Gene Drives: Experience with gene drive systems that may inform an environmental risk assessment

In 2015, several papers were published on genetically modified organisms with a CRISPR-Cas based ‘gene drive’ system. These papers described a ‘gene drive’ system which could spread very efficiently through populations and species. Because of this, some concluded that the escape of an individual with a CRISPR-gene drive from a laboratory would inevitably lead to the alteration or suppression of an entire population or species. Others doubted whether gene drives would be able to spread efficiently through natural populations.

Natural gene drive systems have been described in many organisms. For decades, these gene drive systems have been studied to see if they could be used to control insects. COGEM commissioned a research project on the experiences and knowledge obtained on these natural gene drive systems and on ‘synthetic’ gene drive systems, such as CRISPR-gene drives. The research project was carried out by Perseus BVBA.

Their research showed that the majority of gene drive systems were only studied in the laboratory. A limited number of field trials was carried out. In these field trials, the target population was never fully replaced or suppressed, and the gene drives did not spread to other populations.

‘Synthetic’ CRISPR-gene drives are very efficient in the laboratory, but they have not yet been studied in the field. Due to the mode of action of CRISPR-gene drives, organisms may easily become resistant to them. Resistance against the CRISPR-gene drive was observed in several laboratory experiments. In addition, due to genetic variability, organisms that are naturally resistant may already be present in wild populations

The researchers conclude that the concern that potent gene drives, once released, would inevitably lead to the suppression or replacement of all wild-type individuals should be nuanced.