Gene drives

Nuclear fission – the process that underpins nuclear power and nuclear weapons – relies on the huge amount of energy it produces in a chain reaction; rather like the feedback screech you get when a microphone is placed too close to a speaker it’s connected to via an amplifier.

Before the first creation of nuclear fission in the laboratory, some theorists thought that creating such a chain reaction could result in the Earth’s destruction because they weren’t sure how it could be contained.

This was an extreme case of an innovation that carried a risk, but all innovations are like this to greater or lesser extents. Innovation is about stepping in to the unknown. In the case of nuclear fission, the probability of the chain reaction becoming global was assessed as extremely low, but people’s appetite for risk is changing.

This is evident in the public reaction to many of the issues Defra is responsible for. The technology used to genetically modify organisms is one long-standing issue where there is considerable public interest in the risks. While there is little, if any, reliable evidence of negative environmental and human health effects of genetic modification, despite exhaustive searching, we have to be aware that the technologies being used to change the genetic constitution of organisms are themselves evolving. Genetic modification has demonstrable benefits – many in the area of medical genetics and the manufacture of new medicines but also importantly in agriculture – provided it is used wisely.

One of the latest innovations in genetic techniques involves something called ‘gene drives’ which we’ve heard quite a lot about in the press recently. These allow the rapid spread of genetic traits through populations similar to a chain reaction. Used wisely, they could be a powerful tool for the rapid spread of beneficial traits through populations of organisms, for example to render wild mosquitos incapable of transmitting deadly diseases such as dengue fever and malaria.

For some this will conjure up fears of genes being released and propagating themselves through whole populations and getting out of control. Doubtless what can be a powerful force for good can also be a powerful force for bad, but there are a few facts to bear in mind before we start to worry.

Firstly, they cannot be used in viruses or bacteria because they can only spread within organisms that reproduce sexually. This means they could not be used to worsen, or mitigate, some of the most deadly disease. Secondly, the rate of spread depends entirely on the reproductive rate of the organism concerned. This means that for long-lived organisms like humans, bats, albatrosses, elephants and whales it would take hundreds or perhaps thousands of years for the genes to spread. For species like flies and many plants, including crops, the rate of spread through the population would be much quicker. Third, gene drives are relatively easy to detect so they could be regulated.

However, to my way of thinking the most important feature of gene drives is that they already occur in nature, but they are not very common. This is really good news; it looks as if the equivalent of gene drive chain reactions are very unlikely, and some of the more extreme scenarios that people might conjure up become quite improbable.

Evolution has a way of weeding out or ignoring genetic mechanisms that do not confer a long-term advantage. Scientists know little about how to engineer organisms for evolutionary robustness. Knowing more about how these kinds of traits are maintained in natural populations would be essential to develop the best strategy for stopping gene drives from dying out. Getting gene drives to work may be quite difficult.

So while the down side is that gene drives are probably not as powerful as we first thought, but the up side is that this means they are less likely to create problems that get out of control. So to render mosquitos incapable of transmitting malaria would probably require a long-term effort involving multiple releases of gene drives to prevent the desired characteristic dying out prematurely.

Any new technology needs to be treated with great care and researchers take the need for caution very seriously. However, while planning for the worst case is sensible, just because we are careful in the face of uncertainty doesn’t mean that these worst case risks will necessarily materialise. Like the nuclear fission that brings the UK about one-third of its electricity, genetic engineering technologies are now a part of our every-day existence.

The recently developed ebola vaccine – probably a game-changer for managing that devastating disease – would not have been possible without genetic engineering.  We have a well-developed system of regulation in the UK and across Europe so we can be assured that as technological innovations spring up, they are considered in a balanced and proportionate manner.

For example, Defra operates a committee of independent experts, the Advisory Committee on Releases to the Environment, to advise ministers on any proposals to use genetically modified organisms in the wider environment. This would obviously include gene drive technologies. In addition, we have a legislature that is active in these areas and is highly informed. The House of Lords Select Committee on Science and Technology announced a few weeks ago that it was to conduct an inquiry in to genetically modified insects.

Our society is built upon the technological inventions of past generations. If gene drives are to become a part of this story they have a long way to go but, at the very least, we should welcome the potential they bring to help solve some of the world’s most pressing problems.

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