A New Gene Editing Tool Grants Every Wish,
Except the Power To See the Consequences of Our Wishes
One of the criticisms of genetic engineering during the era of the gene (shot)gun is the pure randomness of the “genetic insertions” that it affords. Tiny gold beads coated with genetic information are literally blasted into a soy or corn leaf in hopes that a bit of the desired gene sequence will insert itself in a functional position somewhere in the crop DNA. Millions of cloned plantlets are subsequently cell-cultured from individual leaf cells from the blast zone in hopes of finding one or more bearing a functioning gene insertion that does what the “engineers” were hoping for...resist herbicide, produce Bt-toxin protein, glow in the dark, etc. Though the process requires a lot of engineering, the resulting genomic modification is hardly designed—it is far more random than any aspect of evolution and selection employed by classical breeders.
But a new era is upon us, a time when specific genes can be guided to specific sites in the DNA sequence to produce predictable results that are permanent, and that can even be designed to spread within an organ tissue to cure genetic diseases (cystic fibrosis, for example) or cancer, or to spread within an ecosystem to eliminate a species. Would you like to rid the world of mosquitoes? Could be done. Perhaps just eliminate the malaria parasite? Yes.
The genie granting these wishes is a genetic control technique derived from bacteria which use a DNA-snipping enzyme (called Cas 9) and bits of “palindromic repeat” DNA to silence invading viral DNA. By combining these bacterial innovations with an engineered “tail” of RNA (designed to locate a particular DNA pattern on the target’s genome), real genetic engineers now have the power to place any gene into any organism. When these gene geniuses say anything is possible, they aren’t kidding.
This system of genetic modification is called the CRISPR/Cas 9 gene drive, and there is nothing theoretical about it. CRISPR is an easy way to say “clustered regularly interspaced short palindromic repeats,” which are actually viral DNA segments commandeered and repurposed by bacteria to defend against viruses. After packaging together the CRISPR/Cas 9 component with a custom RNA “address tag” and whatever genetic payload is desired, the resulting “gene drive” finds the desired DNA location and inserts itself. When the gene drive insertion meets up with its complimentary DNA strand, it copies itself to create a homozygous cell. If these cells are gametes, homozygous progeny will always result. Indeed, the power of gene drives is their viral nature; they copy and paste themselves onto any unmodified DNA strand they meet, meaning that inheritance of the gene driven trait spreads with almost 100% efficiently. If inserted into genetically dysfunctional tissues, gene drives can cure them. If into cancerous tissues, gene drives can normalize them. If into species, they will be changed forever.
So readers, consider the CRISPR, and give it study. Some will promote its benefits, some will point to the dangers of such power. The methods and technology have been released open source, so there is no monopoly on the power. We will be arguing about this topic for some time to come.