CRISPR gene editing can cause hundreds of unintended mutations

CRISPR-associated protein Cas9 (white) through Staphylococcus aureus based on Protein Database ID 5AXW. Credit: Thomas Splettstoesser (Wikipedia, CC BY-SA 4.0)

As CRISPR-Cas9 starts to move into clinical trials, a brand new study published in Nature Methods has found of which the gene-editing technology can introduce hundreds of unintended mutations into the genome.


“We feel of which’s critical of which the scientific community consider the potential hazards of all off-target mutations caused by CRISPR, including single nucleotide mutations in addition to mutations in non-coding regions of the genome,” says co-author Stephen Tsang, MD, PhD, the Laszlo T. Bito Associate Professor of Ophthalmology in addition to associate professor of pathology in addition to cell biology at Columbia University Medical Center in addition to in Columbia’s Institute of Genomic Medicine in addition to the Institute of Human Nutrition.

CRISPR-Cas9 editing technology—by virtue of its speed in addition to unprecedented precision—has been a boon for scientists trying to understand the role of genes in disease. The technique has also raised wish for more powerful gene therapies of which can delete or repair flawed genes, not just add brand new genes.

The first clinical trial to deploy CRISPR can be currently underway in China, in addition to a U.S. trial can be slated to start next year. although even though CRISPR can precisely target specific stretches of DNA, of which sometimes hits different parts of the genome. Most studies of which search for these off-target mutations use computer algorithms to identify areas most likely to be affected in addition to then examine those areas for deletions in addition to insertions.

“These predictive algorithms seem to do a Great job when CRISPR can be performed in cells or tissues in a dish, although whole genome sequencing has not been employed to look for all off-target effects in living animals,” says co-author Alexander Bassuk, MD, PhD, professor of pediatrics at the University of Iowa.

within the brand new study, the researchers sequenced the entire genome of mice of which had undergone CRISPR gene editing within the team’s previous study in addition to looked for all mutations, including those of which only altered just one nucleotide.

The researchers determined of which CRISPR had successfully corrected a gene of which causes blindness, although Kellie Schaefer, a PhD student within the lab of Vinit Mahajan, MD, PhD, associate professor of ophthalmology at Stanford University, in addition to co-author of the study, found of which the genomes of two independent gene therapy recipients had sustained more than 1,500 single-nucleotide mutations in addition to more than 100 larger deletions in addition to insertions. None of these DNA mutations were predicted by computer algorithms of which are widely used by researchers to look for off-target effects.

“Researchers who aren’t using whole genome sequencing to find off-target effects may be missing potentially important mutations,” Dr. Tsang says. “Even just one nucleotide change can have a huge impact.”

Dr. Bassuk says the researchers didn’t notice anything obviously wrong with their animals. “We’re still upbeat about CRISPR,” says Dr. Mahajan. “We’re physicians, in addition to we know of which every brand new therapy has some potential side effects—although we need to be aware of what they are.”

Researchers are currently working to improve the components of the CRISPR system—its gene-cutting enzyme in addition to the RNA of which guides the enzyme to the right gene—to improve the efficiency of editing.

“We wish our findings will encourage others to use whole-genome sequencing as a method to determine all the off-target effects of their CRISPR techniques in addition to study different versions for the safest, most accurate editing,” Dr. Tsang says.

The paper can be titled, “Unexpected mutations after CRISPR-Cas9 editing in vivo.” Additional authors are Kellie A. Schafer (Stanford University), Wen-Hsuan Wu (Columbia University Medical Center), in addition to Diana G. Colgan (Iowa).


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More information:
Unexpected mutations after CRISPR-Cas9 editing in vivo, Nature Methods (2017).

Journal reference:
Nature Methods

Provided by:
Columbia University Medical Center

CRISPR gene editing can cause hundreds of unintended mutations

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