In the first known U.S. study, scientists have successfully corrected a genetic mutation — one which causes the heart muscle to be unusually thick — in human embryos. The MIT Technology Review first learned of the results last week and called them "a milestone." Down the line, the research could advance to clinical trials in which researchers work with parents to correct mutations in embryos, but that raises the ethical question: If something goes wrong, what do you do?
Why it matters: This was "a cleaner study" and a more successful use of the gene-editing technique CRISPR than we've seen before, bioethicist Jessica Berg told Axios. The researchers, based in Oregon, corrected the genetic mutation in one cell and passed that correction to more embryonic cells, as they began to divide. Past studies carried out in China found errors in some cells after division.