CRISPR, Gene-editing and Mutation Breeding: Questions and Answers

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Via Greenpeace

Q: What is gene-editing?

A: Gene-editing covers a range of new laboratory techniques to change the DNA of a living organism. Most gene-editing techniques use enzymes to ‘cut’ the genome at a predefined location which then ‘repairs’ itself resulting in an insertion, replacement or removal of segments of DNA. Often an inserted “DNA template” is used to predefine the change to the DNA of an organism.

These techniques include zinc finger nucleases (ZFN), transcription activator-like effector nucleases (TALENs) and the clustered regularly interspaced short palindromic repeat (CRISPR) systems. Another technique involves the introduction of short strands of synthetic DNA that triggers cells to modify their DNA to match the introduced fragments. This technique is called oligonucleotide directed mutagenesis (ODM). Geneediting techniques can be applied not only to plants but also animals, including insects, as well as to humans.

Q: What is the difference between gene-editing and the ‘old-style’ GMOs?

A: The principal difference is that gene-edited organisms such as crop plants do not necessarily carry any genes that have been transplanted from another species (‘foreign DNA’ or ‘transgenes’). Often, industry claims that this makes them “non-GM”. This ignores the fact that the scientific and legal definition of a “Genetically Modified Organism” in the EU (and “Living Modified Organism” in the Cartagena Protocol) is much broader. The presence or absence of foreign genes isn’t at all a criteria for defining a GMO.

Q: Isn’t gene-editing much more precise than ‘old-style’ genetic engineering?

A: Gene-editing is theoretically more precise in the positioning of the intended alteration to the genetic material, compared to the insertion of genes at random locations that is characteristic of previous techniques. But how this altered DNA will affect interactions with other genes and processes within the cell is largely unknown. In addition, the techniques can also cut and alter DNA in places additional to those intended (so-called ‘off-target effects’). Both on-target and off-target changes can give rise to unexpected and unpredictable effects on the genome, affecting its functioning. Such effects can have implications for food, feed and environmental safety if they increase levels of toxic compounds, reduce levels of nutritional compounds or even produce new allergens. This means that the higher level of precision doesn’t necessarily translate into a higher level of safety.

Q: Would you say that gene-edited plants and animals are as risky as ‘old-style’ GMOs?

A: Given that these techniques are new, it is not yet possible to fully evaluate the potential for adverse effects. The different techniques can also be used in combination and several times over in a single organism. This means that although each change may be small, large changes to the genome can result. The potential for negative effects (such as unintended changes to the genome) increases with each ‘edit’. As yet, there has been no or little assessment of the biosafety implications of combining gene-editing techniques.

Q: Are gene-edited GMOs regulated under EU GMO law?

A: Yes, they are covered by the scope of the existing GMO rules. This is because it is the characteristics of the process, not the characteristics of the resultant organism, that determines whether or not an organism is a GMO under EU law. One example of a GM process, expressly mentioned in EU law, is the insertion of heritable material (e.g. stretches of nucleic acid such as RNA or DNA) prepared outside the organism (‘in vitro’) into a host organism, which then causes an alteration of the organism’s own genetic make-up. The important point here is that, to create a GMO, the inserted material doesn’t have to be taken up into the genome (as it would be with ‘old-style’ GMOs) but can simply cause a change to the organism’s genetic make-up (e.g. by “rewriting” genes).

Q: Some companies say EU GMO law is “onerous”. What are the requirements that GMOs must meet?

A: In the EU, all GMOs need to undergo a full authorisation process, including a case-bycase assessment of health and environmental risks. GMOs cannot be placed on the market unless a detection method has been defined, and their products – except milk, eggs and meat from animals fed with GMOs – are labelled. If gene-edited organisms were to escape EU GMO regulations, any potential negative effects on food, feed or environmental safety would go unchecked. European consumers, farmers and breeders would have no way to avoid using these GMOs.

Q: In what way is gene-editing different from mutation breeding, which has been used for a long time and is not regulated under EU GMO law?

A: Gene-editing techniques are wholly different from mutagenesis. They are in vitro modern biotechnological techniques. This means that the genetic modification is produced by heritable material (or material causing a heritable change) that has, for at least part of the procedure, been handled outside the organism in a laboratory environment. Methods of producing mutagenesis involve an external stressor (a chemical or radiation) being applied, which changes the plant or animal DNA. No genetic material is inserted into the genome.

Q: What if gene-editing creates a change to a gene that could occur naturally?

A: Although two products developed by different (i.e. gene-editing and non-GM) methods may possess the same trait, and even the same DNA sequence in the region of interest, this does not make them equivalent in terms of the whole genome. It does not give any reassurances that the gene-edited organism does not have any unintended effects outside the section of the genome which has been targeted. Whether any unintended changes have occurred elsewhere in the genome can only be found through whole genome sequencing and comparison with an equivalent organism (i.e. one developed through non GM methods). In practice, this is one of the main reasons why risk assessment of GMOs is carried out – in order to determine if any unintended changes have implications for food and environmental safety.

Q: Are there any gene-edited plants or animals already on the market?

A: A gene-edited oilseed rape (developed through ODM) has been on the market since last year in the US, but nowhere else. Other gene-edited plants and animals are in the pipeline. Nothing is being grown in Europe as yet, except perhaps in field trials. However, it is unclear whether any of the oilseed rape grown in the US may find its way to Europe in imported seed or processed products. The industry is hoping to move very fast, and counts on bypassing EU GMO laws to sell the GM seeds into Europe as well.

Q: Most ‘old-style’ GMOs are used to make plants withstand spraying with herbicide, or produce an insecticide. What is gene-editing used for?

A: While it is true that the first gene-edited crop to be grown is a herbicide-resistant oilseed rape, gene-editing can potentially be used to produce many more traits, in just about any organism. Double-muscled pigs are one of many applications of gene-editing being tested in farm animals. Further, gene-editing can be used to create so-called “gene-drives”. These mechanisms can be used to spread traits such as disease resistance into wild populations of plants or animals. Gene-editing in humans, which is covered by separate legislation to the EU GMO regulations, is also possible and the subject of much debate concerning the ethics of such interventions.

Q: The US Intelligence Community has said that gene-editing can create weapons of mass destruction. What does that mean?

A: The Worldwide Threat Assessment of the US Intelligence Community of February 2016 states: “Research in genome editing conducted by countries with different regulatory or ethical standards than those of Western countries probably increases the risk of the creation of potentially harmful biological agents or products”. These are indeed powerful techniques that are easy to use, and still cheap – pending final decision on patents. They can be misused. This is another reason why they mustn’t absolutely escape regulation. If GMO law is applied, then this makes it much harder for misuse to occur “under the radar”