[priyasaravanan_1406]

Clustered Regularly Interspaced Short Palindromic Repeat Sequences (CRISPR) discovered in the year 1987 by Japanese scientists is no more a junk DNA. Yes, CRISPR is identified as an apt tool to cut and edit DNA which is a significant breakthrough in the field of genetic engineering, exciting gene scientists.

CRISPR when initially identified by scientists did not get its importance and was just left out as a junk DNA. Later the fact that CRISPR acting as a bacterial (prokaryotic) immune system fascinated the researchers which led to the detailed study. CRISPR being present as short direct repeats in bacteria and archaea was found to play the role of immune system enabling the prokaryotes to exhibit acquired immunity towards the foreign bodies like phages and plasmids. A part of the foreign DNA coined as spacers is embedded between the regions of CRISPR and stored as memory region which enabled the resistance of bacteria towards future attack by the foreign body.

It was found that CRISPR uses an enzyme called CRISPR associated enzyme (CAS) to chop of the genome of the phage molecule invading the bacteria and this unique property brought CRISPR into the lime light enabling various studies on this interesting piece. Finally, the collaborated work on CRISPR by research team from university of California, Berkeley headed by prof. Jennifer Doudna and the research team from Umea university Sweden headed by prof. Emmanuelle Charpentier ended up with a fascinating outcome that “CRISPR along with CAS9 enzyme can be employed to edit precisely any part of a genome”.

The whole act of editing a genome requires a CRISPR, a programmed RNA molecule and CAS9. With the help of the programmed RNA, CRISPR identifies the target region on the genome and CAS9 cuts the two strands of the DNA enabling the deletion of the sequences from the target region and allowing the insertion of the copied DNA into the target region. This method of gene editing is appreciated by all the gene scientists for its accuracy and flawlessness and is considered to revolutionize the field of genetic engineering.

Following the discovery by Prof. Doudna and team many other scientists tried gene editing using CRISPR in other species in a hierarchy from yeast to mice involving worms, flies and fish. The findings from the application of CRISPR system of gene editing in human cells by the researcher George Church from Harvard University inferred the positive outcomes in human medicine development.

The CRISPR-CAS9 gene editing system is very precise which enables even nucleotide level correction and hence it is outstanding from the existing methods of DNA cutting like the Zinc fingers, Talens and the use of restriction enzymes. Scientists are looking forward to develop gene therapies for various disorders like cancer, Down syndrome, Huntington’s disease and sickle cell anemia and are also discussing the possibility to treat HIV infection using this type of gene editing. They are also focusing on germ cell level gene correction and embryo level gene correction which may bring up some controversy.

From now, DNA scientists can rely on CRISPR-CAS9 tool to edit any region of human genome precisely.