CRISPR gene editing is a technology that can be used to change the DNA in any species, including our own. It’s faster, less expensive, and more precise than previous gene-editing techniques. The precision of the CRISPR method gives scientists the ability to target specific gene sequences.
The CRISPR-Cas9 system occurs naturally in bacteria that use it to defend against viral infections. It’s only been 10 years since scientists discovered CRISPR could be used to edit any organism’s genome. In that time, there has already been tremendous progress in testing applications in medicine, agriculture, research, and biofuels.
The research, though, is still in the early stages. It will probably be many years before CRISPR technology will become a routine part of medical treatment. But scientists are confident that the time will come. They expect an explosion of new CRISPR gene editing applications in the future that will revolutionize our medical care and other aspects of our lives.
How does CRISPR-Cas9 work?
The CRISPR-Cas9 system contains two parts. One is the enzyme Cas9. The other is guide RNA. The beauty and simplicity of the system is that scientists need to change only the guide RNA to target different areas of the genome.
Guide RNA is an RNA sequence that is about 20 bases long. The guide RNA seeks out, finds, and binds to a specific part of the genome where the DNA bases are complementary to those in the guide.
The guide RNA brings the Cas9 enzyme along with it. The function of Cas9 is to cut DNA, like a microscopic pair of scissors. After the Cas9 cuts both DNA strands, the cell goes into repair mode. Scientists can use the cell’s repair mechanism to make desired additions, deletions, or changes to one or more genes using a piece of DNA that carries the new sequence to replace the genome’s original sequence.
CRISPR gene editing can be done in test tubes in a lab or inside a person or other organism’s living cells. These cells can be non-reproductive or, far more controversially, reproductive cells. Changes made in reproductive cells will be passed on to future generations. Reproductive cell gene editing is currently illegal in most countries.
Improving CRISPR-Cas9’s accuracy
While the CRISPR system is significantly more accurate than older gene-editing systems, there is still room for improvement. The problem is that the guide RNA can bind to a spot on the cell’s DNA even if all of the base pairs aren’t complimentary. This increases the chance that the guide RNA could bind to the wrong place on the genome.
One solution being worked on is to create a better guide RNA. Another solution is to use Cas9 enzymes that can cut only a single strand of DNA so that more pieces of guide RNA and Cas9 will have to be lined up in the right place.
The potential of CRISPR-Cas9 gene editing
CRISPR technology already shows great promise for fighting disease. Clinical trials are now being conducted using gene editing to cure sickle cell anemia. The first sickle cell patient treated with CRISPR editing is thriving two years after her initial treatment. CRISPR technology has also been used to restore the vision of people with a rare genetic eye disorder and to treat amyloidosis, a lethal inherited disease.
CRISPR has the potential to treat and even prevent a wide range of both rare and common genetic diseases, including cancer, Alzheimer’s, diabetes, and hepatitis. Beyond treating disease, CRISPR might be used to select desired traits in embryos – a prospect that raises significant ethical questions. Whatever happens, the changes that CRISPR brings will be profound.