Cytoplasmic injection of Cas9 mRNA and sgRNAs (5'-GAGAAGGGAAAATTTCTGG-3' and 5'-AGGGCAGAGTGATGTTGTC-3') into zygotes resulted in compound heterozygous F1 mice (from F0 founder crosses) and homozygous F2 mice (from F1 crosses). This allele contains a single T insertion. (J:226780)