Human embryos modified to eliminate a single-gene disease

By Michael Cook

American and Korean scientists have published in Nature the details of how they successfully edited a single gene in human embryos. A team of American, Chinese and Korean scientists led by Shoukhrat Mitalipov of Oregon Health and Science University used gene-editing CRISPR/Cas9 technology to eliminate a gene, MYBPC3, linked to a heart disorder.

Stem cell scientist Paul Knoepfler said that the highly-anticipated paper was technically strong, innovative and rigorous – which suggests that other scientists will soon be building on Mitalipov’s achievements. Perhaps one of the most significant of these was its safety. The paper claims that there were no off-target mutations and no mosaic embryos.

The potential for the technique is immense. The article focuses on curing diseases. About 10,000 harmful single-gene mutations have been identified from breast cancer to Tay-Sachs. Interest in eliminating these will be intense.

However, when other less competent, less experienced and less ethical scientists scale up the number of embryos, safety could obviously suffer.

Nearly every observer stated the obvious: a technique for safely and effectively editing the human genome has significant ethical implications. It can be used not only for curing diseases but for “enhancing” embryos with “better genes”.

Therefore, Mitalipov’s team took great care to dot their ethical is and cross their ts. “Even though this preliminary effort was found to be safe and effective, it is crucial that we continue to proceed with the utmost caution, paying the highest attention to ethical considerations,” said corresponding author Juan Carlos Izpisua Belmonte.

As Vivek Wadhwa, a technology expert from Carnegie-Mellon, wrote in the Washington Post, “CRISPR’s seductiveness is beginning to overtake the calls for caution.” For some scientists and bioethicists, the danger of haste can be averted with more reports and more ethics committees.

For others, creating and destroying human embryos for research is itself anathema. In this experiment, dozens of embryos were created, and all were destroyed before they had grown beyond a few days. But everyone recognised the potential for a new generation of eugenics, which has so long been under the shadow of the Nazis’ discredited ideology.

David Albert Jones, of the UK’s Anscombe Institute, penned a withering critique, “Unethical research with eugenic goals.”

“The whole rationale for this experiment is to take a step towards genetic modification as an assisted reproductive technology,” he writes. “We are manufacturing new human beings for manipulation and quality control, and experimenting on them with the aim of forging greater eugenic control over human reproduction. This is not a case of using bad means for a good end, but of bad means to a worse end.”

Editor’s note. This appeared at BioEdge and is reposted with permission.

Send to Kindle