There’s been an uproar in the scientific community lately over allegations that Chinese scientists have crossed some ethical boundaries by creating the first genetically modified human embryo.

About a month and a half ago, scientists in the journal Nature express “grave concerns” about the world’s first genetically modified human embryo, which up until that point had been just a rumor, but last week a Chinese group from Sun Yat-sen University confirmed that they had done exactly that, according to a Sydney Morning Herald report.

The research team had taken human tripronucelar embryos and altered the mutant DNA that causes a life-threatening disease that currently impacts 100,000 people around the world. It could help cure diseases such as cystic fibrosis or Huntington’s, or even be used to remove a mutation that causes a woman to be at greater risk of dying of breast or ovarian cancer.

So why is this such a big problem in the scientific community? It’s because the experiments were done on real human embryos, according to the report. The scientists justified it by saying the embryos were non-viable, which means that they weren’t capable of creating human life as the egg had been fertilized by two sperm.

Scientists used what are known as “molecular scissors” to target a segment of the DNA within the embryos, and then cut the disease out.

However, it didn’t go completely smoothly, as there were some “off target effects,” according to the report.

The finding raises some ethical issues about whether human embryos should be used for scientific research, and also whether this kind of research would lead to so-called “designer babies.” A second concern is that the editing went wrong with many embryos.

There’s a lot of uncertainty surrounding the DNA editing process, and scientists are likely a long way away from actually being able to prevent diseases in this fashion, or whether it could ever be made safe.