairns
- Ophthalmology Department, Belfast Health and Social Care Trust Hospitals, Belfast, Northern Ireland
| | - Claire Kirk
- Ophthalmology Department, Belfast Health and Social Care Trust Hospitals, Belfast, Northern Ireland
| | - Jacqueline Turner
- Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Emma S Duignan
- The Research Foundation, Royal Victoria Eye & Ear Hospital, Dublin, Ireland
| | - James J O'Byrne
- Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Giuliana Silvestri
- Ophthalmology Department, Belfast Health and Social Care Trust Hospitals, Belfast, Northern Ireland
| | - Paul F Kenna
- The School of Genetics & Microbiology, Trinity College Dublin, Dublin, Ireland
- The Research Foundation, Royal Victoria Eye & Ear Hospital, Dublin, Ireland
| | - G Jane Farrar
- The School of Genetics & Microbiology, Trinity College Dublin, Dublin, Ireland
| | - David J Keegan
- Clinical Ophthalmic Genetics Unit, Mater Misericordiae University Hospital, Dublin, Ireland
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5
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Stemerdink M, Broekman S, Peters T, Kremer H, de Vrieze E, van Wijk E. Generation and Characterization of a Zebrafish Model for ADGRV1-Associated Retinal Dysfunction Using CRISPR/Cas9 Genome Editing Technology. Cells 2023; 12:1598. [PMID: 37371069 DOI: 10.3390/cells12121598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/26/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
Worldwide, around 40,000 people progressively lose their eyesight as a consequence of retinitis pigmentosa (RP) caused by pathogenic variants in the ADGRV1 gene, for which currently no treatment options exist. A model organism that mimics the human phenotype is essential to unravel the exact pathophysiological mechanism underlying ADGRV1-associated RP, and to evaluate future therapeutic strategies. The introduction of CRISPR/Cas-based genome editing technologies significantly improved the possibilities of generating mutant models in a time- and cost-effective manner. Zebrafish have been recognized as a suitable model to study Usher syndrome-associated retinal dysfunction. Using CRISPR/Cas9 technology we introduced a 4bp deletion in adgrv1 exon 9 (adgrv1rmc22). Immunohistochemical analysis showed that Adgrv1 was absent from the region of the photoreceptor connecting cilium in the adgrv1rmc22 zebrafish retina. Here, the absence of Adgrv1 also resulted in reduced levels of the USH2 complex members usherin and Whrnb, suggesting that Adgrv1 interacts with usherin and Whrnb in zebrafish photoreceptors. When comparing adgrv1rmc22 zebrafish with wild-type controls, we furthermore observed increased levels of aberrantly localized rhodopsin in the photoreceptor cell body, and decreased electroretinogram (ERG) B-wave amplitudes which indicate that the absence of Adgrv1 results in impaired retinal function. Based on these findings we present the adgrv1rmc22 zebrafish as the first ADGRV1 mutant model that displays an early retinal dysfunction. Moreover, the observed phenotypic changes can be used as quantifiable outcome measures when evaluating the efficacy of future novel therapeutic strategies for ADGRV1-associated RP.
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Affiliation(s)
- Merel Stemerdink
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Sanne Broekman
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Theo Peters
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Hannie Kremer
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Erik de Vrieze
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Erwin van Wijk
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
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Zhang H, Deng Y, Ma K, Sun C, Tang J. Case report: A case of corneal deposits between binocular descemet membrane and corneal endothelial layer after small-incision lenticule extraction (SMILE) followed by HPV vaccine. Front Med (Lausanne) 2022; 9:1042405. [PMID: 36619641 PMCID: PMC9811408 DOI: 10.3389/fmed.2022.1042405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/01/2022] [Indexed: 12/24/2022] Open
Abstract
Background Deposits located between the Descemet memberane and the corneal endothelial layer in both eyes has not yet been reported after SMILE. Case report Grayish white fine deposits was found between the Descemet memberane and the corneal endothelial layer in both eyes of the patient's cornea, and no other abnormalities were observed in the anterior and posterior segments of patient's eyes with ophthalmic examination instrument. However, the visual acuity of patient remained unchanged. Significantly, the patient had a sister who had undergone the same procedure a year earlier without any complications. After careful questioning, we learned that the patient received the 9-valent human papillomavirus (HPV) vaccine on the third post-operative day without any other special experiences. We performed immunological examination and genetic testing on the patient. The results of immunological examination of patient showed no obvious abnormality, which was consistent with the routine trend after vaccination. In particular, a homozygous variation of the ARSG gene was found in the patient and her sister. Conclusion There are two possible causes of corneal changes in patients. The first is IGA elevation caused by vaccination, deposited in the cornea. Second, the ARSG gene mutation of the patient leads to a potential congenital corneal dystrophy, and clinical manifestations occur under the stimulation of the vaccine.
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Clarke T, Fernandez FE, Dawson PA. Sulfation Pathways During Neurodevelopment. Front Mol Biosci 2022; 9:866196. [PMID: 35495624 PMCID: PMC9047184 DOI: 10.3389/fmolb.2022.866196] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 03/24/2022] [Indexed: 01/27/2023] Open
Abstract
Sulfate is an important nutrient that modulates a diverse range of molecular and cellular functions in mammalian physiology. Over the past 2 decades, animal studies have linked numerous sulfate maintenance genes with neurological phenotypes, including seizures, impaired neurodevelopment, and behavioral abnormalities. Despite sulfation pathways being highly conserved between humans and animals, less than one third of all known sulfate maintenance genes are clinically reportable. In this review, we curated the temporal and spatial expression of 91 sulfate maintenance genes in human fetal brain from 4 to 17 weeks post conception using the online Human Developmental Biology Resource Expression. In addition, we performed a systematic search of PubMed and Embase, identifying those sulfate maintenance genes linked to atypical neurological phenotypes in humans and animals. Those findings, together with a search of the Online Mendelian Inheritance in Man database, identified a total of 18 candidate neurological dysfunction genes that are not yet considered in clinical settings. Collectively, this article provides an overview of sulfate biology genes to inform future investigations of perturbed sulfate homeostasis associated with neurological conditions.
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Affiliation(s)
- Taylor Clarke
- School of Behavioural and Health Sciences, Faculty of Health Sciences, Australian Catholic University, Banyo, QLD, Australia
| | - Francesca E. Fernandez
- School of Behavioural and Health Sciences, Faculty of Health Sciences, Australian Catholic University, Banyo, QLD, Australia
| | - Paul A. Dawson
- Mater Research Institute, University of Queensland, Brisbane, QLD, Australia
- *Correspondence: Paul A. Dawson,
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The genetic and phenotypic landscapes of Usher syndrome: from disease mechanisms to a new classification. Hum Genet 2022; 141:709-735. [PMID: 35353227 PMCID: PMC9034986 DOI: 10.1007/s00439-022-02448-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 03/04/2022] [Indexed: 12/16/2022]
Abstract
Usher syndrome (USH) is the most common cause of deaf–blindness in humans, with a prevalence of about 1/10,000 (~ 400,000 people worldwide). Cochlear implants are currently used to reduce the burden of hearing loss in severe-to-profoundly deaf patients, but many promising treatments including gene, cell, and drug therapies to restore the native function of the inner ear and retinal sensory cells are under investigation. The traditional clinical classification of Usher syndrome defines three major subtypes—USH1, 2 and 3—according to hearing loss severity and onset, the presence or absence of vestibular dysfunction, and age at onset of retinitis pigmentosa. Pathogenic variants of nine USH genes have been initially reported: MYO7A, USH1C, PCDH15, CDH23, and USH1G for USH1, USH2A, ADGRV1, and WHRN for USH2, and CLRN1 for USH3. Based on the co-occurrence of hearing and vision deficits, the list of USH genes has been extended to few other genes, but with limited supporting information. A consensus on combined criteria for Usher syndrome is crucial for the development of accurate diagnosis and to improve patient management. In recent years, a wealth of information has been obtained concerning the properties of the Usher proteins, related molecular networks, potential genotype–phenotype correlations, and the pathogenic mechanisms underlying the impairment or loss of hearing, balance and vision. The advent of precision medicine calls for a clear and more precise diagnosis of Usher syndrome, exploiting all the existing data to develop a combined clinical/genetic/network/functional classification for Usher syndrome.
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9
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Velde HM, Reurink J, Held S, Li CHZ, Yzer S, Oostrik J, Weeda J, Haer-Wigman L, Yntema HG, Roosing S, Pauleikhoff L, Lange C, Whelan L, Dockery A, Zhu J, Keegan DJ, Farrar GJ, Kremer H, Lanting CP, Damme M, Pennings RJE. Usher syndrome type IV: clinically and molecularly confirmed by novel ARSG variants. Hum Genet 2022; 141:1723-1738. [PMID: 35226187 PMCID: PMC9556359 DOI: 10.1007/s00439-022-02441-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/10/2022] [Indexed: 12/16/2022]
Abstract
AbstractUsher syndrome (USH) is an autosomal recessively inherited disease characterized by sensorineural hearing loss (SNHL) and retinitis pigmentosa (RP) with or without vestibular dysfunction. It is highly heterogeneous both clinically and genetically. Recently, variants in the arylsulfatase G (ARSG) gene have been reported to underlie USH type IV. This distinct type of USH is characterized by late-onset RP with predominantly pericentral and macular changes, and late onset SNHL without vestibular dysfunction. In this study, we describe the USH type IV phenotype in three unrelated subjects. We identified three novel pathogenic variants, two novel likely pathogenic variants, and one previously described pathogenic variant in ARSG. Functional experiments indicated a loss of sulfatase activity of the mutant proteins. Our findings confirm that ARSG variants cause the newly defined USH type IV and support the proposed extension of the phenotypic USH classification.
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Affiliation(s)
- Hedwig M. Velde
- Hearing and Genes, Department of Otorhinolaryngology, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
| | - Janine Reurink
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
| | - Sebastian Held
- Department of Biochemistry, University of Kiel, Kiel, Germany
| | - Catherina H. Z. Li
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
- Department of Ophthalmology, Radboudumc, Nijmegen, The Netherlands
| | - Suzanne Yzer
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
- Department of Ophthalmology, Radboudumc, Nijmegen, The Netherlands
| | - Jaap Oostrik
- Hearing and Genes, Department of Otorhinolaryngology, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
| | - Jack Weeda
- Department of Ophthalmology, Radboudumc, Nijmegen, The Netherlands
| | - Lonneke Haer-Wigman
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
| | - Helger G. Yntema
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
| | - Susanne Roosing
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
| | - Laurenz Pauleikhoff
- Eye Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Clemens Lange
- Eye Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Laura Whelan
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Adrian Dockery
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
- Next Generation Sequencing Laboratory, Pathology Department, The Mater Misericordiae University Hospital, Dublin, Ireland
| | - Julia Zhu
- Mater Clinical Ophthalmic Genetics Unit, The Mater Misericordiae University Hospital, Dublin, Ireland
| | - David J. Keegan
- Mater Clinical Ophthalmic Genetics Unit, The Mater Misericordiae University Hospital, Dublin, Ireland
| | - G. Jane Farrar
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Hannie Kremer
- Hearing and Genes, Department of Otorhinolaryngology, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
- Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands
| | - Cornelis P. Lanting
- Hearing and Genes, Department of Otorhinolaryngology, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
| | - Markus Damme
- Department of Biochemistry, University of Kiel, Kiel, Germany
| | - Ronald J. E. Pennings
- Hearing and Genes, Department of Otorhinolaryngology, Radboudumc, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Nijmegen, The Netherlands
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10
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Abstract
Usher syndrome (USH) is the most common genetic condition responsible for combined loss of hearing and vision. Balance disorders and bilateral vestibular areflexia are also observed in some cases. The syndrome was first described by Albrecht von Graefe in 1858, but later named by Charles Usher, who presented a large number of cases with hearing loss and retinopathy in 1914. USH has been grouped into three main clinical types: 1, 2, and 3, which are caused by mutations in different genes and are further divided into different subtypes. To date, nine causative genes have been identified and confirmed as responsible for the syndrome when mutated: MYO7A, USH1C, CDH23, PCDH15, and USH1G (SANS) for Usher type 1; USH2A, ADGRV1, and WHRN for Usher type 2; CLRN1 for Usher type 3. USH is inherited in an autosomal recessive pattern. Digenic, bi-allelic, and polygenic forms have also been reported, in addition to dominant or nonsyndromic forms of genetic mutations. This narrative review reports the causative forms, diagnosis, prognosis, epidemiology, rehabilitation, research, and new treatments of USH.
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Igelman AD, Ku C, da Palma MM, Georgiou M, Schiff ER, Lam BL, Sankila EM, Ahn J, Pyers L, Vincent A, Ferraz Sallum JM, Zein WM, Oh JK, Maldonado RS, Ryu J, Tsang SH, Gorin MB, Webster AR, Michaelides M, Yang P, Pennesi ME. Expanding the clinical phenotype in patients with disease causing variants associated with atypical Usher syndrome. Ophthalmic Genet 2021; 42:664-673. [PMID: 34223797 PMCID: PMC9233901 DOI: 10.1080/13816810.2021.1946704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 05/28/2021] [Accepted: 06/18/2021] [Indexed: 10/20/2022]
Abstract
Atypical Usher syndrome (USH) is poorly defined with a broad clinical spectrum. Here, we characterize the clinical phenotype of disease caused by variants in CEP78, CEP250, ARSG, and ABHD12.Chart review evaluating demographic, clinical, imaging, and genetic findings of 19 patients from 18 families with a clinical diagnosis of retinal disease and confirmed disease-causing variants in CEP78, CEP250, ARSG, or ABHD12.CEP78-related disease included sensorineural hearing loss (SNHL) in 6/7 patients and demonstrated a broad phenotypic spectrum including: vascular attenuation, pallor of the optic disc, intraretinal pigment, retinal pigment epithelium mottling, areas of mid-peripheral hypo-autofluorescence, outer retinal atrophy, mild pigmentary changes in the macula, foveal hypo-autofluorescence, and granularity of the ellipsoid zone. Nonsense and frameshift variants in CEP250 showed mild retinal disease with progressive, non-congenital SNHL. ARSG variants resulted in a characteristic pericentral pattern of hypo-autofluorescence with one patient reporting non-congenital SNHL. ABHD12-related disease showed rod-cone dystrophy with macular involvement, early and severe decreased best corrected visual acuity, and non-congenital SNHL ranging from unreported to severe.This study serves to expand the clinical phenotypes of atypical USH. Given the variable findings, atypical USH should be considered in patients with peripheral and macular retinal disease even without the typical RP phenotype especially when SNHL is noted. Additionally, genetic screening may be useful in patients who have clinical symptoms and retinal findings even in the absence of known SNHL given the variability of atypical USH.
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Affiliation(s)
- Austin D Igelman
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Cristy Ku
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Mariana Matioli da Palma
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, UK
- Department of Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Elena R Schiff
- UCL Institute of Ophthalmology, University College London, London, UK
- Department of Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Byron L Lam
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Eeva-Marja Sankila
- Department of Ophthalmology, Helsinki University Eye Hospital, Helsinki, Finland
| | - Jeeyun Ahn
- UCLA Stein Eye Institute, Division of Retinal Disorders and Ophthalmic Genetics, Department of Ophthalmology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
- Department of Ophthalmology, Seoul National University, College of Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, South Korea
| | - Lindsey Pyers
- UCLA Stein Eye Institute, Division of Retinal Disorders and Ophthalmic Genetics, Department of Ophthalmology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Ajoy Vincent
- Department of Ophthalmology and Vision Sciences, the Hospital for Sick Children, University of Toronto, Canada
- Department of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Juliana Maria Ferraz Sallum
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Wadih M Zein
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jin Kyun Oh
- Jonas Children's Vision Care, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, New York, USA
- College of Medicine, State University of New York at Downstate Medical Center, Brooklyn, NY, USA
| | - Ramiro S Maldonado
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, KY, USA
| | - Joseph Ryu
- Jonas Children's Vision Care, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, New York, USA
| | - Stephen H Tsang
- Jonas Children's Vision Care, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, New York, USA
- Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | - Michael B Gorin
- UCLA Stein Eye Institute, Division of Retinal Disorders and Ophthalmic Genetics, Department of Ophthalmology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
- Department of Human Genetics, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, London, UK
- Department of Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK
- Department of Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Paul Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Mark E Pennesi
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
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12
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Decoding the consecutive lysosomal degradation of 3-O-sulfate containing heparan sulfate by Arylsulfatase G (ARSG). Biochem J 2021; 478:3221-3237. [PMID: 34405855 DOI: 10.1042/bcj20210415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/17/2021] [Accepted: 08/17/2021] [Indexed: 11/17/2022]
Abstract
The lysosomal degradation of heparan sulfate is mediated by the concerted action of nine different enzymes. Within this degradation pathway, Arylsulfatase G (ARSG) is critical for removing 3-O-sulfate from glucosamine, and mutations in ARSG are causative for Usher syndrome type IV. We developed a specific ARSG enzyme assay using sulfated monosaccharide substrates, which reflect derivatives of its natural substrates. These sulfated compounds were incubated with ARSG, and resulting products were analyzed by reversed-phase HPLC after chemical addition of the fluorescent dyes 2-aminoacridone or 2-aminobenzoic acid, respectively. We applied the assay to further characterize ARSG regarding its hydrolytic specificity against 3-O-sulfated monosaccharides containing additional sulfate-groups and N-acetylation. The application of recombinant ARSG and cells overexpressing ARSG as well as isolated lysosomes from wild-type and Arsg knockout mice validated the utility of our assay. We further exploited the assay to determine the sequential action of the different sulfatases involved in the lysosomal catabolism of 3-O-sulfated glucosamine residues of heparan sulfate. Our results confirm and extend the characterization of the substrate specificity of ARSG and help to determine the sequential order of the lysosomal catabolic breakdown of (3-O-)sulfated heparan sulfate.
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13
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Fuster-García C, García-Bohórquez B, Rodríguez-Muñoz A, Aller E, Jaijo T, Millán JM, García-García G. Usher Syndrome: Genetics of a Human Ciliopathy. Int J Mol Sci 2021; 22:ijms22136723. [PMID: 34201633 PMCID: PMC8268283 DOI: 10.3390/ijms22136723] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 12/21/2022] Open
Abstract
Usher syndrome (USH) is an autosomal recessive syndromic ciliopathy characterized by sensorineural hearing loss, retinitis pigmentosa and, sometimes, vestibular dysfunction. There are three clinical types depending on the severity and age of onset of the symptoms; in addition, ten genes are reported to be causative of USH, and six more related to the disease. These genes encode proteins of a diverse nature, which interact and form a dynamic protein network called the “Usher interactome”. In the organ of Corti, the USH proteins are essential for the correct development and maintenance of the structure and cohesion of the stereocilia. In the retina, the USH protein network is principally located in the periciliary region of the photoreceptors, and plays an important role in the maintenance of the periciliary structure and the trafficking of molecules between the inner and the outer segments of photoreceptors. Even though some genes are clearly involved in the syndrome, others are controversial. Moreover, expression of some USH genes has been detected in other tissues, which could explain their involvement in additional mild comorbidities. In this paper, we review the genetics of Usher syndrome and the spectrum of mutations in USH genes. The aim is to identify possible mutation associations with the disease and provide an updated genotype–phenotype correlation.
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Affiliation(s)
- Carla Fuster-García
- Molecular, Cellular and Genomics Biomedicine Research Group, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain; (C.F.-G.); (B.G.-B.); (A.R.-M.); (E.A.); (T.J.); (G.G.-G.)
- Unidad Mixta de Enfermedades Raras IIS La Fe-Centro de Investigación Príncipe Felipe, 46026 Valencia, Spain
- Biomedical Research Network for Rare Diseases, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain
| | - Belén García-Bohórquez
- Molecular, Cellular and Genomics Biomedicine Research Group, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain; (C.F.-G.); (B.G.-B.); (A.R.-M.); (E.A.); (T.J.); (G.G.-G.)
- Unidad Mixta de Enfermedades Raras IIS La Fe-Centro de Investigación Príncipe Felipe, 46026 Valencia, Spain
| | - Ana Rodríguez-Muñoz
- Molecular, Cellular and Genomics Biomedicine Research Group, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain; (C.F.-G.); (B.G.-B.); (A.R.-M.); (E.A.); (T.J.); (G.G.-G.)
- Unidad Mixta de Enfermedades Raras IIS La Fe-Centro de Investigación Príncipe Felipe, 46026 Valencia, Spain
| | - Elena Aller
- Molecular, Cellular and Genomics Biomedicine Research Group, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain; (C.F.-G.); (B.G.-B.); (A.R.-M.); (E.A.); (T.J.); (G.G.-G.)
- Unidad Mixta de Enfermedades Raras IIS La Fe-Centro de Investigación Príncipe Felipe, 46026 Valencia, Spain
- Biomedical Research Network for Rare Diseases, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain
- Genetics Unit, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain
| | - Teresa Jaijo
- Molecular, Cellular and Genomics Biomedicine Research Group, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain; (C.F.-G.); (B.G.-B.); (A.R.-M.); (E.A.); (T.J.); (G.G.-G.)
- Unidad Mixta de Enfermedades Raras IIS La Fe-Centro de Investigación Príncipe Felipe, 46026 Valencia, Spain
- Biomedical Research Network for Rare Diseases, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain
- Genetics Unit, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain
| | - José M. Millán
- Molecular, Cellular and Genomics Biomedicine Research Group, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain; (C.F.-G.); (B.G.-B.); (A.R.-M.); (E.A.); (T.J.); (G.G.-G.)
- Unidad Mixta de Enfermedades Raras IIS La Fe-Centro de Investigación Príncipe Felipe, 46026 Valencia, Spain
- Biomedical Research Network for Rare Diseases, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain
- Correspondence:
| | - Gema García-García
- Molecular, Cellular and Genomics Biomedicine Research Group, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain; (C.F.-G.); (B.G.-B.); (A.R.-M.); (E.A.); (T.J.); (G.G.-G.)
- Unidad Mixta de Enfermedades Raras IIS La Fe-Centro de Investigación Príncipe Felipe, 46026 Valencia, Spain
- Biomedical Research Network for Rare Diseases, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain
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14
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Douek AM, Amiri Khabooshan M, Henry J, Stamatis SA, Kreuder F, Ramm G, Änkö ML, Wlodkowic D, Kaslin J. An Engineered sgsh Mutant Zebrafish Recapitulates Molecular and Behavioural Pathobiology of Sanfilippo Syndrome A/MPS IIIA. Int J Mol Sci 2021; 22:ijms22115948. [PMID: 34073041 PMCID: PMC8197930 DOI: 10.3390/ijms22115948] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 12/29/2022] Open
Abstract
Mucopolysaccharidosis IIIA (MPS IIIA, Sanfilippo syndrome type A), a paediatric neurological lysosomal storage disease, is caused by impaired function of the enzyme N-sulfoglucosamine sulfohydrolase (SGSH) resulting in impaired catabolism of heparan sulfate glycosaminoglycan (HS GAG) and its accumulation in tissues. MPS IIIA represents a significant proportion of childhood dementias. This condition generally leads to patient death in the teenage years, yet no effective therapy exists for MPS IIIA and a complete understanding of the mechanisms of MPS IIIA pathogenesis is lacking. Here, we employ targeted CRISPR/Cas9 mutagenesis to generate a model of MPS IIIA in the zebrafish, a model organism with strong genetic tractability and amenity for high-throughput screening. The sgshΔex5-6 zebrafish mutant exhibits a complete absence of Sgsh enzymatic activity, leading to progressive accumulation of HS degradation products with age. sgshΔex5-6 zebrafish faithfully recapitulate diverse CNS-specific features of MPS IIIA, including neuronal lysosomal overabundance, complex behavioural phenotypes, and profound, lifelong neuroinflammation. We further demonstrate that neuroinflammation in sgshΔex5-6 zebrafish is largely dependent on interleukin-1β and can be attenuated via the pharmacological inhibition of Caspase-1, which partially rescues behavioural abnormalities in sgshΔex5-6 mutant larvae in a context-dependent manner. We expect the sgshΔex5-6 zebrafish mutant to be a valuable resource in gaining a better understanding of MPS IIIA pathobiology towards the development of timely and effective therapeutic interventions.
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Affiliation(s)
- Alon M. Douek
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia; (A.M.D.); (M.A.K.); (S.-A.S.); (F.K.)
| | - Mitra Amiri Khabooshan
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia; (A.M.D.); (M.A.K.); (S.-A.S.); (F.K.)
| | - Jason Henry
- Neurotoxicology Lab, School of Science (Biosciences), RMIT University, Bundoora, VIC 3083, Australia; (J.H.); (D.W.)
| | - Sebastian-Alexander Stamatis
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia; (A.M.D.); (M.A.K.); (S.-A.S.); (F.K.)
| | - Florian Kreuder
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia; (A.M.D.); (M.A.K.); (S.-A.S.); (F.K.)
| | - Georg Ramm
- Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC 3800, Australia;
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Minna-Liisa Änkö
- Centre for Reproductive Health and Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia;
- Department of Molecular and Translational Sciences, Monash University, Clayton, VIC 3800, Australia
| | - Donald Wlodkowic
- Neurotoxicology Lab, School of Science (Biosciences), RMIT University, Bundoora, VIC 3083, Australia; (J.H.); (D.W.)
| | - Jan Kaslin
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia; (A.M.D.); (M.A.K.); (S.-A.S.); (F.K.)
- Correspondence: ; Tel.: +61-3-9902-9613; Fax: +61-3-9902-9729
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15
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Sánchez-Bellver L, Toulis V, Marfany G. On the Wrong Track: Alterations of Ciliary Transport in Inherited Retinal Dystrophies. Front Cell Dev Biol 2021; 9:623734. [PMID: 33748110 PMCID: PMC7973215 DOI: 10.3389/fcell.2021.623734] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/09/2021] [Indexed: 01/14/2023] Open
Abstract
Ciliopathies are a group of heterogeneous inherited disorders associated with dysfunction of the cilium, a ubiquitous microtubule-based organelle involved in a broad range of cellular functions. Most ciliopathies are syndromic, since several organs whose cells produce a cilium, such as the retina, cochlea or kidney, are affected by mutations in ciliary-related genes. In the retina, photoreceptor cells present a highly specialized neurosensory cilium, the outer segment, stacked with membranous disks where photoreception and phototransduction occurs. The daily renewal of the more distal disks is a unique characteristic of photoreceptor outer segments, resulting in an elevated protein demand. All components necessary for outer segment formation, maintenance and function have to be transported from the photoreceptor inner segment, where synthesis occurs, to the cilium. Therefore, efficient transport of selected proteins is critical for photoreceptor ciliogenesis and function, and any alteration in either cargo delivery to the cilium or intraciliary trafficking compromises photoreceptor survival and leads to retinal degeneration. To date, mutations in more than 100 ciliary genes have been associated with retinal dystrophies, accounting for almost 25% of these inherited rare diseases. Interestingly, not all mutations in ciliary genes that cause retinal degeneration are also involved in pleiotropic pathologies in other ciliated organs. Depending on the mutation, the same gene can cause syndromic or non-syndromic retinopathies, thus emphasizing the highly refined specialization of the photoreceptor neurosensory cilia, and raising the possibility of photoreceptor-specific molecular mechanisms underlying common ciliary functions such as ciliary transport. In this review, we will focus on ciliary transport in photoreceptor cells and discuss the molecular complexity underpinning retinal ciliopathies, with a special emphasis on ciliary genes that, when mutated, cause either syndromic or non-syndromic retinal ciliopathies.
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Affiliation(s)
- Laura Sánchez-Bellver
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
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16
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Fowler NH, El-Rashedy MI, Chishti EA, Vander Kooi CW, Maldonado RS. Multimodal imaging and genetic findings in a case of ARSG-related atypical Usher syndrome. Ophthalmic Genet 2021; 42:338-343. [PMID: 33629623 DOI: 10.1080/13816810.2021.1891552] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background: Atypical Usher syndrome has recently been associated with arylsulfatase G (ARSG) variants. In these cases, characteristic findings include progressive sensorineural hearing loss (SNHL) without vestibular involvement and ring-shaped late-onset retinitis pigmentosa (RP).Materials and Methods: One patient with atypical Usher syndrome and a novel homozygous ARSG variant was included in this study. The patient underwent a comprehensive ophthalmic examination, including multimodal imaging and genetic testing.Results: A 60-year-old male of Persian decent presented to our clinic with a history of 20 years of progressive SNHL, and 10 years of progressive peripheral vision loss and pigmentary retinopathy. Consistent with previous reports of ARSG-related atypical Usher syndrome, fundus examination revealed ring-shaped retinal hyperpigmentation and fundus autofluorescence (FAF) demonstrated a six-zone pattern of autofluorescence. Optical coherence tomography (OCT) showed extensive cystoid spaces concentrated in the ganglion cell layer. Widefield OCT angiography at the level of the choriocapillaris showed signs of atrophy that corresponded to the FAF hypofluorescent zone. The patient was homozygous for a novel ARSG variant c. 1270 C > T, p. Arg424Cys.Conclusion: We report a novel ARSG variant in a case of atypical Usher syndrome and describe multimodal imaging findings that further characterize the effect of ARSG in the pathogenesis of atypical Usher syndrome.
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Affiliation(s)
- Nicholas H Fowler
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - May I El-Rashedy
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Emad A Chishti
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Craig W Vander Kooi
- Molecular and Cellular Biochemistry Center for Structural Biology, University of Kentucky, Lexington, Kentucky, USA
| | - Ramiro S Maldonado
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, Kentucky, USA
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17
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Peter VG, Quinodoz M, Sadio S, Held S, Rodrigues M, Soares M, Sousa AB, Coutinho Santos L, Damme M, Rivolta C. New clinical and molecular evidence linking mutations in ARSG to Usher syndrome type IV. Hum Mutat 2020; 42:261-271. [PMID: 33300174 DOI: 10.1002/humu.24150] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 11/11/2020] [Accepted: 12/06/2020] [Indexed: 11/11/2022]
Abstract
In murine and canine animal models, mutations in the Arylsulfatase G gene (ARSG) cause a particular lysosomal storage disorder characterized by neurological phenotypes. Recently, two variants in the same gene were found to be associated with an atypical form of Usher syndrome in humans, leading to visual and auditory impairment without the involvement of the central nervous system. In this study, we identified three novel pathogenic variants in ARSG, which segregated recessively with the disease in two families from Portugal. The probands were affected with retinitis pigmentosa and sensorineural hearing loss, generally with an onset of symptoms in their fourth decade of life. Functional experiments showed that these pathogenic variants abolish the sulfatase activity of the Arylsulfatase G enzyme and impede the appropriate lysosomal localization of the protein product, which appears to be retained in the endoplasmic reticulum. Our data enable to definitely confirm that different biallelic variants in ARSG cause a specific deaf-blindness syndrome, by abolishing the activity of the enzyme it encodes.
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Affiliation(s)
- Virginie G Peter
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland.,Department of Ophthalmology, University of Basel, Basel, Switzerland.,Institute of Experimental Pathology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Mathieu Quinodoz
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland.,Department of Ophthalmology, University of Basel, Basel, Switzerland.,Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Silvia Sadio
- Department of Ophthalmology, Instituto de Oftalmologia Dr. Gama Pinto, Lisbon, Portugal
| | - Sebastian Held
- Department of Biochemistry, University of Kiel, Kiel, Germany
| | - Márcia Rodrigues
- Department of Medical Genetics, Hospital Santa Maria, Centro Hospitalar Universitário Lisboa Norte (CHULN), Lisbon Academic Medical Center (CAML), Lisbon, Portugal
| | - Marta Soares
- Department of Medical Genetics, Hospital Santa Maria, Centro Hospitalar Universitário Lisboa Norte (CHULN), Lisbon Academic Medical Center (CAML), Lisbon, Portugal
| | - Ana Berta Sousa
- Department of Medical Genetics, Hospital Santa Maria, Centro Hospitalar Universitário Lisboa Norte (CHULN), Lisbon Academic Medical Center (CAML), Lisbon, Portugal.,Department of Basic Immunology, Medical Faculty, University of Lisbon, Lisbon, Portugal
| | - Luisa Coutinho Santos
- Department of Ophthalmology, Instituto de Oftalmologia Dr. Gama Pinto, Lisbon, Portugal
| | - Markus Damme
- Department of Biochemistry, University of Kiel, Kiel, Germany
| | - Carlo Rivolta
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland.,Department of Ophthalmology, University of Basel, Basel, Switzerland.,Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
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18
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Lysosomal sulfatases: a growing family. Biochem J 2020; 477:3963-3983. [PMID: 33120425 DOI: 10.1042/bcj20200586] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/29/2020] [Accepted: 10/02/2020] [Indexed: 02/07/2023]
Abstract
Sulfatases constitute a family of enzymes that specifically act in the hydrolytic degradation of sulfated metabolites by removing sulfate monoesters from various substrates, particularly glycolipids and glycosaminoglycans. A common essential feature of all known eukaryotic sulfatases is the posttranslational modification of a critical cysteine residue in their active site by oxidation to formylglycine (FGly), which is mediated by the FGly-generating enzyme in the endoplasmic reticulum and is indispensable for catalytic activity. The majority of the so far described sulfatases localize intracellularly to lysosomes, where they act in different catabolic pathways. Mutations in genes coding for lysosomal sulfatases lead to an accumulation of the sulfated substrates in lysosomes, resulting in impaired cellular function and multisystemic disorders presenting as lysosomal storage diseases, which also cover the mucopolysaccharidoses and metachromatic leukodystrophy. Bioinformatics analysis of the eukaryotic genomes revealed, besides the well described and long known disease-associated sulfatases, additional genes coding for putative enzymes with sulfatases activity, including arylsulfatase G as well as the arylsulfatases H, I, J and K, respectively. In this article, we review current knowledge about lysosomal sulfatases with a special focus on the just recently characterized family members arylsulfatase G and arylsulfatase K.
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