Text and Data Mining valid from 2018-06-04
Received: 4 April 2018
Accepted: 16 May 2018
First Online: 4 June 2018
Change Date: 23 August 2018
Change Type: Correction
Change Details: In Supplementary Fig. 1b originally published with this Brief Communication, the DNA sequence of nickase Cas9 was incorrect; this has now been amended.
: J.-S.K. is a co-founder of and holds stocks in ToolGen, Inc. All other authors declare no competing interests.