To introduce the deletion between Phosphatidylinositol 4-kinase alpha (Pi4ka) and DiGeorge syndrome critical region 2 (Dgcr2) on mouse chromosome 16, we designed a pair of sgRNAs on each target locus of Pi4ka intron 47 and Dgcr2 intron 4 and an ssODN to bridge two Cas9 cleavage sites directly (Fig. 1b). The gene discussed is PI4KA; the disease is Down syndrome.