Targeted sequencing and in vitro splice assays shed light on ABCA4-associated retinopathies missing heritability.

Autor:	Corradi Z; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands. Electronic address: zelia.corradi@radboudumc.nl., Khan M; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Max Planck Institute for Psycholinguistics, Nijmegen, the Netherlands., Hitti-Malin R; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands., Mishra K; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands., Whelan L; The School of Genetics & Microbiology, Trinity College Dublin, Dublin, Ireland., Cornelis SS; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands., Hoyng CB; Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands., Kämpjärvi K; Blueprint Genetics, Espoo, Finland., Klaver CCW; Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands; Institute of Molecular & Clinical Ophthalmology, Basel, Switzerland., Liskova P; Research Unit for Rare Diseases, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic; Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic., Stöhr H; Institute of Human Genetics, University of Regensburg, Regensburg, Germany., Weber BHF; Institute of Human Genetics, University of Regensburg, Regensburg, Germany; Institute of Clinical Human Genetics, University Hospital Regensburg, Regensburg, Germany., Banfi S; Department of Precision Medicine, University of Campania 'Luigi Vanvitelli,' Naples and Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy., Farrar GJ; The School of Genetics & Microbiology, Trinity College Dublin, Dublin, Ireland., Sharon D; Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel., Zernant J; Department of Ophthalmology, Columbia University, New York, NY, USA., Allikmets R; Department of Ophthalmology, Columbia University, New York, NY, USA; Department of Pathology & Cell Biology, Columbia University, New York, NY, USA., Dhaenens CM; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; University Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, 59000 Lille, France., Cremers FPM; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.
Jazyk:	angličtina
Zdroj:	HGG advances [HGG Adv] 2023 Oct 12; Vol. 4 (4), pp. 100237. Date of Electronic Publication: 2023 Sep 12.
DOI:	10.1016/j.xhgg.2023.100237
Abstrakt:	The ABCA4 gene is the most frequently mutated Mendelian retinopathy-associated gene. Biallelic variants lead to a variety of phenotypes, however, for thousands of cases the underlying variants remain unknown. Here, we aim to shed further light on the missing heritability of ABCA4-associated retinopathy by analyzing a large cohort of macular dystrophy probands. A total of 858 probands were collected from 26 centers, of whom 722 carried no or one pathogenic ABCA4 variant, while 136 cases carried two ABCA4 alleles, one of which was a frequent mild variant, suggesting that deep-intronic variants (DIVs) or other cis-modifiers might have been missed. After single molecule molecular inversion probes (smMIPs)-based sequencing of the complete 128-kb ABCA4 locus, the effect of putative splice variants was assessed in vitro by midigene splice assays in HEK293T cells. The breakpoints of copy number variants (CNVs) were determined by junction PCR and Sanger sequencing. ABCA4 sequence analysis solved 207 of 520 (39.8%) naive or unsolved cases and 70 of 202 (34.7%) monoallelic cases, while additional causal variants were identified in 54 of 136 (39.7%) probands carrying two variants. Seven novel DIVs and six novel non-canonical splice site variants were detected in a total of 35 alleles and characterized, including the c.6283-321C>G variant leading to a complex splicing defect. Additionally, four novel CNVs were identified and characterized in five alleles. These results confirm that smMIPs-based sequencing of the complete ABCA4 gene provides a cost-effective method to genetically solve retinopathy cases and that several rare structural and splice altering defects remain undiscovered in Stargardt disease cases. Competing Interests: Declaration of interests The authors declare no competing interests. (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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