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Villafuerte-de la Cruz RA, Garza-Garza LA, Garza-Leon M, Rodriguez-De la Torre C, Parra-Bernal C, Vazquez-Camas I, Ramos-Gonzalez D, Rangel-Padilla A, Espino Barros-Palau A, Nava-García J, Castillo-Velazquez J, Castillo-De Leon E, Del Valle-Penella A, Valdez-Garcia JE, Rojas-Martinez A. Spectrum of variants associated with inherited retinal dystrophies in Northeast Mexico. BMC Ophthalmol 2024; 24:60. [PMID: 38347443 PMCID: PMC10860328 DOI: 10.1186/s12886-023-03276-7] [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: 08/30/2023] [Accepted: 12/26/2023] [Indexed: 02/15/2024] Open
Abstract
BACKGROUND Inherited retinal dystrophies are hereditary diseases which have in common the progressive degeneration of photoreceptors. They are a group of diseases with clinical, genetic, and allelic heterogeneity. There is limited information regarding the genetic landscape of inherited retinal diseases in Mexico, therefore, the present study was conducted in the northeast region of the country. METHODS Patients with inherited retinal dystrophies were included. A complete history, full ophthalmological and medical genetics evaluations, and genetic analysis through a targeted NGS panel for inherited retinal dystrophies comprising at least 293 genes were undertaken. RESULTS A total of 126 patients were included. Cases were solved in 74.6% of the study's population. Retinitis pigmentosa accounted for the most found inherited retinal disease. Ninety-nine causal variants were found, being USH2A and ABCA4 the most affected genes (26 and 15 cases, respectively). CONCLUSIONS The present study documents the most prevalent causative genes in IRDs, as USH2A, in northeastern Mexico. This contrasts with previous reports of IRDs in other zones of the country. Further studies, targeting previously unstudied populations in Mexico are important to document the genetic background of inherited retinal dystrophies in the country.
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Affiliation(s)
- Rocio A Villafuerte-de la Cruz
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
- Destellos de Luz, San Pedro Garza García, México
| | | | - Manuel Garza-Leon
- Destellos de Luz, San Pedro Garza García, México
- Clinical Science Department, Health Sciences Division, University of Monterrey, Monterrey, México
| | - Cesar Rodriguez-De la Torre
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
| | - Cinthya Parra-Bernal
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
| | - Ilse Vazquez-Camas
- Tecnologico de Monterrey, The Institute for Obesity Research, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
- Tecnologico Nacional de Mexico Campus Tuxtla Gutierrez, Tuxtla Gutierrez, Mexico
| | - David Ramos-Gonzalez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
| | - Andrea Rangel-Padilla
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
| | - Angelina Espino Barros-Palau
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
| | - Jose Nava-García
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
| | | | | | | | - Jorge E Valdez-Garcia
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico
| | - Augusto Rojas-Martinez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico.
- Tecnologico de Monterrey, The Institute for Obesity Research, Ave. Morones Prieto 3000, Col. Los Doctores, Monterrey, CP 64710, Mexico.
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Dulz S, Schwering C, Wildner J, Spartalis C, Schuettauf F, Bartsch U, Wibbeler E, Nickel M, Spitzer MS, Atiskova Y, Schulz A. Ongoing retinal degeneration despite intraventricular enzyme replacement therapy with cerliponase alfa in late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2 disease). Br J Ophthalmol 2023; 107:1478-1483. [PMID: 35772852 DOI: 10.1136/bjo-2022-321260] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 06/11/2022] [Indexed: 11/04/2022]
Abstract
BACKGROUND/AIMS Late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2) is a neurodegenerative, blinding lysosomal storage disorder. The purpose of the current study was to characterise the progression of CLN2-associated retinal degeneration in patients under intraventricular enzyme replacement therapy (ERT) with cerliponase alfa. METHODS We analysed visual function, retinal morphology and neuropaediatric data using preferential looking test (PLT), Weill Cornell Batten Scale (WCBS), optical coherence tomography (OCT) imaging and the Hamburg Motor-Language late-infantile neuronal ceroid lipofuscinosis (LINCL) Scale (M-L scale). RESULTS Fifty-six eyes of 28 patients had baseline PLT, WCBS and OCT. 15 patients underwent serial examinations, resulting in a total of 132 OCT scans and WCBS results, 66 Hamburg M-L scores and 49 PLT results during a mean follow-up time of 18.2 months (range 5-40). A negative correlation (r=-0.69, p<0.001) was found between central retinal thickness (CRT) values and age at examination with a maximal annual decrease of 23 µm between 56 and 80 months of age. A significant correlation was observed between PLT results and the age at examination (r=0.46, p=0.001), the WCBS scores (r=0.62; p<0.001) and CRT values (r=-0.64; p<0.001). The M-L score correlated with the ocular measurements (CRT: r=0.58, p<0.001; WCBS r=-0.64, p<0.001; PLT score: r=-0.57, p<0.001). CONCLUSION Despite intraventricular ERT, retinal degeneration progressed in patients with CLN2 and was particularly pronounced between 56 and 80 months of age. Retina-directed therapies should therefore be initiated before or as early as possible during the phase of rapid retinal degeneration. PLT and WCBS were identified as valuable outcome measures to monitor disease progression. TRIAL REGISTRATION NUMBER NCT04613089.
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Affiliation(s)
- Simon Dulz
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - C Schwering
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jan Wildner
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christoph Spartalis
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Frank Schuettauf
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Udo Bartsch
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Eva Wibbeler
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Miriam Nickel
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Martin Stephan Spitzer
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Yevgeniya Atiskova
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Angela Schulz
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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3
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Cameron JM, Damiano JA, Grinton B, Carney PW, McKelvie P, Silbert P, Lawn N, Scheffer IE, Oliver KL, Hildebrand MS, Berkovic SF. Recognition and epileptology of protracted CLN3 disease. Epilepsia 2023; 64:1833-1841. [PMID: 37039534 PMCID: PMC10952944 DOI: 10.1111/epi.17616] [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: 09/17/2022] [Revised: 04/08/2023] [Accepted: 04/10/2023] [Indexed: 04/12/2023]
Abstract
OBJECTIVE This study was undertaken to analyze phenotypic features of a cohort of patients with protracted CLN3 disease to improve recognition of the disorder. METHODS We analyzed phenotypic data of 10 patients from six families with protracted CLN3 disease. Haplotype analysis was performed in three reportedly unrelated families. RESULTS Visual impairment was the initial symptom, with onset at 5-9 years, similar to classic CLN3 disease. Mean time from onset of visual impairment to seizures was 12 years (range = 6-41 years). Various seizure types were reported, most commonly generalized tonic-clonic seizures; focal seizures were present in four patients. Progressive myoclonus epilepsy was not seen. Interictal electroencephalogram revealed mild background slowing and 2.5-3.5-Hz spontaneous generalized spike-wave discharges. Additional interictal focal epileptiform discharges were noted in some patients. Age at death for the three deceased patients was 31, 31, and 52 years. Molecular testing revealed five individuals were homozygous for c.461-280_677 + 382del966, the "common 1-kb" CLN3 deletion. The remaining individuals were compound heterozygous for various combinations of recurrent pathogenic CLN3 variants. Haplotype analysis demonstrated evidence of a common founder for the common 1-kb deletion. Dating analysis suggested the deletion arose approximately 1500 years ago and thus did not represent cryptic familial relationship in this Australian cohort. SIGNIFICANCE We highlight the protracted phenotype of a disease generally associated with death in adolescence, which is a combined focal and generalized epilepsy syndrome with progressive neurological deterioration. The disorder should be suspected in an adolescent or adult patient presenting with generalized or focal seizures preceded by progressive visual loss. The common 1-kb deletion has been typically associated with classic CLN3 disease, and the protracted phenotype has not previously been reported with this genotype. This suggests that modifying genetic factors may be important in determining this somewhat milder phenotype and identification of these factors should be the subject of future research.
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Affiliation(s)
- Jillian M. Cameron
- Department of Medicine, Epilepsy Research CentreUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
| | - John A. Damiano
- Department of Medicine, Epilepsy Research CentreUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
| | - Bronwyn Grinton
- Department of Medicine, Epilepsy Research CentreUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
| | - Patrick W. Carney
- Eastern Health Clinical SchoolMonash UniversityMelbourneVictoriaAustralia
- Florey Institute of Neuroscience and Mental HealthHeidelbergVictoriaAustralia
| | - Penny McKelvie
- Department of PathologySt Vincent's Hospital MelbourneMelbourneVictoriaAustralia
| | - Peter Silbert
- Department of MedicineUniversity of Western AustraliaPerthWestern AustraliaAustralia
| | | | - Ingrid E. Scheffer
- Department of Medicine, Epilepsy Research CentreUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
- Florey Institute of Neuroscience and Mental HealthHeidelbergVictoriaAustralia
- Department of PaediatricsUniversity of MelbourneMelbourneVictoriaAustralia
- Murdoch Children's Research InstituteParkvilleVictoriaAustralia
| | - Karen L. Oliver
- Department of Medicine, Epilepsy Research CentreUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
- Population Health and Immunity DivisionWalter and Eliza Hall Institute of Medical ResearchParkvilleVictoriaAustralia
- Department of Medical BiologyUniversity of MelbourneParkvilleVictoriaAustralia
| | - Michael S. Hildebrand
- Department of Medicine, Epilepsy Research CentreUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
- Murdoch Children's Research InstituteParkvilleVictoriaAustralia
| | - Samuel F. Berkovic
- Department of Medicine, Epilepsy Research CentreUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
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Sakti DH, Cornish EE, Fraser CL, Nash BM, Sandercoe TM, Jones MM, Rowe NA, Jamieson RV, Johnson AM, Grigg JR. Early recognition of CLN3 disease facilitated by visual electrophysiology and multimodal imaging. Doc Ophthalmol 2023; 146:241-256. [PMID: 36964447 PMCID: PMC10256658 DOI: 10.1007/s10633-023-09930-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 03/07/2023] [Indexed: 03/26/2023]
Abstract
BACKGROUND Neuronal ceroid lipofuscinosis is a group of neurodegenerative disorders with varying visual dysfunction. CLN3 is a subtype which commonly presents with visual decline. Visual symptomatology can be indistinct making early diagnosis difficult. This study reports ocular biomarkers of CLN3 patients to assist clinicians in early diagnosis, disease monitoring, and future therapy. METHODS Retrospective review of 5 confirmed CLN3 patients in our eye clinic. Best corrected visual acuity (BCVA), electroretinogram (ERG), ultra-widefield (UWF) fundus photography and fundus autofluorescence (FAF), and optical coherence tomography (OCT) studies were undertaken. RESULTS Five unrelated children, 4 females and 1 male, with median age of 6.2 years (4.6-11.7) at first assessment were investigated at the clinic from 2016 to 2021. Four homozygous and one heterozygous pathogenic CLN3 variants were found. Best corrected visual acuities (BCVAs) ranged from 0.18 to 0.88 logMAR at first presentation. Electronegative ERGs were identified in all patients. Bull's eye maculopathies found in all patients. Hyper-autofluorescence ring surrounding hypo-autofluorescence fovea on FAF was found. Foveal ellipsoid zone (EZ) disruptions were found in all patients with additional inner and outer retinal microcystic changes in one patient. Neurological problems noted included autism, anxiety, motor dyspraxia, behavioural issue, and psychomotor regression. CONCLUSIONS CLN3 patients presented at median age 6.2 years with visual decline. Early onset maculopathy with an electronegative ERG and variable cognitive and motor decline should prompt further investigations including neuropaediatric evaluation and genetic assessment for CLN3 disease. The structural parameters such as EZ and FAF will facilitate ocular monitoring.
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Affiliation(s)
- Dhimas H Sakti
- Save Sight Institute, Speciality of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney Eye Hospital Campus, 8 Macquarie St, Sydney, NSW, 2001, Australia
- Department of Ophthalmology, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Elisa E Cornish
- Save Sight Institute, Speciality of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney Eye Hospital Campus, 8 Macquarie St, Sydney, NSW, 2001, Australia
- Eye Genetics Research Unit, The Children's Hospital at Westmead, Save Sight Institute, Children's Medical Research Institute, The University of Sydney, Sydney, NSW, Australia
| | - Clare L Fraser
- Save Sight Institute, Speciality of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney Eye Hospital Campus, 8 Macquarie St, Sydney, NSW, 2001, Australia
| | - Benjamin M Nash
- Eye Genetics Research Unit, The Children's Hospital at Westmead, Save Sight Institute, Children's Medical Research Institute, The University of Sydney, Sydney, NSW, Australia
- Sydney Genome Diagnostics, Sydney Children's Hospital Network (Westmead), Sydney, Australia
| | - Trent M Sandercoe
- Department of Ophthalmology, Sydney Children's Hospital Network (Westmead), Sydney, Australia
| | - Michael M Jones
- Department of Ophthalmology, Sydney Children's Hospital Network (Westmead), Sydney, Australia
| | - Neil A Rowe
- Department of Ophthalmology, Sydney Children's Hospital Network (Westmead), Sydney, Australia
| | - Robyn V Jamieson
- Save Sight Institute, Speciality of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney Eye Hospital Campus, 8 Macquarie St, Sydney, NSW, 2001, Australia
- Eye Genetics Research Unit, The Children's Hospital at Westmead, Save Sight Institute, Children's Medical Research Institute, The University of Sydney, Sydney, NSW, Australia
| | - Alexandra M Johnson
- Department of Neurology, Sydney Children's Hospital, University of New South Wales, Sydney, Australia
| | - John R Grigg
- Save Sight Institute, Speciality of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney Eye Hospital Campus, 8 Macquarie St, Sydney, NSW, 2001, Australia.
- Eye Genetics Research Unit, The Children's Hospital at Westmead, Save Sight Institute, Children's Medical Research Institute, The University of Sydney, Sydney, NSW, Australia.
- Department of Ophthalmology, Sydney Children's Hospital Network (Westmead), Sydney, Australia.
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5
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Kuper WFE, Oostendorp M, van den Broek BTA, van Veghel K, Nonkes LJP, Nieuwenhuis EES, Fuchs SA, Veenendaal T, Klumperman J, Huisman A, Nierkens S, van Hasselt PM. Quantifying lymphocyte vacuolization serves as a measure of CLN3 disease severity. JIMD Rep 2020; 54:87-97. [PMID: 32685355 PMCID: PMC7358670 DOI: 10.1002/jmd2.12128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 04/28/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The CLN3 disease spectrum ranges from a childhood-onset neurodegenerative disorder to a retina-only disease. Given the lack of metabolic disease severity markers, it may be difficult to provide adequate counseling, particularly when novel genetic variants are identified. In this study, we assessed whether lymphocyte vacuolization, a well-known yet poorly explored characteristic of CLN3 disease, could serve as a measure of disease severity. METHODS Peripheral blood obtained from healthy controls and CLN3 disease patients was used to assess lymphocyte vacuolization by (a) calculating the degree of vacuolization using light microscopy and (b) quantifying expression of lysosomal-associated membrane protein 1 (LAMP-1), using flow cytometry in lymphocyte subsets as well as a qualitative analysis using electron microscopy and ImageStream analysis. RESULTS Quantifying lymphocyte vacuolization allowed to differentiate between CLN3 disease phenotypes (P = .0001). On immunofluorescence, classical CLN3 disease lymphocytes exhibited abundant vacuole-shaped LAMP-1 expression, suggesting the use of LAMP-1 as a proxy for lymphocyte vacuolization. Using flow cytometry in lymphocyte subsets, quantifying intracellular LAMP-1 expression additionally allowed to differentiate between infection and storage and to differentiate between CLN3 phenotypes even more in-depth revealing that intracellular LAMP-1 expression was most pronounced in T-cells of classical-protracted CLN3 disease while it was most pronounced in B-cells of "retina-only" CLN3 disease. CONCLUSION Lymphocyte vacuolization serves as a proxy for CLN3 disease severity. Quantifying vacuolization may help interpretation of novel genetic variants and provide an individualized readout for upcoming therapies.
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Affiliation(s)
- Willemijn F. E. Kuper
- Department of Metabolic Diseases, Wilhelmina Children's HospitalUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Marlies Oostendorp
- Department of Clinical ChemistryUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Brigitte T. A. van den Broek
- Sylvia Toth Center for the Multidisciplinary Follow up of Lysosomal Storage DisordersUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
- Laboratory of Translational ImmunologyUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Karin van Veghel
- Laboratory of Translational ImmunologyUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Lourens J. P. Nonkes
- Department of Clinical ChemistryUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Edward E. S. Nieuwenhuis
- Department of GastroenterologyWilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Sabine A. Fuchs
- Department of Metabolic Diseases, Wilhelmina Children's HospitalUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Tineke Veenendaal
- Section Cell Biology, Center for Molecular MedicineUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Judith Klumperman
- Section Cell Biology, Center for Molecular MedicineUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Albert Huisman
- Department of Clinical ChemistryUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Stefan Nierkens
- Laboratory of Translational ImmunologyUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
| | - Peter M. van Hasselt
- Department of Metabolic Diseases, Wilhelmina Children's HospitalUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
- Sylvia Toth Center for the Multidisciplinary Follow up of Lysosomal Storage DisordersUniversity Medical Center Utrecht, Utrecht UniversityUtrechtthe Netherlands
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6
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Kuper WFE, van Alfen C, van Eck L, de Man SA, Willemsen MH, van Gassen KLI, Losekoot M, van Hasselt PM. The c.1A > C start codon mutation in CLN3 is associated with a protracted disease course. JIMD Rep 2020; 52:23-27. [PMID: 32154056 PMCID: PMC7052694 DOI: 10.1002/jmd2.12097] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/13/2019] [Accepted: 01/10/2020] [Indexed: 12/12/2022] Open
Abstract
Background CLN3 disease is a disorder of lysosomal homeostasis predominantly affecting the retina and the brain. The severity of the underlying mutations in CLN3 particularly determines onset and course of neurological deterioration. Given the highly conserved start codon code among eukaryotic species, we expected a variant in the start codon of CLN3 to give rise to the classical, that is, severe, phenotype. Case series We present three patients with an identical CLN3 genotype (compound heterozygosity for the common 1 kb deletion in combination with a c.1A > C start codon variant) who all displayed a more attenuated phenotype than expected. While their retinal phenotype was similar to as expected in classical CLN3 disease, their neurological phenotype was delayed. Two patients had an early onset of cognitive impairment, but a particularly slow deterioration afterwards without any obvious motor impairment. The third patient also had a late onset of cognitive impairment. Conclusions Contrasting our initial expectations, patients with a start codon variant in CLN3 may display a protracted phenotype. Future work will have to reveal the exact mechanism behind the assumed residual protein synthesis, and determine whether this may be eligible to start codon targeted therapy.
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Affiliation(s)
- Willemijn F E Kuper
- Department of Metabolic Diseases, Wilhelmina Children's Hospital University Medical Center Utrecht, Utrecht University Utrecht The Netherlands
| | - Claudia van Alfen
- Bartiméus Institute for the Visually Impaired Zeist, Doorn The Netherlands
| | - Linda van Eck
- Bartiméus Institute for the Visually Impaired Zeist, Doorn The Netherlands
| | - Stella A de Man
- Department of Pediatrics Amphia Hospital Breda The Netherlands
| | - Marjolein H Willemsen
- Department of Human Genetics Radboud University Medical Center Nijmegen The Netherlands
| | - Koen L I van Gassen
- Department of Genetics University Medical Center Utrecht Utrecht The Netherlands
| | - Monique Losekoot
- Department of Clinical Genetics Leiden University Medical Center Leiden The Netherlands
| | - Peter M van Hasselt
- Department of Metabolic Diseases, Wilhelmina Children's Hospital University Medical Center Utrecht, Utrecht University Utrecht The Netherlands
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