AsCRISPR: a web server for allele-specific sgRNA design in precision medicine

Abstract

Allele-specific targeting by CRISPR provides a point of entry for personalized gene therapy of dominantly inherited diseases, by selectively disrupting the mutant alleles or diseasecausing single nucleotide polymorphisms (SNPs), ideally while leaving normal alleles intact. Despite unprecedented specificity and tremendous therapeutic utility of allelespecific targeting by CRISPR, few bioinformatic tools have been implemented for the allele-specific purpose. We thus developed AsCRISPR (Allele-specific CRISPR), a web tool to aid the design of guide sequences that can discriminate between alleles. It can process with query sequences harboring single-base or short insertion-deletion (indel) mutations, as well as heterozygous SNPs deposited in the dbSNP database. Multiple CRISPR nucleases and their engineered variants including newly-developed Cas12b and CasX are included for users' choice. AsCRISPR provides the downloadable results of candidate guide sequences that may selectively target either allele. Meanwhile, AsCRISPR evaluates the on-target efficiencies, specificities and potential off-targets of those candidates, and also displays the restriction enzyme sites that might be disrupted upon successful genome edits. Other than designing allele-specific guide sequences for treating diseases, AsCRISPR could also be exploited to help studying the potential functions of genetic variants at certain gene loci by applying allele-specific editings. AsCRISPR is freely available at http://www.genemed.tech/ascrispr.