Genome editing in animals: an overview

Genome editing is the process of making targeted modifications to the genome at site-specific locations. The most common methods for genome editing are sequence-specific programmable nucleases namely protein-guided zinc finger nucleases (ZFNs), transcriptional activator-like effector nucleases (TALENs) and CRISPR/Cas9 system. The class of RNA-guided endonucleases known as Cas9 from the microbial adaptive immune system CRISPR (clustered regularly interspaced short palindromic repeats) is the most rapidly developing genome editing technology. Prior to CRISPR/Cas9, genome editing approaches, like ZFNs or TALENs, relied upon the use of customizable DNA binding protein nucleases that required scientists to design and generate a new nuclease pair for every genomic target. Largely due to its simplicity and adaptability, CRISPR/Cas9 system has outpaced the other methods in its efficacy to obtain precise genetic modifications. With its unprecedented accuracy, variants of Cas9 like Cas9 nickase, Cpf1, Cas9-HF1, HypaCas9, and features like multiplexing, it has provided important advancements in animal agriculture. The rapid progress of genome editing in animals has been remarkable but there are many challenges ahead like ethical issues and public acceptance of genetically modified animals and their products. However, improving the efficiency, on-target specificity, and safety of genome editing will unlock a myriad of applications in animal sciences