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As published yesterday on Nature a team of chinese scientists have edited the genome of human embryos. This is actually a first-time achievement but it’s ready to rise the ethical debate over genetic engineering; there has even be rumors for a moratorium over genetic engineering on human embryos.A written today in ScienceNow (sciencemag.org)

In highly controversial research that some view as crossing an ethical line, Chinese scientists have edited the genomes of human embryos, Nature reports. The study, published online in the journal Protein & Cell, details how the researchers used the genome-editing technology CRISPR-Cas9 on “non-viable” embryos in an attempt to alter the gene responsible for a potentially lethal blood disorder. After encountering obstacles with the technique and “off-target” mutations, the team stopped the process. About a month ago, rumors of the research swirled, stirring calls by some for a moratorium on such genetic engineering of human embryos.

This is an astonishing result but, as everyone of us know, it rises a lot of difficult questions about ethics, science and the very concept of human being.
Moreover the consequences gene editing are far from being understood; in some way we can say that gene editing is in fact evolution, and the long term consequences of evolution are too complex to be fully understood and forecasted.

In the paper, researchers led by Junjiu Huang, a gene-function researcher at Sun Yat-sen University in Guangzhou, tried to head off such concerns by using ‘non-viable’ embryos, which cannot result in a live birth, that were obtained from local fertility clinics. The team attempted to modify the gene responsible for β-thalassaemia, a potentially fatal blood disorder, using a gene-editing technique known as CRISPR/Cas9. The researchers say that their results reveal serious obstacles to using the method in medical applications.

“I believe this is the first report of CRISPR/Cas9 applied to human pre-implantation embryos and as such the study is a landmark, as well as a cautionary tale,” says George Daley, a stem-cell biologist at Harvard Medical School in Boston. “Their study should be a stern warning to any practitioner who thinks the technology is ready for testing to eradicate disease genes.”

Some say that gene editing in embryos could have a bright future because it could eradicate devastating genetic diseases before a baby is born. Others say that such work crosses an ethical line: researchers warned in Nature2 in March that because the genetic changes to embryos, known as germline modification, are heritable, they could have an unpredictable effect on future generations. Researchers have also expressed concerns that any gene-editing research on human embryos could be a slippery slope towards unsafe or unethical uses of the technique.

The paper by Huang’s team looks set to reignite the debate on human-embryo editing — and there are reports that other groups in China are also experimenting on human embryos.

The team injected 86 embryos and then waited 48 hours, enough time for the CRISPR/Cas9 system and the molecules that replace the missing DNA to act — and for the embryos to grow to about eight cells each. Of the 71 embryos that survived, 54 were genetically tested. This revealed that just 28 were successfully spliced, and that only a fraction of those contained the replacement genetic material. “If you want to do it in normal embryos, you need to be close to 100%,” Huang says. “That’s why we stopped. We still think it’s too immature.”

Full open article from Nature available here

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