Taking Evolution Into Our Own Hands: The CRISPR-Cas9 Debate
The phrase ‘gene editing’ is saturated with controversy. The theme of genetic engineering is present throughout modern science fiction, from Jurassic Park to Brave New World, Wolverine to Captain America. Discussing its ethics is complicated, and there may be no right answer. Either way, the technology is advancing — fast. To keep up with new developments, it is critical to understand the basics: what, exactly, is genetic engineering?
The answer actually begins with bacteria. Oftentimes, scientists build ideas for new innovations based on observations of what other organisms have developed in nature. This is one such example. Bacteriophage are a type of virus that specifically target bacteria. As a means of defence against bacteriophage, bacteria have a system known as CRISPR-Cas9. CRISPR stands for ‘clustered regularly interspaced short palindromic repeats’, and Cas9 is the name of the enzyme involved. Without going into too much detail, this system essentially allows bacteria to store DNA fragments from phage, and use them as templates to detect the same sequence upon future viral infection. Not only are the bacteria able to detect viral DNA through this system, but they also use the Cas9 enzyme to literally cut the DNA when detected. Discovering the CRISPR-Cas9 system was revolutionary to geneticists. Suddenly, scientists were presented with a method used by bacteria to cut DNA at specific sites with a high level of precision.
In 2013, thanks to the simultaneous research done by two groups of scientists, a version of CRISPR-Cas9 that utilizes gRNA emerged that can be used to edit human DNA.
CRISPR-Cas9 holds a significant amount of potential, both good and bad, ethical and unethical. Still in it’s infancy, it is impossible to say where the future of CRISPR lies. There are countless possibilities when it comes to what can be done when given the opportunity to edit DNA, and the arguments for and against CRISPR are compelling on both sides.
On one hand, this may offer a treatment for genetic diseases. Cystic fibrosis, an autosomal recessive disorder, occurs due to a mutation in the gene for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. It causes thick mucus which leads to significant problems for patients, especially in the lungs. Imagine if we could treat cystic fibrosis patients by literally cutting into their genome and replacing the mutated gene for the CFTR protein with the correctly sequenced one. And that is just one example.
CRISPR’s potential in biomedicine goes beyond just humans. Some scientists have proposed using CRISPR-Cas9 to genetically edit mosquitoes in order to make them resistant to Plasmodium, the apicomplexan that is responsible for malaria. If that were to prove successful, the same process could, in theory, provide protection against the zika, chikungunya, and dengue viruses. Kurzgesagt — In A Nutshell has a fantastic video on Youtube about this.
While there is potential for gene editing to provide real solutions to painful medical problems, there is also potential for this technology to backfire. One argument against gene editing is that we are delving into the territory of eugenetics, which has a dark and brutal history. According to Oxford Dictionary, eugenetics is “the science of improving a population by controlled breeding to increase the occurrence of desirable heritable characteristics”. This introduces an obvious problem: who decides which heritable characteristics are or aren’t desirable? Will it provide a means of discrimination akin to that in Gattaca?
It is extremely unlikely that CRISPR will lead to the Eugenics Wars a la Star Trek. However, it is important to remember how new this technology is: CRISPR-Cas9 was proven to work on human DNA only six years ago. Almost everything that we know about it so far comes from studies done on other organisms or in petri dishes. There is only one case in which the CRISPR-Cas9 method was attempted on embryos who were actually born. Chinese researcher He Jiankui claims to have used CRISPR-Cas9 to disable the CCR5 gene, which encodes a protein that the HIV virus can use to enter immunological cells. This sparked a massive debate about the ethics and safety of CRISPR even though Jiankui has only published portions of his data, which show little proof that he actually did what he claims to have done. Regardless, the consensus seems to be that, if he is telling the truth, Jiankui’s attempt came far too soon.
Is CRISPR-Cas9 going to be one of the largest advances in medicine? What about its many other applications in fields that aren’t discussed here, such as agriculture? When, if ever, should future studies move out of test tubes and into real people?
What do you think?
