A snRNA:U6:96Ab (U6.2) promoter expresses dual gRNAs (dgRNAs) targeting the gene. The first gRNA was designed to target the first coding exon and the second gRNA was designed to target the last coding exon, ensuring that neither had any mismatches when compared against any of three genomes (the genomes of the line used for microinjection, S2R+ cells and the reference genome).