In this lecture, we're going to explore four genetic technologies that are exciting, in the news, and also raise some interesting ethical and moral questions. First we're going to talk about CRISPR/Cas9 gene editing, then preimplantation genetic diagnosis, or PGD, the science of de-extinction, and finally three-parent babies. We'll start with CRISPR/Cas9. Although it was mentioned earlier in this module that gene editing has been around since the 1980s, when CRISPR/Cas9 technology was first introduced as a gene editing tool in 2012, it allowed scientists to edit and change DNA more accurately, faster, and cheaper than ever before. The CRISPR/Cas9 system is based on a rudimentary immune system used by bacteria. In bacteria, this system allows the bacteria to recognize the DNA of and consequently destroy an invading virus. Using the same basic principles, biologists can use this molecular machinery to find a specific DNA sequence and modify it. So what are the pros and cons to this? Well, it's much cheaper than current gene therapy options, which can cost millions of dollars. It can also be used to treat diseases that are caused by single genes like sickle-cell anemia or cystic fibrosis. There's also the potential to treat more complicated diseases as well, like mental illness. It can also lead to better food options as well, and there's prospective uses as a vaccine. For example, some people are suggesting that we can use CRISPR/Cas9 to engineer people to be resistant to COVID-19, therefore developing vaccine. There's also the science of de-extinction too, but we'll come back to that in a minute. So here are the pros of CRISPR/Cas9, so how about the cons as well? Well, there's always the potential for engineering super humans. And the thought of making changes in the germ cells, to the gametes, the sperm and the egg, and having some kind of future unknown impact is of high moral and ethical concern. There's also the issue that technology is just moving faster than policy. CRISPR/Cas9 technology still isn't good enough to be used in humans yet, but that hasn't stopped people from trying. There's also a lot of fear mongering associated with it, again getting back to this issue of fear with science. And some people have even been cited as saying that CRISPR/Cas9 is a weapon of mass destruction. It's going to be really interesting over the next few years to see when the CRISPR/Cas9 technology goes. So that wraps up CRISPR/Cas9, so now let's move on into PGD, or pre-implantation genetic diagnosis. PGD is a way of screening embryos for certain maladaptive genes prior to implantation. It starts with in vitro fertilization. So in vitro fertilization refers to mixing human gametes in a dish. So in glass, because vitro means glass, rather than letting it occur within the body, in vivo. Once the egg is fertilized, it starts to mitotically divide. So if you remember from earlier in this course, mitotic divisions give rise to identical daughter cells. And geneticists can go in and pluck off one of those identical daughter cells, and sequence all the DNA. because remember, each of our cells contain a copy of all of our DNA. So for example, one common use of PGD right now is to screen embryos for cystic fibrosis. Only embryos that do not have the genes that cause cystic fibrosis can be implanted into the mother. And this can save immeasurable heartache for families, and that's one of the main pros of this. Early screening for the healthiest and embryos saves a lot of heartache, and time, and money for families. Cons might be what we've talked about before, majority of human diseases are not caused by a single gene. It's also difficult to know what to edit, what to look at, as we're just beginning to scratch the surface of understanding the relationship between genes and the environment. There's also the issue that the embryos can't consent to this process. And those embryos you don't want get discarded, which raises its own moral and ethical questions of its own. This could also encourage ableist thought. So ableism is a form of discrimination against people who have some form of a disability. So in the movie Gattaca, which I've referenced a couple of times in this module, needing glasses was considered a disability, and that I was at a disadvantage. I've worn glasses my whole life, how is that something that we're now going to consider as being a lesser trait? And of course issues and questions about designer babies as well. So right now PGD has very limited application, but it may have more in the future. It will also be interesting to see how PGD can be connected to CRISPR/Cas9 technology in the future. For now both technologies are sitting at this interesting junction between science fiction and medicine. Let's move on into the science of de-extinction. We'll talk more about what extinction is in course three, but for now extinction refers to when all of the species has died. It can be extinct, meaning there's no individuals left of that species, or extinct in the wild, meaning we can only see that species in zoos. Extinction is unfortunately in overdrive right now, with some postulating that we're in the midst of the sixth mass extinction. And unfortunately a major driver of extinction is human-driven habitat destruction. Although there are efforts in place like the national wildlife refuges and species survival plans that are trying to save these species, what do we do about species that we've already lost? So this is where de-extinction comes into play. De-extinction harvests tools like CRISPR/Cas9 to edit the genes of existing animals to look like their extinct relatives. So for example editing elephant DNA to look more like a woolly mammoth, therefore bringing mammoths back from extinction, sounds neat, right? So let's break down some of the pros and cons. Well, this could be great for tourism, how much would people pay to go see a mammoth? You can learn a lot about the physiology and behavior of extinct animals. And maybe we can use this to undo some of the damage caused by humans as well. Cons, is it okay to bring these animals back if they have nowhere else to go but captivity? If their habitats are gone, what right do we have bringing them back? So if we bring animals back are they going to survive now or are they going to go extinct again? And what would the impacts be on local ecology? It's one thing we've talked about already quite a bit, and we'll get into more detail in the next module, so we're all very interconnected with one another. So how does bringing a species back would either benefit or hurt a species that are already here? So let's move on to our final technology, three-parent babies. Okay, so how do we get a child with three biological parents and why is that desirable? Why would people want to have three biological parents? So generally speaking people have two biological parents, should be a male parent and a female parent. And each of these parents contribute nuclear DNA, Okay? And what's special is from our biological mothers we also get mitochondrial DNA. And this can only come from our mothers. So if you remember from earlier in the course, mitochondria is the powerhouse of the cell. It's where the ATP is produced, and it also has a completely separate genome. And because of that, and because we only get our mitochondrial DNA from our mothers, genes that are in the mitochondria that can be mutated to lead to devastating diseases. If mom has a mutant copy that's going to lead to a devastating disease, all children will have that mutation and have that disease. And so the mother may or may not be affected, because there's multiple mitochondria in each cell. So they may not be sick at all, but they're unable to have healthy children. So if mom has some kind of mutation in her mitochondrial DNA, we can replace it by using the mitochondrial DNA from a third woman. So she's not going to give any of the nuclear DNA, that still comes from these two parents, but she's going to give her mitochondrial DNA. So if we wanted to color code this, Let's see, we'll make her mitochondrial DNA purple. And then we'll make this other mother's nuclear DNA green, and then we'll make dad red here. The resulting offspring would have nuclear DNA from dad, Nuclear DNA from mom, And then the mitochondrial DNA from the donor, so three biological parents. So again, the biological father contributes the nuclear DNA via his sperm, that's parent number one. The first biological mother contributes nuclear DNA from her egg, and so she's parent number two. And so what we can do is we can pull out just this nuclear DNA here, and leave the faulty mitochondrial DNA behind. So when we have a nucleus that is comprised of both, so let me change my color again. So we have a nucleus with dad's DNA and mom's DNA. Then we can take that nucleus out and put it in a cell from the other biological mother that has this correct mitochondrial DNA in it. So the resulting embryo has the genetic material, again, from two different women and one father. Then this fertilized egg can then be transferred into the mother. And in 2016 the very first child from this procedure was born. So this is a potentially very exciting avenue for people who are unable to have healthy biological children to be able to do so. However, this technology is currently still illegal in the United States, and it was recently legalized in countries like the United Kingdom. So what are some pros and cons? So pros, this is a game changer for families. Similar to pre-implantation genetic diagnosis, saves a lot of heartache, allows for healthier children. The cons, well, we're manipulating human gametes, and that's ethically questionable, and the embryo cannot consent to this process. We really don't know what the long term implications of this process could be. There's also some other legal questions. So for example does parent 3 have the same parental rights as parent 1 and parent 2? So in summary, we talked about four different genetic technologies that are simultaneously very exciting, thought provoking, and more importantly have been in the news and will continue to be in the news. It's a really exciting time watching how these genetic technologies unfold. And it's important to keep these ideas at the forefront, so that we can be engaged and educated consumers. So that we can make our health decisions, and we can decide on future policies governing these technologies. What futuristic science fiction technology is going to be next?
