Two gene-KO rabbits obtained by the Cas9/gRNA system in a single step. (A) Generation of 2 gene-KO (IL2rg/RAG1) rabbits via the Cas9/gRNA system. Zygotes (n = 67) were microinjected with 200 ng/μL of Cas9 mRNA, 20 ng/μL of gRNA for IL2rg and 20 ng/μL of gRNA for RAG1 and transferred into 5 recipient mothers, 2 of which gave birth to 5 live kits. (B) Detailed mutations of the IL2rg and RAG1 genes in the 5 KO founders. The number of founder KO rabbits is shown in the left column. For each gene, the WT sequence is shown at the top with the target sites in underline, deletions are indicated by dashes and insertions are indicated in blue, and the sizes of the deletions (-) or insertions (+) are shown in the right column.