Gene drives

In genetics, gene drive is the phenomenon in which the inheritance of a particular gene or set of genes is favorably biased. Gene drive can arise through a variety of mechanisms and results in its prevalence increasing in a population. Engineered gene drives have been proposed to provide an effective means of genetically modifying populations or even whole species.

Applications of gene drive include preventing the spread of insects that carry pathogens (in particular, mosquitoes that transmit malaria, dengue, and zika pathogens), controlling invasive species, or eliminating herbicide or pesticide resistance. The technique can be used for adding, disrupting, or modifying genes, such as to cause a crash in the populations of a disease vector by reducing their reproductive capacity.

Several molecular mechanisms can mediate gene drive. Naturally occurring gene drive mechanisms arise when alleles evolve molecular mechanisms that give them a transmission chance greater than the normal 50%. Synthetic genetic modules with similar properties have been developed as a technique for genome editing of laboratory populations. This entry focuses on endonuclease-based gene drive, the most versatile and actively developing molecular backend for synthetic gene drives. Since gene drives function only in sexually reproducing species, they cannot be used to engineer populations of viruses or bacteria.

Because it is a way to artificially bias inheritance of desired genes, gene drive constitutes a major change in biotechnology. The potential impact of releasing gene drives in the wild raises major bioethical concerns regarding their development and management.

In sexually-reproducing species, most genes are present in two copies (which can be different alleles or not), each of which has a 50% chance of being inherited. For a particular allele to spread through a large population, it must increase the fitness of each individual. However, some alleles have evolved molecular mechanisms that confer on them a greater transmission chance than the normal 50%. This allows them to spread through a population even if they reduce the fitness of each individual organism. By similarly biasing the inheritance of particular altered genes, synthetic gene drives might be used to spread alterations through wild populations.

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