Normal 0 21 false false false TR X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Normal Tablo"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Targeted nucleases are widely used as tools for genome editing. Recently, the clustered regularly interspaced short palindromic repeat (CRISPR)-associated Cas9 nuclease was used in the genome editing studies for the first time, and since then has largely revolutionized the field. The great success of the CRISPR/Cas9 genome editing tool is powered by the simple design principle of the guide RNA that aims Cas9 to the target DNA locus, and by the high specificity and efficiency of CRISPR/Cas9-generated DNA breaks. Several studies lately used CRISPR-Cas9 to successfully arrange disease-causing alleles in vivo in animal models and ex vivo in somatic and induced pluripotent stem cells, increasing hope for therapeutic genome editing in the clinics. In this study, we focus on the CRISPR-Cas9 Type II system, provide specific examples for use of the system, and highlight the advantages and disadvantages of CRISPR versus other techniques. Also in this review, we briefly describe the development and applications of Cas9 which is derived from a remarkable microbial defense system for a variety of research or translational applications while highlighting challenges.