학술논문
Identification of a Complex Allele in IMPG2 as a Cause of Adult-Onset Vitelliform Macular Dystrophy.
Document Type
Academic Journal
Author
Vázquez-Domínguez I; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.; Li CHZ; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.; Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands.; Fadaie Z; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.; Haer-Wigman L; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.; Cremers FPM; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.; Garanto A; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.; Department of Pediatrics, Amalia Children's Hospital and Radboud Institute of Molecular Life Sciences (RIMLS), Radboud University Medical Center, Nijmegen, the Netherlands.; Hoyng CB; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.; Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands.; Roosing S; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.
Source
Publisher: Association For Research In Vision And Ophthalmology (Arvo) Country of Publication: United States NLM ID: 7703701 Publication Model: Print Cited Medium: Internet ISSN: 1552-5783 (Electronic) Linking ISSN: 01460404 NLM ISO Abbreviation: Invest Ophthalmol Vis Sci Subsets: MEDLINE
Subject
Language
English
Abstract
Purpose: Inherited retinal diseases are a group of clinically and genetically heterogeneous disorders with approximately 270 genes involved. IMPG2 is associated with adult-onset vitelliform macular dystrophy. Here, we investigated two unrelated patients with vitelliform macular dystrophy to identify the underlying genetic cause.
Methods: Whole-exome sequencing identified a putative causal complex allele consisting of c.3023-15T>A and c.3023G>A (p.(Gly1008Asp)) in IMPG2 in both individuals. To assess its effect, in vitro splice assays in HEK293T and further characterization in patient-derived photoreceptor precursor cells (PPCs) were conducted.
Results: The results of the midigene splice assays in HEK293T showed that the complex allele causes a variety of splicing defects ranging from a small deletion to (multiple-)exon skipping. This finding was further validated using patient-derived PPCs that showed a significant increase of out-of-frame transcripts lacking one or multiple exons compared to control-derived PPCs. Overall, control PPCs consistently showed low levels of aberrantly spliced IMPG2 transcripts that were highly elevated in patient-derived PPCs. These differences were even more obvious upon inhibition of nonsense-mediated decay with cycloheximide.
Conclusions: We report a heterozygous complex allele in IMPG2 causative for adult-onset vitelliform macular dystrophy in two unrelated individuals with mild visual loss and bilateral vitelliform lesions. The predicted causal missense mutation c.3023G>A, located in the consensus splice acceptor site, enhances the splicing effect of the upstream variant c.3023-15T>A, leading to the generation of aberrant transcripts that decrease the full-length IMPG2 levels. These results suggest a haploinsufficiency mechanism of action and highlight the complementarity of using different models to functionally assesses splicing defects.
Methods: Whole-exome sequencing identified a putative causal complex allele consisting of c.3023-15T>A and c.3023G>A (p.(Gly1008Asp)) in IMPG2 in both individuals. To assess its effect, in vitro splice assays in HEK293T and further characterization in patient-derived photoreceptor precursor cells (PPCs) were conducted.
Results: The results of the midigene splice assays in HEK293T showed that the complex allele causes a variety of splicing defects ranging from a small deletion to (multiple-)exon skipping. This finding was further validated using patient-derived PPCs that showed a significant increase of out-of-frame transcripts lacking one or multiple exons compared to control-derived PPCs. Overall, control PPCs consistently showed low levels of aberrantly spliced IMPG2 transcripts that were highly elevated in patient-derived PPCs. These differences were even more obvious upon inhibition of nonsense-mediated decay with cycloheximide.
Conclusions: We report a heterozygous complex allele in IMPG2 causative for adult-onset vitelliform macular dystrophy in two unrelated individuals with mild visual loss and bilateral vitelliform lesions. The predicted causal missense mutation c.3023G>A, located in the consensus splice acceptor site, enhances the splicing effect of the upstream variant c.3023-15T>A, leading to the generation of aberrant transcripts that decrease the full-length IMPG2 levels. These results suggest a haploinsufficiency mechanism of action and highlight the complementarity of using different models to functionally assesses splicing defects.