Submitted by Trudi Zundel on
On Thursday, December 15, 2016 the Civil Society Working Group on Synthetic Biology circulated a short fact sheet to help clear up four of the most common questions arising about gene drives.
1. Are gene drives naturally occurring?
In brief: the engineered gene drives being discussed at COP 13 are NOT naturally occurring elements.
The idea and concept of a gene drive derives from the observation that certain genes in nature persist and spread more aggressively than others. These more persistent genes generally are referred to as 'selfish' genes. However, to call these ‘selfish’ elements ‘gene drives’ is not accurate. Though they are to an extent based on naturally occurring systems, CRISPR-Cas9 and/or other engineered gene drives are very different than these naturally occurring selfish genes. They are all strongly redesigned and engineered in order to alter or eradicate whole populations or entire species.
Introducing CRISPR-Cas9 into an organism, which requires genetic engineering, establishes within the organism a unique “cut-copy-paste” mechanism that can replace, edit or alter a specific section of an organism’s genome, causing the organism to behave differently and to pass this difference to all their offspring. CRISPR-Cas9 gene drives do this cut-copy-paste during the reproductive cycle to make sure they are present in all reproductive cells (e.g. sperm or egg cells) and are thus always passed down to offspring – so if you engineer the expression of a specific trait through a gene drive, all future generations of the organism should express that trait as well as the CRISPR-Cas9 system. [1]
CRISPR-Cas9 imitates the way some bacteria defend themselves against invading viruses, just as the first generation of transgenics came from observing the way that agrobacterium infects plants – it is as wrong to call engineered gene drives natural as it is to call transgenic plants natural; they are both deliberately engineered.
Genetically engineering an entire species by releasing an engineered gene drive would be deliberate wide-spread human interventions in organisms and ecosystems, at a scale, scope and manner that has not been attainable before.
2. Are all gene drives synthetic biology?
Yes – all genetically-engineered gene drives fit the definition of synthetic biology.
They are either organisms altered through synthetic biology – as they are clearly designed or redesigned and contain redesigned genetic materials. Furthermore, they also give rise to redesigned biological systems, as a whole population/species is being altered or eliminated, thus changing the related ecosystems. The operational definition of synthetic biology agreed for use under CBD discussions is:
“Synthetic biology is a further development and new dimension of modern biotechnology that combines science, technology and engineering to facilitate and accelerate the understanding, design, redesign, manufacture and/or modification of genetic materials, living organisms and biological systems.”
To date, all engineered gene drive systems fit under that definition.
3. Can gene drives be managed within one country under national biosafety frameworks?
Gene drives are inherently transboundary. Gene drive systems are designed to intentionally and aggressively spread through natural populations in the wild until they potentially alter an entire species. They will not respect national boundaries and may move across borders and even across large distances because of human transport, weather events and natural spread between ecosystems. Gene drives more closely resemble the behaviour of invasive or pathogenic species than “normal” LMOs. The gene drive mechanism may persist or thrive in circumstances where the engineered organism is not usually expected to survive – thereby overturning assumptions about risk assessment.
Because a single gene drive organism released in one country may potentially, over time, affect all organisms of that species worldwide, gene drives require a global governance approach. Proposals exist to develop engineered ‘local gene drives’ but at this point these are unproven and highly speculative.
4. Why is it important that the CBD act now?
Gene drives pose potentially irreversible effects on populations, species and ecosystems. The CBD is the only global treaty that addresses threats to biodiversity. Currently, there is only a poor ability to predict the effects a gene drive would or could unleash – precaution is absolutely vital.
The CBD must build on Decision XII/24 which calls for precautionary approach to synthetic biology – gene drives are new and very powerful, and need specific actions:
1) Do not approve the creation of gene drives in the lab until gene drive-specific regulations for biocontainment are developed and implemented
2) Do not approve the release of gene drives until thorough risk assessments are performed, including of ecosystem and socioeconomic risks
3) Inform and obtain consent from other governments whose biodiversity could be affected by any proposed gene drive before approval of its release.
“There are considerable gaps in knowledge regarding a gene drive’s effectiveness, both on the target organism and the environment, over time and across diverse genetic backgrounds. It is also essential to consider how gene drives will propagate throughout a population and affect not only the target species, but its entire ecological community.
“Because gene-drive modified organisms are intended to spread in the environment, there is a widespread sense among researchers and commentators that they may have harmful effects for other species or ecosystems. For example, using a gene drive to suppress a non-native weed population may lead to unexpected consequences, such as the loss of habitat for native species or even the establishment of a second, more resilient invasive species.”
– US National Academy of Sciences, June 2016[i]
[1] For more information, see Champer, Jackson, Anna Buchman, and Omar S. Akbari. "Cheating evolution: engineering gene drives to manipulate the fate of wild populations." Nature Reviews Genetics 17, no. 3 (2016): 146-159.
“Most proposed engineered gene drives are based on naturally existing ‘selfish’ genetic elements that function by increasing in frequency with each generation even without conferring a fitness advantage upon their host, thus forcing non-Mendelian inheritance patterns.”
[i] National Academies of Sciences, Engineering, and Medicine. Gene Drives on the Horizon: Advancing Science, Navigating Uncertainty, and Aligning Research with Public Values. Washington, DC: The National Academies Press, 2016. doi:10.17226/23405.