CRISPR-CAS9
- SCIENCE AND TECHNOLOGY
News:
Death of lone volunteer
in US gene therapy study sparks a quest for answers
What's in the news?
●
The lone volunteer in a unique study
involving a gene-editing technique has died, and those behind the trial are now
trying to figure out what killed him.
● Terry Horgan, a 27-year-old who had Duchenne muscular dystrophy, died last month, according to Cure Rare Disease, a Connecticut-based non-profit founded by his brother, Rich, to try and save him from the fatal condition.
Gene
editing:
●
It is a set of technologies that give
scientists the ability to alter the DNA
of an organism.
●
These technologies help add, remove, or
replace genetic material at particular locations in the genome.
● Several genome editing approaches have been developed, with the more recent technique being CRISPR-Cas 9.
CRISPR-Cas9
genome editing:
●
CRISPR-Cas9 is a unique technology that
enables scientists to edit parts of the genome by removing, adding or altering
sections of the DNA sequence.
●
CRISPR
full form - Clustered Regularly Interspaced Palindromic Repeats.
●
CRISPRs are specialized stretches of DNA,
and the protein Cas9
(“CRISPR-associated”) is an enzyme that acts like a pair of molecular scissors,
capable of cutting strands of DNA.
●
CRISPR is a dynamic, versatile tool that
allows us to target nearly any genomic location and potentially repair broken
genes.
● It can remove, add or alter specific DNA sequences in the genome of higher organisms.
How
does it work?
●
DNA sequence is cut at a particular spot
and then with help of a guide RNA (gRNA) that place is re-made with desired
base pairing. This way genes can be altered.
●
It allows scientists to selectively edit
genome parts and replace them with new DNA stretches
●
Cas9 is the enzyme which acts as a
“molecular scissors” and helps in cutting the DNA sequence.
● CRISPR is a collection of DNA sequences that direct Cas9 where to cut and paste.
Applications
of CRISPR-Cas9 genome editing:
1.
Embryonic stem cell and transgenic animals - CRISPR-Cas
systems can be used to rapidly and efficiently engineer one or multiple genetic
changes to murine embryonic stem cells for the generation of genetically
modified mice.
2. Disease modelling - With the help of genome editing technologies, many applicable models with specific mutations which could mimic clinical phenotypes have been generated.
3.
Cancer models - With the help of genome editing tools,
numerous studies have been carried out through modifying key genes for
generating accurate and specific cancer models.
4.
Genome editing based therapy - Genome editing
technologies are not only used for generating disease animal models but also
destined to enter the therapeutic area through
●
inactivation or correction of harmful
mutations
●
introduction of protective mutations
●
insertion of therapeutic exogenous genes
●
destruction of viral DNA.
5.
Productivity improvement - Genome editing helps in enhancing
crop productivity to overcome the shortcomings of traditional transgenic
methods like irregular breeding cycles, lack of precision in intended trait
selection and uncertainty in getting desirable mutations.
6.
Allergy-free food - With CRISPR, it could be possible to
make milk, eggs or peanuts that are safe for everyone to eat.
7.
Greener fuels - Gene editing could improve the
production of biofuels by algae.
8. Eradicating pests - CRISPR could help us control the numbers of animal species that transmit infectious diseases or that are invasive in a particular ecosystem. The gene-editing technology can be used to create ‘gene drives’ that ensure a genetic modification will be inherited by all the offspring, spreading throughout an animal population over several generations.
Challenges
of CRISPR-Cas9 genome editing:
1.
Ethical concerns - unnaturalness or against nature.
2.
Safety concerns - slight changes in the results will lead
to enormous consequences.
3.
Against diversity - detrimental effect on our genetic
diversity, a key to evolution on earth.
4.
High cost - affordable issues.