Bill Gates is worried about gene editing worsening inequality. Now a top ethicist is raising new red flags.

New scientific technology now makes it possible to treat disease at the genetic level, which could potentially cure many difficult rare diseases.The new type of medicine also brings with it many thorny ethical issues. The billionaire philanthropist Bill Gates has warned that high costs could prevent patients from accessing the treatments.And price is just one of a broad range of difficult ethical questions confronting the burgeoning field, Stanford ethicist Holly Tabor said this week at the Gene Therapy for Rare Disorders conference in Boston, Massachusetts. An exciting new scientific technology has made it possible to tinker with the very DNA that makes us who we are, offering up fresh hope of new cures for difficult diseases.But the cutting-edge new approach also brings with it a barrel of thorny ethical questions about how the technology should be used, approached and paid for.Experts and public figures like the billionaire philanthropist Bill Gates have warned that these are serious problems that everyone should care about.Gates has especially expressed worries about how high prices for these “gene therapies,” which aim to treat diseases at their genetic root causes, could mean that only wealthy people get access. And that‘s a very valid concern, Holly Tabor, associate director for clinical ethics and education at Stanford University’s Center for Biomedical Ethics, told Business Insider.“Being a person with a rare disease may become, ‘There’s a treatment, and I can‘t afford it,’” Tabor said.A limited number of gene therapies are already being sold in the US and elsewhere, but there‘s also a kind of gene therapy rush afoot, with even more products in development and big deals being inked for biotechs working in the space. By one estimate, up to 30 such “million-dollar drugs” are expected to launch in the next five years. Read: Drugs that cost as much as a house are on the way to treat rare and devastating diseases. The US is scrambling to figure out how to pay for them.That means companies are already grappling with ethical dilemmas, even if they think of it more in terms of how to get patients engaged and involved in their research, Tabor said.An ethical issue with a tragic historyIn addition to price, there’s also a broad and wide-ranging basket of ethical issues confronting companies testing out experimental gene therapies, and even trickier problems to come as more products come to market, Tabor said on Wednesday, speaking at the Gene Therapy for Rare Disorders conference in Boston this week. Companies need patients to participate in their clinical trials and try out experimental medicines to get them approved and ultimately, sell them.But patients who are participating also must fully understand both the risks and potential benefits, an obscure science research concept called “informed consent” that has been especially controversial in this area.That‘s because in the 1990s, a young man named Jesse Gelsinger became the first patient to die in gene-therapy research. Questions about how well he was informed about the risks, along with issues around conflicts of interest among the scientists involved, sparked public outcry and investigations by players like the Food and Drug Administration.Gelsinger’s story has also shaped a debate about how informed consent, how it should be handled and whether risky new products should only be tested on the sickest patients that continues to this day.Scientists have existing frameworks for thinking about promising new medications and the heavy ethical questions they bring up, Tabor noted, but there are limits to how much even the scientists know about gene therapy.There‘s lots of uncertainty about just how well gene therapies will work, for how long, and what the risks could be, as well as when they might show up.Patients who participate in trials are taking big risks. But they and their families may also be desperate for better options and want to overlook those risks.“Hope in humans is a wonderful thing,” Tabor said. But it “can be a challenging, risky thing if not addressed in clinical trials.”And these ethical questions will likely become even more pronounced as more gene therapies come to market, Tabor said. The therapies are “on this knife’s edge of benefit and risk,” she said, and could well stay in that place for some time.Read more:A revolutionary drug that could treat a rare and devastating disease is prohibitively expensive. But one state has a plan to pay for its potential $5 million price tag.A biotech is proposing a plan to pay for its pricey rare-disease treatment the same way you'd buy a TV or dishwasher. Here's the inside story.The CEO of Merck says he got the best advice of his life from his father over getting trendy new sneakers, and it helped him turn the company into a $210 billion drug giantBig Pharma has tried and failed to cure Alzheimer's more than 200 times. The latest $18 billion flop leaves scientists hunting for a new path forward.