CRISPR—the gene editing tool that is revolutionizing medicine
Imagine you could take any gene you want—maybe one that could give you green eyes, or one that makes you resistant to getting HIV—and plant it in your DNA. Or what if you could simply delete a certain gene in your DNA—say, one that is linked to getting a certain cancer?
Well, guess what folks—that isn’t science fiction anymore. In 2012, a gene editing tool was discovered that is completely transforming the world of medicine, and it is called CRISPR.
CRISPR is one of the most powerful scientific breakthroughs of our time and will have some seriously profound impacts on life around the world—in fact, it already has.
What is CRISPR?
CRISPR is essentially a gene-editing tool (that scientists initially isolated from a bacteria cell).
Back up—what is a gene?
Many of you probably recognize the classic ‘double helix’ DNA that looks like a spiraling ladder. Certain sections of your DNA code for genes—which are like recipes—telling your cells what proteins to make and ultimately determining how you look and how you function. It is estimated that humans have over 20,000 genes, determining everything from skin color to blood type.
How CRISPR works
CRISPR can search over an entire strand of DNA, target a specific sequence (a gene) and cut it out with an enzyme that acts as a ‘molecular scissor.’ This allows scientists to target certain genes that they want to remove, and sometimes even replace it with another gene. It is like reading over a paragraph you wrote to find the word you spelled wrong, using white out to remove it and then writing the correct word back in. Just like how you edit a paper you wrote, CRISPR provides the ability to edit genes in organisms—which can mean removing genes that cause certain diseases, like Huntington’s Disease.
It allows scientists to target a specific gene, cut it out, and even replace it with a different gene—basically, ‘editing’ the genome of any organism. That is freakin nuts.
So what does this mean for society?
CRISPR has been used to genetically modify mice, pigs, monkeys and even human embryos (though that was VERY controversial). A Chinese scientist genetically modified two twin girl embryos by inserting an HIV-resistant gene, since their father is HIV positive. This sparked immense controversy, as it instigated a global debate of the ethics behind genetically engineering human embryos. While CRISPR can and will be used more in the future for curing illness and preventing people from suffering from genetic disorders, it also has the potential to alter humans in other ways, such as controlling what a child might look like.
Gene editing isn’t a new thing—scientists have been able to modify genes for decades, though it used to be a much more difficult and expensive process. CRISPR is the cheapest and easiest gene editing tool ever discovered—which makes it the ideal prospect for curing and preventing diseases with genetic markers, including using it for cancer treatments.
CRISPR can sound dauntingly complicated—but it is important that we all at least have a basic understanding of what it is, since it is transforming how we are able to treat and prevent diseases and genetic conditions that have been unpreventable in the past.
Since it has the potential to genetically modify any type of living organism, it is an incredibly powerful tool that can be used beyond just human medicine. As exciting of a discovery as this is, there is reason to be wary about putting so much power in the hands of people. The ability to easily modify genes will likely extend beyond preventing disease; for example, it could be used to enhance certain human qualities. Some people are concerned that this could lead to a eugenics movement—where only ‘desirable’ genes are selected for the human population, ultimately resulting in humans changing the course of evolution by natural selection.
My hope is that we utilize this technology for good, but that as a global society we take caution not to abuse this power in ways that will be unredeemable.
This might be the first time you have heard of CRISPR, but I doubt it will be the last.
Cheers,
AT
A little more detail on what CRISPR is—a little more technical
The CRISPR system is made up of a protein called Cas9, and a guide strand of RNA (which is similar to DNA). Imagine a ball and chain—the ball is the Cas9 protein and the chain is the strand of RNA that matches a certain segment of DNA coding for a particular gene. This CRISPR unit moves along a strand of DNA until the RNA recognizes its match in the DNA strand. The RNA unravels the DNA strand, attaches itself to the DNA and the Cas9 protein uses its ‘molecular scissors’ and cuts the DNA strand.
At this point, a specific region of DNA, potentially coding for a gene that causes Cystic Fibrosis, let’s say, has been cut out. And perhaps the most impressive part about CRISPR, is that you can go back and insert a new section of DNA into the space that you just cut out—putting in a new gene where the old one once was.
Sources:
Brokowski, C., & Adli, M. (2019). CRISPR Ethics: Moral Considerations for Applications of a Powerful Tool. Journal of Molecular Biology,431(1), 88-101. doi:10.1016/j.jmb.2018.05.044
Martinez-Lage, M., Puig-Serra, P., Menendez, P., Torres-Ruiz, R., & Rodriguez-Perales, S. (2018). CRISPR/Cas9 for Cancer Therapy: Hopes and Challenges. Biomedicines, 6(4), 105. doi:10.3390/biomedicines6040105
Jennifer Doudna (the woman who discovered CRISPR) TED talk:
https://www.youtube.com/watch?v=TdBAHexVYzc
http://sitn.hms.harvard.edu/flash/2014/crispr-a-game-changing-genetic-engineering-technique/