The hype behind gene editing: Myth busting CRISPR
Would you change your own genetic code if you could? Would you eliminate a disease even if it meant another species would go extinct?
CRISPR has opened the door to some incredible possibilities but it’s easy to get caught up in the hype. In theory, both scenarios above are possible using CRISPR, but there’s a lot more to it than that. Some of the complicated research behind today’s gene editing headlines tends to get overlooked and this can make a tool like CRISPR seem even more powerful than it really is. Here, we take a look at some of the
Super humans and designer babies
Every parent wants the best for their kids and to make sure they are safe and healthy. Based on the headlines, it seems like we might be able to chose things like their personality, intelligence, and physical appearance—before they’re even conceived. The idea of designer babies, or babies where the parents have artificially selected their traits, has been discussed for some time. While modern medicine already allows us to check for major problems during gestation thanks to techniques such as ultrasound and amniocentesis, we haven’t yet been able to pick and choose what our kids look like before conception. But—CRISPR lets a scientist edit the genetic code very precisely, so couldn't it be used to make a designer baby or even give us superpowers?
As is the case most of the time, the truth isn’t as exciting as the myth. Setting aside the potential ethical issues, there are two main challenges to confront before we could even consider designer babies. First, most of the traits we’d want to change are polygenic, or controlled by many different genes. For a trait like intelligence, we don’t even know all the genes involved. How could we make a baby more intelligent using CRISPR if we don’t know which genes to edit? Second, it is still challenging to reliably introduce genetic edits into sperm cells, egg cells, or embryos using CRISPR. A scientist recently reported conducting illegal human genome editing experiments. More recent analysis of his work shows that the mutations he introduced were not the same as what he intended, showing how we must be cautious with this type of work. Ethical concerns aside, understanding the science behind modifying genes to "design" a human being is a long way off.
The idea of “super humans” refers to people who have abilities not normally found anywhere else in the human population. On top of the issues with designer babies, there are two more major challenges when it comes to making a superhuman. First, you’d need to edit every single cell in their body with the new mutations—and scientists don’t currently have a way to do that. Second, if a trait doesn’t already exist somewhere in the human population or elsewhere in nature, it’s nearly impossible for scientists to determine the genetic code required to make it happen. Unfortunately, this means it’ll be a long time before we create X-Men in real life.
Eliminating malaria with gene drives
Imagine a world without malaria. Humans have been attempting to control the impact of this disease mostly by providing access to anti-malarial drugs and controlling the mosquito population that spreads the malaria parasite. Mosquito nets are only partially effective, and insecticides are temporary, but what if we could eliminate malaria-carrying mosquitos permanently? Gene drives are a potential method of doing that. Using a technology like CRISPR, scientists could engineer a small number of mosquitos with genes that make all of their offspring male. When released into the wild, these genes would begin to spread, causing more and more male mosquitos to be born and fewer females. Within a few generations, there would be almost no females left, resulting in a population collapse and driving that species of mosquito to extinction.
Scientists have demonstrated that this is possible in a laboratory setting, but there are serious ethical concerns about using it in the wild. For example, it would mean causing a species to go extinct, something which many people believe shouldn’t be done intentionally. Also, since gene drives are self-propagating, there is no way to contain them if something goes wrong. Unlike an insecticide that we can stop using if it turns out to be dangerous, a gene drive eventually becomes a permanent part of that species’ genetic makeup. Although this is a promising idea, it will be some time before we see it used in a real-world application.
DIY genome editing
We’ve all probably done at least one home renovation project ourselves. Most of us can figure out how to paint the walls or change out a faucet, but we would probably hire someone to replace the roof or install a new electrical panel. Some renos should be left to the experts and the same goes for the human body. It’s one thing to dye your own hair or go to the gym to improve your health, but it’s another to set a broken bone yourself or even to edit your own genome.
Do-it-yourself genome editing has been proposed and even attempted by a few people, but scientists and legislators have largely dismissed the possibility of it happening anytime soon. Gene editing is complicated, especially in multicellular organisms like humans. You must try to account for all the known and unknown effects the new mutation will have, and you need to figure out a way to safely edit millions of individual cells at a time. Never mind the fact that there is an ongoing debate about the ethical considerations of human genome engineering and whether we should be even pursuing that. The dangers of DIY genome engineering on top of the technical challenges means that even if we do end up editing human genomes, it will probably always be left to the professionals.
It seems that everywhere you look in the grocery store, foods are labeled as “GMO-free,” but what does that really mean? “GMO” stands for genetically modified organism and is generally used to describe a food product where the organism’s genome was altered using genetic engineering techniques. GMO foods, however, are useful—they can have desirable traits such as improved nutritional value, better disease resistance, and faster growing cycles with increased yields. Despite that, there is widespread opposition to these products as they are viewed as unnatural and something we don’t fully understand. Are GMO foods a threat to our safety, or are they the next step in how humans feed ourselves?
The truth is somewhere in the middle. Humans have been genetically modifying food sources for millennia, just without the use of tools like CRISPR. The process of artificial selection allows us to produce dairy cattle that make more milk, fruit that is larger and sweeter, and chickens with more breast meat. Artificial selection can be accomplished using selective breeding of animals with desirable traits. For example, the way humans bred wild canines into the hundreds of breeds of dog we know today. This process also altered the genetic code of these animals, even though we aren’t explicitly editing their genomes. In fact, artificial selection sometimes carries undesired traits with the ones we want. Just look at how common hip dysplasia is in some larger dog breeds.
GMO foods aim to do the same thing that artificial selection does by bypassing the selective breeding of plants or animals for many generations in favor of editing the genetic code directly. If scientists know the gene that causes the desired trait, they can make a specific mutation to introduce that trait. Although this method is much newer than artificial selection, the risk of carrying along an undesired trait (like the hip dysplasia in dogs) is much lower since it targets the genetic code directly. While there are certainly ethical concerns around genome editing organisms that might end up breeding with wild populations, the safety concerns with GMO foods are largely unfounded and based on opinion, not fact. GMO foods are likely to play an important role in increasing food yields and allowing us to grow food in areas impacted by climate change, making them an important tool to help feed all humans.
Gene editing and beyond
There’s no doubt gene editing is changing the world more than ever before. The headlines will keep reporting these amazing results and sometimes they’ll be right while other times they'll be off the mark. Take a critical look at where the information comes from and what the scientist who did the work said themselves. Is the information coming from someone who really knows what they’re talking about? New myths about the powers of CRISPR are bound to keep popping up and they usually have a grain of truth in them. Someday your neighbor might be a real superhuman, but for the foreseeable future they’ll probably just be an average person like you and me.