In a controversial move, a senior US scientific committee has given the green light to one of the most contentious forms of genome editing: where genetic changes made to human embryos will then be inherited by following generations.
For the first time, a panel of experts from two of the most recognised scientific institutions in the US has advised that this process – called germline editing – should be seriously considered as an option in the future, and not outright prohibited.
It's a considerably more positive tone than the assessment of an international summit of scientists in December 2015, which declared that it would be "irresponsible to proceed" with germline editing unless safety issues and social consensus could be satisfied.
The new position, outlined in a report released this week by the US National Academy of Sciences and the National Academy of Medicine, stipulates that heritable editing of early embryos, eggs, or sperm should only take place to prevent serious disease or disability – and only when research has demonstrated that the process is safe, per a number of strict criteria.
"Previously, it was easy for people to say, 'This isn't possible, so we don't have to think about it much,'" MIT researcher Richard Hynes, who helped lead the committee, explained to The New York Times.
"Now we can see a path whereby we might be able to do it, so we have to think about how to make sure it's used only for the right things and not for the wrong things."
In that context, the panel envisages germline editing being used to prevent heritable conditions like Huntington's disease from being passed on from parents to their children, but critics say the tampering could have lots of untold consequences.
One such consequence could be the introduction of new heritable conditions, diseases, or mutations, which only become evident once the embryos mature into people.
Another risk could be opening the door to a society where developments in gene-editing techniques such as CRISPR/Cas9 lead to a dystopian world of 'designer babies' – where affluent people can afford genetic protections, and poorer members of society cannot.
"These kinds of scenarios used to be science fiction; they used to be seen as far-off hypotheticals," biotechnologist Marcy Darnovsky from the Centre for Genetics and Society told Rob Stein at NPR. "But actually, right now, I think they're urgent social justice questions."
"[W]e're going to be creating a world in which the already privileged and affluent can use these high-tech procedures to make children [with] biological advantages," she added. "And the scenario that plays out is not a pretty one."
In an attempt to counter that kind of situation, the committee's report recommends that gene-editing techniques should be reserved for treating or preventing disease or disability, and not used for "enhancement" of any human traits such as physical strength, appearance, or even intelligence – if such tampering is even possible.
In other words, super-humans are off the cards for now – but there are concerns that as gene editing becomes a more mainstream medical procedure, ethical guides over its usage will inevitably become relaxed.
"This opens the door to advertisements from fertility clinics of giving your child the best start in life with a gene-editing packet," Darnovsky told Amy Harmon at The New York Times.
"And whether these are real advantages or perceived advantages, they would accrue disproportionately to people who are already advantaged."
At present, germline editing research in the US is prohibited by the Food and Drug Administration – and similar bans are in place in the UK – with the exception of certain mitochondrial donation techniques – and in many other countries around the world.
But if those restrictions become removed, a new world of genetic possibilities will be open to scientists and patients – and we can only hope that it's one we want to live in.
The report is available on the the National Academies Press website.