Power and responsibility – the CRISPR debate

To edit or not to edit? Science is making major advances by the second, and with all this new-found power and knowledge comes responsibility, but where do we draw the line? As with subjects like Law and Philosophy, science is having to answer a difficult question along a very thin line; and us black and white, right or wrong scientists are going to have a pretty hard time finding a universal, one-fits-all solution that we strive so hard to achieve in our research.

CRISPR, a gene-editing tool, has opened up many doors for scientists, inside and outside of the lab, and is a revolutionary new way to explore life, and change it. It’s a technique used by bacteria to edit DNA. Now that we have sequenced the human genome, we can edit in or out any gene that we want, thus enabling us to change life at its core. For those with little scientific knowledge: a gene codes for a protein. A gene is made up of DNA, which is transcribed into RNA, which is translated into a protein. Everything in our body is made up of proteins; our hair, skin, blood, heart.. everything. So with the power to alter genes, we can change anything in the human body.

The science bit

CRISPR was first discovered in the immune systems of bacteria to fight infections.

Surprisingly, bacteria get infections too by even smaller organisms called bacteriophages. Bacteriophages to Bacteria, are viruses to people.

Bacteriophage inject small sections of DNA into its host bacteria in order to recruit the mechanisms present in bacteria in order to make new proteins for the bacteriophage, eventually killing the bacteria, and enabling the bacteriophage to reproduce.

40% of bacteria (and 90% of archaea) have a specific defence mechanism against bacteriophage that allow them to target foreign DNA inside the bacterial cell and cut it so it’s unusable.

This is CRISPR.

The bacteria incorporate the foreign DNA (injected by the bacteriophage) into their own DNA, in between genes that code for enzymes and proteins that are used to target and kill foreign DNA.

This section of DNA is called Clusters of Regularly Interspaced Palindromic Repeats (hence CRISPR).

One of these genes codes for an enzyme called cas9 which is used to cut DNA.

The inserted foreign DNA is transcribed into RNA (which can be used as a complimentary code for DNA) which pairs up with cas9 to form an RNA-enzyme complex.

The RNA finds the DNA it codes for (the foreign, harmful DNA) and cas9 cuts it up. It’s the perfect team. So now scientists are able to extract the cas9 enzyme, and pair it with any RNA sequence they like, thus being able to target any gene they know the sequence of (most genes) and cut it.

The DNA will automatically try to fix itself by activating the repair pathway which will result in mistakes and ultimately silence or disrupt the gene, making it redundant.

Taking this one step further, if you inject the correct, functional sequence of a gene you want to replace it with (making sure it has complementary ends to the cut section of DNA) the repair pathway will incorporate this new gene into the DNA.Β 

Back to normal

The practical application of this with regards to people, is that we now have a relatively easy and cheap way of altering DNA. We can replace a faulty gene with a new gene of our choosing. Absolutely fantastic when it comes to hereditary diseases caused by the mutation of a single protein, such as Huntington’s Disease (a mutant version of the protein Huntingtin causes brain damage in the areas that control movement, thinking and motivation) and Cystic Fibrosis (a sufferer has to have inherited a faulty gene from both parents because the cause of symptoms is a lack of function of a particular protein that acts as an ion channel. If one normal gene is present, the functional protein is produced and symptoms are not seen, this person would be a carrier).Β The potential is incredible and is limited only by our knowledge of genes and their function.

At present, all of this is only possible in embryos as they are a single cell. Once the embryo starts dividing exponentially to become a whole organism, we no longer have the technology to insert CRISPR into every cell. So the only way this technology works is by changing the DNA of an embryo before its even a person. Making the choice on behalf of a potential human being. Having the technology to edit out or in ANY protein of your choosing. Choosing a gender. Choosing hair and eye colour. Curing a disease. Making a mistake and causing a new disease. Producing unknown and unwanted consequences.

Enter: the Medical Ethics society, Religious groups, Scientists, Feminists, Lawyers, Parents, Human Rights Activists, Politicians and anyone else who’s interested.

Go.

It’s an awfully big debate with a million right answers. And the scary thing is that every time an answer gets decided and a line drawn, it will become obsolete with every new discovery. In the future we may have the technology to edit genes in adults. Do we draw the line before mental illness and anxiety disorders? Do children decide their own fate? Do we use this technology to enhance normal people?

I’ll repeat a point I made at the start of this article: with great power, comes great responsibility. Who’s given scientists the right to play God? Food for thought.

2 thoughts on “Power and responsibility – the CRISPR debate

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