The team led by the Chinese Academy of Sciences' Xingxu Huang implemented a CRISRP/Cas9-fueled base-editing approach in which edits to single bases can be made without forming double-stranded breaks. As they report in Molecular Therapy, the researchers first applied this method to correct the Marfan syndrome mutation, FBN1T7498C , in cells before testing it on heterozygous human embryos.
This approach, Huang and colleagues report, could make edits efficiently and specifically. In particular, they report a nearly 90 percent efficiency rate for correcting the Marfan mutation. However, they did note a few unwanted base conversion events, suggesting that the editing window needs to be tightened.
Still, Huang and colleagues say their findings show base editing of a pathogenic variant in a human embryo to be feasible.
"It's a nice demonstration of the use of base editors to correct a well-known point mutation that causes a human genetic disease in a setting that may become therapeutically relevant," Harvard's David Liu, who has also worked on a base editor for Marfan's, tells Wired.