New CRISPR editing tool could potentially fix 89% of genetic variations in human diseases

Scientists have raised fresh hopes for treating people with genetic disorders by inventing a powerful new molecular tool that, in principle, can correct the vast majority of mutations that cause human genetic diseases.

The procedure, named “prime editing”, can mend about 89% of the 75,000 or so harmful mutations known to mangle the human genome and lead to conditions such as thalassaemia, sickle cell anaemia, and cystic fibrosis.

The landmark work opens the door to a new era of genome editing, but scientists caution that more research is needed before it can be safely used in humans. Beyond proving its safety, another major hurdle is how to deliver the molecular machinery to cells that need it in sufficient amounts to treat a disorder.


“This first report of prime editing is the beginning rather than the end of a longstanding aspiration in the life sciences to be able to make any DNA change in any position of a living cell or organism, including potentially human patients with genetic diseases,” said David Liu at the Broad Institute of MIT and Harvard in Cambridge, Massachusetts.

Writing in the journal Nature, the scientists describe how they made 175 different DNA edits to human cells with impressive precision. In one demonstration, they corrected mutations that cause the inherited blood disorder, sickle cell anaemia. In another, they removed the four extra DNA letters in a particular gene that cause Tay-Sachs disease, a rare condition that destroys children’s nerves and usually proves fatal by five years old.

Before prime editing, it was impossible to make such a range of DNA changes in so many different cell types without leaving behind insertions, deletions and other genetic detritus that can interfere with the workings of the edited cell.

“You can think of prime editors as being like word processors capable of searching for target DNA sequences and precisely replacing them with edited DNA sequences,” Liu said. “Potential impacts include being able to directly correct a much larger fraction of the mutations that cause genetic diseases, and being able to introduce DNA changes into crops that result in healthier or more sustainable foods.

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Sources: Guardian, Nature

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