Report: Human embryo edited for first time in US, pushes limits

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A team of researchers in Oregon have become the first in the US to attempt genetically altering human embryos, according to reporting by MIT Technology Review. The attempt is said to represent an advance in the safety and efficacy of methods used to correct genetic defects that spur disease.

Until now, the only three published reports of human embryo gene editing were from researchers in China. But their experiments-using a gene-editing method called CRISPR-caused "off-target" genetic changes, basically sloppy changes in the DNA that were not intended. Also, not all the cells in the embryos were successfully edited, causing an effect called "mosaicism." Together, the problems suggested that the technique was not advanced enough to safely alter human embryos without unintended or incomplete genetic consequences.

Scientists familiar with the new US work told MIT Technology Review that the Oregon team has improved these issues. They're said to have shown in experiments with "many tens" of human embryos that they can correct genetic mutations that cause disease while avoiding mosaicism and off-target effects. Their improved method allows for earlier delivery of CRISPR into cells at the same time sperm fertilize an egg.

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