In the first of this two-part series, Council Member and Trustee, Ralph Early, explores some of the science and history behind gene-editing. The second article, found here, delves into some of the ethical issues surrounding gene-editing by employing a food ethics lens.
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In May 2022, the UK government introduced into Parliament its Genetic Technology (Precision Breeding) Bill intended to pave the way for gene-editing in relation to agriculture and food. In March 2023, the Genetic Technology (Precision Breeding) Act 2023 passed the final stages of parliamentary scrutiny and received Royal Assent, immediately coming into force as UK law.
Following the UK’s secession from the EU, the UK’s government stated its commitment to diverge from the EU’s regulatory structures, for instance by the encouragement and support for research and commercialisation of gene-editing technologies understood as ‘modern biotechnology’. It is of note to recognise that genetically modified organisms (GMOs) are little used within the European Union (EU) and the technology is carefully controlled under regulations which enforce restricted use. In 2021 the EU did however publish a study on new genomic techniques which may lead to revised regulation affecting both the science and application of gene-editing as well as, for instance, the labelling of food products derived from gene-edited plants and animals.
The regulatory framework of the Genetic Technology (Precision Breeding) Act 2023 has been devised to provide support for research and the commercialisation of genetically altered plants and animals of value to UK agriculture and food production. Gene-editing enables changes to be made to the genomes and gene-caused nature of organisms, manifested as both genotypic characteristics and phenotypic traits. These are heritable and can be passed from one generation to the next. But what exactly is gene-editing? What are the issues associated with it? What might be the benefits for society, the agri-food industry and the natural world? Can application of the science of gene-editing as a technology give rise to harms? These are just some of the questions that gene-editing provokes.
This article provides a short overview of the science of gene-editing. It does not address the numerous ethical issues that gene-editing reveals. Gene-editing as a source of moral concern is explored in part two of this series.
The possibilities in gene-editing
In 1953, the Nobel prize-winning scientists Francis Crick and James Watson cracked the genetic code. Their insights began the process by which the structure of DNA was revealed, and we now know that the organisation of DNA itself determines the heritability of characteristics of all living organisms, from single celled bacteria to human beings. With the development of genetics as a science in its own right, dreams of artificially altering the genetic make-up of plants and animals began to emerge. For instance, the elimination of inherited human diseases such as cystic fibrosis, muscular dystrophy and thalassaemia began to be thought a distinct possibility.
Apart from addressing matters of human health, geneticists and the mix of scientists that constitute the life-sciences have expressed the possibility of using genetic techniques to alter or effectively redesign many of the crops and animals upon which human food systems are based. Such possibilities advanced by proponents of gene-editing include, for example, crops altered to achieve characteristics such as pest and disease resistance, drought tolerance, frost tolerance, enhanced nutritional qualities, ability to fix atmospheric nitrogen as fertiliser and to increase yield. Similarly, advocates assert that potential exists to change the genomes of farmed animals for the benefit of the agri-food industry, such as imparting immunity to microbial and viral diseases, enabling resistance to parasitic infection, causing double muscles in meat animals to increase yield and varying milk chemistry in dairy cows to enhance both functional and nutritional properties.
The possibilities to be found in altering the genomes of plants and animals seem almost limitless. Technologies that enable the redesign of species are considered by many government policy-makers, corporate bodies and members of the scientific community to be societally valuable, commercially exciting and morally worthy. Reservations do exist however about the technology and its applications, particularly in relation to unintended consequences for the natural world. These ethical issues are addressed in part two of this series
Gene-editing and CRISPR-Cas9
Gene-editing itself is based on a bacterial antiviral defence mechanism named CRISPR/Cas9, where CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. Genes are formed when chemical compounds known as nucleotides are organised in pairs – adenine (A) pairs with thymine (T) while guanine (G) pairs with cytosine (C) – to create the double helix structure characteristic of DNA. A palindromic repeat occurs when the order of the nucleotides running in one direction on a strand or helix of DNA, is matched by the same nucleotides running in the opposite direction on the other, paired strand.
The Cas9 component of the CRISPR/Cas9 expression is the CRISPR-associated protein 9, which is one of a number of enzymes or nucleases with the ability to open DNA double-helix strands and then cut each in order to insert strands of RNA (ribonucleic acid) so altering genetic function. When a virus infects a bacterial cell, the cell produces two short strands of RNA in response to the detection of viral DNA. One short strand RNA is known as the guide RNA, while the other short strand RNA contains a sequence of bases which match a part of the genome of the invading viral DNA. The two short RNAs form a complex with Cas9 and when the guide RNA finds its target – when it is able to match the other short strand RNA’s gene sequence with a sequence of the viral DNA, i.e. the CRISPR gene sequence – the Cas9 enzyme cuts the viral DNA and the virus is disabled.
The CRISPR-Cas9 mechanism is fundamental to the processes of gene-editing. By mimicking the bacterial mechanism, scientists can alter the genomes and genotypes of organisms to change the nature of expressed traits, or phenotypes. The UK government considers gene-editing effectively to be no different from traditional selective breeding, also known as cross-breeding, which has been used by farmers for thousands of years to change and improve both crops and farmed animals. Indeed, the proponents of gene-editing assert that while the technology can achieve the same ends as traditional selective breeding, the only difference of importance is that gene-editing is said to be more accurate and does the job very much faster.
As a final point on gene-editing as a technology, it should be noted that gene-editing is not the same as genetic modification (GM). Both are forms of genetic engineering in the sense that genomes are engineered to effect desired alterations which change the nature of resultant organisms. However, while gene-editing mainly concerns the alteration of a target organism’s genome without the introduction of alien DNA, i.e. DNA from a different species, GM is a technology that utilises such alien gene transfer. For example, by insertion of genes from the bacterium Bacillus thuringiensis into crop genomes, e.g. maize, brinjal (aubergine or eggplant) and cotton, crop varieties which produce a natural insecticide have been created. Similarly, transgenic crops (alfalfa, canola, cotton, maize, sugar beet, soya, wheat) resistant to the herbicide glyphosate have been engineered by transfer of genes from species of the bacterial genus Agrobacterium.
A food ethics lens
At face value, gene-editing appears to offer myriad possibilities and opportunities to change the nature of plants and animals, thereby benefiting the agricultural and food industries as well as humanity more broadly. However, as with many sciences and technologies, gene-editing is unlikely to be free from risk. Altering the heritable characteristics of living organisms may indeed present unique forms of associated hazard. Gene-editing is then a field within the life-sciences which would appear to demand careful control and a cautious approach, not least by the inclusion of ethical evaluation in all related decision making. In matters of gene-editing in relation to agriculture and food, ethical evaluation may best be undertaken by means of a food ethics lens, as discussed in part two of this series.