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Crispr-Cas9 is a new genetic engineering method that is credited with being more accurate than previous transgenics. Several recent scientific studies show the opposite: two indicated that it can cause cancer and another showed unwanted effects, among them the accidental deletion or rearrangement of long DNA sequences and the silencing or activation of genes that were not intended to be modified, all with pathogenic potential.
The most recent article, from Allan Bradley's team at the Wellcome Sanger Institute in the UK, was published in the scientific journalNature Biotechnologyon July 16, 2018 (here).
Crispr-Cas9 is an artificial enzymatic construct that acts like molecular scissors with GPS: it finds the place where you want to manipulate the DNA and cuts the two strands of the helix, inhibiting the expression of the intervened gene and / or inserting new genetic material, creating a transgenic organism.
The study by Bradley et al., Conducted with human and mouse cells, showed that Crispr-Cas9 frequently produces additional unwanted effects, such as removing long DNA sequences (hundreds to thousands of bases) or rearranging them, but far from the site of cut. They conclude that these changes can generate some disease.
Bradley stated that these types of side effects have been underestimated in previous studies, although there were indications about them probably because they did not appear in the analyzes, since in general DNA sequences close to the intervention site are reviewed with Crispr-Cas9, but the changes they are shown in distant sequences. As for removal or rearrangement, since this phenomenon is not intended, it may go unnoticed in the laboratory, but it has potentially harmful effects on humans and other organisms.
Although the studies refer mainly to the use of Crispr-Cas9 in medicine, the problem also manifests itself in the handling of crops: the same effects occur in plants, leading to unforeseen impacts on the plantations and also on their consumption because the activation or deactivation of genes and the deletion or rearrangement of sequences can cause allergies and other forms of toxicity.
Bradley's team's study raised the alarm created by two previous papers: one from the renowned Karolinska Institute in Sweden, which noted that Crispr-Cas9 increases the risk of cancer in patients who are inserted cells modified with this method (here). This is because the action of Crispr-Cas9 is not effective against the reaction of the p53 gene, which is a kind of first aid kit for cells, associated with the prevention of many forms of cancer. This gene tries to repair the cut produced by Crispr-Cas9, and if it fails to do so, it instructs the cell to die so as not to reproduce the abnormality. When p53 does not work, Crispr-Cas9 is much more effective, so scientists select cells where this gene does not work, but could be inserting cells that will be cancerous into organisms, like a time bomb.
Consulted by the GMWatch organization, Dr. Michael Antoniu, from King's College London, explained that the reaction of repair agencies to the Crispr-Cas9 cut is a natural defense mechanism and, therefore, it is not a question of adjusting the new biotechnologies, since the mechanism will continue to act. Selecting cells where it does not work involves serious side effects, such as cancer or, in the case of plants, serious food safety problems. Antoniu also suggests that other new biotechnologies, such as Talen or single nucleotide mutagenesis, possibly generate the same effects and therefore studies should be done on these as well. It questions that other methods of mutagenesis, such as radiation, could be causing toxicity that has not been associated with them, with impacts on food safety and security (here).
Timely, a few days after the publication of the aforementioned studies, the European Union court of justice ruled - after a process initiated by a legal claim from La Via Campesina, Friends of the Earth and other organizations in France - that the products of the new biotechnologies (which include mutagenesis and Crispr) are genetically modified organisms, that is, transgenic, and must pass through the risk analysis of biosafety laws and their consideration must be based on the precautionary principle. This was a victory for farmer, environmental and consumer organizations over the malicious insistence of the biotech industry that new biotechnologies do not need to undergo biosafety evaluation (here).
This same absurd position of the industry is defended by Víctor Villalobos, announced secretary of agriculture of Andrés Manuel López Obrador, for whom the peasant organizations are calling for early dismissal (here). The new studies strongly deny that these new transgenics have no risks.
BySilvia Ribeiro – ETC Group Researcher