Gene editing has been both exciting and controversial since the development of CRISPR-Cas9, a technology that repairs genetic errors by essentially cutting and pasting sections of DNA. Now a much more precise technique is raising the stakes.

CRISPR has been heralded as a medical miracle. The technique, however, isn’t perfect. In some cases, the process can miss the target altogether or make cuts in places other than the targeted area, leading to considerable unintended effects. Research published in 2020 in the journal Cell found that CRISPR can not only miss its target, but it could lead to the loss of entire chromosomes. These and other findings have raised major safety concerns, making CRISPR not yet ready for clinical use.

Base editing, however, allows for much more precise changes. A variation of CRISPR, base editing is a refined form of the technique that changes single letters of DNA rather than cutting both strands of the double helix. The method has been previously attempted in early-stage embryos; however, the embryos grew only for a short time.

This June 2026, however, researchers led by Dieter Egli, a geneticist at Columbia University who also led the 2020 research, announced that they had successfully used base editing to make changes in the DNA of early-stage embryos. After discovering that messenger RNA (mRNA), which was previously used in the cut-and-paste process, impaired early-stage embryos, they synthesized a protein in the lab and used that instead. The researchers detected no chromosomal alterations, and the survival time of the embryos greatly improved.

These latest results were published June 1, 2026, on the bioRxiv preprint server. The paper is currently undergoing peer review for publication in a scientific journal, Egli told Discover.

Read More: How a CRISPR Gene Therapy Could Change Life for Young Children With Sickle Cell Disease

Issues and Concerns that Could Arise in the Future

Egli and colleagues are not claiming that this technique is anywhere near ready for clinical use. As they stated in the preprint, “translation to a clinical context remains premature.” However, they also wrote that these results should “contribute to the conversations surrounding the risks and benefits of embryo editing.”

Ellen Wright Clayton, a physician, lawyer, and professor of law and of health policy at Vanderbilt University, is a part of those conversations.

She served on the advisory committee for the National Academies report on the scientific, medical, and ethical considerations of human genome editing. One of the concerns about gene editing of embryos, she said, is its downstream effects.

“If you introduce a gene change, and the person reproduces, those things would be passed on to their offspring,” Clayton said. In other words, this could potentially release into the gene pool changes that are still not fully understood.

Funding of Genetic Research

Clayton is also concerned that once these treatments are successful, they could be heavily available only to the wealthy.

“In this country, we are not going to spend two to four million dollars a person to cure every single person who has sickle cell disease or other disorders such as spinal muscular atrophy, of which we have six cases a year here in Tennessee,” said Clayton.

“And that means only the wealthy will be able to receive these treatments. I think that the outcome of this is going to be a radical expansion of disparities in health outcomes,” she added.

Another concern is “off-label” use, said Jeffrey Kahn, director of the Berman Institute for Bioethics at Johns Hopkins University, and an expert on the ethics of genetic modification. In the U.S., physicians can choose to use FDA-approved medications for conditions other than the ones they were approved to treat, so-called off-label uses.

This means that if a gene-editing technique were to be approved to prevent a birth defect, pressure could arise for a physician to select preferred traits, said Kahn, who serves on the International Commission on the Clinical Use of Human Germline Genome Editing.

Potential Benefits

Though the risks, both clinical and social, are real, the potential benefits are enormous. Clayton, whose medical specialty is pediatrics, said she spent much of her medical residency caring for children with severe combined immunodeficiency (SCID), one of the diseases targeted by gene therapy.

“It’s a terrible disease,” she told Discover, and she’s thrilled that there is finally a therapy for these kids.

Results like these do indeed add to the conversation, even as they add to hope for preventing some inherited diseases.

This article is not offering medical advice and should be used for informational purposes only.

Read More: Scientists Use CRISPR to Target the Extra Chromosome Behind Down Syndrome

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information from a preprint study in bioRxiv: Efficient base editing and development in human embryos without chromosomal alterations
• This article references information from a report in Nature: Precise genome editing of human embryos triggers praise and alarm
• This article references information from the National Academies: Human Genome Editing Initiative
• This article references information from the National Academies: International Commission on the Clinical Use of Human Germline Genome Editing