Just How Safe Is Gene Editing? New Research Claims CRISPR Is More Accurate Than We Thought

Credit: Shaury Nash
Credit: Shaury Nash

Gene editing has incredible potential and could give us an unprecedented control of the biological world. The newest addition CRISPR offers unprecedented speed and ease, but there have been questions over its accuracy and reliability. New data hints we can relax a little; it’s safer than we thought.

A brief overview of CRISPR

CRISPR has made gene editing big news in very little time. While it may not be the most accurate method, the system is customisable, cheap and fast and has clear advantages over its predecessors. The system is essentially made of two parts: an enzyme called Cas9 which snips the target DNA sequence, and a guiding sequence made up of RNA which binds to a matching DNA sequence. The system also needs a small 3 letter sequence called PAM, which is required next to the site for Cas9 to cut. Together these can accurately target a specific sequence in the genome, allowing you to make tiny changes or insert a new sequence by hijacking the cell’s own repair systems.

A diagram of the CRISPR-Cas9 complex Credit: Horizon Discovery
A diagram of the CRISPR-Cas9 complex Credit: Horizon Discovery

A cautious beginning

CRISPR has shown promising results in laboratory settings, but researchers have been cautious about moving onto humans, due to fears the complex may cut other sites and cause unwanted mutations elsewhere. While CRISPR is an accurate system, the human genome is enormous and even one off-target snip could cause problems.

Some good news

Because of these remaining fears and questions, researchers from UC Berkeley including the co-discoverer of CRISPR Jennifer Doudna, set to analyse and test just how accurate the CRISPR-Cas9 system actually is.

Their new report lays out how CRISPR scans billions of base pairs to find its target, and that the Cas9 enzyme has at least 3 check points before it can cut – meaning the system is much more reliable and accurate than was feared. This is potentially great news for the field.

“CRISPR-Cas9 has evolved for accurate DNA targeting, and we now understand the molecular basis for its seek-and-cleave activity, which helps limit off-target DNA editing”