Ironically, CRISPR might also enable the opposite: forcible extinction of unwanted animals or pathogens. Yes, someday soon, CRISPR might be employed to destroy entire species—an application I never could have imagined when my lab first entered the fledgling field of bacterial adaptive immune systems just ten years ago. Some of the efforts in these and other areas of the natural world have tremendous potential for improving human health and well-being. Others are frivolous, whimsical, or even downright dangerous. And I have become increasingly aware of the need to understand the risks of gene editing, especially in light of its accelerating use. CRISPR gives us the power to radically and irreversibly alter the biosphere that we inhabit by providing a way to rewrite the very molecules of life any way we wish. At the moment, I don’t think there is nearly enough discussion of the possibilities it presents—for good, but also for ill.
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We have a responsibility to consider the ramifications in advance and to engage in a global, public, and inclusive conversation about how to best harness gene editing in the natural world, before it’s too late.
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If the first of these gene drives (for pigmentation) seems benign and the second (for malaria resistance) seems beneficial, consider a third example. Working independently of the California scientists, a British team of researchers—among them Austin Bud, the biologist who pioneered the gene drive concept—created highly transmissive CRISPR gene drives that spread genes for female sterility. Since the sterility trait was recessive, the genes would rapidly spread through the population, increasing in frequency until enough females acquired two copies, at which point the population would suddenly crash. Instead of eradicating malaria by genetically altering mosquitoes to prevent them from carrying the disease, this strategy presented a blunter instrument—one that would cull entire populations by hindering reproduction. If sustained in wild-mosquito populations, it could eventually lead to outright extermination of an entire mosquito species.
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It’s been estimated that, had a fruit fly escaped the San Diego lab during the first gene drive experiments, it would have spread genes encoding CRISPR, along with yellow-body trait, to between 20 and 50 percent of all fruit flies worldwide.
The author of this book, Jennifer Doudna, is one of the first scientists that discovered the groundbreaking gene editing technique CRISPR-Cas9.
The book was finished in September 2016 (and published in June 2017), so the warning is quite recent.
You may also want to watch Doudna’s TED Talk about the bioethics of CRISPR: How CRISPR lets us edit our DNA.