A team of biologists based in the U.S has edited a human embryo’s DNA. There was not much information on exactly what was edited because there is not yet a published paper to accompany the research. Scientists have used CRISPR to remove genes from an early-stage embryo. It has been reported that the rate of mosaicism in these embryos was lower than in previous attempts.
Mosaicism happens when you use CRISPR on an embryo, which has multiple cells. CRISPR can hunt down specific genes and snip them out, but with multiple cells, each with its own copy of the genetic code, there is no guarantee that the targeted gene will be edited out everywhere. Even if it works in nine out of 10 cells, that one unedited cell will go on to produce millions of other cells. In many cases, those errant genes could do enough damage to render the treatment ineffective.
Does this mean we are getting designer babies?
CRISPR is said to make so-called designer babies, the most useful genes to edit would be those for serious genetic diseases. The ability to change a mutation and prevent a baby from such suffering would be invaluable to some parents, even though the idea might make others uneasy.
CRISPR will edit every cell in a future baby, including sex cells. This is known as “germline editing.” It’s not just changing one child’s genes, but also changing everyone in that child’s future lineage. Do you have the right to change a whole branch of a family tree? And if there’s some downside researchers can’t predict, something which could be passed down to offspring and their offspring, is it ethical to put that out into the gene pool?
The degree to which we should be allowed to edit a human being raises another moral question. There has been a strict warning against CRISPR being used for enhancement purposes like super-intelligence and that it should be reserved for serious diseases or disabilities. But at some point, someone will need to draw a line. Is it just fatal diseases that are okay to avoid? What about survivable, but lifelong disorders? What about physical disabilities? These are difficult questions to face, but to some degree, parents already face them.
Couples who know they’re carriers for genetic diseases can go through in vitro fertilization, choosing to only implant embryos that have tested negative for the mutation. The choice is not quite as direct no one is meddling with any genes—but in effect, those parents are choosing to perpetuate one germline and let the rest die out. For those couples, the idea of having a child with a severe disorder is too much to bear, and if it can be avoided, they’d like to do so. It’s certainly not a natural choice, but it’s one that plenty of people are grateful to be able to make.
Couples who otherwise wouldn’t want to have kids for fear of passing on a potentially devastating disease can now control their offspring’s health—to some degree. But some parents of children with genetic conditions have spoken out to say they find the idea that they would want to have avoided having a child-like theirs offensive. The act of choosing not to have a baby with a disorder or disability seems to imply that a person with those conditions is somehow lesser or undesirable. As a society, we already have trouble treating people with disabilities with the same respect as able-bodied people. If we can choose not to have kids with those conditions in the future, what does that say about what we think of disability?
The scientific paper on these experiments is yet to go public, so once they are clear, we’ll know more about exactly how successful Mitalipov’s lab was in editing (and what they were editing in the first place). The National Academies of Science and Medicine have already said that though there would need to be stringent oversight, edited human embryos hold promise for the prevention of the many genetic severe diseases for which there are no treatments. There will certainly be an ongoing debate, but it will be increasingly rushed as other countries push ahead.