by Emily Mullin, OneZero
A team of scientists has used the gene-editing technique CRISPR to create genetically modified human embryos in a London lab, and the results of the experiment do not bode well for the prospect of gene-edited babies.
Biologist Kathy Niakan and her team at the Francis Crick Institute wanted to better understand the role of a particular gene in the earliest stages of human development. So, using CRISPR, they deleted that gene in human embryos that had been donated for research. When they analyzed the edited embryos and compared them to ones that hadn’t been edited, they found something troubling: Around half of the edited embryos contained major
“There’s no sugarcoating this,” says Fyodor Urnov, a gene-editing expert and professor of molecular and cell biology at the University of California, Berkeley. “This is a restraining order for all genome editors to stay the living daylights away from embryo editing.”
While the embryos were not grown past 14 days and were destroyed after the editing experiment, the results provide a warning for future attempts to establish pregnancies with genetically modified embryos and make gene-edited babies. (The findings were posted online to the preprint server bioRxiv on June 5th and have not yet been peer-reviewed.) Such genetic damage described in the paper could lead to birth defects or medical problems like cancer later in life.
Since CRISPR’s debut as a gene-editing tool in 2013, scientists have touted its possibilities for treating all kinds of diseases. CRISPR is not only easier to use but more precise than previous genetic engineering technologies — but it’s not foolproof.
Niakan’s team started with 25 human embryos and used CRISPR to snip out a gene known as POU5F1 in 18 of them. The other seven embryos acted as controls. The researchers then used sophisticated computational methods to analyze all of the embryos. What they found was that of the edited embryos, 10 looked normal but eight had abnormalities across a particular chromosome. Of those, four contained inadvertent deletions or additions of DNA directly adjacent to the edited gene.
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