A total of 58 embryos were created using healthy eggs and sperm donated by males who had the genetic mutation. The team, led by Shoukhrat Mitalipov, PhD, director of the Oregon Health and Science University Center for Embryonic Cell and Gene Therapy, and co-authors from the Salk Institute for Biological Studies and Korea’s Institute for Basic Science, said that the CRISPR–Cas9 genome editing tool was able to replace a mutant version carried by sperm with a normal copy from the egg cell, yielding an embryo with two normal copies.
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December 2017However, a team of prominent stem cell scientists and geneticists from Cold Spring Harbor Laboratory in New York posted doubts about whether the mutation actually was fixed (bioRxiv. doi: 10.1101/181255). In their paper, the authors noted there is no plausible biological mechanism to explain how a genetic mutation in sperm could be corrected based on the egg’s version of the gene. More likely, “Mitalipov’s team failed to actually fix the mutation and were misled into thinking they had by using an inadequate genetics assay,” according to an article in Nature News (Nature. Published online August 31, 2017. doi:10.1038/nature.2017.22547).
In a statement to Nature News, Dr. Mitalipov said his team stands by their results. “We will respond to their critiques point by point in the form of a formal peer-reviewed response in a matter of weeks.”
According to Retraction Watch, Nature also added an editorial note: “Readers are alerted that some of the conclusions of this paper are subject to critiques that are being considered by editors. Some of these critiques have been publicly deposited in preprint form. A further editorial response will follow the resolution of these issues”.