Generation and Characterization of a Zebrafish Model for ADGRV1-Associated Retinal Dysfunction Using CRISPR/Cas9 Genome Editing Technology

Around 40,000 patients in the world have Usher syndrome type 2C, which typically presents with congenital hearing loss and retinitis pigmentosa (RP) due to mutations on the ADGRV1 gene. While hearing aids or cochlear implants can help address the hearing impairment, there are currently no treatment options for ADGRV1-mutated RP.

Animal models such as mice are commonly used to study disease and function before moving to in-human clinical trials. However, mouse models are insufficient for retinal dysfunction studies since they cannot closely mimic the retinal phenotype of patients. Instead, zebrafish have a retinal structure comparable to humans and have been used successfully in other retinal-based studies. Here, scientists used CRISPR/Cas9 gene editing technology to delete (remove) a small portion of the ADGRV1 gene. This deletion resulted in an absence of ADGRV1 in the photoreceptor cells, correlated to impaired retinal function, and successfully generated a zebrafish-based mutant model suitable for further studies on ADGRV1-associated retinal dysfunction.

What this means for Usher syndrome: Usher 2C is a more rare form of Usher syndrome, and there has not been a lot of research on ADGRV1 thus far. The confirmation of a suitable animal model and generation of a mutant model for ADGRV1 studies gives USH2C patients hope that research can progress more quickly, leading to a better understanding of this gene, and potential treatment options in the future.

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