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Hundreds of scientists are convening in Washington Tuesday for an international summit on genome editing. That technology, which lets scientists easily eliminate or replace sections of DNA, caused a stir in April when researchers in China announced that they had used it to edit the genomes of nonviable human embryos, which could not develop into babies.

At the summit, which is sponsored by Britain’s Royal Society, the Chinese Academy of Sciences, and the US National Academies, experts will discuss several applications of genome editing, including treating human diseases and using gene drive to rapidly spread new traits throughout a population. The most controversial involve altering human sperm, eggs, and embryos.

Why is that controversial? Because such “germline engineering” for the purpose of making babies is widely (though not universally) regarded as unethical. Changing the DNA in reproductive cells changes not only the resulting individual but all of that individual’s descendants, essentially allowing humans to direct their own evolution. There’s deep concern that we’re not smart enough, let alone wise enough, to do that, as Dr. Francis Collins, director of the National Institutes of Health, told STAT this month. If time-traveling scientists had edited out the gene for sickle cell disease a few thousand years ago, for instance, humankind might have been wiped out by malaria; the sickle cell gene protects against that disease. Germline engineering also brings us closer to designer babies whose traits parents pick and choose, exacerbating inequality and violating basic principles of self-determination.


What’s the counterargument? That editing the genomes of eggs, sperm, or very early embryos is sometimes the only way to prevent an awful inherited disease like thalassemia or Tay-Sachs. In October, Harvard geneticist George Church told a summit-planning workshop that “treating sperm so they no longer carry a disease [gene] could be the best option” for preventing such maladies. Pre-implantation genetic diagnosis of IVF embryos can help some women become pregnant with only healthy embryos (those with the disease gene are discarded). But if both parents carry harmful genes, that option is off the table — every embryo they conceive will have the genetic disease.

Gene drives have the potential to change the genetic makeup of entire populations, like mosquitos that carry malaria. Hyacinth Empinado/STAT

Wasn’t editing embryos possible with the “genetic engineering” that started in the 1970s? That genetic engineering is to the genome editing of today what hunting, shooting, gutting, butchering, and cooking a mastodon is to ordering from GrubHub on your iPhone 6S. The old genetic engineering, aka recombinant DNA or gene splicing, is still going strong; it’s the technique behind genetically modified organisms such as pesticide-resistant soybeans and fast-growing salmon, not to mention drugs including insulin. But CRISPR, the genome-editing technique that triggered all the excitement and concern, is easier to use, faster, more precise, and, crucially, a multitasking marvel. “We can make multiple changes in a genome in one experiment,” CRISPR pioneer Jennifer Doudna of the University of California, Berkeley, told the workshop last month.


What’s going to happen at the summit? Twenty-eight hours (including breaks) of speakers, discussants, and Q&A’s spread over three days.

Any famous names? Angelina Jolie Pitt isn’t expected, sorry. But White House science adviser John Holdren will speak, as will Doudna (who organized a meeting on human genome editing in California’s Napa Valley last January, which led to this one); CRISPR phenom Feng Zhang of the Broad Institute; Harvard’s Church, author of the 2012 book “Regenesis: How Synthetic Biology Will Reinvent Nature and Ourselves”; and Broad director Eric Lander, a leader of the project to sequence the human genome in the 1990s.

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Do we know what people are going to say? Sort of. At the October workshop, several of these speakers gave hints of where they stand. Church, for instance, told the committee he and colleagues have used CRISPR to “humanize pigs,” editing 62 pig genes at once to make the animals’ organs suitable for transplanting into humans. And he made no bones about his support for bringing human germline engineering into the clinic. Dr. George Daley of Boston Children’s Hospital and Harvard, another scheduled speaker, told the October conclave that editing human embryos “can be safely done if we chose to do it.” Summit chairman David Baltimore of the California Institute of Technology is on record about where he stands. In an essay that he, Doudna, and 16 others wrote for Science in March, they urged scientists to “strongly discourage . . . attempts at germline genome modification for clinical application in humans,” but left the door open to such research if it doesn’t lead to a pregnancy.

People are comparing this to something called Asilomar; what’s that? In the 1970s scientists fretted that genetic engineering, which had just been invented and was then called recombinant DNA, might lead to something terrible, like cancer-gene-carrying bacteria or a civilization-destroying Andromeda strain escaping from laboratories. Scientists, lawyers, and bioethicists including Baltimore and Stanford’s Paul Berg, an inventor of recombinant DNA, gathered at the Asilomar conference center in Pacific Grove, Calif., to figure out what the threats might be. The result was guidelines about how to do recombinant DNA safely — such as only with bacteria that can’t live outside a lab — and, eventually, creation of the Recombinant DNA Advisory Committee at NIH, which for decades has said yay or nay to recombinant DNA proposals.

So will this be Asilomar Redux? No. The world has changed since 1975. Forty years ago, no one was crowdfunding a company to sell CRISPR kits to all comers, like this one on Indiegogo that has raised $26,000 and counting. At the time of Asilomar, maybe 12 labs in the world could do recombinant DNA, said Stanford law professor and bioethicist Hank Greely, who is chairing a summit session. It was such a tiny community that they could impose a moratorium on recombinant DNA experiments in the summer of 1974 and stick to it until the Asilomar meeting came out with its guidelines. Today, thousands of scientists use CRISPR technology. It’s naive to think they’ll all agree to whatever guidelines the summit proposes. In fact, the Asilomar agreement had teeth because NIH adopted it, Greely explained—as in, if you don’t agree to do recombinant DNA this way, you don’t get funding. In April NIH said it’s not funding genome editing in human embryos. That, of course, leaves private money and other countries.

Any other differences between then and now? The participants at Asilomar felt they could speak freely, and did. “It wasn’t going out on Twitter or being webcast,” Greely noted dryly. The summit will be.

Are there laws against human germline editing? Only sort of. A 2014 global survey by a Japanese bioethicist found a hodgepodge of regulations, as Nature nicely summarized. For instance, Britain bans genome editing for clinical use — that is, making babies — but allows it for lab research, something a scientist has applied for a license to do in human embryos (which would be destroyed at 14 days) as a way to understand early development. Japan, China, India, and Ireland have guidelines that restrict genome editing of human embryos, but they’re unenforceable. In the United States, researchers can’t use federal money for experiments that alter the genomes of human embryos, but since genome editing isn’t banned, they can use other funding. “I’m sure scientists will seek out private funding,” said Dr. Bernard Lo, president of the bioethics-focused Greenwall Foundation, one of the sponsors of the National Academies’ genome-editing study that the summit is part of. “I can see advocacy groups that focus on single-mutation diseases asking, shouldn’t we look at genome editing as a way to solve the root cause of this disease?”

What will come out of the summit? Eventually, some sort of consensus document. The smart money says it will endorse a ban on using genome editing to make “designer babies,” but allow it for research, such as to understand forms of infertility or early human development. There’s no way any ban could be binding, however, and it’s hard to imagine any global enforcement mechanism. Any force it has will have to come from moral suasion. Berg once noted that “so many issues in science and technology today are beset by economic self-interest and, increasingly, by nearly irreconcilable ethical and religious conflicts” that a “conference that sets out to find a consensus among such contentious views would, I believe, be doomed to acrimony and policy stagnation.” That was in 2008. We’ll see if he’s right.