News, Technology

Why even scientists sweat over the implications of gene drives

Anna Wall

Amie Haven, Journalist

It’s the pesky unknowns that keep CRISPR scientists up at night, as they ponder the release of mosquitos with gene drives designed to prevent the spread of malaria.

Are the benefits worth the potential risks? How can the risks be mitigated? These are questions that scientists take very seriously as they consider using gene drives in mosquitos to prevent the spread of malaria.

Speaking to Nature, molecular biologist and bioethicist Natalie Kofler points out the unknown unknowns are the reason that this powerful technology should only progress with great care, respect, consultation, and awareness.

But the potential benefit of this technology cannot be underestimated. The WHO reported that in 2017, there were 219 million reported cases of malaria across 87 countries. 

Africa is worst hit, with 92% of cases occurring in African countries – and it is often the children, the elderly, and the sick who are most affected. 

Certain species of female mosquito spread malaria through their bite, massively increasing infection rates in countries with high mosquito populations.

Scientists want to use CRISPR technology to possibly wipe out the mosquito or use more subtle techniques to activate gene drives only in those mosquitoes carrying a disease.

What are gene drives and how are they used?

Gene drives use CRISPR technology to increase the chances of edited genes being taken up in the offspring of mosquitos. 

If only one parent has the modified gene, the gene drive will be passed down to the offspring via one chromosome. 

The CRISPR technology will then edit the inherited gene of the non-modified parent whilst repairing it using the drive of the modified chromosome as a guide – creating matching gene modifications. 

The result is an increase in gene drive inheritance. 

Can gene drives be stopped? 

Cautious scientists and wary US government officials have made sure that the current research always has external overrides or in-built failsafe mechanisms as a ‘just in case’ precaution. 

Due to the unknown implications of this technology and fears over malicious use, scientists have devised ways of gradually degrading the technology, so it disappears over generations.

But despite these precautions, the technology is still 3 years away from being tested in the field. 

For now, scientists are creating complex testing environments that can allow them to see what happens to the modified mosquitos as they experience different climates and conditions.

Social and ecological implications

Once the technology is ready, Africa is the most logical starting point for field testing. 

However, Natalie Kofler of Yale University’s Editing Nature group points out that Western scientists using African countries as test sites is not an appropriate way to introduce the technology.

Fredros Okumu, director of science at the Ifakara Health Institute in Tanzania, believes that African countries need to be able to make their own decisions about the use of this technology. 

Okumu wants to encourage African scientists to work with gene drives so that the African people feel a sense of local trust before they accept its use. 

Incidently, Kofler also points out that wiping out mosquitoes may not actually work and could even make things worse. 

Malaria may simply adapt and become more virulent in an attempt to survive.

But whatever precautions are taken, however much trust is built, the implications of altering the genes of mosquitos or wiping them out are as yet unknown. 

In 3 years’ time this technology may be released into the wild and humanity could be jumping off a cliff with no parachute. 

Human curiosity and scientific endeavour can be a beautiful thing, so let’s hope it proves to be the case with gene drives.

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