Introduction: Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR associated (CRISPR-Cas) system is an adaptive immune system present in the most of bacteria and archaea. During the recent years, CRISPR-Cas has been introduced as a genome editing technology with high compatibility to different laboratory conditions in eukaryotic cell.

Methods: In the present review study, recent advances of this system and key points with regard to improving its efficiency in research and clinical application will be covered. In this regard, keywords including CRISPR-Cas, efficiency improvement, and off target have been analyzed in PubMed and 72 titles were selected and used in this paper. 

Results: CRISPR-Cas system is widely used for studying the function of genomic loci, development of engineered organisms as animal models and also clinical research of genetic diseases in stem cells due to the simplicity of its design. In this regard, improving the performance and precision of this system is necessary for the accomplishment of the efficient and safe genetic manipulation.

Conclusion: Different approaches have been used for improving the function of CRISPR-Cas system including optimization of the design, target recognition, binding and cutting of the target sites.