THIRD WORLD NETWORK BIOSAFETY INFORMATION SERVICE
Dear Friends and Colleagues
Novel Features of Gene Drives Warrant Advanced Risk and Technology Assessments
CRISPR/Cas accelerates the development of synthetic gene drive organisms to quickly spread a genetic modification among the target species. The question of whether we have sufficient experience and knowledge to handle this technology safely depends on the degree of continuity and novelty of synthetic gene drive organisms (GDOs), compared to existing genetically modified organisms (GMOs).
A recent journal article asserts that GDOs have five novel features that differ from currently released GMOs. A sufficient understanding of these characteristics is necessary to properly evaluate the impact of GDOs on the environment.
1) From indirect protection to direct action: Compared to current GM crops, the goals for GDOs are substantially different. Many GDOs are expected to work directly against a stressor: to suppress a disease vector or a pest species. This changes the ecological burden as species and habitats are affected beyond the agroecosystem.
2) Common goods: Unlike GMOs, some GDOs may create a common good: for instance, the control of malaria which could theoretically eradicate a whole mosquito species and thereby potentially achieve a partial reduction of the global malaria burden. Public goods have to be evaluated against public burden that might arise from their ecological and socio-economic impacts for present and future generations.
3) Outcrossing and spread of transgenes: While the transfer of a transgene to wild relatives is considered a hazard in GM crops, inheritance and spread of the transgene is a required prerequisite for GDOs. Wild populations, targeted by GDOs, are genetically diverse. The interactions between transgene and genetic background become more complex and less predictable. Unsuccessful suppression gene drives could, in addition, reduce the genetic diversity of the target species and affect the fitness of a population in ways that are hard to predict.
4) The lab in the field: Gene drives are designed to genetically modify organisms in the wild, affecting every generation of the target organism. The laboratory therefore moves into the environment. Non-intended effects, such as resistance or off-target effects, are difficult to predict and characterize before the release into the environment, particularly in genetically diverse wild populations. This creates great challenges for any monitoring of GDOs. In addition, the transgenic modification of the germline by gene drive is not time restricted and can therefore not be withdrawn.
5) Modifying wildlife: The most important novel aspect of synthetic gene drives is that it can be applied to wildlife. Upon release into the environment, the genetic modification will likely invade and affect other habitats and ecosystems beyond the area of release. The same would hold true for gene drive applications in agriculture. Risk assessors as well as existing frameworks will be heavily challenged by this change in the spectrum of organisms and environments.
Data on the genetic variability, ecology and the specific roles in ecosystems are incomplete or lacking for most wild species. Thus, in the area of ecological impact assessment, estimating risks will become highly complex and multi-layered, especially for global gene drives. This may mean that current GMO risk assessment approaches need to be updated and adapted to account for the novel features of GDOs. At the same time, the safe handling of GDOs in contained use needs special attention, since even a small unintended release can already lead to an extensive spread of the gene drive.
The authors strongly argue that prior to any release of GDOs into the environment, a wise risk assessment strategy is needed, which should be complemented with a broader technology assessment approach. Technology assessment has developed instruments for feedback loops to society that could prove adequate given the potential impact of GDOs to go global and trigger huge effects on biological diversity and the socio-economic and cultural use of biodiversity. Meanwhile, scientists and regulators working on gene drive technology should take adequate precautionary measures.
The article entitled ‘Synthetic gene drive: between continuity and novelty’ is available at: http://embor.embopress.org/content/early/2018/04/12/embr.201845760
With best wishes,
Third World Network
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Malaysia
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