Prime editing is a novel genome editing method that enables precise and efficient genetic modifications without requiring double-strand breaks (DSBs) or donor DNA templates. This technique uses a modified Cas9 enzyme fused to an engineered reverse transcriptase, guided by a prime editing guide RNA (pegRNA) that specifies the target site and encodes the desired edit. The pegRNA provides a template for reverse transcription, allowing the direct insertion, deletion, or replacement of genetic information at the target site. Prime editing has been successfully applied to correct genetic mutations in human cells, including those responsible for sickle cell disease and Tay-Sachs disease, and to install protective mutations in the PRNP gene. It also enables the precise insertion of various tags and epitopes into target loci. Prime editing demonstrates higher or similar efficiency and fewer byproducts compared to homology-directed repair (HDR), and it has complementary strengths and weaknesses compared to base editing. It also shows much lower off-target editing than Cas9 nuclease at known Cas9 off-target sites. Prime editing significantly expands the scope and capabilities of genome editing, with the potential to correct up to 89% of known genetic variants associated with human diseases. The prime editing strategy involves the use of a pegRNA that contains both the target site information and the desired edit. The pegRNA is used to prime reverse transcription, which is then used to incorporate the desired edit into the genome. This process is facilitated by a nickase activity that allows for the precise replacement of the non-edited strand. Prime editing has been validated in vitro and in yeast, demonstrating its ability to correct genetic mutations and insert or delete genetic sequences with high efficiency and minimal byproducts. Prime editing systems, including PE1, PE2, and PE3, have been developed to enhance the efficiency and precision of the editing process. PE1 is the initial prime editing system, while PE2 and PE3 have been optimized to improve editing efficiency and reduce off-target effects. These systems have been tested in various cell types, including human cells and primary post-mitotic mouse cortical neurons, demonstrating their broad applicability. Prime editing has been compared to other genome editing methods, including base editing and HDR, showing its advantages in terms of efficiency, precision, and off-target effects. It has been shown to be particularly effective in correcting transversion, insertion, and deletion mutations that are difficult to correct with other methods. The ability to perform these edits without DSBs or donor DNA templates makes prime editing a powerful tool for genome editing. Overall, prime editing represents a significant advancement in genome editing technology, offering a versatile and precise method for modifying genetic information in a wide range of cell types and organisms. Its ability to correct a large number of genetic variants associated with human diseases highlights its potential for therapeutic applications.Prime editing is a novel genome editing method that enables precise and efficient genetic modifications without requiring double-strand breaks (DSBs) or donor DNA templates. This technique uses a modified Cas9 enzyme fused to an engineered reverse transcriptase, guided by a prime editing guide RNA (pegRNA) that specifies the target site and encodes the desired edit. The pegRNA provides a template for reverse transcription, allowing the direct insertion, deletion, or replacement of genetic information at the target site. Prime editing has been successfully applied to correct genetic mutations in human cells, including those responsible for sickle cell disease and Tay-Sachs disease, and to install protective mutations in the PRNP gene. It also enables the precise insertion of various tags and epitopes into target loci. Prime editing demonstrates higher or similar efficiency and fewer byproducts compared to homology-directed repair (HDR), and it has complementary strengths and weaknesses compared to base editing. It also shows much lower off-target editing than Cas9 nuclease at known Cas9 off-target sites. Prime editing significantly expands the scope and capabilities of genome editing, with the potential to correct up to 89% of known genetic variants associated with human diseases. The prime editing strategy involves the use of a pegRNA that contains both the target site information and the desired edit. The pegRNA is used to prime reverse transcription, which is then used to incorporate the desired edit into the genome. This process is facilitated by a nickase activity that allows for the precise replacement of the non-edited strand. Prime editing has been validated in vitro and in yeast, demonstrating its ability to correct genetic mutations and insert or delete genetic sequences with high efficiency and minimal byproducts. Prime editing systems, including PE1, PE2, and PE3, have been developed to enhance the efficiency and precision of the editing process. PE1 is the initial prime editing system, while PE2 and PE3 have been optimized to improve editing efficiency and reduce off-target effects. These systems have been tested in various cell types, including human cells and primary post-mitotic mouse cortical neurons, demonstrating their broad applicability. Prime editing has been compared to other genome editing methods, including base editing and HDR, showing its advantages in terms of efficiency, precision, and off-target effects. It has been shown to be particularly effective in correcting transversion, insertion, and deletion mutations that are difficult to correct with other methods. The ability to perform these edits without DSBs or donor DNA templates makes prime editing a powerful tool for genome editing. Overall, prime editing represents a significant advancement in genome editing technology, offering a versatile and precise method for modifying genetic information in a wide range of cell types and organisms. Its ability to correct a large number of genetic variants associated with human diseases highlights its potential for therapeutic applications.