His worry is that people will be less likely to agree to any form of sequencing if there’s a risk that their data can be used against them. Those risks are already a significant deterrent. Green’s team is running two large studies to see if genomics can help to guide the medical care of adults and babies. In both cases, between 15 and 20 percent of people who initially express interest eventually decide not to enroll specifically because they fear insurance discrimination. Another 25 percent or so decline because they’re worried about the privacy of their data.

If GINA protections fall, the reticence will rise—and reasonably so. “Even when GINA wasn’t under attack, it was difficult for researchers to allay the concerns that people had,” says Wagner. But the new bill “creates a context where it makes it hard to even articulate what the risks of participation are.”

She isn’t convinced that the bill will have an impact on research. So little data gets returned to study participants that they’d have little to disclose to prying employers, she says. But ironically, many geneticists and advocates have been pushing to change that. They argue that people should be treated as active participants in research, and trusted with their own personal data. “You get to learn about us… so it seems both intuitive and only fair that we should get to learn what you’ve learned, however uncertain,” wrote Misha Angrist from Duke University, who was among the first people to have his genome sequenced and made public.

“But returning results is predicated on the notion that the information will be transmitted securely, and without anyone else having access to it unless individuals choose to share it,” he says. If employers can demand those results, the debate changes. “I’m less sanguine about the unfettered sharing of that information. If I’m conducting a research study, what can I say to my participants about the legal protections that I can afford them?”

To be clear, the stakes aren’t about any particular study, or any scientist’s career. If people are put off from taking part in research, medical progress will slow. That would be particularly disastrous for rare genetic diseases, where research into cures often depends on finding enough patients who share the same disorder. “Anything we can do to get clinical trials off the ground is a complete non-starter without participants,” says Sonia Vallabh from the Broad Institute

Five years ago, Vallabh learned that she has a lethal genetic disorder called fatal familial insomnia, inherited from her mother. “I decided that I was willing to take the gamble of putting my privacy aside, but I vividly remember the early days when that decision was desperately unclear,” he says. “We now face such an uphill battle in helping other families figure out whether they want to be tested. Even with GINA solidly in place, when someone asks if I can guarantee that their info will never be used against them, I’m not able to say yes. I’m so worried about people getting scared off.”