While no releases of modified organisms carrying gene drives have yet taken place, the development of such ‘gene drive organisms’ is advancing closer to this step. Crucial questions, however, remain unanswered. For example, if released in the wild, could the spread of synthetic gene drives be contained? How could the impact on ecosystems be predicted or monitored? If there are unanticipated harmful effects, could wild populations be restored to their original genetic makeup? Could synthetic gene drives ‘jump’ into other species? Given that gene drive organisms would likely carry active CRISPR-Cas DNA cutters, how might such organisms change over multiple generations? And, given the complexity of biological systems involved, how great is the potential for harmful outcomes that we completely fail to anticipate?
Owing to these concerns, and others, the technology remains highly controversial, with many researchers and communities arguing, that the risks make a moratorium on releases of gene drive organisms essential.