The use of CRISPR-Cas9—the genetic editing tool, triggers hundreds of random mutations throughout the genome.
This was discovered by American scientists on carrying out research on a murine genome after modifying one of its genes using the CRISPR-Cas9 tool. They found that although the defective gene had been perfectly and correctly targeted by CRISPR, at the same time it also caused over 1,500 mutations of a nucleotide and over a hundred more significant mutations affecting whole DNA fragments.
Whilst the mutated mice did not show any signs of ill health, the discovery has triggered warning bells and the researchers are asking the scientific community to take the potential danger caused by these uncontrolled mutations into account. They are asking for caution to be exercised when using CRISPR in humans.
"Even a single nucleotide change can have a huge impact", stressed Doctor Stephen H. Tsang, from Columbia University, a co-author of the study. "We feel it's critical that the scientific community consider the potential hazards of all off-target mutations caused by CRISPR".
According to these scientists, these side effects had not been detected because the generally algorithm-based predictive detection methods used did not take whole genome sequencing into account.
"We hope our findings will encourage others [scientists] to use whole-genome sequencing as a method to determine all the off-target effects of their CRISPR techniques and study different versions for the safest, most accurate editing", urges Doctor Tsang.
This request for caution followed the announcement by a Chinese team at Sun Yat-Sen University of a gene-editing study starting next July and using CRISPR-Cas9 directly in the human body.
Usbek et Rica, Vincent Lucchese (02/06/2018)