CRISPR - Gene Editing Tool

CRISPR, it sounds like an app, but it really stands for "clusters of regularly interspaced short palindromic repeats." It is the worlds most advanced gene editing tool, which means it can alter DNA sequences and change DNA function in any cell. As we have discussed this semester a lot of the different diseases and disorders that occur when a DNA sequence is changed via a mutation I have been curious to better understand what possibilities we as humans have at either fixing these mutations or creating one of our own that would be beneficial. 

CRISPR acts as a pair of "molecular scissors" and was first tested by Rodolphe Barrangou and other researchers at Danisco, the food company, in 2007. They tested Streptococcus Thermophilus, a bacteria usually found in yogurt to see if the CRISPR segments of DNA were able to have an effect on the immunity of the bacteria against certain viruses. What they found is that once the CRIPSR region was genetically modified, the bacteria in the yogurt was able to fight off the viral strain much better than it previously had. This gave them the first clue of the potential that the CRISPR region might hold. CRISPR is used with Cas9, which is a protein that acts as an enzyme that allows DNA to be cut and new DNA replaced. When the CRIPSR was used, the bacteria was able to remember the DNA of the virus that had attacked it, which enabled them to fight off future attacks easier. 

CRISPR further works as a gene editing tool by cutting a part of the DNA, and tricking the DNA repair mechanisms to replace the DNA in a different order. In 2012 Robert Winthrop, a Professor at Harvard Medical School, discovered that this ability to cut DNA could be directed to any piece of DNA using a guide RNA. Similar to transcription, a corresponding RNA sequence could be sent in to match the DNA sequence desired to cut. Once that material was cut by the Cas9, scientists can introduce a new DNA sequence that will allow the section that was cut to be reorganized into whatever sequence is desired. 

Obviously the implications of this process are huge, and also ethically challenging. In 2013 the first attempts to apply this process to human cells were tested, and they found the technology could be effective at preventing certain diseases such as cystic fibrosis, cataracts, and fanconi anemia. It has also been applied to increase crop yield, make farming plants more resistant to disease, etc. At this time however, all reports have come back that CRISPR is only 50% effective at replacing the desired DNA. Before it could be applied to much larger and bigger respects such as an adult human cell, it must be much more accurate. Another possible side effect is if a negative mutation occurred in an adult human cell that was undesirable, the trait or defect could potentially be transferred onto offspring. 

Ultimately there are many different possibilities and issues, but the implications are huge and could effect potentially millions of lives for the better. 

Vidyasagar, Aparna. “What is CRIPSR?” Live Science, Apr. 2017. https://www.livescience.com/58790-crispr-explained.html. Accessed 16 November 2017