CRISPR _ CAS 9




 




 Why in the news? 

It's been ten years since microbiologist Emmanuelle Charpentier and biochemist Jennifer Doudna published the research that paved the way for CRISPR _ Case 9 gene editing. 

What clustered Regularly Interspaced Short Palindromic Repeats ( CRISPR)? 

CRISPR is a genetic code or sequence found in bacteria. These are formed due to the activity of the previous bacteriophages that had infected them.

● Bacteria use CRISPR sequence to remember each specific virus that attacks them.They do this by incorporating virus' DNA into their own bacteria genome. 

● This method then given the bacteria protection or immunity when a specific virus tries to attack again.

● Cas 9 are the, genes that are always located nearby.

● Once activated,these genes make special enzymes that seem to have co_ evolved with CRISPR. The significance of these Cas enzymes is their ability to act as " molecular scissors" that can cut into DNA,




●Important definitions 

DNA: 

DNA, or deoxyribonucleic acid, is the hereditary material in most of living beings.

RNA: 

RNA or Ribonucleic acid molecules are single stranded nucleic acids.They are hereditary material in some viruses. 

GENES:

A gene is a ' specific' section of DNA it is involved in making RNA ( transcription) or protein ( translation).

 

Genome:

A genome is an organism's complete set of DNA. It includes all chromosomes, which house the DNA, and Gene's 

 

Molecular scissors 

act as the scissors that cut out the unwanted DNA. They are also called Restriction Enzymes.It is because of their ability to restrict the unwanted Gene's at the site identified by the Guided RNA.

How does CRISPR work?

These are the 3 key elements to CRISPR _ Cas9 

Work: 

● Guide RNA:

A piece of RNA that locates the targeted gene.This is engineered in a lab.

● CRISPR _ associated protein 9 ( Cas9):

The " Scissors" that snip the undesired DNA out.

● DNA:

The desired piece of DNA that is inserted after the break.

Benefits of CRISPR 

●Predictive and Preventive Healthcare: 

This can help in faster and efficient diagnosis of rare genetic diseases. This will also help in determining epidemiology of genetic tests, enabling efficient diagnosis of heritable cancers, etc.

● Food security:

 It can have a major impact on addressing  food insecurity around  the world by Engineering  more water-efficient crops and high yielding varieties of plants and animals.

○As a corollary, it can make farming more efficient and robust by creating resilient crops which are impervious to droughts and other environmental impacts.

● Pharmaceutical and Biotechnology:

 CRISPR can bring customized and individualized therapies to market more quickly  than was previously dreamed.     
The CRISPR generated knowledge base would also help in speeding up the traditional drug discovery process.

● To adapt to climate change: 

It can play a role in limiting agricultural emissions, making crops more resilient to a more variable and extreme climate, and using crops and soil microbes to store and sequester more carbon.
Scientific breakthroughs using CRISPR-cas9

●Cancer: 

The first ever human trials of CRISPR in china focused on treating or range of cancer.

● HIV:

 Scientists form Kobe University in japan used CRISPR to block HIV from spreading inside infected human cells.

● Parkinson: 

US-based biopharmaceutical company  seelos Therapeutics acquired  the right to SLS-004 gene editing therapy for Parkinson's disease.

Genetic manipulation: 

In 2015, Chinese scientists created super muscular bangles by disabling  the myostatin gene, which direct normal muscle  development. 

Advancement by India in CRISPR-cas9 technology 

● Sickle Cell Anaemia:

 Scientists at Delhi's institute of genomics and integrated biology are trying  to find a solution to prevent genetically inherited sickle cell anaemia using the game-ending tool.

Agri-food:

 Using CRISPR CAS-9 researchers at National agri-food biotechnology edited the banana genome to improve its nutritional quality and pathogen resistance. 

● Minimize side-effects: 

To overcome the problems of ' off-targeting', research is being conducted for deploying naturally occurred bacteria Francisella novicida instead of widely used streptococcus pyogenes Cas9.
○ Off-target effects can be defined as unintended cleavage and mutations at untargeted genomic siste showing a similar but not an identical sequence compared to the target site.

Challenges 


● Ethical Challenges 

○ Concerns over 'Designer Babies':

 Engineering human embryos raises the prospect of designer babies, where embryos  are altered for social rather than medical reasons. E.g. to increase height or intelligence.

○ Justice and Equity: 

It will further widen the disparities between  rich and poor since only the rich would be able to afford the genes for perhaps better intelligence or a fairer complexion.

● Balancing Risks and Benefits:

 While humankind is seeing several medical treatments which were hitherto only theoretically possible are now taking the shape, this warrants caution vis-รก-vis poor or non-standardlization applications of this technology and associated grievance Redressal.

● Ecological impact: 

It can cause non-reversible permanent damage to the environmental gene pool. This could propagate a set of genes with negative traits throughout a population which may lead to the disappearance of the whole targeted population  with severe ecological consequences.

Way forward 


● Altruistic Science: 

Research must be designed to increase human health and wellbeing. Early stage and uncertain application should be avoided to minimize the risk. The benefits and burdens of the research must be broadly and equitably accessible.

● Consensus-based application: 

Bioethicists and researchers believe that human genome editing for reproductive purpose should not be attempted until safe and effective research confirms the same and a social consensus  is reached. 

● Last Report to treatment: 

All clinical trials proceeding in human germline editing should be permitted only when there is no reasonable alternative for disease prevention.
○ Germline editing is the process by which the genome of an individual is edited in such a way that the change is heritable.
● The Drugs and Cosmetics  Act,1940 provides that all clinical trials in India should follow the guidelines prescribed in the Belmont report based on the ethical principle of respect for person, beneficence, and justice.





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