Gene editing and ethical concerns #41

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Syllabus: GS paper 3: S&T, GS paper 4: Ethics

What are designer babies? What are the ethical concerns associated with gene editing?

What is the issue?

There are ethical concerns over the clinical application of gene editing technique in recent times.

What is CRISPR?

It is a gene editing technique which stands for Clustered Regularly Interspaced Short Palindromic Repeats.
It harnesses the natural defence mechanisms of bacteria to alter an organism’s genetic code.
The bacteria are likened to a pair of molecular scissors that can cut the two DNA strands at a specific location and modify gene function.
The cutting is done by enzymes like Cas9, guided by pre-designed RNA sequences, which ensure that the targeted section of the genome is edited out.
CRISPR – Cas9 is the most prominent genome editing technique .
It allows researchers to permanently modify genes in living cells and organisms.
This can be used to correct mutations at precise locations in the human genome to treat genetic causes of diseases.
Correcting the mutation in an embryo ensures that the child is born healthy and the defective gene is not passed on to future generations.

How does gene editing work?

The gene editing tool has two components :

A single-guide RNA (sgRNA) that contains a sequence that can bind to DNA.
The Cas9 enzyme which acts as a molecular scissor that can cleave DNA.

In order to selectively edit a desired sequence in DNA, the sgRNA is designed to find and bind to the target.
The genetic sequence of the sgRNA matches the target sequence of the DNA that has to be edited.
Upon finding its target, the Cas9 enzyme swings into an active form that cuts both strands of the target DNA.
One of the two main DNA-repair pathways in the cell then gets activated to repair the double-stranded breaks.
While one of the repair mechanisms result in changes to the DNA sequence, the other is more suitable for introducing specific sequences to enable tailored repair.
In theory, the guide RNA will only bind to the target sequence and no other regions of the genome.
But the CRISPR-Cas9 system can also recognise and cleave different regions of the genome than the one that was intended to be edited.
These “off-target” changes are very likely to take place when the gene-editing tool binds to DNA sequences that are very similar to the target one.
Though many studies have only found few unwanted changes suggesting that the tool is probably safe, researchers are working on safer alternatives.

Why is CRISPR- Cas9 system significant?

Normally, if sperm from a father with one mutant copy of the gene is fertilized in vitro with normal eggs, 50% of the embryos would inherit the condition.
However, when the gene-editing tool was used, the probability of inheriting the healthy gene increased from 50 to 72.4%. There was also no off-target snipping of the DNA.
The edited embryos developed similarly to the control embryos indicating that editing does not block development.
Clinical trials are under way in many countries to use this tool for treating cancer.
It was shown in mice that it is possible to shut down HIV-1 replication and even eliminate the virus from infected cells.
In agriculture, a new breed of crops that are gene-edited will become commercially available in a few years.
Given all these, making gene editing possible in human reproductive cells deserves serious considerations in terms of legal, social and ethical consequences.

What are the practical applications?

CRISPR was used successfully to repair a heart-damaging gene in human embryos.
It marked a step towards preventing inherited diseases from being passed on to the next generation.
It can be useful in learning how genes cause disease or influence development and what therapies might help.
It was also found that gene editing in the brain can help decrease the repetitive behaviours, which is a symptom of autism spectrum disorders.
The approach can also be used to treat other neurological diseases such as epilepsy and the brain cancer glioblastoma.
Scientists in the UK have used genome editing to study DNA function in human embryos that could help better understand the biology of our early development.
The findings could improve IVF treatments and understand some causes of pregnancy failure in the future if key genes responsible for successful development of embryos are identified.
Researchers also are using gene editing to hatch malaria-resistant mosquitoes, grow strains of algae that produce bio-fuels, improve crop growth, even make mushrooms that don’t brown as quickly.

What are the concerns?

Safety is a key question because gene editing has the possibility of accidentally cutting DNA that is similar to the real target.
A study published in the journal Nature Medicine, found that therapeutic application of the genome-editing tool may increase the risk of cancer.
It could be potentially used to edit out undesirable traits in human beings in the name of improving genetic quality of a human population, as Eugenics.
It could also be used by governments to create a ‘superior’ race and by the private sector in the name of creating a perfect child for the parents.
Altering genes in sperm, eggs or embryos through “germ line” engineering leads to concerns regarding creation of designer babies with enhanced traits.
This leads to the argument that gene editing be reserved for serious diseases with no good alternatives and performed under rigorous oversight.

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Hemant Bhatt

Chief Mentor at Oracle IAS

Hemant Bhatt is a B. Tech from Pantnagar University and has studied Social Sciences at SciencesPo, Paris. He teaches at Oracle IAS, Dehradun. He has given 5 UPSC mains back to back along with 2 interviews.
He is a bibliophile,accomplished writer and a fitness enthusiast.

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