The term “gene drive” refers to a process by which a genetic trait can spread within a population more quickly than would be expected through natural selection. There are naturally-occurring genes that show drive, and biologists are working to develop synthetic modifications that show drive. Because the trait increases in frequency over successive generations, the techniques are particularly applicable to fast reproducing species.
How does it work?
Gene drive allows the amplification of a genetic trait so that it becomes prevalent in a specific species or population. The genes responsible for the drive can be viewed as “artificial/synthetic selfish DNA” systems.
The rules of normal evolution allow for a gene or trait to be passed on through a population when it has a beneficial effect. Gene drive subverts this by spreading the gene(s) rapidly even if they don’t confer an evolutionary advantage – and indeed, even if they cause some disadvantage.
Generally speaking, in sexually reproducing organisms where a parent has two different versions of a gene, each has have a 50% chance of being inherited, as each member of the next generation inherits only one copy from each parent. With drive this can be increased to up to 100%.
Use of gene drive to modify wild populations was first suggested in 19681, but technology which would enable realisation of this suggestion is only recently sufficiently advanced. Meganucleases were suggested for this purpose in 20032, and a number of techniques may be applicable of which the CRISPR-Cas9 system is one of the most easily engineered.
Why might it be useful?
It has been suggested that the technology may be applied in pest and disease control, for instance when used to genetically engineering mosquitoes which carry malaria, Dengue fever and West Nile virus.
With gene drive techniques it may be possible to engineer insects so that they can no longer carry the disease or so that they are sterile and hence bring about a population crash.
In a similar manner the techniques have been suggested to introduce and propagate defects in an invasive species population, and hence reduce or eliminate the organism from the affected area.
It is likely that some species will prove easier to engineer than others, and current scope for applications in slower reproducing species is more limited.
Why is it controversial?
Genetic engineering of plants and animals has long been an area of dispute, especially when it comes to modification of populations in the wild. Effects on the specific species as well as their ecosystem would need to be carefully examined and monitored.
Some worry that off-target effects will produce unexpected consequences which cannot be controlled once in the wild, whether such technology was released intentionally or not.
As with many technologies there are concerns about so-called “dual-use” by which gene drives could be put to malicious ends, such as creating pesticide resistant populations.
Because of such concerns some have suggested that inclusion of safeguards to control engineered populations or erase the mutation is necessary, a process which has reported to have been made possible in yeast3.
Alphey, L. (2014) “Genetic Control of Mosquitoes.” Annual Review of Entomology59: 205-224.
James, A. A. (2005) “Gene drive systems in mosquitoes: rules of the road.” Trends in Parasitology21(2): 64-67
Oye, K. A., et al. (2014) “Regulating gene drives.” Science345(6197): 626-628.
This is a Factsheet issued by the Science Media Centre to provide background information on science topics relevant to breaking news stories. This is not intended as the ‘last word’ on a subject, but rather a summary of the basics and a pointer towards sources of more detailed information. These can be read as supplements to our Roundups and/or briefings.