Creators of genetic ‘scissors’ win chemistry Nobel

In News

  • The Royal Swedish Academy of Sciences has awarded the 2020 Nobel Prize (Read Comprehensive Analysis of Nobel Prize) in Chemistry to Emmanuelle Charpentier and Jennifer A. Doudna for development of a method for genome editing.
  • Their discovery, known as Crispr-Cas9, is a way of making specific and precise changes to the DNA contained in living cells.
    • The CRISPR (short for Clustered Regularly Interspaced Short Palindromic Repeats) technology for gene-editing was developed in the year 2012.
  • Using these, researchers can change the DNA of animals, plants, and microorganisms with extremely high precision.

About: DNA and RNA

  • Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA) are nucleic acids.
  • Along with lipids, proteins, and carbohydrates, nucleic acids constitute one of the four major macromolecules essential for all known forms of life.
  • DNA is the chemical name for the molecule that carries genetic information in all living things.
  • The DNA molecule consists of two strands that wind around one another to form a shape known as a double helix.
  • RNA is a molecule essential in various biological roles in coding, decoding, regulation and expression of genes. Unlike DNA, RNA is single-stranded.

In Focus: Genome editing

  • Genome editing (or genome engineering, or gene editing) enable scientists to make changes to DNA, leading to changes in physical traits, like eye colour, and disease risk.
  • Editing, or modifying gene sequences is not new and scientists have been using different technologies for gene editing for several decades.
  • These technologies have been used particularly in the field of agriculture, where several crops have been genetically modified to provide particular traits.

CRISPR/Cas9 technology:

  • In essence, the technology works in a simple way — it locates the specific area in the genetic sequence which has been diagnosed to be the cause of the problem.
  • It then cuts that area and replaces it with a new and correct sequence that no longer causes the problem.
  • The technology replicates a natural defence mechanism in some bacteria that uses a similar method to protect itself from virus attacks.
  • An RNA molecule is programmed to locate the particular problematic sequence on the DNA strand.
  • A special protein called Cas9, which is now often described as a ‘genetic scissor’, is used to break and remove the problematic sequence.
  • A DNA strand, when broken, has a natural tendency to repair itself, but the auto-repair mechanism can lead to the re-growth of a problematic sequence.
  • Scientists intervene during this auto-repair process by supplying the desired sequence of genetic codes, which replaces the original sequence.

Development process of the scissors:

  • During her research ona common harmful bacteria, Prof. Charpentier discovered a previously unknown molecule.
  • This was a part of the bacteria’s immune system that made viruses powerless, by cutting off parts of the virus’ DNA.
  • Later Prof. Charpentier worked with Prof. Doudna to recreate the bacteria’s genetic scissors and simplified the tool to use and apply it to other genetic material.
  • They then reprogrammed the scissors to cut any DNA molecule at a predetermined site.

Benefits of the technology

  • The CRISPR technology is simpler, faster, cheaper, and more accurate than older genome editing methods. Many scientists who perform genome editing now use CRISPR.
  • The technology can not only transform basic research but can also be used to treat various illnesses.
  • It has led to innovative cancer treatments, and many experts hope it could one day make inherited diseases curable through gene manipulation.
  • It is currently being investigated for its potential to treat sickle cell anaemia, a blood disorder that affects millions of people worldwide.
  • It has already contributed to significant gains in agriculture, by altering the genetic code of crops to help them withstand drought and pests.

Issues with the technology

  • In 2018, a Chinese researcher had altered the genes of a human embryo that eventually resulted in the birth of twin baby girls.
  • This was the first documented case of ‘designer babies’ being produced using the new gene-editing tools like CRISPR. It raised exactly the kind of ethical concerns that scientists like Doudna have been speaking about.
  • In the case of the Chinese twins, the genes were edited to ensure that they do not get infected with HIV, the virus that causes AIDS.
  • The concerns were not over the reason for which the technology was used but around the ethics of producing babies with particular genetic traits (designer babies).
  • If genome-edited children grow up and have children, any alterations to their genomes could be passed down to their generations. This can introduce permanent changes in the human population.
  • It has also been pointed that while CRISPR technology is very precise, it is not 100 per cent accurate, and it is possible that some other genes could also get altered by mistake.

Way Ahead

  • Professor Doudna herself has been campaigning for the development of international rules and guidelines for the use of CRISPR technology.
  • She has also advocated that various applications should not be allowed till proper rules and regulations are in place.

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