Gene therapy entails the introduction of specific, functional genes into cells for therapeutic or preventive purposes. This process may be used in vitro or directly in vivo. One of the novel methods of gene therapy and genome editing that has been introduced in recent years and have made great changes in the field of genetic engineering and biotechnology is CRISPR-Cas gene-editing system. This system is faster, cheaper, more accurate and efficient than another genome editing one, such as TALEN and ZFNs. As with any other emerging process, the ethical concerns and challenges associated with the genome editing methods including the potential application of this technique for nefarious purposes, such as, bioterrorism, harmful mutations to the living being, and disrupting ecological balance. This review was prepared using the databases of Science Direct, Pub-Med, SID, Scopus, Web of Science, and then, the selected papers were fully reviewed and information was extracted and summarized. According to the ethical and legal considerations surrounding the processes in gene therapy, it is expected that appropriate conditions will be provided to make the best use of gene therapy and to reduce concerns and possible abuses. The purpose of this review was to investigate ethical issues of the genome editing and gene therapy with an emphasis on the CRISPR-Cas system.
