Saturday, September 18, 2021

Scientists use CRISPR to edit human embryo genes


The scientific journal Nature published a research paper today in which scientists at the Oregon Health & Science University and other research centers report being able to edit the human genome in embryos in order to remove certain genetic abnormalities that are controlled by only one gene.

The response from the scientific community was swift, noting that the work represented a tremendous breakthrough, the New York Times reports. “The achievement is also an example of genetic engineering, once feared and unthinkable, and is sure to renew ethical concerns that some might try to design babies with certain traits, like greater intelligence or athleticism,” the Times added.

Look, there’s not much chance of that. Ever. Period.

Traits as broad as “athleticism” or “intelligence” involve many, many genes that interact in complex ways. As high school biology students know, genes code for proteins, and sometimes those proteins don’t work properly because of a mutation. Some of those mutations involve a single base in the very long human genome. So while the authors of the paper certainly would love it if this genetic engineering were to have clinical applications, it isn’t likely to contribute to traits the Times says it might apply to.

What is more likely is that diseases that involve a single mutation—the paper’s authors suggest Huntington’s, Tay-Sachs, beta thalassemia, and even sickle cell anemia, cystic fibrosis, or some cases of early-onset Alzheimer’s—can potentially be edited to remove the abnormality, but even that gets quite tricky.

For one thing, how would you know you had fixed the problem if you used the gene-editing tool known as CRISPR? We’re talking about a human embryo here, and before too many cells divide in the zygote, you would have to remove some cells for testing.

The rest of the cells have to be left in place to make, you know, a baby. You’re only going to be able to do this so long before the embryo simply has way too many cells and editing the DNA in all of them becomes a daunting task.

Not only that, but University of California cell biologist Paul Knoepfler says in order to get the procedure approved by the FDA for use in human reproduction, we would need to sacrifice thousands of human embryos for testing:

What if to get to a clear answer on whether this technology is safe and effective it takes 1,000 or 10,000 human embryos, and hence eggs? CRISPR’ing human embryos at that scale might be needed to get clearer answers on efficacy and safety. Does the hypothetical potential benefit of pursuing human germline editing justify that? These are not every day run of the mill cells. Procurement and use of human eggs and embryos requires extra consideration.

Paul Katula
Paul Katula is the executive editor of the Voxitatis Research Foundation, which publishes this blog. For more information, see the About page.

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