A new method for gene editing, called prime editing, offers greater control over modifications and could be safer for use in humans than the widely popular CRISPR-Cas9 system.
CRISPR systems have revolutionised gene editing since their applications were realised in 2012. So much so, the CRISPR-Cas9 system (one of the most often used systems) has been used in research on human embryos since 2015 and the world’s first CRISPR-modified babies were born in 2018. However, the CRISPR-Cas9 system is less effective in certain regions of the genome, is error-prone, and often results in unintended, or ‘off-target’, effects (where other areas of the genome are modified). For example, the modifications were only partially successful in the CRISPR-edited babies.
The latest advance, published in Nature on the 21st October, uses an adapted CRISPR-Cas9 system to bypass these limitations. The lead author of the study, David Liu, estimates that prime editing could help tackle almost 90% of the 75,000 known disease-associated DNA variants listed in the public database ClinVar. Prime editing, therefore, opens up a wealth of previously intractible genetic manipulations.
Prime editing is the latest advance amongst many in gene editing technologies. The breadth and precision of mutations that this new system is capable of is beyond any of its predecessors. “This first study is just the beginning — rather than the end — of a long-standing aspiration in the life sciences to be able to make any DNA change at any position in an organism,” says Liu.
Yet the bioethics debate surrounding the use of CRISPR is raging in the wake of multiple researchers across the world currently researching its applications in human embryos despite a moratorium being called for in March 2019 (this is not the first time a moratorium has been called for).
The precision offered by prime editing could see its use in future human embryo modification, but the global scientific community need to agree if this area of research should be allowed to continue and under what circumstances and regulations.