CRISPR-Cas9 could change the human genome for generations. Here’s why its inventor is trying to press pause.
Should scientists edit the human genome, striking out undesirable traits like so many typos? “My own views are still forming,” says Jennifer Doudna, who with her research partner, Emmanuelle Charpentier, developed a powerful gene editing technique at her University of California, Berkeley lab several years ago (TED Talk: We can now edit our DNA. But let’s do it wisely). “I’m still trying to get a handle on how and when and why would we want to use this.”“This” is a genetic editing process that uses an enzyme with the ungainly name of CRISPR-Cas9 to precisely slice into a strand of DNA, snipping out genetic material with the precision of a scalpel. Aside from offering an unexpectedly high level of precision at removing specific As, Ts, Gs and Cs, the CRISPR-Cas9 technique opens a new Pandora’s box: when used on embryos, the genetic changes can be inherited from parent to child.
Since its invention, the CRISPR-Cas9 technique been used to put lab rats, monkeys, even non-viable human embryos under the genetic knife. But an ethical question hangs over whether the technique should be applied to living human embryos, where an edited gene can be inherited from one generation to the next. One fix could strike out a genetic illness from a family’s bloodline; one mistake could irrevocably alter the human genome in ways we can’t know.
That’s why Doudna, along with a panel of influential genetic scientists, has called for a worldwide pause on any experiment with the human genome. It’s also why she’s helping to convene a three-day summit this December at the National Academy of Sciences in Washington, D.C., where she and others will debate how far the world should take this technology. Doudna hopes the attendees will agree to some framework, any framework, for guiding responsible experimentation. Here’s what to expect.
Forget about a global consensus. “Oh, no,” Doudna says. “That’s not even remotely possible.” Gene editing is a polarizing issue, and her informal survey of the research community has turned up wildly divergent opinions. Some researchers favor a complete ban on edits to human embryos, preferring alternative treatments for genetic illnesses (in vitro screening, for instance, that identifies embryos with harmful mutations). Others believe that constraints on research could delay or prevent still-undiscovered cures. Doudna does not expect to solve these differences in three days, but she hopes that the opinions of scientific heavyweights can help shape the conversation. “Highly respected scientists do have a role to play in making a statement that invites people at least to consider their viewpoint,” she says. Bioethicists, lawyers, patient advocacy groups and government regulators will also be there to have their say. If that sounds like an unwieldy conversation, well, it will be. Fortunately, for Doudna, there’s a playbook for this sort of powwow.
This isn’t the first time scientists have paused unpredictable experiments. Doudna is following a script from the early 1970s, when the biochemist Paul Berg set off alarm bells with his groundbreaking research into recombinant DNA. In his experiments, Berg discovered a technique to join the DNA of two separate organisms into an artificially constructed hybrid. But he stopped short of actually combining one strand of cancerous DNA with another strand in a form that could multiply in gut bacteria — and potentially spread in unpredictable ways. His self-restraint, though, didn’t win him many points from the public. “I was inundated by calls,” he says, “calling me a ‘monster,’ so to speak, by ‘putting the general public and your colleagues at risk of getting cancer by the stupid experiment that you want to do.’” And he had to admit, his critics had a point. “It came down to saying, ‘What’s the probability of a bad outcome?’ and the answer was, ‘I couldn’t say that it was zero.’” So he and several colleagues published an open letter in Science calling for a worldwide moratorium on potentially hazardous DNA combinations, pending further discussion to take place one year later at a conference at Asilomar in California.
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http://ideas.ted.com/the-promising-and-perilous-science-of-gene-editing/
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