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Wednesday, 2 August 2017 13:56

UPDATE Wednesday, 2 August 2017 13:56

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Will there be a day birth to babies free of genetic disease, such as in a science-fiction film? Genes are carriers of a hereditary disease to have been fixed in human embryos for the first time thanks to a technique that raises as many hopes as well as ethical issues.

These works have been published Wednesday in the journal Nature. They are at a very preliminary stage, but potentially open up the way to major advances in the treatment of genetic diseases.

They also raise the ethical concerns worthy of a brave new world of Aldous Huxley. Because theoretically, this technique could be used to produce babies genetically modified to choose the color of their hair or to increase their physical strength.

The research on human embryos is strictly regulated and there was no question of implementing those of the study in a womans uterus to initiate a pregnancy. This is why scientists have not been allowed to develop over a few days.

This method, which still requires extensive research, can potentially be used to prevent the transmission of genetic diseases to future generations, commented during a press conference call one of the authors of the study, Paula Amato.

But this prospect is still distant: additional research, as well as an ethical debate will be needed before clinical trials, has taken care to specify the professor Amato.

Typo

The study was conducted within the university of the Sciences and of the Health of Oregon (OHSU) in the United States by american scientists, the chinese and south koreans. The tool used is the technique CRISPR-Cas9, a major discovery unveiled in 2012.

It is based on an enzyme that acts like molecular scissors. These can remove unwanted parts of the genome in a very precise way to replace them with new pieces of DNA, a bit like when one corrects a typo in a word processing software.

The team of researchers has used the revolutionary tool to correct, in human embryos, the gene carrier of the cardiomyopathy hypertrophic. This hereditary cardiac disease may cause sudden deaths, in particular during the practice of a sport.

The researchers have achieved in vitro fertilization of oocytes female normal by sperm carrying the defective gene. At the same time as the sperm, they also introduced the editing tools genetic.

The purpose: to cut the defective DNA to bring about its repair.

The result has been conclusive. 72% of the embryos (42 of 58) were adjusted so that the rate would have been 50% without the famous scissors genetic (naturally, the embryos would have had a chance on two to inherit a healthy gene).

A precedent in China

These tools can be further improved to achieve a success rate of 90 or even 100%, predicted another of the authors of the study, Shoukhrat Mitalipov.

A similar experiment had been conducted in China in 2015, but with mixed results. The phenomenon of mosaicism (simultaneous presence of genes in healthy and defective in embryo) could not be avoided, the researchers of the new study have been able to do.

The question that will be most debated is whether the same principle of modifying the genes of an embryo in vitro is acceptable, analyzed by an independent expert, professor Darren Griffin (University of Kent), quoted by the Science Media Centre.

According to him, one other question must be taken into account: is it morally right not to act if we have the technology to prevent these deadly diseases?

In December 2015, an international group of scientists convened by the us national Academy of sciences (NAS) in Washington had estimated that it would be irresponsible to use the technology of CRISPR to modify the embryo for therapeutic purposes as long as issues of safety and effectiveness have not been resolved.

But in march, the NAS and the american Academy of medicine were of the view that the advances in this area, opened up the realistic possibility that deserved serious consideration. In France, a parliamentary report has expressed a similar position.

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Molecular scissors to correct the genes: the medicine taken in the crossfire between hope and ethical debate - The Sherbrooke Times