CRISPR Gene Editing Used on Mammals for the First Time

For the first time ever, a controversial gene editing technique has been used on mammals. A new research was recently published that details how one team is developing gene drives that could be used to eliminate certain animal populations using a CRISPR technique. 

The technique would work by ensuring that specific mutations are passed to an animal's offspring. This would give researchers the ability within one or two generations of animals to kill off invasive species entirely. The technique was already used on mosquitoes in a lab setting, as a potential solution to control malaria. 

However, the new study isn't perfect. The technique gave researchers inconsistent results when used on the technique's first ever mammal species -- lab mice. There are also a number of tools that need to be considered and perfected before a team would ever use it in a natural setting. 

“There’s an indication it could work, but it’s also sobering,” said Paul Thomas, a development geneticist at the University of Adelaide in Australia, who was not involved in the research. “It’s a lot longer to go where you could consider gene drives for a useful tool for population control of rodents.”

Thomas's work with the University of Adelaide covers similar research and specifically deals with invasive rodent species. 

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Gene drives help guarantee that a large portion of an organism's offspring will get a 'selfish gene.' Normally, that would happen entirely by chance, but the genetic editing gives the mutated or foreign gene the ability to quickly spread throughout a population. These genes do occur naturally in certain animals (like mice), and they can lead to death or infertility within a species. 

Given the latest advances with the CRISPR-Cas9 gene editor, those types of genes can be made in a laboratory setting. These synthetic gene drives are the ones used to eradicate problematic species like mosquitoes that transmit malaria. 

The team from University of Calfornia San Diego didn't attempt their gene drive to promote infertility in lab rats. Their goal was to only see if the process would work. Thus, they wanted to see if they could develop an inheritance for mice of all-white coats -- not the detrimental 'selfish' genes. They used the CRISPR-based gene drive to copy a mutation on one chromosome to the second of a pair during an animal's early development. 

The UC San Diego team attempted this process on the mice and noted that the mutation did not always copy correctly and it only successfully worked on female embryos. The team estimated that the mutation would be transmitted to 73 percent of female mice's offspring. 

The UC San Diego team has yet to comment on their work. According to Kim Cooper, a developmental geneticist who led the group, they haven't made statements about the work because it hasn't been published in a peer-reviewed journal.