A SWEDISH developmental biologist is trying to edit the DNA of healthy human embryos, stoking concerns over the potential production of designer babies.

It’s the first known case in which a scientist has tried to modify the DNA of healthy human embryos by using a famous new genetic engineering tool known as CRISPR-Cas9.

Swedish scientist Fredrik Lanner is undertaking the work in order to find out more about embryos, stem cells and ultimately help women suffering from infertility, miscarriages as well as a number of diseases, reports NPR.

CRISPR-Cas9 is a recently emerged technology that can be thought of as acting like a tiny pair molecular scissors that can cut and alter nucleotides which make up DNA, enabling scientists to find and modify or replace genetic defects.

“If we can understand how these early cells are regulated in the actual embryo, this knowledge will help us in the future to treat patients with diabetes, or Parkinsons, or different types of blindness and other diseases,” Lanner said.

“It’s not a technology that should be taken lightly. I really, of course, stand against any sort of thoughts that one should use this to design designer babies or enhance for aesthetic purposes,” he added.

NPR reporter Rob Stein who broke the story travelled to Sweden to tour the laboratory where the unprecedented work is taking place. The revolutionary technology has the potential to eradicate large swathes of diseases but it is not without its challenges and potential pitfalls, he noted.

There is a plausible concern that such a technique could accidentally introduce an error into the human gene pool, thereby inadvertently creating a new disease which could be passed on for generations.

The use of CRISPR has also set off a fierce debate about the ethical implications of using the cutting-edge science to pick and choose the human condition.

“The fear is that they could use these techniques to create, someway, genetically modified people. You know designer babies where parents pick and choose the traits of their babies, make them taller, stronger, smarter or something like that,” Mr Stein said.

“We’re nowhere near being able to do that but the concern is that this could open the door to someway somebody trying that.”

Despite the lack of understanding about the precise heritability of intelligence, it is plausible that CRISPR could be used to enhance the intellect of unborn babies, not just its physical traits.

“In my opinion, CRISPR could in principle be used to boost the expected intelligence of an embryo by a considerable amount,” James J. Lee, a researcher at University of Minnesota told Scientific American this month.

He was a part of a team of scientists that found 74 genetic variants which can be used to predict a 20 per cent variation in educational performance, resulting in a study published in the Journal Nature.

Prof Lanner said his sole concern with his work was to fight disease and help women having trouble reproducing, but said it’s impossible to completely mitigate the concerns of critics.

“I think this is something with all new technology, that it has good use and it has use that is not morally acceptable, like designing babies or making sure you have a blue-eyed baby or something similar,” he said.

“The only way we can sort of prevent that from happening is to have good laws regulating this.”

Earlier in the year UK scientists won permission to edit the genes of human embryos in order to do similar work to that being carried out by Prof Lanner, despite protests made by groups opposed to embryonic and stem cell research.

As Mr Stein pointed out; “there are other scientists in other parts of the world that are starting to do experiments that are using genetically modified embryos.”

In April last year Chinese scientists reportedly edited the genomes of human embryos which confirmed widespread rumours that such experiments were being conducted. Despite the fact they did not use healthy human embryos, it sparked a heated global debate and prompted calls for tight regulation across the globe.

George Daley, a stem-cell biologist at Harvard Medical School called reports of the Chinese experiments “a cautionary tale”.

“Their study should be a stern warning to any practitioner who thinks the technology is ready for testing to eradicate disease genes,” he said.