Should it be legal to modify the genes of embryos to prevent babies from developing serious diseases?

While the United States has no laws that ban creating genetically modified embryos for clinical uses, the National Institutes of Health has banned editing the DNA of human embryos.

However, a growing number of scientists are expressing concern over the possibility of "designer babies" as rapid advances are made in the potential to change an embryo's DNA.

Scientists became concerned after Chinese researchers used a technique known as Crispr-Cas9 to fix a gene that can cause a blood disorder.

The technique has also been used to repair genetic mutations that cause metabolic disorders, to design cells to attack tumors, and to make other cells resistant to HIV.

The National Institutes of Health reaffirmed its ban on editing human embryos in April, expressing concern of both safety of the procedure and the ethical repercussions of altering genes that would be passed on to future generations.

In a statement published in Nature, NIH director Francis Collins says that the question of editing embryos is not a new one, and is "viewed almost universally as a line that should not be crossed."

The United Kingdom bans modifying the genes of embryos for clinical uses, but allows them to be used for research provided they are destroyed after 14 days.

The ability of the Crispr-Cas9 to alter DNA, however, is prompting scientists to call for a national debate on the ethics of modifying human embryos to prevent disease, reports the Guardian.

"We believe that genome-editing technologies may hold significant potential for clinical applications in the future, and we would be open to supporting the development of new therapeutic approaches should the evidence from research advance sufficiently to justify their use," said a statement from five leading scientists.

But they also stated that the possibility of modifying embryos, especially to create "designer babies" with characteristics desired by parents, raises ethical and regulatory questions "which need to be anticipated and explored."