RT Journal Article SR Electronic T1 CasFinder: Flexible algorithm for identifying specific Cas9 targets in genomes JF bioRxiv FD Cold Spring Harbor Laboratory SP 005074 DO 10.1101/005074 A1 John Aach A1 Prashant Mali A1 George M. Church YR 2014 UL http://biorxiv.org/content/early/2014/05/12/005074.abstract AB CRISPR/Cas9 systems enable many molecular activities to be efficiently directed in vivo to user-specifiable DNA sequences of interest, including generation of dsDNA cuts and nicks, transcriptional activation and repression, and fluorescence. CRISPR targeting relies on base pairing of short RNA transcripts with their target DNA sequences that must also be adjacent to fixed DNA motifs. However, rules for Cas9 targeting specificity are incompletely known. With increasing numbers of Cas9 systems being developed and deployed in more and more organisms, there is now strong need for a flexible and rational method for finding Cas9 sites with low off-targeting potential. We address this through the CasFinder system, which we demonstrate by generating human and mouse exome-wide catalogs of specific sites for three varieties of Cas9 – S. pyogenes, S. thermophilus (ST1), and N. meningitidis – that each target 56-74% of all exons. We also generate reduced sets of up to 3 targets per gene for use in high-throughput Cas9-based gene knockout screens that target 75-80% of all genes.