CRISPR–Cas9 in genome editing: Its function and medical applications

Abstract The targeted genome modification using RNA‐guided nucleases is associated with several advantages such as a rapid, easy, and efficient method that not only provides the manipulation and alteration of genes and functional studies for researchers, but also increases their awareness of the molecular basis of the disease and development of new and targeted therapeutic approaches. Different techniques have been emerged so far as the molecular scissors mediating targeted genome editing including zinc finger nuclease, transcription activator‐like effector nucleases, and clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR‐associated protein 9 (Cas9). CRISPR–Cas9 is a bacterial immune system against viruses in which the single‐strand RNA‐guided Cas9 nuclease is linked to the targeted complementary sequences to apply changes. The advances made in the transfer, modification, and emergence of specific solutions have led to the creation of different classes of CRISPR–Cas9. Since this robust tool is capable of direct correction of disease‐causing mutations, its ability to treat genetic disorders has attracted the tremendous attention of researchers. Considering the reported cases of nonspecific targeting of Cas9 proteins, many studies focused on enhancing the Cas9 features. In this regard, significant advances have been made in choosing guide RNA, new enzymes and methods for identifying misplaced targeting. Here, we highlighted the history and various direct aspects of CRISPR–Cas9, such as precision in genomic targeting, system transfer and its control over correction events with its applications in future biological studies, and modern treatment of diseases.