New Editing Genome Technique to Possibly Prevent Tweaking of DNA

By Johnny Ha

Methods of discovering the inside of the human body has been around and everywhere all the time. A few years ago, scientists developed a technique, known as dubbed Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), which provided gene editing by cutting DNA at specific locations to determine gene-caused diseases. However, the results were very diverse and the approach was not the best because having errors in the human genome are highly unfavorable.

CRISPR are small pieces of bacterial DNA containing genetic information identical to those in viruses which are part of many microbial immune systems along with Cas enzymes. When viruses invade the body, the bacteria from CRISPR recognizes them and cuts them with Cas enzymes to prevent reproduction. A few years ago, scientists at the Broad Institute at MIT and Harvard found way to employ the CRISPR/Cas method to edit DNA in the human genome, but there were flaws because the Cas enzymes would often cut DNA pieces that resembled the intended target or repair parts and not all of the faulty DNA present.

Seeking an alternate way to provide a safer gene editing process, researchers approached RNA editing because it’s a less permanent component of the human genome and causes less damage compared to slicing DNA. While DNA contains encoded information about our genetics and controls our traits by dictating which proteins will be produced by our cells, RNA is typically DNA’s messenger because complementary RNA molecules carry out those instructions. Plus, the human body creates new RNA all the time, so, changes in the genetic makeup won’t be as permanent as in DNA.

Recently, researchers used a variation of CRISPR to edit RNA, known as the REPAIR system which utilizes the enzyme Cas13 and the protein ADAR2. The Cas13 enzyme finds and latches onto the targeted RNA area to make more space while the ADAR2 protein hops in to repair the faulty protein sequence, without cutting anything. The process works by swapping individual a single base change in the RNA sequence, from an adenosine to a guanosine, known as A/G mutations. When the technique was tested on human cells in the lab, the REPAIR mechanism corrected sequences that typically lead to Fanconi anemia, a type of inherited bone marrow disease. Although the DNA still carried instructions that would cause faulty traits, REPAIR was able to create enough properly coded RNA to effectively cure the disease. However, there are some downsides to RNA editing because the body constantly creates and recycles RNA. This implies that errors in the corrected sequences eventually disappears, so therapies that worked by editing RNA would need to be given continuously.