Gene drive—a form of genetic engineering that may impact not only individual organisms, but also entire species and ecosystems—is not yet ready for environmental testing, insists the National Academies of Sciences, Engineering, and Medicine. A committee convened by the Academies is circulating a report that calls for a patient approach to gene drive technology, even while potential gene drive applications, such as the suppression of Zika-carrying mosquitoes, rise in urgency.
Gene drives are systems of biased inheritance that enhance a genetic element's ability to pass from parent organism to offspring. With the advent of new, more efficient, and targeted gene-editing techniques such as CRISPR/Cas9, gene modifications can, in principle, be spread throughout a population of living organisms intentionally and quickly via a gene drive, circumventing traditional rules of inheritance and greatly increasing the odds that an altered gene spreads throughout a population.
Gene drive works by harnessing the power of site-specific selfish genes known as homing endonuclease genes (HEGs). When a gene is part of an HEG construct, it can be passed on nearly 100% of the time, not just 50% of the time, favoring the propagation of the gene, even if it confers little or no survival advantage.
Gene drives have the potential to address public health threats, conservation-related issues, agricultural pests, and other challenges. For example, gene drives might be developed to modify organisms that carry infectious diseases. In agriculture, a gene drive might be used to control or alter organisms that damage crops or carry crop disease. Yet gene drives could also lead to unintended and even dire circumstances. For example, the uncontrolled release of gene drive–modified organisms could disrupt nontarget species or lead to the establishment of a second, more resistant invasive species.
The potential harms of gene drive technology led the Academies to publish “Gene Drives on the Horizon: Advancing Science, Navigating Uncertainty, and Aligning Research with Public Values.” The 214-page report recommends a phased testing approach to gene drive research to guide research from the laboratory to the field.
“A phased testing pathway, such as the one outlined by the World Health Organization (WHO) for testing genetically modified mosquitoes, can facilitate a precautionary, step-by-step approach to research on gene drives,” stated the report. “Each step in such a pathway promotes careful study and evaluation, includes checkpoints to determine whether and when research should move to the next phase, and provides vital data to inform and enhance the effectiveness of other phases.”
The report also emphasized the importance of conducting deliberations that could engage diverse stakeholders. For example, the report called for collaboration among multiple fields of study, including molecular biology, population genetics, evolutionary biology, and ecology. In addition, open-access, online data banks and standard operating procedures should be established to share information and guide research design. In addition, the report cited the importance of public input.
“Responsible research on gene drives and gene drive technology requires consideration of values and public engagement throughout the process,” said committee co-chair Elizabeth Heitman, associate professor of medical ethics, Vanderbilt University Medical Center's Center for Biomedical Ethics and Society. “From conducting basic research, to choosing a problem to address and an organism to modify, to devising strategies to pursue field testing safely, it is essential to examine each gene drive on a case-by-case basis and to engage stakeholders and the public in assessing their potential development.”
Public engagement can help frame and define the potential harms and potential benefits of using a gene drive–modified organism, and these elements must be built into risk assessment and practical decision making. The outcomes of public engagement may be as crucial as scientific outcomes in making decisions about whether or not to release a gene drive–modified organism into the environment. The report recommends that the governing authorities, including research institutions, funders, and regulators, develop and maintain clear policies and mechanisms for how public engagement will factor into research, ecological risk assessments, and public policy decisions about gene drives.
The report finds that the current regulatory practices for assessing risks or potential environmental effects of field experiments or planned releases are inadequate for gene drives. At present, the regulation of gene drive research does not fit within the purview of any of the U.S. agencies involved in the Coordinated Framework for the Regulation of Biotechnology, which includes the Food and Drug Administration, U.S. Department of Agriculture, and the U.S. Environmental Protection Agency. Gene drive research also raises regulatory concerns about biosafety, biosecurity, and the potential for this technology intended for human benefit to be intentionally misused for harmful purposes.