Genetic scissors and rewriting the code of life

Genetic scissors and rewriting the code of life

Context:

• The 2020 Nobel Prizes for Chemistry has been awarded to two women scientists Jennifer Doudna and Emmanuelle Charpentier “for the development of the CRISPR/Cas9 genetic method for genome editing”.

About CRISPR/Cas9

• CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats.
• The CRISPR are a part of bacteria’s immunological systems that help them in recognising threatening viruses.
• When they detect a virus, the bacteria produce customised RNA, which contains Cas (CRISPR-associated) genes that are used to produce enzymes such as Cas-9.
• These enzymes are used to chop the DNA of the virus and destroy them.

Importance of CRISPR/Cas9

• The CRISPR/Cas9 system allows for adding, altering and deleting the genomic code in living beings and hence could lead to the emergence of novel biological applications by making it easier to edit genes.
• Using the tool, researchers can change the DNA of animals, plants and microorganisms with precision.
• Other genome editing systems like TALENs and Zinc-Finger Nucleases can do similar jobs, but the CRISPR method is more adaptable and easier to use.

Applications:

1. Treatment:

• Recently a person with hereditary blindness became the first to have a CRISPR/Cas-9-based therapy directly injected into her body.
• Similarly two patients with beta thalassemia and one with sickle cell disease have been cured after their bone marrow stem cells were edited using CRISPR techniques.
• There are efforts to begin work on treatments for amyotrophic lateral sclerosis.
• The system holds promise for treating complex diseases, such as cancer, heart diseases, mental illnesses, and the human immunodeficiency virus (HIV) infection.

2. Testing:

• There have been cases where CRISPR technology has been employed in the battle against the COVID-19 too, to develop a test to detect infections.
• The CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB) in Delhi developed a COVID-19 testing kit, nicknamed ‘Feluda’, based on the CRISPR/Cas9 system.

3. Research benefits:

• The technology allows researchers to find out what genes do, move mutations that are identified and associated with the disease into systems where they can be studied and tested for treatment, or where they can be tested in combinations with other mutations.

Ethical Issues

• There are concerns over the possibility of the tool being misused.
• The 2018 application of CRISPR/Cas9 by Chinese researcher to create ‘gene-edited twins’ Lula and Nana via in-vitro fertilisation has invited widespread.

Other issues

• There are also concerns over a host of other unintended mutations that can be triggered in gene editing exercises. The technology has still not reached the level of precision required to be sure that it does not cause unintentional side effects.
• There are concerns that such mutations could spread to humanity more widely in due course.