A gene drive involves potentially transforming an entire wild species over a few generations by modifying just a few individuals.
A revolutionary technology known as “gene drive,” which for the first time gives humans the power to alter or perhaps eliminate entire populations of organisms in the wild, has stirred excitement and fear since scientists proposed a means to construct it two years ago.
Scientists dream of deploying gene drive, for example, to wipe out malaria-carrying mosquitoes that cause the deaths of 300,000 African children each year or invasive rodents that damage island ecosystems. But some experts have warned the technique could lead to unforeseen harm to the environment. Some scientists have called on the federal government to regulate it, and some environmental watchdogs have called for a moratorium.
On Wednesday, the National Academies of Sciences, Engineering and Medicine, the premier advisory group for the federal government on scientific matters, endorsed continued research on the technology, concluding after nearly a yearlong study that while it poses risks, its possible benefits make it crucial to pursue. The group also set out a path to conducting what it called “carefully controlled field trials,” despite what some scientists say is the substantial risk of inadvertent release into the environment.
“The potential to reduce human suffering and ecological damage demands scientific attention,” said Elizabeth Heitman, a medical ethicist at Vanderbilt University who helped lead the committee. “Gene drive is a fascinating area of science that has promise if we can study it appropriately.”
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The report underscores that there is not yet enough evidence about the unintended consequences of gene drives to justify the release of an organism that has been engineered to carry one. But the green light for gene-drive research from the influential group, scientists said, would likely open the door to new funding and provide an impetus for governments around the world to consider how it might be regulated and deployed.
So far, gene-drive research has focused largely on mosquitoes that transmit infectious diseases to humans. The Bill & Melinda Gates Foundation, which helped pay for the Academy of Sciences report, has spent some $40 million on a gene-drive project aimed at eradicating the species of mosquitoes that spreads malaria.
For centuries, people have tinkered with the genetic makeup of living things whose survival and reproduction is already largely under our control: pets, farm animals, crops and assorted species of laboratory animals. With the advent of new gene-editing tools like one called CRISPR, there is even growing debate about modifying human embryos with traits that could be passed to their descendants. But a gene drive involves potentially transforming an entire wild species over a few generations by modifying just a few individuals.
Our ability to do that has been stymied because any changes humans might make typically reduce an organism’s ability to survive and reproduce in its natural habitat: Natural selection eliminates the altered genes.
Gene drives overcome this by ensuring that a particular gene is transmitted to all of an individual’s offspring, rather than the usual half, even if that makes them less fit. The phenomenon has long been known to exist in nature, and CRISPR provides an effective way to harness it. By encoding the CRISPR editing system itself into an organism’s DNA, scientists can cause a desired edit to recur in each generation, “driving” the trait through the wild population.
The science has attracted intense interest, but it is uncertain how the technology will be regulated. Existing laws, the report noted, are aimed at containing genetically engineered organisms rather than managing those whose purpose is precisely to spread swiftly.
The report pointed out the difficulty in predicting what might happen if an organism carrying a gene drive was deliberately or accidentally released, saying it “raises many ethical questions and presents a challenge for existing governance paradigms.”
Coming up with an international regulatory framework is especially crucial, members of the committee said, given that gene drives will not recognize national or political boundaries. For now, the U.S. Food and Drug Administration has authority over animals that have been engineered with foreign DNA under a rule that regards them as a type of drug.
The report suggests that other agencies, such as the Fish and Wildlife Service or the Bureau of Land Management, might be seen to have a stake in the concerns at the heart of gene-drive experiments.
“It would be good if we could get our act together to provide a regulatory model for the rest of the world,” said Jason Delborne, a professor of science, policy and society at North Carolina State University and one of the 16 experts on the panel that produced the report.
Some independent scientists say the panel, which included ethicists, biologists and others, struck a good balance by permitting more gene-drive research while limiting the use of the technology. But opponents of genetic engineering argue the panel should have demanded a halt to research on gene drives until some of the many questions it raised are answered.
The committee considered six case studies, including using gene drive to control mice destroying biodiversity on islands, mosquitoes infecting native Hawaiian birds with malaria and a weed called Palmer amaranth that has become resistant to herbicides and a scourge for some farmers.
Each potential use of gene drive carries its own set of risks and benefits, the report says, and should be assessed independently. Even modeling the “cascade of population dynamics and evolutionary processes’’ that would influence the ecological effects, the report noted, requires far more research. Risks include the possibility that a gene drive might jump to another species for which it was not intended, or that the suppression of one undesirable organism will lead to the emergence of another that is even worse.
The group recommends “phased testing,’’ which would include safeguards at each step before eventually releasing organisms into the wild.
Anthony James, a mosquito researcher at the University of California, Irvine, who is among those advocating the use of gene drive to eradicate the Aedes aegypti mosquito that transmits the Zika virus, called the report “reasonable.’’
“The key thing is there’s no moratorium,” he said.
But environmental watchdog groups say the report should have recommended that research be halted. Jim Thomas, program director of the ETC Group in Montreal, said the panel gave short shrift to how to prevent commercial and military interests from misusing the technology, which he said should be placed under the control of the United Nations.
Kevin Esvelt, an MIT evolutionary biologist who has also pioneered the technology, said the report failed to adequately flag its key risk. “They assume you can safely run a contained field trial,” he said. “But anytime you release an organism with a gene drive system into the wild you must assume there is a significant chance that it will spread — globally — and factor that in.”