CRISPR-CAS9
Subject: Science and tech
Context:
French-American duo Emmanuelle Charpentier and Jennifer Doudna have been awarded the 2020 Nobel Prize for the chemistry of CRISPR, which allows scientists to ‘cut-paste’ inside a genetic sequence
Concept:
The CRISPR technology
The CRISPR is an acronym for Clustered Regularly Interspaced Short Palindromic Repeats, developed in the year 2012
CRISPR has made gene editing very easy and simple, and at the same time extremely efficient.
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, cuts it out, 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 use a similar method to protect itself from virus attacks.
Working of CRISPR
An RNA molecule is programmed to locate the particular problematic sequence on the DNA strand.
A special protein called Cas9, often described in popular literature as ‘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.
It is like cutting a portion of a long zipper somewhere in between and replacing that portion with a fresh segment.
Because the entire process is programmable, it has a remarkable efficiency and has already brought almost miraculous results.
Uses of CRISPR
There are a whole lot of diseases and disorders, including some forms of cancer, that are caused by an undesired genetic mutation.
These can all be fixed with this technology. There are vast applications elsewhere as well. Genetic sequences of disease-causing organisms can be altered to make them ineffective.
Genes of plants can be edited to make them withstand pests, or improve their tolerance to drought or temperature.
Ethical concerns
In November 2018, a Chinese researcher in Shenzen created an international sensation with his claim that he 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 a ‘designer babies’ being produced using the new gene-editing tools like CRISPR.
What made matters worse was that the gene-editing was probably done without any regulatory permission or oversight.