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The promising experimental technique Crispr-Cas9, used to modify defective genes, is less accurate than previously thought and causes unexpected mutations, according to a study published Monday.
These genetic scissors caused significant mutations during the experiments. "And" common "in mice and in human cells, according to the study published in the journal" Nature Biotechnology ".
In particular, the research developed by the Wellcome Sanger Institute of the Kingdom -Uni warns against some consequences of using this revolution.The "cut-and-paste" technique, which allows experts to remove and replace sections of DNA in the cells of any organism, including humans.
Scientists have revealed that standard tests designed to detect changes in DNA are not able to predict such genetic damage, so they recommend caution and propose specific tests for evaluate the validity of genetic therapies.
"Any attempt to use this technique in gene therapy must accompany many precautions, monitoring the possible negative effects," said Allan Bradle y, Wellcome Sanger Institute
In addition to its widespread use in scientific research, CRISPR / Cas9 has yielded positive results in the design of genome editing therapies to treat cancer, VHI or falcemia. However, remember, previous studies have not detected the existence of unexpected mutations in the DNA in the precise domain of genome editing performed with CRISPR / Cas9.
Therefore, Wellcome Sanger experts undertook a large systematic study in mice and humans and found that CRISPR / Cas9 often causes significant mutations, although they are located some distance from the site editing the genome. .
As a result, many genetic cells have undergone significant rearrangements, with "deletions" and "insertions" of DNA, which can cause the activation or deactivation of certain key genes.
"This is the first systematic badysis of the unexpected effects caused by editing with CRISPR / Cas9 on therapeutically relevant cells, and we discovered that the modifications on the DNA has been underestimated up to now ". communicated one of the authors, Allan Bradley.
This work, they point out, raises questions regarding the use of CRISPR / Cas9 and should pave the way for the scientific community to find alternatives to this standard method of genetic publishing. "In my early experiences, I used CRISPR / Cas9 as a tool to study genetic activity, however, it became clear that something unexpected was happening," said Michael Kosicki, the expert in charge of this research.
For Robin Lovell-Badge, of the Francis Crick Institute in London, the report confirms that in genetic publishing, "it must be ascertained that the changes that are produced are only those desired".
"These results do not justify panicking or losing faith in these techniques," said this researcher, who was not involved in the study.
What is the technique
Crispr-Cas9 supposed? a beautiful discovery in 2012, attributed to the Franco-American duo Emmanuelle Charpentier and Jennifer Doudna, often quoted in Nobel paris.
It is based on an enzyme that acts as molecular scissors, able to eliminate the unwanted parts of a genome to replace them with new pieces of DNA, as if to correct a typographical error in a word processing program.
The technique, in a state of research, has not been used for the moment in humans. But researchers have managed to correct a genetic defect in human embryos, potentially opening the way for great progress in the treatment of genetic diseases, not without posing great ethical questions.
And theoretically, this technique could be used to create genetically modified babies, for example to choose the color of their hair or to increase their physical strength.
EFE and AFP
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