CRISPR – Cas9

BY ANNELIESE MOLL
For the UAS Whalesong
Earlier this semester, I wrote a brief article about GMOs. Within it, I mentioned that humans have been slowly modifying organisms for thousands of years. Since the discovery of DNA, the technology and methods used to understand and edit DNA have changed and improved. CRISPR, or Clustered Regularly Interspaced Short Palindromic Repeats, are segments of prokaryotic DNA that have short repetitions of base sequences. Cas9 is an associated enzyme.
In December of 1987, CRISPR sequences were found, but not characterized, in E. coli. Eight years later these sequences are found in other microbes. Jump to 2007: a Danish food company called Danisco found that these sequences are part of a bacterial defense against viruses. In 2011 several biotech companies started to utilize this new technology, focusing on agriculture, therapeutics, and more research. The following year it is reported that scientists are able to use CRISPR to edit genomes. More energy is placed on researching therapeutics in several locations worldwide, and CRISPR has begun to be heavily used with mouse and human cells. During March of 2015 the first report of the CRISPR gene drive that is able to spread a modified gene rapidly. Earlier this year a group of researchers edited human embryos.
CRISPR-Cas9 is not the first of its kind though. Another example of a technology that was able to made edits within a genome is called zinc finger nucleases. It consists of synthetic proteins made from engineered zinc finger DNA-binding domain fused to the cleavage domain of a specific restriction endonuclease, in other words it is an artificially engineered section of DNA that binds with an enzyme in a specific section where the natural DNA has been cut. This was supposedly going to be able to edit DNA accurately and efficiently. However, it ended up being difficult to engineer and very expensive. Zinc finger nucleases cost at least $5,000 USD whereas CRISPR-Cas9 is highly flexible while still able to target specific sections of DNA, which allows for it to be easily manipulated, and this technology costs about $30 USD. This is what makes CRISPR so amazing.
With more research and knowledge CRISPR could rapidly become a life saving technology because of its ability to precisely delete and insert genes into the genome of an organism. People with genetic diseases may finally be able to receive effective help through gene therapy. Gene therapy is when a person with a non-functional gene has a normal (functional) gene inserted into their cells. This is currently an experimental technique that still has many risks involved, but for some patients where medications or surgery is not an option this could be a powerful tool. However, while this technology has the ability to become another tool for treating disease many people worry that this could also be used to modify human embryos, and that those modifications are be passed down other generations. One of the large questions out there is about what would happen if and when these modified genes mutate.
Ultimately, this technology is going to require us to have some long and difficult conversations about the moral and ethical uses as well as having more research and understanding about the affects this could have on our world.

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