Abstract: The present invention contemplates allele-specific gene editing based on targeting a heterozygous single nucleotide polymorphism (SNP) in a protein coding sequence associated with a genetic disease. The data shown herein demonstrates that the outcome of such gene editing creates a nonesense mutation that results in a marked and selective reduction of mutant protein without affecting wild type protein expression. Expression of a single CRISPR-Cas9 nuclease in neurons generated a high frequency of mutations in the targeted HD allele that included both small insertion/deletion mutations and viral vector insertions. Thus, as disclosed herein, allele-specific targeting of InDel and insertion mutations to heterozygous coding SNPs provides a feasible approach to inactivate autosomal dominant mutations that cause genetic disease.

Abstract: Chemically modified crRNAs and tracrRNAs are provided. crRNAs and tracrRNAs with 5? and/or 3? conjugated moieties are provided. crRNAs and tracrRNAs with modifications in the repeat region of the crRNA or the anti-repeat region of the tracrRNA are provided. Methods of using the crRNAs and tracrRNAs for genome editing with a CRISPR nuclease and kits for performing the same are also provided.