Josie Fischels

Updated: Jun 5, 2026 / 04:25 PM CDT

FILE – This undated image made available by the National Human Genome Research Institute shows the output from a DNA sequencer. (NHGRI via AP, File)

(NewsNation) — Scientists at Columbia University have edited the DNA of human embryos with greater precision than ever before by using a newer gene editing technique called base editing.

The breakthrough could one day allow doctors to repair disease-causing mutations in embryos before birth, but it’s also renewed a long-running ethical debate over “engineered” babies.

According to reporting by The New York Times, the research, led by geneticist Dieter Egli, improves upon a gene-editing tool that became the scientific standard after 2012, called CRISPR. While CRISPR works by cutting out segments of DNA, base editing makes smaller, more precise changes that replace individual genetic letters rather than cutting out entire sections.

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A previous experiment led by Egli in 2020 using CRISPR on human embryos ended in disaster, with what he described as “absolutely catastrophic consequences.” In some cases, entire chromosomes were destroyed.

But in the new experiments with base editing, Egli’s team successfully edited two genes: one linked to LDL cholesterol levels and heart disease risk, and another that directs hemoglobin production in fetuses. In some cases, both genes were edited at the same time, in the same embryo.

The method still isn’t perfect, and Egli told The New York Times that the technology isn’t ready for clinical use. In some embryos, the base editing molecules didn’t reach their targets, which left a mix of edited and unedited cells that could cause medical problems if those embryos developed into babies.

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Bioethicist Ana Iltis told The New York Times that some harmful effects of DNA editing might not show up until after birth. UC Berkeley geneticist Fyodor Urnov questioned whether embryo editing made sense at all when standard IVF screening has already been safely used for decades.

The research is being partially funded by Nucleus Genomics, a company that screens IVF embryos for genetic disorders and also analyzes genes linked to traits like height and intelligence. Fast Company reported that the company became the source of controversy last November when it ran New York City subway ads encouraging commuters to “have your best baby.”

NewsNation reported that Silicon Valley startup Preventive drew scrutiny last November for reportedly attempting to engineer human embryos, potentially abroad, where regulations are less restrictive. Genetic modification of human embryos remains illegal in the United States and many other countries.