- About the Discovery
- What is Gene Editing?
- What is CRISPR-Cas9?
- Situation in India
- The way forward
Chemistry Nobel on Gene editing
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The recently announced Nobel Prize in Chemistry for 2020 has two women scientists as its recipients. Emmanuelle Charpentier, microbiologist and Jennifer Doudna, a biochemist shared the honour for the development of a method for genome editing.
About the Discovery:
- The two scientists have pioneered the use of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) – Cas9 (CRISPR-associated protein 9) system as a gene-editing tool.
- In a short period of eight years since its discovery, the method has already made a significant impact in biology, medicine, and agriculture.
- It is not often that one sees practical applications of scientific findings in such a short time. The only other work with such a quick and revolutionary impact, is PCR (polymerase chain reaction) invented by Kary Mullis in 1983.
- The Nobel committee recognised Charpentier and Doudna as the sole discovers for programming a Cas9 protein to cut a piece of DNA at a specific site with the help of a small piece of RNA, thereby proving the ability of CRISPR-Cas9 to function as a gene-editing tool.
What is Gene Editing?
- Genome editing (also called gene editing) is a group of technologies that give scientists the ability to change an organism’s DNA (Deoxyribonucleic acid).
- These technologies allow genetic material to be added, removed, or altered at particular locations in the genome. Several approaches to genome editing have been developed.
- There are currently three powerful Gene editing technologies: Zinc-finger nucleases (ZFNs), Transcription activator-like effector nucleases (TALENs) and CRISPR-Case9 Technology.
- There are two different types of gene editing technology depending on which types of cells are treated:
- Somatic gene therapy: transfer of a section of DNA to any cell of the body that doesn’t produce sperm or eggs. Effects of gene therapy will not be passed onto the patient’s children.
- Germline gene therapy: transfer of a section of DNA to cells that produce eggs or sperm. Effects of gene therapy will be passed onto the patient’s children and subsequent generations.
What is CRISPR-Cas9?
- It is a Gene editing technique which is short for Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9.
- The CRISPR-Cas9 gene editing tool has two components — a short RNA (Ribonucleic acid) sequence that can bind to a specific target of the DNA and the Cas9 enzyme which acts like a molecular scissor to cut the DNA.
- To edit a gene of interest, the short RNA sequence (gRNA) that perfectly matches with the DNA sequence that has to be edited is introduced.
- Once it binds to the DNA, the Cas9 enzyme cuts the DNA (like scissors) at the targeted location where the RNA sequence is bound. Once the DNA is cut, the natural DNA repair mechanism is utilised to add or remove genetic material or make changes to the DNA.
- In the last six years, the tool has enabled scientists to edit human DNA in a dish and early-stage clinical trials are being attempted to use the tool to treat a few diseases, including inherited disorders/diseases and some types of cancer.
- In the male-dominated world of science, this year’s Nobel chemistry prize should be widely celebrated worldwide.
- The recognition that Charpentier and Doudna’s work has received will encourage women to take up science as a career, despite the hard struggle to balance family life and an arduous life in a scientific career.
- The CRISPR technology can detect specific sequences of DNA within a gene and uses an enzyme functioning as molecular scissors to snip it.
- It also allows researchers to easily alter DNA sequences and modify gene function.
- The technology can also be configured for detection of multiple other pathogens in the future.
- Unlike in the case of humans, the tool is being extensively used in agriculture. It is being tried out in agriculture primarily to increase plant yield, quality, disease resistance, herbicide resistance and domestication of wild species.
- The huge potential to edit genes using this tool has been used to create a large number of crop varieties with improved agronomic performance; it has also brought in sweeping changes to breeding technologies.
Situation in India:
- In India, several rules, guidelines, and policies backed by the Rules for the Manufacture, Use, Import, Export and Storage of Hazardous Microorganisms/Genetically Engineered Organisms or Cells, 1989 notified under the Environment Protection Act, 1986, regulate genetically modified organisms.
- The above Act and the National Ethical Guidelines for Biomedical and Health Research involving human participants, 2017, by the Indian Council of Medical Research (ICMR), and the Biomedical and Health Research Regulation Bill implies regulation of the gene-editing process.
- This is especially so in the usage of its language modification, deletion or removal of parts of heritable material. However, there is no explicit mention of the term gene editing.
- It is time that India came up with a specific law to ban germline editing and put out guidelines for conducting gene-editing research giving rise to modified organisms.
The way forward:
- In India, there is a long way to go before realising the utility of gene editing for therapeutic applications.
- India cannot be complacent and wait for a rogue individual or entity to try it out in humans.
- The world was alarmed by such a mission in 2018 when Chinese scientist He Jiankui edited genes in human embryos using the CRISPR-Cas9 system that were subsequently implanted and resulted in the birth of twin girls.
- He claimed this was ostensibly to prevent them from contracting HIV, and the incident became known as the case of the first gene-edited babies of the world.
- Following a global outcry, the World Health Organization formed a panel of gene-editing experts which said a central registry of all human genome editing research was needed in order to create an open and transparent database of ongoing work.
- It called upon WHO to start setting up such a registry immediately.
While the tool is most often used to make a cut in the DNA, newer approaches are being attempted to add or make minor changes to the DNA. All these approaches may at some time in the future make it easy to rewrite the code of life. The gene-editing tool has indeed taken life sciences into a new epoch.