Abstract: Strategies, systems, compositions, and methods for efficient production of knock-in cellular clones without reporter genes. An essential gene is targeted using a knock-in cassette that comprises an exogenous coding sequence for a gene product of interest (or “cargo sequence”) in frame with and downstream (3?) of an exogenous coding sequence or partial coding sequence of the essential gene. Undesired targeting events create a non-functional version of the essential gene, in essence a knock-out, which is “rescued” by correct integration of the knock-in cassette, which restores the essential gene coding region so that a functional gene product is produced and positions the cargo sequence in frame with and downstream of the essential gene coding sequence.

Abstract: Strategies, systems, compositions, and methods for efficient production of knock-in cellular clones without reporter genes. An essential gene is targeted using a knock-in cassette that comprises an exogenous coding sequence for a gene product of interest (or “cargo sequence”) in frame with and downstream (3?) of an exogenous coding sequence or partial coding sequence of the essential gene. Undesired targeting events create a non-functional version of the essential gene, in essence a knock-out, which is “rescued” by correct integration of the knock-in cassette, which restores the essential gene coding region so that a functional gene product is produced and positions the cargo sequence in frame with and downstream of the essential gene coding sequence.

Abstract: Compositions for use in treating subjects with USH2A-associated retinal and/or cochlear degeneration that result from mutations in exon 13 of the USH2A gene by deletion of exon 13 from the USH2A gene or transcripts, and methods of use thereof, as well as genetically modified animals and cells.