“There’s no sugarcoating this. This is a restraining order for all genome editors to stay the living daylights away from embryo editing.”
Fyodor Urnov, a gene-editing expert and professor of molecular and cell biology at the University of California, Berkeley, doesn’t beat around the bush after reading the preprint paper, “Frequent loss-of-heterozygosity in CRISPR-Cas9-edited early human embryos.” A loss of heterozygosity is a common occurrence in cancer where a tumor-suppressing gene is lost. What Fyodor Urnov is warning about (other than the ethics of gene editing on human embryos – we’ll get to that) is that CRISPR, the most popular gene-editing tool today, is like a surgeon operating with a saw rather than a scalpel.
“However, studies assessing gene correction in early human embryos report low efficiency of mutation repair, high rates of mosaicism and the possibility of unintended editing outcomes that may have pathologic consequences.”
OK, early scientific experiments can be risky, but a) “the unintended genome editing outcomes were present in approximately 22% of the human embryo cells analysed” and b) that’s “human embryo cells” they’re gene editing. “They” are biologists and genetic researchers from The Francis Crick Institute, King’s College London and the University of Oxford. The “pathological consequences” they’re referring to include cancer and birth defects. And 22% is 1 in 5 embryos developing “unintended” problems from otherwise successful gene edits. – what the review in OneZero calls “off-target effects.”
Biologist Kathy Niakan says the embryos edited (18 were edited and seven more acted as a control group) were left over from fertility treatments and donated by patients and were destroyed after 14 days. Moreover, the lab was the first in the U.K. to get government permission to CRISPR on human embryos – but for research only, not secret experiments carried to term like the experiment in China that resulted in twin girls being born.
“One must ensure that the outcome will be the birth of healthy, disease-free children, without any potential long-term complications.”
Niakan doesn’t want anyone letting edited embryos survive past 14 days until they can guarantee healthy babies. Really? Nature can’t guarantee healthy babies and it has had millions of years of practice. That means more experiments on human embryos to get it right. But … is it right to edit them in the first place? That’s fast becoming a non-debatable moot point as gene editing falls under the control of individual governments that can resist standards organizations and ethics groups which have little power.
What can go wrong with gene-editing of human embryos? Think of your local day care center. Five kids go in. Four come out. Are you willing to let the management practice until they get it right?
This is just the beginning.