Gene-therapy approaches

How does the CRISPR/Cas system work?

Now that we have established that there are different kinds of gene editing, let’s focus on 1 type: the CRISPR/Cas system. The CRISPR/Cas system is made up of different parts, working together, to edit DNA. These parts consist of an enzyme, called a Cas enzyme, and a guide called a guide RNA.

The CRISPR/Cas system

The CRISPR/Cas system is designed to scan millions of lines of genetic code in DNA to search for the target gene that might be preventing your body from doing its job.

The guide RNA locates the specific gene

The CRISPR/Cas system relies on a guide RNA to find and target a specific sequence of genetic code. Think of the guide RNA as a GPS device.

Guide RNA-locating gene illustration in CRISPR/Cas process
Guide RNA-locating gene illustration in CRISPR/Cas process

The Cas enzyme enables the edits

Once the guide RNA has directed the Cas enzyme to a precise location in the DNA, the enzyme cuts a specific section of DNA to allow for changes to be made.

Cas enzyme cutting DNA illustration
Cas enzyme cutting DNA illustration

How the CRISPR/Cas system is thought to work

Targeting a specific gene

Targeting a specific gene

First, the guide RNA directs the Cas enzyme to a specific site in the DNA where the gene that should be modified lives.

Guide RNA-locating gene illustration in CRISPR/Cas process
Guide RNA-locating gene illustration in CRISPR/Cas process

Matching

Once the site has been found, the Cas-RNA complex causes the DNA to unravel. The guide RNA then lines up with the unraveled DNA.

DNA unraveling with Cas–RNA complex
DNA unraveling with Cas–RNA complex

Cutting the DNA

Next, the Cas enzyme cuts the DNA strand at a precise location so that the gene editing can take place. The body’s natural repair process plays a role in repairing the cut DNA.

Next, the Cas enzyme cuts the DNA strand at a precise location so that the gene editing can take place. The body’s natural repair process plays a role in repairing the cut DNA.

Cas enzyme cutting DNA strand
Cas enzyme cutting DNA strand

Editing complete

We have now activated a new set of instructions within the cell.

Gene-editing process illustration with complete edited DNA strand
Gene-editing process illustration with complete edited DNA strand

What comes next?

Once this process is complete, your modified genes can function with a new set of instructions.

Learn more about the history of gene therapy and discover the research currently underway for future therapies.

Check out the timeline of innovation

Learn more

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