Future Tense

Yes, U.S. Scientists Edited an Embryo’s Genes, but Super-Babies Are a Ways Away

The technique known as CRISPR brings genetic engineering to a new level.


MIT Technology Review reported Thursday that a team of researchers from Portland, Oregon were the first team of U.S.-based scientists to successfully create a genetically modified human embryo. The researchers, led by Shoukhrat Mitalipov of Oregon Health and Science University, changed the DNA of—in MIT Technology Review’s words—“many tens” of genetically-diseased embryos by injecting the host egg with CRISPR, a DNA-based gene editing tool first discovered in bacteria, at the time of fertilization. CRISPR-Cas9, as the full editing system is called, allows scientists to change genes accurately and efficiently. As has happened with research elsewhere, the CRISPR-edited embryos weren’t implanted—they were kept sustained for only a couple of days.

In addition to being the first American team to complete this feat, the researchers also improved upon the work of the three Chinese research teams that beat them to editing embryos with CRISPR: Mitalipov’s team increased the proportion of embryonic cells that received the intended genetic changes, addressing an issue called “mosaicism,” which is when an embryo is comprised of cells with different genetic makeups. Increasing that proportion is essential to CRISPR work in eliminating inherited diseases, to ensure that the CRISPR therapy has the intended result. The Oregon team also reduced the number of genetic errors introduced by CRISPR, reducing the likelihood that a patient would develop cancer elsewhere in the body.

Separate from the scientific advancements, it’s a big deal that this work happened in a country with such intense politicization of embryo research. But the climate around these issues has changed recently: The U.S National Academy of Sciences has repeatedly endorsed basic research related to embryo editing, doing so again this February.

But there are a great number of obstacles between the current research and the future of genetically editing all children to be 12-foot-tall Einsteins.

Possibly chief among these obstacles is that a CRISPR intervention would have to be completed at or just after fertilization to yield a super child. The authors of the upcoming paper (which is apparently scheduled to be published, though it’s unclear where) used the donated sperm of men carrying inherited disease mutations to create embryos with those mutations with the goal of then editing out the genetic diseases. This required the authors to know the disease carried by the sperm, and to be able to correct for that disease at the time of fertilization. Since human eggs can be fertilized by sperm half an hour after sex, CRISPR editing would likely require IVF, which is increasingly common but still out of reach for many families.

Furthermore, Stanford University law professor Hank Greely tweeted that the “key point” was that no team had yet implanted a CRISPR-edited embryo in a uterus for development. Until this research is done with real embryos that are allowed to reach maturity, and not research embryos, we are still far away from CRISPR being used widely.

And no matter the amount of academic interest in the topic, further research and clinical trials won’t take place unless funding is given. Right now, all federal agencies in the U.S., including the National Institute of Health, are prohibited from funding research that edits genes in embryos. Science magazine reports this is “because of a congressional prohibition on using taxpayer funds for research that destroys human embryos.” This means that funding for embryo editing must (and will) come from private sources, inherently reducing the degree to which the government can supervise and direct this kind of research.

There’s also the issue of price. Several commercial CRISPR-based gene therapies have gone to market abroad in the last couple years. They’re intended for already-born humans, not embryos. None of them have yet made it to the U.S, but one company that may be the first, Spark Therapeutics of Philadelphia, estimates that its treatment will cost roughly $500,000.  to treat a genetic eye condition in one eye if it finally gets FDA approval. Spark’s treatment isn’t even the most expensive. A 2012 drug called Glybera cost $1.4 million in Germany for genetic treatment of an ultra-rare disease called lipoprotein lipase deficiency.

So, while this research is an important building block for the future, it doesn’t mean the future is already here.