Scientists tweak DNA in viable human embryos

Scientists for the first time have used a CRISPR genome-editing technique to edit a disease mutation in viable human embryos, STAT reports. Researchers from China used a variation of CRISPR known as a base editor to correct a single amino acid that causes Marfan syndrome, a connective tissue disorder that can affect the heart, bones, and joints. The researchers, who describe their work as “proof of principle” this month in Molecular Therapy , did not detect any off-target effects of CRISPR or unwanted insertions or deletions in the genomes of the seven modified embryos, none of which was implanted.