Erratum to: Guide Picker is a comprehensive design tool for visualizing and selecting guides for CRISPR experiments

Engineering Point Mutant and Epitope-Tagged Alleles in Mice Using Cas9 RNA-Guided Nuclease

Mice carrying patient-associated point mutations are powerful tools to define the causality of single-nucleotide variants to disease states. Epitope tags enable immuno-based studies of genes for which no antibodies are available. These alleles enable detailed and precise developmental, mechanistic, and translational research. The first step in generating these alleles is to identify within the target sequence-the orthologous sequence for point mutations or the N or C terminus for epitope tags-appropriate Cas9 protospacer sequences. Subsequent steps include design and acquisition of a single-stranded oligonucleotide repair template, synthesis of a single guide RNA (sgRNA), collection of zygotes, and microinjection or electroporation of zygotes with Cas9 mRNA or protein, sgRNA, and repair template followed by screening of born mice for the presence of the desired sequence change. Quality control of mouse lines includes screening for random or multicopy insertions of the repair template and, depending on sgRNA sequence, off-target mutations introduced by Cas9. © 2018 by John Wiley & Sons, Inc.

Exploiting off-targeting in guide-RNAs for CRISPR systems for simultaneous editing of multiple genes

Bioinformatics tools to design guide-RNAs (gRNAs) in Clustered Regularly Interspaced Short Palindromic Repeats systems mostly focused on minimizing off-targeting to enhance efficacy of genome editing. However, there are circumstances in which off-targeting might be desirable to target multiple genes simultaneously with a single gRNA. We termed these gRNAs as promiscuous gRNAs. Here, we present a computational workflow to identify promiscuous gRNAs that putatively bind to the region of interest for a defined list of genes in a genome. We experimentally validated two promiscuous gRNA for gene deletion, one targeting FAA1 and FAA4 and one targeting PLB1 and PLB2, thus demonstrating that multiplexed genome editing through design of promiscuous gRNA can be performed in a time and cost-effective manner.