Recent advances in sequencing methods have prompted an upsurge in research into the modification of diseaseassociated genes or genes involved in drug resistance. In the early days of genome-editing, immunogenic and difficult to deliver tools with high off-target effects such as Zinc Finger Nucleases (ZFNs) and Transcription activatorlike effector nucleases (TALENs) proteins were used. This was followed by the discovery of the Clustered Regularly Interspaced Short Palindromic Repeat s, CRISPR/Cas9 system. This “self-non-self-discriminatory” natural defence mechanism in bacteria and archaea identifies and degrades extrachromosomal genomes or foreign genetic elements to prevent them from integrating into the prokaryotic genomes. Unlike traditional gene therapies that can merely insert a gene in a random pattern, the inexpensive and expedient CRISPR/ Cas9 system was harnessed by scientists to precisely cut, add or manipulate multiple DNA sequences at specific sites.
This review will focus on the most recent studies in genome-editing by giving an overview of the past and modern methods in this field with an emphasis on the bacterial adaptive immune system called CRISPR/Cas9. This article will also analyze the applications of CRISPR/ Cas9 in rewriting the human genome in clinical and research settings and its potential future therapeutic applications. In addition, we shall consider the technical complexities which need to be overcome for the safe and effective delivery of this novel therapy and how the ethical concerns associated with this revolutionary genome engineering technique have constrained research in germ-line genome-editing. Furthermore, we shall highlight the role of scientific regulatory committees in evaluating and assessing safety issues such as potential complications before translating this proof-of-concept evidential approach to clinical reality. More research is required to explore the risk of hazardous genome edits and to fine-tune and improve this novel therapeutic system. Although the inexpensive and easy to use CRISPR/ Cas9 platform paves new ways for precise genome editing, clinical application is still at an early stage.
Kinan Mokbel and Kefah Mokbel