In a quietly dramatic turn for New York science, Columbia University researchers say they have used a newer form of gene editing to make extremely precise DNA changes in very early human embryos. The team reports edits to a cholesterol-related gene and a fetal-hemoglobin regulator in IVF embryos, and the work, posted online while still under peer review, has reignited the long-running fight over whether germline changes should ever be used in pregnancies.
Study details and who led it
According to The Seattle Times, the project was led by Dieter Egli at Columbia and used a technique called base editing to alter the PCSK9 gene and the HBG locus in human embryos. Columbia’s own symposium abstract describes on-target editing rates above 70 percent, the derivation of embryonic stem cell lines from edited blastocysts and only a small number of indels, findings the researchers say show far fewer of the large chromosomal disruptions that plagued earlier CRISPR experiments. Columbia University posted program materials describing the work.
How base editing differs from older CRISPR methods
Base editors swap single DNA letters instead of cutting both strands of a chromosome, which reduces the double-strand breaks that can trigger large deletions or even chromosome loss. Early embryo work with base editors has shown high on-target precision under laboratory conditions, although researchers still screen carefully for rare byproducts and off-target conversions. Protein & Cell was among the first journals to report base editing in human embryo material and lays out the technical logic for why the approach might be safer.
What the results show, and what they do not
The Columbia group reports robust on-target edits in many blastomeres, but not every embryo was uniformly edited. Some showed genetic mosaicism, with edited and unedited cells living side by side, a pattern that makes it much harder to predict eventual outcomes. Independent technical reviews and analyses have repeatedly flagged mosaicism, unexpected rearrangements and other subtle byproducts as reasons to be cautious about any move from laboratory embryos to pregnancies. PubMed Central highlights that some harms from germline edits might not emerge until years later.
Industry interest and Nucleus Genomics
The Seattle Times reports that Nucleus Genomics, a commercial embryo-screening startup, will support the next phase of the Columbia group’s work, underscoring how private companies are already circling embryo-editing science. Nucleus has marketed embryo analysis and "optimization" services and has attracted scrutiny from researchers and ethicists, coverage that includes CBS News and TechCrunch, adding a commercial twist to the safety debate.
Regulatory and ethical backdrop
Major scientific bodies have been urging restraint. An international commission convened by the National Academies and the Royal Society advised in 2020 that edited embryos should not be used to start pregnancies until edits can be made reliably and without unwanted changes. At the same time, gene-editing tools have already arrived in the clinic for somatic diseases, where changes are not passed to offspring. The FDA approved the first CRISPR-based therapy, CASGEVY (exagamglogene autotemcel), for sickle-cell disease in December 2023, illustrating how somatic and germline uses of the same tools are diverging in both practice and policy. National Academies guidance and the FDA approval together set the current regulatory mood.
A cautionary history
The field’s recent history is a standing warning. The 2018 revelation of gene-edited infants by He Jiankui prompted global condemnation and criminal penalties, a reminder of what critics say can happen when science sprints ahead of oversight. For background on that episode and the broader ethics debate, see coverage from Scientific American and reporting on commercialization and ethics in Undark.
Columbia scientists stress that these experiments were confined to the lab and were not a step toward pregnancies, but with private backing and faster, more accurate editors, the question of whether germline edits should ever reach the clinic is no longer hypothetical. For Manhattan and New York City readers, the stakes are close to home, as some of the most consequential biotech debates are playing out in local labs while regulators and ethicists try to keep pace.
