Unexpected mutations were expected and unrelated to CRISPR-Cas9 activity
The scientific journal Nature Methods have just retracted a publication that reported numerous unexpected mutations after a CRISPR-Cas9 experiment based on collecting whole genome sequencing information from one control and two experimental genome edited mice. In the intervening 10 months since publication the data presented have been strongly contested and criticized by the scientific and biotech communities, through publications, open science channels and social networks. The criticism focused on the animal used as control, which was derived from the same mouse strain as the experimental individuals but from an unrelated sub-colony, hence control and experimental mice were genetically divergent. The most plausible explanation for the vast majority of the reported unexpected mutations were the expected underlying genetic polymorphisms that normally accumulate in two different colonies of the same mouse strain which occur as a result of spontaneous mutations and genetic drift. Therefore, the reported mutations were most likely not related to CRISPR-Cas9 activity.
KeywordsOff target mutations CRISPR Cas9 Safety Genome editing applications Safety Gene therapy
LM’s laboratory is funded through the Spanish Ministry of Economy and Competitiveness (MINECO) [BIO2015-70978] and the Spanish Biomedical Research Networking Centre on Rare Diseases (CIBERER) from the National Institute of Heath Carlos III (Instituto de Salud Carlos III, ISCIII). A timeline of the events and publications around this case can be easily followed from the corresponding section at the CRISPR web page at CNB-CSIC (http://wwwuser.cnb.csic.es/~montoliu/CRISPR/). CBAW is funded by the Biotechnology and Biological Research Council (BBSRC) through ISP support to The Roslin Institute.
- Begley S (2017) CRISPR stocks sank on news the gene editing tool can veer off target. But that’s hardly news. STAT 30 May 2017. https://www.statnews.com/2017/05/30/crispr-stocks-off-target/. Last accessed 6 Apr 2018
- Burgio G (2017) Should we be worried about CRISPR/Cas9 off target effects? Medium blog (https://medium.com) 3 June 2017. https://medium.com/@GaetanBurgio/should-we-be-worried-about-crispr-cas9-off-target-effects-57dafaf0bd53. Last accessed 6 Apr 2018
- Uchimura A, Higuchi M, Minakuchi Y, Ohno M, Toyoda A, Fujiyama A, Miura I, Wakana S, Nishino J, Yagi T (2015) Germline mutation rates and the long-term phenotypic effects of mutation accumulation in wild-type laboratory mice and mutator mice. Genome Res 25:1125–1134. https://doi.org/10.1101/gr.186148.114 CrossRefPubMedPubMedCentralGoogle Scholar
- Wilson CJ, Fennell T, Bothmer A, Maeder ML, Reyon D, Cotta-Ramusino C, Fernandez CA, Marco E, Barrera LA, Jayaram H, Albright CF, Cox GF, Church GM, Myer VE (2018) Response to “Unexpected mutations after CRISPR-Cas9 editing in vivo”. Nat Methods. https://doi.org/10.1038/nmeth.4552 PubMedGoogle Scholar