The Gene Editing Process
In a lab at Oregon Health & Science University, biologist Shoukhrat Mitalipov and a team of experts have been exploring and learning how to edit the DNA in human embryos efficiently and safely. This month, they announced their successful edit and correction of a mutation which causes a heart condition that can be fatal — hopefully the first landmark step of many on the road to preventing thousands of genetic diseases with editing.
To edit an embryo, a researcher will begin by taking a human egg and monitoring it on a computer screen. They will then inject, with a pipette, donor sperm and CRISPR, microscopic chemical sequences that act as a gene-editing tool, that is designed to make the precise desired edit. CRISPR then goes to work, slicing the target defect from the DNA. After this editing process, the scientists place the embryos created using the process in an incubator and monitor them.
Mitalipov and the team believe that the editing process finally started to work when they began to inject the sperm and CRISPR into the egg simultaneously. Waiting until the embryos were already created produced results that were less accurate and more likely to be plagued by dangerous mutations. And, while the team isn't totally certain on how the process works, they believe that the slice CRISPR makes as it targets defects triggers the repair process in the embryo.
Incredible Potential, Mixed Feelings
Thus far, the results from this study appear to be promising. However, many questions in the scientific community about the technique itself and the underlying ethics of the process remain. For example, the technique has not yet been reproduced by other teams, and some scientists believe that the data doesn't support the conclusions Mitalipov and the team are claiming.
Others are more concerned that this kind of technology has not been proven safe. worried that less careful scientists might rush ahead too quickly and attempt to make babies before the technique has been proven to work and be safe. Any change to the genome, or germline editing, could be passed along for generations, perpetuating mistakes and even potentially leading to the development of new diseases. Harvard Medical School Dean George Daley told NPR, “I think it would be professionally irresponsible for any clinician to use this technology to make a baby. It's just simply too early. It would be premature.”
Still, others are critical of the technique from an ethical standpoint, arguing that scientists editing embryos are “playing God,” and pushing the field toward selling the ability to create designer babies to parents who can afford the technology. “I think it's extraordinarily disturbing,” Marcy Darnovsky, head of the watchdog group the Center for Genetics and Society, told NPR. “We'll see fertility clinics advertising gene editing for enhancement purposes. We'll see children being born who are said to biologically superior.”
Mitalipov and the team acknowledge these criticisms and agree, specifically, that the technique requires reproduction and further testing and should be used for medical purposes only. However, they point out the amazing potential that the technology has to improve our world and the quality of human life. Mitalipov thinks the process may eventually be able to wipe out many genetic diseases:
“[There are] about 10,000 different mutations causing so many different conditions and diseases,” he said to NPR. “We're talking about millions of people affected. So I think the implications are huge.”