by GMWatch


As a new study reveals that hundreds of unintended mutations were induced in mice by a genome editing technique, GMWatch asks what the implications are for the safety of genome-edited food products

A new study published in Nature Methods has found that the genome editing technology CRISPR introduced hundreds of unintended mutations into the genome of mice.

In the study, the researchers sequenced the entire genome of mice that had undergone CRISPR gene editing to correct a genetic defect. They looked for all mutations, including those that only altered a single nucleotide (DNA base unit).

They found that the genomes of two independent gene therapy recipients had sustained more than 1,500 single-nucleotide mutations and more than 100 larger deletions and insertions. None of these DNA mutations were predicted by the computer algorithms (software packages) that are widely used by researchers to screen the genome (the total DNA base unit sequence) of an organism to look for potential off-target effects.

While this study was conducted in the arena of gene therapy, it has clear implications for the regulation of food plants and animals derived from CRISPR and other genome editing techniques.

Regulatory agencies across the world are currently engaged in a debate about how to assess genome-edited products for safety. Many GMO proponents are proposing “light-touch” regulation or even no regulation at all, based on the assumption that the outcome genome editing techniques like CRISPR are precise, predictable, and therefore safe.

The new study shows that this assumption is false. So how should these products be regulated?

One suggestion that has been put forward is to require whole genome sequencing of gene-edited organisms to be conducted and submitted to biosafety authorities.

But this raises a further question: if the whole genome sequence does not show any mutations or off-target effects, other than those intended, should we be reassured?

We asked Dr Michael Antoniou to comment. Dr Antoniou is a London-based molecular geneticist who uses genetic engineering techniques, including genome editing, to develop gene therapies.

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