One gene (IL2rg)-KO rabbit embryos and newborn rabbits. (A) Sequenced mutations in the IL2rg gene in injected embryos. Deletions are indicated by dashes, insertions are indicated in blue and substitutions are indicated in pink. (B) Generation of IL2rg KO rabbits via the Cas9/gRNA system. Zygotes (n = 66) microinjected with 200 ng/μL of Cas9 mRNA and 20 ng/μL of gRNA for IL2rg were transferred to 5 recipient mothers, 3 of which gave birth to 8 live kits. (C) Detailed mutations of the IL2rg gene in the 8 KO founders. The number of founder KO rabbits is shown in the left column. (D) Picture of 26 days old IL2rg KO rabbits. (E) The thymus of IL2rg KO rabbits was obviously smaller than that from age-matched WT ones. In A and C, the WT sequence is shown at the top with the target sites in underline; the sizes of the deletions (-) or insertions (+) are shown in the right column. At least 8 TA-clones for each embryos or KO rabbit were used for sequencing to obtain detailed information of the mutation.