Date: 15/09/2022

Relevance: GS-3: Awareness in the fields of IT, Space, Computers, robotics, nano-technology, and biotechnology.

Key Phrases: Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), genome-editing technology, Nobel Prize for Chemistry in 2020, CRISPR-based therapeutic solutions, Clinical trials, cas9, Permanent cure for incurable genetic disorders.

Why in News?

• In the 10 years since it was developed, the genome-editing technology called CRISPR has begun to deliver on the nearly unlimited potential that scientists say it has to improve the quality of human life.

The CRISPR technology:

• CRISPR is short for Clustered Regularly Interspaced Short Palindromic Repeats, which is a reference to the clustered and repetitive sequences of DNA found in bacteria, whose natural mechanism to fight some viral diseases is replicated in this gene-editing tool.
• Its mechanism is often compared to the ‘cut-copy-paste’, or ‘find-replace’ functionalities in common computer programmes.
• A bad stretch in the DNA sequence, which is the cause of disease or disorder, is located, cut, and removed — and then replaced with a ‘correct’ sequence.
• And the tools used to achieve this are not mechanical, but biochemical — specific protein and RNA molecules.
• The technology replicates a natural defence mechanism in some bacteria that use a similar method to protect themselves from virus attacks.
• CRISPR-based therapeutic solutions are not in the form of a pill or drug. Instead, some cells of every patient are extracted, the genes are edited in the laboratory, and the corrected genes are then re-injected into the patients.

Technology in action:

• The first task is to identify the particular sequence of genes that is the cause of the trouble.
• Once that is done, an RNA molecule is programmed to locate this sequence on the DNA strand, just like the ‘find’ or ‘search’ function on a computer.
• After this, a special protein called Cas9, which is often described as ‘genetic scissors’, is used to break the DNA strand at specific points, and remove the bad sequence.
• A DNA strand, when broken, has a natural tendency to re-attach and heal itself.
• But if the auto-repair mechanism is allowed to continue, the bad sequence can regrow. So, scientists intervene during the auto-repair process by supplying the correct sequence of genetic codes, which attaches to the broken DNA strand.
• It is like cutting out the damaged part of a long zipper and replacing it with a normally functioning part.
• The entire process is programmable, and has remarkable efficiency, though chances of error are not entirely ruled out.

Possibilities it presents:

• Permanent cure for incurable genetic disorders:
  • A vast number of diseases and disorders are genetic in nature — that is, they are caused by unwanted changes or mutations in genes.
  • These include common blood disorders like sickle cell anaemia, eye diseases including colour blindness, several types of cancer, diabetes, HIV, and liver and heart diseases. Many of these are hereditary as well.
  • This technology opens up the possibility of finding a permanent cure to many of these diseases.
  • This is also true for the deformities arising out of abnormalities in gene sequences, like stunted or slow growth, speech disorders, or inability to stand or walk.
• Specific solution for every disorder:
  • CRISPR is just a platform; a tool to edit gene sequences. What is to be edited, and where, is different in different cases?
  • Therefore, a specific solution needs to be devised for every disease or disorder that is to be corrected.
  • The solutions could be specific to a particular population or racial group since these are also dependent on genes.
• Clinical trials:
  • Over the last three years, several such solutions have been undergoing clinical trials.
  • These mainly pertain to blood disorders, diabetes, inherited eye diseases, and some kinds of cancers.
  • Japan has already approved the commercial cultivation of a tomato variety that has been improved using CRISPR-based intervention.

The ethical dilemma:

• Misuse of the technology:
  • Because of CRISPR’s power to induce dramatic changes in an individual, scientists, including the main developer Doudna, have been warning of the potential for misuse of the technology.
• Designer baby:
  • In 2018, a Chinese researcher disclosed that he had altered the genes of a human embryo to prevent the infection of HIV. This was the first documented case of creating a ‘designer baby’, and it caused widespread concern in the scientific community.
• Changes in the embryo pass on to future generations:
  • Preventive interventions to obtain special traits are not something that scientists currently want the technology to be used for.
  • Also, because the changes were made in the embryo itself, the newly acquired traits were likely to be passed to future generations.
  • In the case of therapeutic interventions, the changes in genetic sequences remain with the individual and are not passed on to the offspring.
• Precision:
  • Though the technology is fairly accurate, it is not 100 per cent precise and could induce a few errors as well, making changes in other genes. This has the possibility of being inherited by successive generations.

India’s efforts:

• Last year, the Indian government approved a five-year project to develop this technology to cure sickle cell anaemia which mainly afflicts the tribal populations of the country.
• In India, Debojyoti Chakraborty and Souvik Maiti at CSIR’s Institute of Genomics and Integrative Biology have indigenously developed a CRISPR-based therapeutic solution for sickle cell anaemia, which is now being readied for clinical trials.

Conclusion:

• CRISPR technology has undoubtedly revolutionised various sectors such as health care, agriculture, energy, etc.
• Concerned authorities should formulate and authorize laws and regulations that permit the safe and ethical use of this emerging technology for basic research and clinical purposes.

Source: Indian Express

Mains Question:

Q. What is CRISPR genome-editing technology? Discuss its possible applications and ethical concerns raised around it.