In a scientific first, researchers were able to edit human embryos and remove a disease-causing mutation.
The research, published in the journal Nature, is a milestone in genomics.
But, despite some hyperbolic headlines, we are not on the verge of designer babies. If anything, this study shows that modifying embryos to give them more desirable traits is more difficult than believed.
A team led by Shoukhrat Mitalipov, director of the Center for Embryonic Cell and Gene Therapy at Oregon Health and Science University in Portland, fiddled with a total of 112 laboratory-created human embryos, using the gene-editing tool CRISPR-Cas9. (CRISPR is a RNA molecule that can target a specific site of DNA, and Cas9 is a bacterial enzyme that functions as molecular scissors to snip out, edit or replace a piece of genetic code, which the body then repairs.)
The embryos were made using donated eggs from healthy women and sperm from men with a mutation on the MYBPC3 gene that can cause hypertrophic cardiomyopathy (HCM), a common cause of sudden cardiac arrest in young people. The idea was to cut out the mutated gene and replace it with a normal one.
The research was relatively successful, with 72 per cent of the embryos ending up mutation-free. Just as important, all the cells in the healthy embryos were mutation-free; there was no "mosaicism," a problem that arose in earlier, smaller experiments.
But let's not forget that, when one parent carries a single-gene mutation, the chance of a child inheriting the faulty gene is 50 per cent.
Despite all the fancy science, the odds of producing a baby without the HCM mutation did not improve all that much. But that's not what matters.
These are experiments, designed to help us understand if and how genes can be modified and, just as importantly, how specific genes function. This research showed, for example, that gene editing is more successful if done right before the moment of fertilization.
But the most fascinating aspect of the study is that attempts to insert a lab-made gene that was free of the MYBPC3 mutation failed; instead, the healthy gene from the women's eggs was copied.
In other words, inserting desirable traits is far more difficult than removing undesirable ones – at least so far.
The science is advancing at breakneck speed.
The challenge is for ethics and the law to keep up. It's worth noting that this type of experiment is illegal in Canada; in the United States, research can be done on embryos in the lab, but it cannot be done clinically. Put more plainly, we won't be creating genetically altered babies any time soon. Too often, genomic advances provoke hysterical responses about the coming Gattaca-like world and the predictable headlines about an imminent race of super-babies. We saw it when in vitro fertilization was pioneered, when Dolly the sheep was cloned, when three-parent IVF was done and now with genetic editing.
We need to keep our wits about us, to consider the promise of this technology as much, if not more, than the potential perils.
We also have to keep them in context.
There are about 10,000 single genetic-mutation disorders. We could potentially prevent a lot of hurt, heartache and premature death if we use technology responsibly.
We have to remember, too, that these are refinements to what we are doing now. We can already test for many genetic disorders, and we do so routinely for common ones such as cystic fibrosis and Tay-Sachs disease.
Parents can do testing at the fetal stage and choose to abort. They can also do preimplantation genetic diagnosis (PGD): If they carry a genetic mutation, their egg and sperm are fertilized in the lab, the embryos are screened and only healthy ones are implanted.
The type of genetic editing now being done with CRISPR-Cas9 will bolster the precision of PGD, not replace it.
Of course, the potential for abuse does exist. If we can snip away the gene that causes cystic fibrosis, then why not the gene(s) for Down syndrome, autism and red hair?
Maybe, some day, genomics will evolve to the point where we can create desirable traits. But that will be a challenge for our grandchildren and great-grandchildren.
In the meantime, we should be using the technology we have as responsibly as possible to ensure those future generations are as healthy as possible.
And we have to have to talk openly and frankly about the pros and cons because, ultimately, the most dangerous enemies we have are not scientific advancement and gene editing, they are ignorance and secrecy.