CRISPR: The New Craze

CRISPR(Clustered Regularly Interspaced Short Palindromic Repeats) is receiving international acclaim after showing great promise in the medical world. This type of genetic engineering, discovered when CRISPR loci were found in the genomes of bacteria and archaea, is proving to be a cheaper, more precise, more accessible and less time-consuming way of altering DNA.

Certain types of viruses (namely bacteriophages or “bacteria eaters”) can attack and infect bacteria, using the bacteria as a host in order to replicate themselves. Bacteria, in response to the attack, can save a part of the virus DNA in their own genetic code in a DNA archive known as CRISPR, which stores the virus DNA until it is needed. Once the virus attacks the bacterium again, the bacterium can make a RNA copy from the DNA archive and use a protein called CAS9 to scan the bacterium’s insides for traces of the virus- comparing every bit of DNA the protein finds to the virus sample from the DNA archive. When CAS9 finds a perfect match, it is activated in order to cut out the virus DNA and protect the bacterium against the virus.


There are many different implications of using the CRISPR-CAS9 system in medicine: the programmable system offers the ability to edit living cells, switch genes on and off and study DNA sequences from any type of cell. This form of genetic engineering can essentially take on the role of a “DNA surgeon”.


In 2015, scientists used CRISPR to cut out the HIV virus from cells grown in the lab before carrying out a clinical trial on HIV-infected rats by injecting CRISPR into the rats’ tails- removing 50% of the virus in the animals. A year later, scientists decided to treat lung cancer patients by modifying immune cells with CRISPR to make them detect cancerous cells more easily.

A more controversial implication of using CRISPR is the creation of designer babies, a concept that has already been instilled in people’s minds with pregnant women, for example, taking embryo screening tests and terminating their pregnancies based on the medical conditions of their unborn children. Scientists warn that altering the human genome in order to pre-select features for future children will make gradual but irreversible changes to the human gene pool, causing the engineered traits to be passed onto future generations- leading to a slippery slope, with modified humans set as the new standard.


As a result, it is now more important than ever that the scientific community acts cautiously and respectfully as technologies advance, especially in light of the fact that there are limitations associated with the CRISPR system itself: CRISPR may not cut out the desired sections of DNA; CRISPR may insert sections of DNA the wrong way around and CRISPR may delete DNA sections altogether, triggering unexpected changes to the modified organisms.

Ultimately, CRISPR is still very much a first-generation tool which cannot be utilised to the best of its ability until we understand enough about genes to avoid the unpredictable consequences of genetic engineering. Nevertheless, CRISPR has paved the way forward for medical research, making us one step closer to treating patients in the most humane way possible.

Thank you for reading!
By Kumaran


Sources:
https://www.youtube.com/watch?v=UfA_jAKV29g&index=3&list=PLboc_P9zcJhjXdwmsdo6_Z5c1lXbRI2GF https://www.newscientist.com/article/mg22830500-400-editing-life-a-guide-to-the-genetic-revolution-on-our-doorstep/ https://www.sciencealert.com/this-video-explains-perfectly-why-crispr-really-will-change-humanity-forever https://www.youtube.com/watch?v=UfA_jAKV29g

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