A team of researchers engineered a type II CRISPR system to enable RNA-guided genome editing in human cells. By using custom guide RNAs (gRNAs), they demonstrated the ability to target and modify specific genomic regions with high efficiency. The system was tested on various human cell types, including 293T cells, K562 cells, and induced pluripotent stem cells (iPSCs), achieving targeting rates of 10-25%, 13-8%, and 2-4%, respectively. The process was shown to be sequence-specific and capable of multiplex editing when multiple gRNAs were introduced simultaneously. The researchers also developed a genome-wide resource of approximately 190,000 unique gRNAs targeting about 40.5% of human exons. This resource provides a valuable tool for efficient and multiplexed genome engineering. The study confirmed that the CRISPR system could induce homologous recombination (HR) and non-homologous end joining (NHEJ) at the AAVS1 locus, demonstrating its potential for precise genome modification. The study highlights the advantages of the CRISPR system over other genome editing tools like zinc finger nucleases (ZFNs) and TALENs, offering higher efficiency and ease of use. The researchers also noted that the system is robust and can be adapted to target other genomic sites by modifying the gRNA expression vector. However, they emphasized the need for further research to improve specificity and reduce off-target effects, which are critical for safe and effective genome modification. The study's findings demonstrate the promise of CRISPR-mediated gene targeting for robust and multiplexable mammalian genome engineering. The system's ability to efficiently integrate foreign DNA at endogenous loci in human cells opens new possibilities for synthetic biology, gene network perturbation, and gene therapy applications. The study also acknowledges the importance of continued research to enhance the safety and precision of CRISPR-based genome editing technologies.A team of researchers engineered a type II CRISPR system to enable RNA-guided genome editing in human cells. By using custom guide RNAs (gRNAs), they demonstrated the ability to target and modify specific genomic regions with high efficiency. The system was tested on various human cell types, including 293T cells, K562 cells, and induced pluripotent stem cells (iPSCs), achieving targeting rates of 10-25%, 13-8%, and 2-4%, respectively. The process was shown to be sequence-specific and capable of multiplex editing when multiple gRNAs were introduced simultaneously. The researchers also developed a genome-wide resource of approximately 190,000 unique gRNAs targeting about 40.5% of human exons. This resource provides a valuable tool for efficient and multiplexed genome engineering. The study confirmed that the CRISPR system could induce homologous recombination (HR) and non-homologous end joining (NHEJ) at the AAVS1 locus, demonstrating its potential for precise genome modification. The study highlights the advantages of the CRISPR system over other genome editing tools like zinc finger nucleases (ZFNs) and TALENs, offering higher efficiency and ease of use. The researchers also noted that the system is robust and can be adapted to target other genomic sites by modifying the gRNA expression vector. However, they emphasized the need for further research to improve specificity and reduce off-target effects, which are critical for safe and effective genome modification. The study's findings demonstrate the promise of CRISPR-mediated gene targeting for robust and multiplexable mammalian genome engineering. The system's ability to efficiently integrate foreign DNA at endogenous loci in human cells opens new possibilities for synthetic biology, gene network perturbation, and gene therapy applications. The study also acknowledges the importance of continued research to enhance the safety and precision of CRISPR-based genome editing technologies.