Gene Editing in Human Embryos Advances With Base Editing Techniques

Recent research has focused on improving the precision and safety of gene editing in human embryos, with new results highlighting progress using base editing techniques.

A research group led by Dieter Egli at Columbia University applied base editing, a method that alters a single DNA letter, to healthy two-cell human embryos. The team reported achieving one targeted genetic change in roughly three-quarters of embryo cells without unwanted mutations, while a second targeted change was successful in about half of the cells but often resulted in unintended alterations.

The group published their findings as a preprint on the bioRxiv platform on 1 June 2026. This public posting allows other researchers to review and assess the results before formal peer review.

Base editing differs from earlier gene editing methods by modifying DNA without cutting both strands, which can reduce the likelihood of large-scale genetic errors or chromosomal problems. The first-generation CRISPR-Cas9 technique, by contrast, often causes double-strand breaks that can result in mosaicism, off-target mutations, and chromosomal abnormalities.

What the numbers show

• One targeted change was achieved in about 75% of embryo cells without unwanted mutations
• A second targeted change was successful in approximately 50% of cells but often with unintended alterations
• The preprint was posted on bioRxiv on 1 June 2026

The Columbia University team stated that after completing their initial experiments, they refined their procedures to reduce the occurrence of mosaicism, a condition where edited and unedited cells coexist within the same embryo.

Earlier research in 2017 by a Chinese team also used base editing in discarded human embryos, reporting nearly complete desired edits with few unintended changes. This previous work provided a reference point for evaluating the progress of newer techniques.

The adoption of base editing is part of ongoing efforts to address challenges associated with earlier gene editing methods. The approach aims to minimize risks linked to double-strand DNA breaks, which have been a concern with CRISPR-Cas9 applications in embryos.

Current developments in base editing procedures continue to be documented in scientific publications and preprints, contributing to the broader understanding of gene editing outcomes in early-stage human embryos.

* This article is based on publicly available information at the time of writing.