New gene drive technology carries hope and risk.

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New gene drive technology could wipe out malaria, but is it safe?

BOSTON—If you could protect children in Africa from malaria by genetically transforming the entire mosquito population, would you do it? That’s the dilemma posed by a new technology known as gene drive, evolutionary ecologist James Collins from the Arizona State University in Tempe told a session here Friday at the annual meeting of AAAS, which publishes Science. Based on CRISPR, the up-and-coming genome-editing technology, gene drives bias the inheritance of a trait, such as resistance to a parasite, causing it to spread through a population. But because of the possible unintended consequences of transforming the genetics of an entire population, the National Academies of Sciences, Engineering, and Medicine last year said extensive testing should precede any release into the environment. Collins sat down with Science to discuss some of the concerns. This interview has been edited for clarity and length. 
Q: Should we be looking at how the environment might be affected by gene drives?
A: Absolutely, this is a manipulation of nature. We don’t know how it would affect population dynamics and ecosystems. In some cases, the purpose of gene drives would be to reduce population sizes of an organism, which could influence processes like pollination and transmission of parasites. In other cases, we would use gene drives to weed out disease by driving the population that carries that disease to extinction. 
Q: What is the worst-case scenario of releasing these organisms?
A: Eliminating an organism or reducing its numbers greatly. By eliminating one plant species, you cause the proliferation of others, and this leads to a series of changes in the ecosystem. We need to understand the system well enough so that we can take ethical concerns into account as we make decisions. 

Evolutionary ecologist James Collins.

Charles Kazilek
Q: Who gets to make these decisions?
A: Social scientists are trying to come up with better ways to sample human populations to get a better sense of what’s tolerable and what’s not tolerable in terms of their release. … If you release [modified mosquitoes] in Town A, the mosquitoes may not have any problem flying to Town B, even though Town B is not interested in having them. They’ll go anyway.
Q: The Food and Drug Administration approved the release of genetically modified mosquitoes, altered to control the Zika virus, in certain areas of Florida. If that technology is acceptable, why be so cautious about gene drives?
A: The advantage of these other technologies is that they are effective only as long as you’re releasing modified male mosquitoes. When you stop the manipulation, the population would bounce back to normal levels. You have a control over the system that is yet to be demonstrated for gene drives where once you alter the genes in these populations, they just keep changing.
Check out our full coverage of AAAS 2017.