학술논문
Scrutinizing pathogenicity of the USH2A c.2276 G > T; p.(Cys759Phe) variant
Document Type
article
Author
Janine Reurink; Erik de Vrieze; Catherina H. Z. Li; Emma van Berkel; Sanne Broekman; Marco Aben; Theo Peters; Jaap Oostrik; Kornelia Neveling; Hanka Venselaar; Mariana Guimarães Ramos; Christian Gilissen; Galuh D. N. Astuti; Jordi Corominas Galbany; Janneke J. C. van Lith-Verhoeven; Charlotte W. Ockeloen; Lonneke Haer-Wigman; Carel B. Hoyng; Frans P. M. Cremers; Hannie Kremer; Susanne Roosing; Erwin van Wijk
Source
npj Genomic Medicine, Vol 7, Iss 1, Pp 1-9 (2022)
Subject
Language
English
ISSN
2056-7944
Abstract
Abstract The USH2A variant c.2276 G > T (p.(Cys759Phe)) has been described by many authors as a frequent cause of autosomal recessive retinitis pigmentosa (arRP). However, this is in contrast with the description of two asymptomatic individuals homozygous for this variant. We therefore assessed pathogenicity of the USH2A c.2276 G > T variant using extensive genetic and functional analyses. Whole genome sequencing and optical genome mapping were performed for three arRP cases homozygous for USH2A c.2276 G > T to exclude alternative genetic causes. A minigene splice assay was designed to investigate the effect of c.2276 G > T on pre-mRNA splicing, in presence or absence of the nearby c.2256 T > C variant. Moreover, an ush2a p.(Cys771Phe) zebrafish knock-in model mimicking human p.(Cys759Phe) was generated and characterized using functional and immunohistochemical analyses. Besides the homozygous c.2276 G > T USH2A variant, no alternative genetic causes were identified. Evaluation of the ush2a p.(Cys771Phe) zebrafish model revealed strongly reduced levels of usherin expression at the photoreceptor periciliary membrane, increased levels of rhodopsin localization in the photoreceptor cell body and decreased electroretinogram (ERG) b-wave amplitudes compared to wildtype controls. In conclusion, we confirmed pathogenicity of USH2A c.2276 G > T (p.(Cys759Phe)). Consequently, cases homozygous for c.2276 G > T can now receive a definite genetic diagnosis and can be considered eligible for receiving future QR-421a-mediated exon 13 skipping therapy.