CRISPR-Cas9: Road to an Artificial Evolution
A little more than two decades back, scientists witnessed an epic fight; between a virus and a bacterium. This microscopic war opened up avenues never known before to mankind.
Researchers noticed a fascinating adaptive immunological system in prokaryotes (bacteria and archaea).These single celled organisms had certain DNA sequences that “remembered” every virus it fought by storing a fragment of the virus’s genome in a system later termed as Clustered Regularly Interspaced Short Palindromic Sequences(CRISPR). Cas 9, a protein in the CRISPR system, matches the virus DNA with the stored sequences if it attacks again and cuts it off, disarming the virus. The interesting thing about Cas 9 is that it is highly precise and programmable. This means we can give the protein a certain “guide” RNA sequence to find the desired DNA sequence and make it cut out that part of the gene. If we want to replace it with a different sequence then cells already have a repair mechanism that we can harness and program.
This was a revolutionary discovery and a major breakthrough in genome editing of all species. This tool works in all living cells and is by far the easiest and cheapest method to edit genes. A simple CTRL-F disguised in the form of a small injection, if you will. It opened up limitless possibilities and let’s look at a few applications in the human genome itself.
- A cure for HIV: The CRISPR system has already been tested on mice with all their cells infected with HIV and were successful in making around half of the cells HIV-free. Scientists used CRISPR to cut out the HIV gene sequence from their cells. Other viruses which hide in the human DNA can also be eradicated in this way.
- A cure for cancer: This tool can edit a cancer patient’s immune system cells to help them detect cancerous cells better and destroy them at an early stage.
- A cure for genetic diseases: Over 3000 genetic diseases are caused by a single error in our DNA. A modified Cas 9 could rectify that error and fix these diseases forever in humans.
- Immortality: Aging is a process where our cells aren’t able to repair and regenerate properly. With gene editing, we can replace inactive DNA and RNA to regenerate cells again. This can vastly extend the longevity of the human species.
Another major application of this highly efficient system of editing genes would be to make designer babies. Once you remove genetic diseases from your child’s genome, why not give it good height, a muscular physique, a high IQ and other conventionally attractive features? These are not mere speculations of a far off future, mind you. The technology has already developed enough to achieve most of these. Countless clinical tests on the cells of various species have been carried out successfully. This could lead to a much faster, artificial evolution.
Of course there are a few cumbersome barriers left to jump over. For example, the study of the genome is not complete. So scientists are not sure if the CRISPR system can corrupt untargeted genetic material. Or how the modification of a gene may impact other genes. We do not have complete knowledge of which genes are responsible for the characteristics we desire to modify. But we have to keep in mind that when we do uncover this knowledge, the CRISPR tool is ready to edit it.
We have to also prepare for the social impact of this technology. The rapid development of gene editing is overwhelming to say the least. It raises various ethical questions. So much so, in early 2015, Emmanuelle Charpentier, Jennifer Doudna and her colleagues who discovered this technology called for a global pause in this industry to take time to address all the ethical questions being raised.
Since then various organisations have made ethical policies to supervise the development of CRISPR. He Jiankui and his two collaborators were the first researchers to produce genetically altered babies in 2018. A year later they were found to have forged ethical review documents and face hefty fines and jail time.
With millions of cancer cases every year and over 6000 genetic diseases in existence, the human genome is long overdue for a software update. CRISPR-Cas9 is a tool that will allow scientists to do just that. To recognise this great feat, Emmanuelle Charpentier and Jennifer A. Doudna were jointly awarded the Nobel Prize in Chemistry on 7th October, 2020.
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