Gene drive techniques hold promise for addressing public health threats such as dengue, malaria, and Zika, but important ethical questions remain.
- Scientists can quickly spread genetic changes throughout a species.
- A central concern is the possibility of introducing irreversible changes.
- The current regulatory structure is not designed for the kind of questions that the technology raises.
A recent report from the National Academies of Sciences, Engineering, and Medicine examines the ethics of gene drive research.1 Developing gene drives would allow scientists to engineer genetic changes in sexually reproducing organisms, and quickly spread them throughout an entire species. (The report can be downloaded at: http://bit.ly/2d9eywQ.)
“This is a promising approach to limiting vector-borne diseases and addressing some very complicated human health and environmental problems, and it warrants careful investigation,” says Elizabeth Heitman, PhD, a co-chair of the committee that wrote the report. Heitman is an associate professor of medical ethics at Vanderbilt University Medical Center’s Center for Biomedical Ethics and Society in Nashville, TN.
Gene drives hold promise for addressing public health threats such as dengue, malaria, and Zika by modifying the organisms that carry these diseases. “Rather than try to make humans immune to malaria, it might be possible to make mosquitoes immune to malaria,” explains Heitman. Likewise, if mice can be made immune to the pathogen that causes Lyme disease, ticks that bite the mice won’t be able to transmit the disease to humans.2
By creating gene drives, researchers can introduce a dominant trait and “drive” it into an entire population. “Current research is exploring how to eliminate both human health threats and ecological problems caused by invasive species,” says Heitman.
Answers Needed on Safety
Heitman says, “The science is intriguing, but there is much we don’t know about the safety of gene drive-modified organisms.”
A central concern is the possibility of introducing irreversible changes to the environment by changing one or more genetic traits in a given species. It’s unclear how researchers will know it’s safe to release gene drive-modified mosquitoes, how to predict “off-target” effects, and longer-term ecological changes. Some have suggested using “reverse drives” to restore modified species to their earlier state, if unexpected harms arise. However, “the committee was not content with using the same technology to address unanticipated consequences of gene drives,” says Heitman. “There need to be other mechanisms for prevention and remediation of unwanted effects as well.”
The committee recommended using a “phased testing” approach similar to that used by the World Health Organization, where researchers are required to show a high level of evidence of safety at each stage before proceeding to the next step.
“As gene drive safety is evaluated, we need to think about how the public understands their possible harms and benefits,” says Heitman. How best to do this is unclear. “We don’t have good strategies for doing public engagement on that wide a scale,” says Heitman. “And international public engagement across many cultures, with potentially different perspectives, will be a real challenge.”
How gene drive techniques will be regulated is another challenge. “Neither the U.S. nor the international regulatory structures are designed for the kind of questions that the technology raises,” says Heitman. The traditional regulation of genetically modified organisms through containment is a poor fit because gene drives are intended to spread.
Because the first research on gene drives was published at the same time as stories about human genome editing, many people associate these separate and distinct techniques. How to explain the science behind gene drives in a way that honestly conveys its potential harms and benefits will be an important question for ethicists and policymakers, as well as researchers.
“The science involves so many disciplines that it was often difficult even for our expert committee members, who are senior scientists in their individual fields, to get a handle on all the pieces of the big picture,” says Heitman.
- National Academies of Sciences, Engineering, and Medicine, 2016. Gene drives on the horizon: Advancing science, navigating uncertainty, and aligning research with public values. Washington, DC: The National Academies Press.
- The New York Times. Fighting Lyme Disease in the Genes of Nantucket’s Mice. June 7, 2016. http://nyti.ms/2ee9LGt.