A simple guide to CRISPR, one of the biggest science stories of the decade, by Brad Plummer.
If you haven’t heard of CRISPR yet, the short explanation goes like this: In the past five years, scientists have figured out how to exploit a quirk in the immune systems of bacteria to edit genes in other organisms — plant genes, mouse genes, even human genes. With CRISPR, they can now make these edits quickly and cheaply, in days rather than weeks or months. (The technology is often known as CRISPR/Cas9, but we’ll stick with CRISPR, pronounced “crisper.”)
Let that sink in. We’re talking about a powerful new tool to control what genes get expressed in plants, animals, and even humans. The ability to delete undesirable traits and, potentially, add desirable traits with more precision than ever before.
In a dramatic step forward for human gene editing, researchers reported in Nature in August that they’d successfully used CRISPR in human embryos to fix a mutation that causes a terrible heart muscle disorder called hypertrophic cardiomyopathy. (Other researchers have since called some of the conclusions into question.) …
Much of the hype around CRISPR has focused on whether we might engineer humans with specific genetic traits (like heightened intelligence). But in some ways, that’s a sideshow. “Designer babies” are still far off, and there are enormous obstacles to making those sorts of complex genetic modifications.
At the most basic level, CRISPR can make it much easier for researchers to figure out what different genes in different organisms actually do — by, for instance, knocking out individual genes and seeing what traits are affected. This is important: While we’ve had a complete “map” of the human genome since 2003, we don’t really know what function all those genes serve. CRISPR can help speed up genome screening, and genetics research could advance massively as a result. …
The real fun — and, potentially, the real risks — could come from using CRISPRs to edit various plants and animals. …
Crop scientists are already looking to use CRISPR to edit the genes of various crops to make them tastier, or more nutritious, or better survivors of heat and stress. They could potentially use CRISPR to snip out the allergens in peanuts. Korean researchers are looking to see if CRISPR could help bananas survive a deadly fungal disease. Some scientists have shown that CRISPR can create hornless dairy cows — a huge advance for animal welfare. …
Scientists have even shown that CRISPR can knock HIV infections out of T cells. So far, however, scientists have only tested this on cells in the lab. …
The Cas9 enzymes can occasionally “misfire” and edit DNA in unexpected places, which, in human cells, might lead to cancer or even create new diseases. Over the past year, there have been major advances in improving CRISPR precision and reducing these off-target effects, but scientists are urging caution on human testing until standards can be developed here. …
CRISPR could be used, in theory, to modify not just a single organism but to modify an entire species. It’s an unnerving concept called “gene drive.” It works like this: Normally, whenever an organism like a fruit fly mates, there’s a 50-50 chance that it will pass on any given gene to its offspring. But using CRISPR, scientists can alter these odds so that there’s a nearly 100 percent chance that a particular gene gets passed on. …
By harnessing this technique, scientists could (say) genetically modify mosquitoes to only produce male offspring — and then use gene drive to push that trait through an entire population. Over time, the population would go extinct. Or we could modify ticks so that they don’t spread Lyme, or eliminate weeds. You name it.
Imagine if the PC crew — led by people like Hillary Clinton — were in charge of using CRISPR on humans. Morlocks and Eloi in no time.
hat-tip Bob, Philip Barton
