In modern genetic engineering, there is always development towards better ways for therapies of different diseases in the most efficient way. Genetic engineering approaches use the nucleases to cut the DNA. Meganucleases, ZFN, TALEN and CRISPR i.e. clustered regularly interspaced short palindromic repeats determine PAM sequence. These sequences are present as direct repeats that are separated by specific Spacers and have Cas genes which are present adjacent to the spacer regions. Microbe's immunity is related to the presence of CRISPR sequences, which can cleave and bind the DNA at specific sequences. CRISPR is classified into two classes that are further divided into 5 types. Most commonly used class is type 2 which work along the CRISPR associated protein called Cas 9 obtained from Streptococcus pyogene. Cas 9 is a multi-subunit protein with two nuclease domains called HNH and RuvC like domains. The presence of a smaller sequence upstream to the DNA that is to be targeted is important for specific cleavage and is called the Seed Sequence. CRISPR have many applications in genome editing and beyond genome editing. Keywords: AML; Pathogenesis; Treatment; Relapse