The next generation of genetic modification technologies will not simply introduce lab-fine-tuned genes into organisms, but target and remove specific natural genes with lab-fine-tuned genes. Such technologies are called gene drives .
If an animal that contains a gene drive (Parent A) mates with an animal that does not (Parent B), the gene drive from Parent A will immediately kick in in an embryo that combines their genetic material. It recognizes its native version of the gene in parent B’s chromosomes and destroys it—cutting it out of the DNA strand. Parent B’s chromosome then repairs itself — but replicates parent A’s gene drive. So the embryo and the resulting offspring are almost guaranteed to have the gene drive, rather than the 50 percent chance of a standard transgene—because the embryo gets half the genes from each parent. Gene drives can be created by adding the gene editing technology Crispr to genes. This tells it to target a natural version of itself in the DNA of the other parent in the new embryo. Gene drives also contain an enzyme that does the actual cutting.
We hope that gene drives can be used to drastically reduce the number of Anopheles mosquitoes and other pests or invasive species. One group at the forefront is Target Malaria, which has developed gene drives that prevent mosquitoes from producing female offspring. This is important for two reasons – only female mosquitoes bite, and without females, mosquito populations plummet. Its core goal is to drastically reduce the number of people dying from malaria, which according to the World Health Organization will be 627,000 in 2020 – a sad number. It could also lessen the economic impact of the disease. With 241 million cases in 2020, mainly in Africa, malaria is estimated to cost the continent $12 billion in lost economic output annually.
American biologist and MIT assistant professor Kevin Esvelt is one of the pioneers in the development of gene drives in the world. He first proposed the technology in 2013. Professor Esvelt said the technology is provided in a way called “daisy chain”. In this way, gene drives are designed to stop working after a few generations. Or the chance of transmission is halved each generation until it eventually stops. Using this technique, he said, the spread of gene drives could be controlled and isolated. “GMOs with restrictions can be released in one town to alter the population of (specific organisms) while minimizing the impact on neighbouring towns,” he said.
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