New techniques can have major unintended knock-on effects – genetic engineer

An article in Food Navigator, "Forget genetically modified, here's to genetically edited", reports a new study as saying that genome editing techniques are "advances" that allow "precise editing of genomes… without the need to introduce foreign genes".

Food Navigator says, "with awareness of what makes these biotechnologies new and different, genetically edited fruits might be met with greater acceptance by society at large than genetically modified organisms".

We've addressed such claims of "precision editing" of genomes previously.

Now Dr Michael Antoniou, a London-based molecular geneticist, has commented:

"As an approach to generating a novel GM plant, gene editing is of limited scope, being able to alter only one host gene at a time. As the technology currently stands, you would need to do multiple rounds of gene editing to bring about changes in more than one gene, which may be what is required. With each round of gene editing the potential damaging, off-target effects listed below will be compounded.

"Nevertheless, changing the function of a single gene in a crop can have major undesirable knock-on effects, depending on the nature of the modification. Changes in genes coding for enzymes are particularly worrying as there is a high probability that this can change their specificity, leading to their being able to perform novel biochemical reactions. Gene function and the biochemical reactions they lead to are finely balanced. If you simply disrupt ('knock-out') a gene function by gene editing you will inevitably (I would say) lead to unintended disturbances in biochemical pathways other than the one you are targeting.        

"Gene editing has an off-target component, which varies depending on the editing method used. So gene mutations elsewhere in the genome of the plant will occur, with unknown consequences.

"Also, gene editing is a tissue culture-based method as with all other GM approaches. Thus the vast number of tissue culture-induced mutations that can occur will also be present in a gene editing approach.

"If you are gene editing a vegetatively propagated crop such as bananas and apples; i.e. bred on not via seed but through cuttings, then the mutations arising from off-target gene editing and tissue culture will be present in the final commercialised product.

"From a combination of the above this is how these so-called 'precision' GM methods can still give rise to toxic and allergenic products and nutritional disturbances."