Author: Tina Hesman Saey / Source: Science News
When researchers announced last year that they had edited human embryos to repair a damaged gene that can lead to heart failure, critics called the report into question.
Now new evidence confirms that the gene editing was successful, reproductive and developmental biologist Shoukhrat Mitalipov and colleagues report August 8 in Nature. “All of our conclusions were basically right,” Mitalipov, of Oregon Health & Science University in Portland, said during a news conference on August 6.
But authors of two critiques published in the same issue of Nature say they still aren’t convinced.
At issue is the way that the gene was repaired. Mitalipov and colleagues used the molecular scissors CRISPR/Cas9 to cut a faulty version of a gene called MYBPC3 in sperm (SN: 9/2/17, p. 6). People who inherit this version of the gene often develop heart failure. Cutting the gene allows cells to fix the problem by replacing erroneous instructions in the gene with correct information.
Researchers supplied the correct information in the form of small foreign pieces of DNA, but the embryos ignored that repair template. Instead, Mitalipov and colleagues say, embryos used a healthy version of the gene on the mother’s chromosome to fix the error. That action is called gene conversion.
Gene conversion typically happens when reproductive, or germline, cells swap DNA before making eggs and sperm. So it was completely unexpected to find that type of repair happening in embryos, says geneticist Paul Thomas of the South Australian Health & Medical Research Institute in Acton.
If human embryos do ignore foreign bits of DNA that could be a problem for fixing…
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