It feels like something out of a science fiction novel: parents lining up at fertility clinics, selecting from a menu of specific traits they want their children and grandchildren to embody. They pick and choose body types, hair and eye colors, bone strength, and muscle density. If they want their child to fare well in middle school, they might even decide to make them smarter and not have any body odor. We’re still a long way off from the ability to design children on demand, but some of this may be reality one day. Recent technological advances have made it possible for scientists to eradicate gene mutations at the embryo stage. A study published in the journal Nature sent waves through the medical community when it was released in August 2017. It was the first successful large-scale experiment of germline editing we’ve seen yet. Germline editing refers to tampering with DNA at the sperm, egg, or embryo stage of reproduction. Germline editing is a highly controversial technique, and its potential ramifications have drawn battle lines across social, political, and scientific divides. Paula Amato, MD, a reproductive endocrinologist and associate professor of obstetrics and gynecology at Oregon Health & Science University (OHSU), was one of several co-authors on the groundbreaking Nature study.
The idea here was to see if we could correct that gene mutation in a human embryo such that you would stop transmission of the disease.
“The goal of the study was to see if we could correct a disease-causing gene mutation in human embryos, with the ultimate goal of preventing transmission of that disease to a future child and future generations,” Amato says. People who have gene mutations in their DNA are at risk for passing those mutations on not only to their children but to future generations as well. “The idea here was to see if we could correct that gene mutation in a human embryo such that you would stop transmission of the disease. So the child would be healthy … and not at risk for passing [the disease] on to their future children.” Amato’s role was on the clinical side of the experiment. She found egg donors for the more than 300 eggs it took to conduct the study and create the embryos. The OHSU team recruited a man with a genetic disease called hypertrophic cardiomyopathy, a condition that causes the heart’s muscle cells to enlarge, thickening the ventricle’s walls. “He had one mutated copy of this gene, MYD-PC3,” Amato says. “Then we recruited healthy egg donors that didn’t have this gene mutation, created embryos, and introduced CRISPR into the embryo to ‘cut’ the DNA.” CRISPR is a technology that Amato describes as a molecular “scissors.” “It kind of makes cuts in the DNA,” she says. “Then [we] replaced the abnormal gene with a corrected gene.” Typically, when CRISPR is used, a corrected copy of the mutated gene is provided, and it’s this copy that the DNA uses to correct itself. However, this time something different happened. “In this case, we found that the embryo didn’t use the donor DNA or the foreign template DNA that we provided,” Amato says. “It seemed to use … the normal copy of the gene that came from the egg to correct itself.” At the end of the experiment, 72 percent of the embryos in the study contained two normal copies of the formerly mutated gene. “That’s a much higher efficiency than we would have expected,” Amato observes.
Anybody who carries a genetic disease could access this technology and prevent that disease in their children.
She adds that some of the normal issues usually reported with using CRISPR weren’t in evidence. While similar studies on germline editing have been done in China, it’s never been done on this scale, and it’s never been done with healthy, mature eggs. It was also the most successful so far. “We corrected the gene with the highest efficiency compared to the previous studies,” Amato says. The technological advances in this field are very preliminary and nowhere near ready for clinical use, but if it’s ever deemed safe, the potential benefit could have dramatic ramifications. “Anybody who carries a genetic disease could access this technology and prevent that disease in their children,” Amato says. “And not just in their children, but in future generations. There’s literally thousands of genetic diseases that this theoretically could work for.” As for the many social and ethical questions using such technology raises, Amato says there’s not much room for concern—yet. “People worry about misusing the technology for things other than preventing serious disease,” she says. “There are fears about using it for enhancement-type purposes, like if you could use it to create a more intelligent [person], stronger [person], a taller [person]… We think that those concerns, at least at this point, are more theoretical, because we don’t know the genes that cause a lot of the traits that some people would want to enhance.”
Any time you have a new technology, whether it’s a medical innovation such as this, or computer technology or military technology, whatever it is, I think there’s always the risk of misuse.
The process would be much more complicated, since rather than a singular gene, enhancements would most likely mean editing a combination of genes, so it would not be so easy to do. Amato says it’s good to question the downsides, as with any new technology. But she feels that the potential benefits of CRISPR far outweigh the risks. “Any time you have a new technology, whether it’s a medical innovation such as this, or computer technology or military technology, whatever it is, I think there’s always the risk of misuse,” she says. “The people working in this area [of study] are compelled by the potential benefits. We think there’s compelling reason to use it, because the benefit would be that you could prevent serious diseases in tens of thousands, potentially millions of people… To me, that’s not that different from any other type of preventive medicine that we practice… So it’s still worth pursuing.” That’s a statement that Marcy Darnovsky, PhD, executive director of the Center for Genetics and Society, couldn’t disagree with more. The Center, a non-profit public interest organization based in Berkeley, California, has been tracking the social, political, and ethical dimensions of human biotechnologies for 15 years. “This concern about using human genetic technologies to modify the genes and the traits that we pass on to children and future generations is really at the center of our concern,” Darnovsky says.
To me, it sounded like openly proposing that we revisit eugenics.
The Center was formed after an earlier wave of advocacy for germline modifications around the end of the 20th century—events like the cloning of Dolly the Sheep and the mapping of the human genome. Darnovsky, who was teaching at a university at the time, says that reading several scientists’ recommendations about genetic modifications made her jaw drop to the floor. “To me, it sounded like openly proposing that we revisit eugenics,” she says. “Perhaps because I grew up in the shadow of the Holocaust, hearing about it as American Jews trying to come to grips with how that could have happened, and what it meant, and what was underneath and behind it, to me, it appeared right away that that was the risk of using genetic technologies in that way—to control what kind of people are going to be with us and what traits count as worthy and superior.” According to Darnovsky, advances such as CRISPR, which makes gene editing more accurate and easier to use, are playing with fire. She contends that the medical argument for using it is dubious.
The FDA is only allowed to consider safety and efficacy. They’re not allowed to consider, by mandate, social questions like social justice or human rights.
For one, there’s very little regulation from the U.S. Food and Drug Administration (FDA) over matters like this. “The FDA is only allowed to consider safety and efficacy. They’re not allowed to consider, by mandate, social questions like social justice or human rights.” Second, tremendous commercial pressure from the fertility industry could lead to misuse of such technologies to generate revenue. And third, germline editing is technically not even necessary. Darnovsky points out that there are already ways to avoid passing on genetic diseases to one’s children while still having a child that is genetically related to the parent. The process is embryo screening and selection. These techniques, Darnovsky says, “themselves raise some questions about ethical appropriateness, but are far less powerful and therefore, far less socially fraught than trying to genetically engineer traits into future children,” she says. George Church, a molecular engineer and professor of genetics at Harvard Medical School, has been at the forefront of the debate over CRISPR and other gene editing technologies for years. He says that in some ways, we already use enhancements on our offspring without realizing it. “Humans are already greatly enhanced relative to our ancestors (for example, accelerating to and surviving in the cold vacuum of space),” he says. “We already ‘enhance’ the biology of subsequent generations without their consent (e.g., education, etc.)” Like Amato, Church believes that the potential misuses of technology should be considered, but says that concerns over enhancing our genes in an effort to move the human race forward shouldn’t slow the benefits. “It seems unlikely that there exists a human ‘superior’ in all categories, just as there is no means of transportation that is superior in all ways,” he says.
Gray areas are common for many technologies, and can be regulated.
Church adds, “If we are concerned about humans that are ‘superior’ in some narrow category, like an Olympic sport or memorizing books, then we already have such people, without grave consequences. We could and should worry about fads, distorting commercial advertisements, monocultures and other unexpected long-term consequences, but these worries and discussions should lead to innovative preventions of negative consequences without stopping the positive impact. Gray areas are common for many technologies and can be regulated (e.g., speed limits and age limits).” Yet Darnovsky argues that even the perception of biological superiority is enough to exacerbate social inequality and discrimination. “What is racism if not a perception of one group being biologically superior than another, based on a particular genotype?” she says. And there’s a larger question: Are we sure we want to eradicate all human disease? Not every mutation is detrimental, but even the ones that are perceived as such might one day lead to less diversity.
If we find genes correlated with autism, are we eliminating people who are actually just part of normal human variation? I think that question’s worth asking.
“I think it’s worth thinking about: Do we want to eradicate all congenital deafness?” Darnovsky asks. “Do we want to eradicate so much Down syndrome that people who are going to have Down syndrome babies anyway have no social supports? If we find genes correlated with autism, are we eliminating people who are actually just part of normal human variation? I think that question’s worth asking.”