New GM techniques can create different genetic changes to those from conventional breeding, say scientists

New GM techniques – or "NGTs", as gene editing technologies like CRISPR/Cas are being labelled – can create both intended and unintended changes in the genome  that would be unlikely to occur with conventional breeding methods, including the non-targeted mutagenesis breeding methods that have been used for several decades by a minority of conventional breeders. This is the main message of a review of the scientific literature recently published in Frontiers in Bioengineering and Biotechnology.

The authors of the review explain that the biological effects of these changes on the health of consumers and the environment might also be different from those arising from conventional breeding and may pose risks. This directly contradicts the rationale put forward by the GMO lobby to justify the deregulation of new GMOs – that the changes brought about by new GM techniques are no different to those that might be caused by conventional breeding, and so there are no novel risks that need assessing.

The review cites evidence showing that:
* In comparison to methods of conventional breeding (including non-targeted mutagenesis), new GM techniques can overcome the boundaries of natural genome organisation.
* By overcoming these boundaries, new GM techniques can make the genome much more extensively available for genetic changes – and that may bring new risks.

In the review, the authors write that even when the overall number of mutations (DNA damage) is lower in NGT plants in comparison to non-targeted mutagenesis plants, "due to the technical characteristics of NGTs, the sites of the mutations, their genomic context and their frequency (in regard to specific sites) can differ if compared to plants derived from conventional breeding methods".

In conventional breeding, including mutagenesis breeding, mutations occur randomly along the genome, whereas the mutations arising from new GM techniques are non-random and are targeted to specific regions of the genome. Their biological effects may depend on the genomic regions that are targeted by the GM processes used – and these effects cannot be generally equated to those emerging from conventional breeding. On the contrary, the biological effects can be different and "may cause specific risks for health and the environment".

Regarding the authors' statement that the number of mutations is typically lower in NGT plants compared with non-targeted mutagenesis plants, GMWatch would add that the screening methods generally used by new GMO developers and researchers are inadequate and therefore miss many unintended mutations. In addition, in the case of gene edited plants, it is not enough to only consider mutations arising from the activity of the gene-editing tool. Gene editing involves a compulsory tissue culture stage, which also creates hundreds or thousands of mutations.

The authors of the review also note that the processes of NGTs involve several technical steps that, in the case of plants, often include GM transformation processes which are also used in older-style GMOs.

They list five categories of unintended genetic changes resulting from NGT processes that can affect risk. They are:
* Unintended genetic changes resulting from the insertion of transgenes
* Unintended insertion of transgenes
* Unintended changes without insertion of transgenes
* Chromothripsis (a catastrophic shattering of the genome), and
* Unintended genetic changes that may cause the formation of new gene products – proteins and mRNAs (messenger RNAs, which tell your DNA how to make specific proteins).

The authors conclude that the assessment of intended as well as unintended genetic changes should be part of a mandatory comprehensive molecular characterisation and risk assessment of new GM plants obtained from NGTs.

The review comes at a time when the EU institutions are considering the European Commission's proposal to exempt the vast majority of new GMOs from regulation, which would mean that no safety checks for health or the environment would be carried out and the current requirements for traceability and labelling would not apply.
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The review:
Franziska Koller and Michael Cieslak (2023). A perspective from the EU: unintended genetic changes in plants caused by NGT — their relevance for a comprehensive molecular characterisation and risk assessment. Front. Bioeng. Biotechnol. 11. 27 October. Sec. Biosafety and Biosecurity. https://doi.org/10.3389/fbioe.2023.1276226


Read this article on the GMWatch site and access linked sources:
https://gmwatch.org/en/106-news/latest-news/20339

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