CRISPR-cas9 … Genetic engineering offers real hope of advancement
The year 2015 ended with the announcement of great news for the DMD community. Indeed, the scientific community has been voicing much enthusiasm at the discovery of a genetic engineering technique that will eventually help us with a wide array of things, such as protecting certain endangered species, stopping malaria and curing diseases …!
Genetic “cut and paste”
The event is of such scientific importance that Science magazine awarded the title of a scientific breakthrough of the year to the genetic engineering technology referred to as CRISPR/cas9. La Presse + published an interesting and informative article on the subject in its January 17, 2016, edition.
Derived from a bacterial defence mechanism, a new gene suppression and insertion technique is spreading like wildfire in laboratories everywhere. Thanks to its high targeting accuracy, CRISPR-cas9 is by far the most effective technique to correct DNA defects. It’s described as a “molecular kit” of sorts, a clever and complex toolkit that enables us to perform “cut and paste” operations in the DNA of living things.
This technology basically works as follows:
- The CRISPR component – a type of gene sequence found naturally in certain organisms, including viruses – is able to recognize a specific genome sequence, that is to say, go to the place where lies the defect responsible for the disease.
- The Cas9 component acts as a pair of scissors and can “cut” in the DNA at a specific location, i.e., where action must be taken.
- From here, one can either choose to remove a genetic mutation or insert a fix for the faulty gene.
- Using its normal DNA repair mechanisms, the cell will then naturally reattach the strands.
The latest results obtained in mice demonstrate the CRISPR method’s potential for correcting certain genetic abnormalities after birth.
An encouraging step in the fight against DMD
As we know, DMD is the result of an error in the “writing” of the gene responsible for producing dystrophin. In people suffering from Duchenne muscular dystrophy, the dystrophin gene has undergone a genetic mutation: the gene is badly written, the cellular machinery expected to read it cannot do it, and as a result, the protein is simply not produced.
Researchers have undertaken to use CRISPR/Cas9 to remove the mutated part of the gene. By erasing the illegible component blocking the genetic material’s decoding process and introducing a proper genetic sequence, researchers have restored production of dystrophin, which is essential to the proper functioning of the muscle.
In order to spread their molecular kit in all of the body’s cells of the researchers found a way to put it on board of viruses that have a particular attraction to muscle cells. They then injected this mixture into diseased mice. After a few weeks, the muscles of these rodents began synthesizing dystrophin, a substance they were previously unable to produce…
Cautiously excited…
As exciting as the news of this extraordinary discovery is, we are still far from our common goal: it must be kept in mind that testing has only been performed on mice at this time, and researchers warn that the real challenge will be to transpose this in humans and potentially have to deal with an immune response from the patient.
That being said, it will be extremely interesting to see where it takes us!
A few relevant links:
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