Logo image
Exonic splice variant discovery using in vitro models of inherited retinal disease
Journal article   Open access   Peer reviewed

Exonic splice variant discovery using in vitro models of inherited retinal disease

Nathaniel K. Mullin, Laura R. Bohrer, Kristin R. Anfinson, Jeaneen L. Andorf, Robert F. Mullins, Budd A. Tucker and Edwin M. Stone
HGG advances, Vol.6(1), 100357
01/2025
DOI: 10.1016/j.xhgg.2024.100357
PMCID: PMC11550365
PMID: 39354715
url
https://doi.org/10.1016/j.xhgg.2024.100357View
Published (Version of record) Open Access

Abstract

Correct identification of the molecular consequences of pathogenic genetic variants is essential to the development of allele-specific therapies. However, such molecular effects may remain ambiguous following genetic sequence analysis alone. Here, we identify exonic codon-altering variants that are also predicted to disrupt normal RNA splicing in the context of inherited retinal disease. NR2E3 c.932G>A (p.Arg311Gln) is a variant commonly associated with Enhanced S Cone Syndrome (ESCS). Previous studies using mutagenized cDNA constructs have shown that the arginine to glutamine substitution at position 311 of NR2E3 does not meaningfully diminish function of the rod-specific transcription factor. Using retinal organoids, we explored the molecular consequences of NR2E3 c.932G>A when expressed endogenously during human rod photoreceptor cell development. Retinal organoids carrying the NR2E3 c.932G>A allele expressed a transcript containing a 186-nucleotide deletion of exon 6 within the ligand binding domain. This short transcript was not detected in control organoids or control human donor retina samples. A minigene containing exons 5 and 6 of NR2E3 showed sufficiency of the c.932G>A variant to cause the observed splicing defect. These results support the hypothesis that the pathogenic NR2E3 c.932G>A variant leads to photoreceptor disease by causing a splice defect and not through an amino acid substitution as previously supposed. They also explain the relatively mild effect of Arg311Gln on NR2E3 function in vitro. We also used in silico prediction tools to show that similar changes are likely to affect other inherited retinal disease variants in genes such as CEP290, ABCA4, and BEST1. Using patient-derived retinal organoids, minigene assays, and in silico prediction, this study shows that nonsynonymous exonic variants can act through splice alteration in inherited retinal disease. The NR2E3 variant c.932G>A (R311Q) causes aberrant splicing when expressed in retinal cells, contrary to previous reports of this variant’s mechanism.

Details

Metrics

64 Record Views
Logo image