By James Maynard

The first genetic modifications of human embryos by researchers in China have left scientists and the global public divided over ethics. People around the world are grouping into several camps over the scientific breakthrough, which has added fuel to the already heated debate.

Genetic editing of humans while they develop in the womb could lead to the elimination of a wide variety of diseases. The practice could also slide into parents designing custom babies with particular eye colors, physical abilities and a myriad of other qualities. These changes would not only be adapted into a developing person — their traits would also be passed onto offspring, compounding the ethical dilemma.

Junjiu Huang lead researchers at Sun Yat-sen University in China as they utilized the Crispr/Cas9 technique to cut and replace segments of genetic material, a process known as germline editing. This was conducted on embryos that had been fertilized by two sperm cells, making them non-viable for live birth.

Gene coding for a dangerous blood disorder was replaced with other strands of DNA, resulting in genetic code that was free of the condition in some cases. In other trials, unexpected mutations known as off-target effects were seen, suggesting the results of genetic modification could not be accurately predicted.

The announcement of the study confirmed months of rumors that some researchers were working on altering genetic codes in human embryos.

Edward Lanphier from the Alliance for Regenerative Medicine and many other researchers are calling for a moratorium on the modification of human embryos for research purposes.

“We need a halt on anything that approaches germline editing in human embryos,” Lanphier said.

Investigators who took part in the new study deny that their study crossed ethical bounds, since the embryos used in the investigation could not have developed into viable babies. Along with numerous other biologists and ethicists, they compare this study to in vtro fertilization (IVF), a process that produces what is commonly known as test-tube babies.

“It’s no worse than what happens in IVF all the time, which is that non-viable embryos are discarded. I don’t see any justification for a moratorium on research,” said John Harris, a bioethicist at the University of Manchester.

A third group of researchers is calling for continued research using germline editing, while still avoiding the production of fully developed human embryos. Proponents of this idea believe the practice could answer many of the unanswered questions in human biology, even without producing the world’s first designer human.

Germline editing of the human genetic code is legal under federal law, although studies in the field may not be funded by federal funds. Some states have already passed legislation barring the practice.