Part Ⅰ: Mouse androgenetic haploid embryonic stem cells (AG-haESCs) can support full-term development of semi-cloned (SC) embryos upon injection into MⅡ oocytes and thus have potential applications in genetic modifications.However,the very low birth rate of SC pups limits practical use of this approach.Here,we show that AG-haESCs carrying deletions in H19-DMR and IG-DMR,designated as DKO-AG-haESCs,can efficiently support the generation of SC pups.Genetic manipulation of these DKO-AG-haESCs in vitro using CRISPR-Cas9 can produce SC mice carrying multiple modifications with high efficiency.Moreover,transfection of DKO-AG-haESCs with a constitutively expressed sgRNA library and Cas9 allows functional mutagenic screening.DKO-AG-haESCs are therefore an effective tool for the introduction of organism-wide mutations in mice in a single generation.