CRISPR: Changing the World One Gene at a Time
CRISPR will change the world forever by introducing a multitude of new possibilities. Let’s see why.
Genes — they decide our defining characteristics and are the reason why we look the way we do. For most people, there is nothing wrong with their genetic code, but those with genetic diseases like certain types of cancer and genetic blindness would probably appreciate it if their genes could be altered slightly to treat their disease. Until now, this has not possible, but with CRISPR, we may be able to treat any genetic diseases using technology and potentially eliminate them one day. Let’s take an in-depth look at what CRISPR is and the positive role it could play in the future.
What is CRISPR?
CRISPR is a new gene-editing technology that can be used to turn certain genes on and off and even remove, add, or fix faulty genes. CRISPRs in nature are repeated sequences of DNA with small, repetitive sequences of DNA called “spacers” dispersed throughout the large sequences of DNA, hence the name CRISPR: clusters of regularly interspaced short palindromic repeats. In bacteria, these spacers are copies of viral DNA from previous viral attacks. When the same virus attacks again, some of the DNA in these spacers is transcribed into CRISPR RNA. Then, a Cas (short for “CRISPR associated”) protein, an enzyme that cleaves, or cuts, foreign DNA, is guided by this RNA to the invading viral DNA to cleave it and protect the bacteria. When genome editing with CRISPR, we tend to use the Cas9 protein to lead the guide RNA.
Genome Editing with CRISPR
This CRISPR gene-editing process explained in the previous paragraph only occurs naturally and could not be done in a controlled environment by humans for a long time. Luckily, in 2008, food and bio-product production company Danisco became the first people to use the CRISPR/Cas9 gene-editing system by using it to improve the immunity of bacteria against viruses. From then on, it has been used to improve the durability and increase the yield of crops, treat genetic diseases like Leber congenital amaurosis (a type of inherited blindness), and more.
According to Harvard Medical School genetics professor George Church, the first step in editing a gene using CRISPR is designing “a stretch of 20 [nucleotide] base pairs that match a gene that you want to edit.” Then, a corresponding RNA strand is constructed. This RNA leads a Cas9 protein to wherever the sequence of 20 nucleotide pairs is located in the genome so that the Cas9 enzyme can cut these nucleotide pairs out for modification. Scientists can then provide a short DNA template with whatever modifications they want to replace the nucleotides that were just cleaved.
Constraints
The CRISPR genome-editing system is far from perfect, as it is still a relatively new technology and certain limits prevent it from always doing what you want it to do. One of the biggest limitations is the inefficiency of CRISPR/Cas9, as not all cells that receive a guide RNA and a Cas9 enzyme will edit the DNA strand. Some tests have reported that as low as 50% of cells edit the DNA, while other experiments report higher than 80% efficiency. CRISPR is also not completely accurate, as occasionally, the wrong genes are cut or edited, and even though these “off-target edits” are rare, they can have severe consequences. Additionally, it is hard to deliver the CRISPR system to a large number of cells at once. All of these limitations make it difficult to decide whether or not using CRISPR is worth the risk, especially in clinical applications.
Applications
CRISPR is a powerful technology that can change the world for the better. Although it has mostly been used for research purposes in the past couple of years, we have used CRISPR to genetically modify foods (GMO’s), including yogurt and various crops, and treat certain genetic diseases, including treating many types of cancers through CAR-T therapy (using genetically altered T-cells to fight cancer).
We have not yet unlocked CRISPR’s full potential just yet, but in the future, we will be able to change the world through genetic engineering. CRISPR may offer the ability to fight diseases caused by genetic mutations like cystic fibrosis, increase the nutritional value of crops to make future generations of humans healthier, and create gene drives to make certain genes more likely to be passed on. The possibilities are endless, and the future of CRISPR looks extremely bright, with better and more efficient Cas proteins being discovered every year.
Ethical Limitations
Genome editing is a fascinating science, but it has its fair share of ethical issues. Having the power to change someone at a genetic level is amazing when it comes to curing diseases, but this power could be abused by those wanting to enhance advantageous traits or change their physical appearance, which would affect both them and their potential offspring. Because of these ethical issues, scientists have decided to temporarily prohibit “changing heritable DNA (in sperm, eggs or embryos) to make genetically modified children.” Until these ethical issues are resolved, the use of CRISPR will be limited.
CRISPR will hopefully revolutionize the world in many ways, but as of now, it is still new and has many problems, both ethical and scientific. Genome editing is predicted to become more and more popular as time progresses, and in the future, even humans could be genetically altered. All we can do now is wait.
Want to learn more? Check out these websites to gain a deeper understanding of CRISPR:
