By Michael Le Page
The results of a much-publicised study claiming mutations in human embryos can be safely corrected with CRISPR have been called into question by other researchers.
The team behind the work say they stand by their findings, but at the very least the dispute shows there are still major issues that need to be resolved before anyone should attempt to use gene-editing to prevent children inheriting disease-causing mutations.
“There are lots of unanswered questions,” says embryologist Anthony Perry of the University of Bath in the UK.
The first studies to try using the CRISPR genome-editing technique to alter the DNA of human embryos revealed several major problems. For instance, it only corrected mutations in a small proportion of embryos.
Last month, however, a team led by Shoukhrat Mitalipov of Oregon Health and Science University claimed they had managed to improve efficiency while avoiding other key problems such as unwanted alterations. The study was widely proclaimed as a breakthrough.
Now doubts have been raised. Genome editing works by breaking DNA, and letting a cell’s natural repair mechanisms fix it. This is usually quite haphazard, and precise repairs were thought to be rare.
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