This December, as it does each year, the journal Science announced the top science breakthrough of the past year.
This December, as it does each year, the journal Science announced the top science breakthrough of the past year. Its chosen breakthrough for 2015 was the CRISPR genome-editing technology I discussed in my September and November columns. The reason for this choice was partially the topic of my two previous columns: the potential to change our human genome, as well as its impact in other areas of biology. These uses of CRISPR have raised questions about its impact and long-term consequences across all of biology.
The CRISPR technique has many other uses that can have long-term benefits for all. With plants two uses of CRISPR are being explored: longer-lasting tomatoes and allergen-free peanuts, both hopefully without any changes to their taste, but perhaps its most interesting use that is currently being explored is in the insect world.
A number of years ago, in a column on mosquitoes and their place in God’s creation, I argued that we might be better off with no mosquitoes in the world. One reason for this stance is the role of mosquitoes in spreading malaria in much of the world, a disease killing about 438,000 people a year, mostly children. The costs of this illness, both in health care and due to lost productivity, are staggering. Without mosquitoes to infect humans, this disease would largely disappear.
Now CRISPR may make my dream possible! Laboratory researchers have been able to use CRISPR to edit the genome of mosquitoes so that they are no longer able to harbour malaria parasites. This change would break the life cycle of malaria, because it requires a phase in mosquitoes before being passed on to humans through mosquito bites.
CRISPR has also been used to test and develop genetic manipulations that render the female mosquito infertile; these manipulations would wipe out all mosquitoes. To make these changes work, the biologists put the CRISPR-induced changes close to genetic DNA elements called “selfish” because they copy themselves from one place to the other on the genetic chromosome. The CRISPR-induced changes, being closely linked to these “selfish” genes, are driven through the population very quickly and expressed in all members of the species within a very few generations. An experiment in fruit flies using what has been called the mutagenic chain reaction technique achieved 97 percent transmission of a new genetic element in one generation. With this mutagenic chain reaction, the infertility of a female mosquito would spread very quickly through the whole population and ultimately wipe out all mosquitoes.
All possible outcomes
The discussion now is whether we should move this technology beyond the laboratory and release such modified mosquitoes into the wild, making the change occur in all mosquitoes. What are the risks and possible unintended consequences of such a release? On the positive side, these genetic modifications would be a clear benefit to humans currently plagued with malaria, largely the poor with little opportunity to avoid the disease. But, on the negative side, we are aware that human changes, such as introducing foreign species into new ecosystems, can bring adverse consequences, both deliberate and accidental. Think, for example, of the introduction of rabbits in Australia or the effects of the Asian long-horned beetle in Canada and the United States. It is critical to explore any possible outcomes as fully as possible before engaging in actions we may not be able to reverse. It is possible that we are not aware of some benefits mosquitoes have in the real world.
As Christians we have been charged with caring for God’s creation, and we have long been active in changing aspects of our world, hopefully for the better. For example, farmers have increase in grain yields using tradition cross-breeding procedures, resulting in more food for all. The use of CRISPR simply continues this technique, perhaps more efficiently.
Another principle worth considering is to make our changes as small as is necessary to achieve our longer-term goals. We know that DDT, while effective in fighting mosquitoes, also had other adverse effects. With the mosquito we have a choice between making the mosquito unable to transmit malaria and making females infertile, thereby wiping out mosquitoes completely. The better choice may be making mosquitoes malaria-proof but continuing to live with mosquito bites.
It is thus not surprising that CRISPR is Science’s breakthrough of 2015. Pray that we may use this powerful technology wisely.