According to an article by Science News, CRISPR/Cas9 corrected a gene defect in a human embryo that can lead to heart failure. The gene editing scissors were able to eliminate the gene in 72% of tested embryos with the mutation. Along with the successful editing, researchers also found that an advance that may limit the production of patchwork embryos that are not fully edited. This will be important if CRISPR is used for disease prevention says Shoukhrat Mitalipov, a reproductive and developmental biologist at Oregon Health & Science University in Portland. If even one cell in an early embryo is unedited, “that’s going to screw up the whole process,” says Mitalipov. He worked with colleagues in Oregon, California, Korea and China to develop the embryo-editing methods. The reearchers found that by editing genes before fertilization, the patchwork embryos can be avoided.
In the United States, clinical trials of human gene editing are banned by a rule that prevents the FDA from reviewing applications for any procedure that would introduce heritable changes in human embryos. Changing embryo DNA, called germline editing, is controversial because of fears that the technology will be used to spawn designer babies. These designer babies would have chosen traits by the parents, such as height, athleticism, hair color, or specific talents. “This paper is not announcing the dawn of the designer baby era,” says R. Alta Charo, a lawyer and bioethicist at the University of Wisconsin Law School in Madison. The researchers have not attempted to add any new genes or change traits, only to correct a disease-causing version of a gene. None of the tested embryos showed any sign of cutting in incorrect spots, a concern for creating new DNA mutations, and the embryos would only self heal if one of the parents had a healthy copy of the gene. This discovery could mean it would be difficult for scientists to fix embryos where neither parent has a healthy gene, but could prevent designer babies because embryos would simply reject new DNA being implemented.