Columbia Scientists Precisely Edit Human Embryo DNA

Scientists at Columbia University have achieved unprecedented accuracy in editing the DNA of early human embryos using a newer technology called base editing, an advancement that could eventually enable parents to safely repair disease-causing mutations in embryos or select desired traits. The research, led by geneticist Dieter Egli, successfully altered two genes in early human embryos without causing the extensive DNA damage often observed with earlier CRISPR methods. The study, which is under review for publication in a scientific journal, found that base editing could change the PCSK9 gene (linked to heart disease risk) and the HBG gene (which directs hemoglobin production) with much greater precision than previous techniques. However, some embryos became mosaics, meaning different cells retained different versions of the genes, which could cause medical problems if the embryos developed into babies. The advancement has reignited longstanding ethical debates about human embryo editing. While the technology could potentially help parents using in vitro fertilisation avoid passing on hereditary diseases, critics have warned it could be used to engineer babies with desired traits, a practice some ethicists have compared to eugenics. The research was supported by Nucleus Genomics, a company that screens IVF embryos for genetic disorders and has faced criticism for ads promoting "genetic optimisation" of babies. Dr. Paula Amato, a fertility expert at Oregon Health and Science University, called the method "promising" but said further scrutiny would be needed. Bioethicist Asa Iltis of Wake Forest University warned that harmful effects might not be evident until after birth. The development builds on earlier breakthroughs, including the invention of CRISPR in 2012 and base editing by Harvard geneticist David Liu in 2016. In 2018, Chinese scientist He Jiankui used CRISPR to alter human embryos and was subsequently imprisoned for three years, though the status of the resulting children has never been independently verified. The FDA approved a CRISPR-based treatment for sickle cell anaemia in 2023, and in 2025, a baby was cured of a genetic disorder using base editing. Egli called for a public conversation about the pros and cons of altering embryonic DNA, noting that while multiple genes could potentially be edited together, there are likely limits to how many changes can be safely made in a single embryo.