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sgRNAcas9: A Software Package for Designing CRISPR sgRNA and Evaluating Potential Off-Target Cleavage Sites

                                                                             

       Although the CRISPR/Cas9/sgRNA system efficiently cleaves intracellular DNA at desired target sites, major concerns remain on potential “off-target” cleavage that may occur throughout the whole genome. In order to improve CRISPR-Cas9 specificity for targeted genome editing and transcriptional control,  we describe a bioinformatics tool “sgRNAcas9”, which is a software package developed for fast design of CRISPR sgRNA with minimized off-target effects.


         This package consists of programs to perform a search for CRISPR target sites (protospacers) with user-defined parameters, predict genome-wide Cas9 potential off-target cleavage sites (POT), classify the POT into three categories, batch design oligonucleotides for constructing 20-nt (nucleotides) or truncated sgRNA expression vectors, extract desired length nucleotide sequences flanking the on- or off-target cleavage sites for designing PCR primer pairs to validate the mutations by T7E1 cleavage assay. Importantly, by identifying potential off-target sites in silico, the sgRNAcas9 allows the selection of more specific target sites and aids the identification of bona fide off-target sites, significantly facilitating the design of sgRNA for genome editing applications (https://sourceforge.net/projects/sgrnacas9/).