Human embryo

New Embryo Editing Technique Takes Us a Step Closer to Designing Babies Without Disease

Gene-editing human embryos may now be a reality.

Elizabeth Nolan Brown | 6.8.2026 12:15 PM

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(Illustration: Midjourney)

Gene-editing human embryos—the sci-fi scenario that many have feared and many others have cheered—may now be a reality. Columbia University scientists say they have found an "efficient and precise" way to edit human embryos. Unlike earlier methods using CRISPR alone, this method works without introducing chromosomal abnormalities into the embryo or deleting large sequences of DNA.

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In their study, the scientists used a technique called base editing to repair "DNA nicks and mismatches" in human embryos, according to a preprint study published on June 1.

The process could allow scientists to repair embryonic DNA that might otherwise result in disease.

In the new study, Dieter Egli and colleagues—which include Nathan Treff of the DNA-testing startup Nucleus Genomics—focused on the PCSK9 gene, which regulates cholesterol, and the HBG genes, which control fetal hemoglobin production. Mutations in the PCSK9 gene can lead to high LDL cholesterol. Some think changes to the HBG genes could prevent sickle cell disease and thalassemia. The scientists inserted their base editors into early stage embryos with an eye toward altering these genes.

It wasn't perfect. In many cases, some cells in an embryo were successfully edited but not all of them, creating what are known as "mosaics."

But the genes they wanted to change were changed—without the sort of damage seen in the earlier technique.

"We're not saying this is going to be used tomorrow in the clinics," lead study author Dieter Egli told The New York Times. Even their paper has not yet been peer-reviewed.

Still, the results are already being heralded as promising and "impressive."

They're a big improvement on earlier techniques, such as using CRISPR alone. In 2020, Egli and colleagues tried using this on human embryos to snip out a mutation that could cause blindness. But after that, the embryo repaired the removed gene effectively only about half of the time. Other times, the embryo would delete long sequences of DNA or destroy the entire chromosome where the gene in question was located. "It........

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