Find in Library

Retinitis pigmentosa (RP) is an inherited retinal disease (IRD) with an overall prevalence of 1 in 4000 individuals. Mutations in <i>EYS</i> (<i>Eyes shut homolog</i>) are among the most frequent causes of non-syndromic autosomal recessively inherited RP and act via a loss-of-function mechanism. In light of the recent successes for other IRDs, we investigated the therapeutic potential of exon skipping for <i>EYS</i>-associated RP. CRISPR/Cas9 was employed to generate zebrafish from which the region encompassing the orthologous exons 37-41 of human <i>EYS</i> (<i>eys</i> exons 40-44) was excised from the genome. The excision of these exons was predicted to maintain the open reading frame and to result in the removal of exactly one Laminin G and two EGF domains. Although the <i>eys^Δexon40-44</i> transcript was found at levels comparable to wild-type <i>eys,</i> and no unwanted off-target modifications were identified within the <i>eys</i> coding sequence after single-molecule sequencing, <i>Eys^Δexon40-44</i> protein expression could not be detected. Visual motor response experiments revealed that <i>eys^Δexon40-44</i> larvae were visually impaired and histological analysis revealed a progressive degeneration of the retinal outer nuclear layer in these zebrafish. Altogether, the data obtained in our zebrafish model currently provide no indications for the skipping of <i>EYS</i> exons 37-41 as an effective future treatment strategy for <i>EYS</i>-associated RP.