I wrote previously about the rumors that scientists were using a new biotech tool, the CRISPR/Cas9 nuclease system, to genetically engineer human embryos.
Nature News broke the story today that this work was just published in the journal Protein & Cell.
The scientists were using polyspermic embryos that made them not applicable for in vitro fertilization. They then tried to edit a gene responsible for causing the genetic disease Beta-thalassemia by cutting the gene repsonsible with the Cas9 nuclease, and editing it by providing a repair template that would generate verifiable changes in the genome. Their goal was to determine with what efficiency they could edit this gene. They injected 84 embryos, of which 71 survived for 48 hours. Of these 71, Cas9 had successfully cut the gene, but only 4 embryos had undergone repair using the repair template provided they provided - a success rate of less than 5%. Furthermore, Cas9 had cut DNA at what are called off-target sites, suggesting that even if targeted repair occurs, there is a significant risk of additional mutations. Their conclusion:
Taken together, our work highlights the pressing need to further improve the fidelity and specificity of the CRISPR/Cas9 platform, a prerequisite for any clinical applications of CRSIPR/Cas9-mediated editing.My question to you is, should this work even have been done in the first place?