CRISPR/Cas9 system as an innovative genetic engineering tool: Enhancements in sequence specificity and delivery methods.

While human gene therapy has gained significant attention for its therapeutic promise, CRISPR/Cas9 technology has made a breakthrough as an efficient genome editing tool by emulating prokaryotic immune defense mechanisms. Although many studies have found that CRISPR/Cas9 technology is more efficient, specific and manipulable than previous generations of gene editing tools, it can be further improved by elevating its overall efficiency in a higher frequency of genome modifications and reducing its off-target effects. Here, we review the development of CRISPR/Cas9 technology, focusing on enhancement of its sequence specificity, reduction of off-target effects and delivery systems. Moreover, we describe recent successful applications of CRISPR/Cas9 technology in laboratory and clinical studies.