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Warning of Ecological Risks of Gene Drives

Scientists have issued a call to ensure that the use of gene drives in conservation will only affect local populations.

Gene drives promote the inheritance of a particular genetic variant to increase its frequency in a population. In conservation, a gene drive could spread infertility and ultimately eliminate a pest population. New Zealand, for instance, is considering gene drives to help eliminate rats, mice, stoats and possums.

Prof Neil Gemmell of the University of Otago believes there is still “huge merit” in using genetic technologies for conservation work, but says that standard self-propagating versions “may be uncontrollable” and therefore unsuited to conservation.

In an article published in PLOS Biology, Gemmell and A/Prof Kevin Esvelt of MIT examined the possible consequences of the accidental spread of existing self-propagating gene drive systems. Esvelt is credited with first describing how gene drives could be created using CRISPR bacterial DNA to edit specific genes in a target organism, and had suggested that self-propagating gene drive systems might be suitable for conservation. However, Gemmell and Esvelt now say this suggestion “was a mistake” as it is “equivalent to creating a new, highly invasive species – both will likely spread to any ecosystem in which they are viable, possibly causing ecological change”.

Therefore they say that introducing such a system “without the permission of every other country harbouring the target species would be highly irresponsible. Even assuming that national sovereignty is morally irrelevant, the social and diplomatic consequences of an unconstrained release should give us pause.

“CRISPR-based gene drive is arguably the technology most likely to help eradicate human scourges such as malaria and schisto­somiasis. It would be a profound tragedy if New Zealanders – or anyone else – inadvertently caused an international incident and the consequent loss of public confidence in scientists and governance prevented us from realising other benefits of biotechnology.”

Gemmell says there is strong impetus to use gene drives and other tools to meet the goal set by the New Zealand government to eradicate mammalian pests by 2050, but only localised drive systems are safe enough to consider. “The rationale for this goal is simple,” he said. “Mammalian pests remain one of the key threats to the ongoing persistence of New Zealand’s native flora and fauna, which has evolved in isolation without such threats for at least 28 million years or more.”

For more coverage see Expert Opinion.