Ultevursen (QR-421a) is a splice-modulating antisense oligonucleotide targeting exon 13 of the USH2A gene, which restores the functional expression of Usherin protein by inducing exon skipping. Ultevursen binds to USH2A pre-mRNA and modulates the splicing process to specifically skip exon 13 carrying the pathogenic mutation c.2299delG, generating an in-frame transcript and a truncated yet functionally normal protein. Ultevursen exhibits concentration-dependent exon skipping activity in human cells and retinal organoid models, and restores Usherin expression and retinal function in zebrafish and gene-edited mouse models. Ultevursen can be used for related research on type 2 Usher syndrome and non-syndromic retinitis pigmentosa[1][2].
